High Availability Configuration Guide, Cisco IOS XE 17.x - Configuring Nonstop Forwarding [Cisco IOS XE 17]

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We are working to resolve the problem as quickly as possible.</p> </script> <script type="text/html" id="mobileSearchFooterTemplate"> <div id="mobileSearchFooter"> <button class="mobileSearch" title="Search in this Book"></button> <button class="closeFooter"><span></span><span></span></button> <div class="matches"> </div> </div> </script> </div> </div> <div class="row blowout narrow-wide-v2 flip visitedlinks"> <div class="col narrow-v2"> <div id="documentInfo"> <dl> <dt>Updated:</dt><dd> November 5, 2022</dd> </dl> </div> </div> <div id="chapterTitleDiv" class="col wide-v2 indent-at-xlarge">  <h2 class="chapter-title">Chapter: Configuring Nonstop Forwarding </h2> </div> </div> <div class="row blowout wide-narrow-v2 visitedlinks"> <div id="pageContentDiv" class="col wide-v2 indent-at-xlarge" role="main"> <div id="chapterToc" class="base-blowout"> <button><span></span>Chapter Contents</button> <div> <ul> <li><a href="#GUID-F6AD4C60-1C2C-4581-A2C5-BDCE0034625F">Configuring Nonstop Forwarding</a></li> <li><a href="#GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E">Prerequisites for Nonstop Forwarding</a></li> <li><a href="#GUID-930C0B6C-FF01-44E8-9FEA-C6D0E769C8D8">Restrictions for Nonstop Forwarding</a> <ul> <li><a href="#GUID-3FE0FFC5-F67D-42CD-B0CF-5FBBAA85ACF0">General Restrictions</a></li> <li><a href="#GUID-1CA8BA39-3D64-4735-A7F9-A7A39DEF2E1D">BGP NSF Restrictions</a></li> <li><a href="#GUID-CE0E561B-17A5-43A8-A3D3-BD50661A28AE">EIGRP NSF Restrictions</a></li> <li><a href="#GUID-A06F7B62-95B8-4DC7-84E8-85A268EBBA01">OSPF NSF Restrictions</a></li> </ul></li> <li><a href="#GUID-ABC26FEE-E0CC-4FCC-9D02-7D76E1A03594">Information About Nonstop Forwarding</a> <ul> <li><a href="#GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8">Nonstop Forwarding</a></li> <li><a href="#GUID-EC89C83D-FBC9-4DD8-908E-96CD3227208B">Cisco NSF Routing and Forwarding</a></li> <li><a href="#GUID-E8C73C05-5FBA-4D7C-A864-B7EC1855A9B7">Cisco Express Forwarding and NSF</a></li> <li><a href="#GUID-3FF82CF4-CDB1-4C42-8FC4-569B83155BCF">BGP NSF Operations</a></li> <li><a href="#GUID-CCDE4394-3390-4C7A-905F-D63D4939247E">EIGRP NSF Operations</a></li> <li><a href="#GUID-3FC93CEB-564F-40A0-8D76-8C26E08CACB6">IPv6 support for NSF Operations</a> <ul> <li><a href="#GUID-BEC37ED8-5AE0-4A49-BA4C-B9BBA06A3065">Nonstop Forwarding and Graceful Restart for MP-BGP IPv6 Address Family</a></li> <li><a href="#GUID-9F897034-EA06-4FB9-8E08-91F954C0E09B">Nonstop Forwarding for IPv6 RIP</a></li> <li><a href="#GUID-B75B97C9-3A7B-4C77-8492-14AF9BDF3CA1">Nonstop Forwarding for Static Routes</a></li> </ul></li> <li><a href="#GUID-53E2A6DF-3323-4CEC-B0BC-C186EBC4DFBD">IS-IS NSF Operations</a> <ul> <li><a href="#GUID-FA2B8F35-C603-42B1-BA15-DD8D8C249DC8">IETF IS-IS Configuration</a></li> <li><a href="#GUID-90EFF3DA-BF68-418D-95D0-C5D472380D0C">Cisco IS-IS Configuration</a></li> </ul></li> <li><a href="#GUID-C56A2BB8-2860-4EFD-9BA6-B314684F3126">NSF-OSPF Operations</a></li> </ul></li> <li><a href="#GUID-0EFE26FF-30FB-47C5-864F-8F02167AE305">How to Configure Nonstop Forwarding</a> <ul> <li><a href="#GUID-4AA08479-0F33-46A4-A3DF-72987758A27A">Configuring and Verifying BGP NSF</a></li> <li><a href="#GUID-05853C5E-3576-46F6-AD42-BD97DFC949A8">Configuring and Verifying EIGRP NSF</a></li> <li><a href="#GUID-AC860E95-F8EE-4ED5-8130-4F5B6406D520">Configuring NSF-OSPF</a> <ul> <li><a href="#GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD">Configuring Cisco NSF-OSPF</a></li> <li><a href="#GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9">Configuring IETF NSF-OSPF</a></li> </ul></li> <li><a href="#GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6">Configuring and Verifying IS-IS NSF</a></li> <li><a href="#GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF">Troubleshooting Nonstop Forwarding</a></li> </ul></li> <li><a href="#GUID-4103D75F-A60C-443F-B7E6-BF7A3CB98684">Configuration Examples for Nonstop Forwarding</a> <ul> <li><a href="#GUID-0F182D6B-ED73-4892-8754-2BA9845B7D68">Example NSF-Capable CEF</a></li> <li><a href="#GUID-0DCC9858-BFDE-4B09-B347-52CE02FDEA76">Example BGP NSF</a></li> <li><a href="#GUID-B2D2628D-4B8E-4F48-85F5-F554667C033B">Example: EIGRP NSF</a></li> <li><a href="#GUID-65684839-CAFD-498A-B70B-1D396AA1097A">Example: Configuring Cisco NSF-OSPF</a></li> <li><a href="#GUID-57D3DD5C-852B-4437-AB55-2A2665E81424">Example: Configuring IETF NSF-OSPF</a></li> <li><a href="#GUID-AC1C0F79-56EA-4B32-B63E-CFD00B66C277">Example IS-ISNSF</a></li> </ul></li> <li><a href="#GUID-F216276F-864E-4061-B4B5-9A67DE29D015">Additional References</a></li> <li><a href="#GUID-00848F77-D98A-45D5-986C-31F354790EB9">Feature Information for Nonstop Forwarding</a></li></ul> <button id="chapterToc-close">Close<span></span></button> </div> </div> <div id="chapterContent"> <h1 class="title topictitle1" id="GUID-F6AD4C60-1C2C-4581-A2C5-BDCE0034625F__GUID-642CDE94-66C3-4245-9BDF-635E582B6AD2">Configuring Nonstop Forwarding</h1> <section class="body conbody"> <p class="p"> This module describes how to configure Nonstop Forwarding (NSF) in Cisco software to minimize the amount of time a network is unavailable to its users following a switchover. The main objective of NSF is to continue forwarding IP packets following a Route Processor (RP) switchover. NSF is supported by the BGP, EIGRP, IPv6, IS-IS, and OSPF protocols for routing and by CEF for forwarding. </p> <p class="p"> The following terms are used throughout this document: </p> <ul class="ul" id="GUID-F6AD4C60-1C2C-4581-A2C5-BDCE0034625F__UL_8817B662F4754C68B4B62465C94FEA83"> <li class="li" id="GUID-F6AD4C60-1C2C-4581-A2C5-BDCE0034625F__LI_80368DAD19EB496586C04C97A182DFFF"> <p class="p"> NSF-aware device--A device that is running NSF-compatible software </p> </li> <li class="li" id="GUID-F6AD4C60-1C2C-4581-A2C5-BDCE0034625F__LI_C17E6D9394BE47C1B3FE59F0ACB5D322"> <p class="p"> NSF-capable device--A device that is configured to support NSF. NSF-capable devices can rebuild routing information from either NSF-aware or NSF-capable neighboring devices. </p> </li> </ul> </section>  <nav role="navigation" class="related-links"> <ul class="ullinks"> <li class="link ulchildlink"><a href="#GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E">Prerequisites for Nonstop Forwarding</a></li> <li class="link ulchildlink"><a href="#GUID-930C0B6C-FF01-44E8-9FEA-C6D0E769C8D8">Restrictions for Nonstop Forwarding</a></li> <li class="link ulchildlink"><a href="#GUID-ABC26FEE-E0CC-4FCC-9D02-7D76E1A03594">Information About Nonstop Forwarding</a></li> <li class="link ulchildlink"><a href="#GUID-0EFE26FF-30FB-47C5-864F-8F02167AE305">How to Configure Nonstop Forwarding</a></li> <li class="link ulchildlink"><a href="#GUID-4103D75F-A60C-443F-B7E6-BF7A3CB98684">Configuration Examples for Nonstop Forwarding</a></li> <li class="link ulchildlink"><a href="#GUID-F216276F-864E-4061-B4B5-9A67DE29D015">Additional References</a></li> <li class="link ulchildlink"><a href="#GUID-00848F77-D98A-45D5-986C-31F354790EB9">Feature Information for Nonstop Forwarding</a></li> </ul> </nav>  <article class="topic concept nested1 prerequisites" aria-labelledby="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__GUID-4F8C9367-B3FC-4109-9349-E1EB06207443" lang="en-US" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E"> <h2 class="title topictitle2" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__GUID-4F8C9367-B3FC-4109-9349-E1EB06207443">Prerequisites for Nonstop Forwarding</h2> <section class="body conbody"> <ul class="ul" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__UL_72F5D2DCEFD24FCFAB39C005471ECDF2"> <li class="li" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__LI_AFD4E007E2854BF9A6A3245C5E8994FD"> <p class="p"> The networking device that is to be configured for NSF must first be configured for SSO. For information, see the Configuring Stateful Switchover section. </p> </li> <li class="li" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__LI_2AC1C64F5FC54F8693A6B57B82308A0F"> <p class="p"> For Border Gateway Protocol (BGP) NSF, all neighboring devices must be NSF-aware and must be configured for BGP graceful restart. </p> </li> <li class="li" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__LI_7B1647BA56CF442B8F5F5B9A4820BB51"> <section class="p"> For Enhanced Interior Gateway Routing Protocol (EIGRP) NSF: <ul class="ul" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__UL_2B83AB4AB62E4907853500F4A235CFF1"> <li class="li" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__LI_2B56B1212200415DB57F2C7E2CE04FBE"> All neighboring devices must be NSF-capable or NSF-aware. </li> <li class="li" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__LI_3C242E68C0FB4A7790525C532DB5C170"> An NSF-aware device must be completely converged with the network before it can assist an NSF-capable device in an NSF restart operation. </li> </ul> </section> </li> <li class="li" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__LI_50392B162F074F59A781AECD2C72D094"> <p class="p"> For Internet Engineering Task Force (IETF) Intermediate System to Intermediate System (IS-IS), all neighboring devices must be NSF-aware. </p> </li> <li class="li" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__LI_666CB59C98E9432393B1432A3C446D02"> <p class="p"> For Open Shortest Path First (OSPF) NSF, all networking devices on the same network segment must be NSF-aware. </p> </li> <li class="li" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__LI_9AABDE03D351429CB2A32267C8356BFD"> <p class="p"> For IPv6 NSF, IPv6 must be enabled on your networking device. </p> </li> <li class="li" id="GUID-19AFD6C0-8BF2-462F-8681-B44278D84D8E__LI_339CBCB7675440AFA19821F2F35DD843"> <p class="p"> On platforms supporting the Route Switch Processor (RSP), and where the Cisco Express Forwarding (CEF) switching mode is configurable, configure distributed CEF (dCEF) switching mode using the <span><span class="keyword kwd">ip</span> <span class="keyword kwd">cef</span> <span class="keyword kwd">distributed</span> </span> command. </p> </li> </ul> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested1 restrictions" aria-labelledby="GUID-930C0B6C-FF01-44E8-9FEA-C6D0E769C8D8__GUID-AB7D12D2-8064-4EFA-A360-A02E7D17533C" lang="en-US" id="GUID-930C0B6C-FF01-44E8-9FEA-C6D0E769C8D8"> <h2 class="title topictitle2" id="GUID-930C0B6C-FF01-44E8-9FEA-C6D0E769C8D8__GUID-AB7D12D2-8064-4EFA-A360-A02E7D17533C">Restrictions for Nonstop Forwarding</h2> <section class="body conbody"></section>  <nav role="navigation" class="related-links"> <ul class="ullinks"> <li class="link ulchildlink"><a href="#GUID-3FE0FFC5-F67D-42CD-B0CF-5FBBAA85ACF0">General Restrictions</a></li> <li class="link ulchildlink"><a href="#GUID-1CA8BA39-3D64-4735-A7F9-A7A39DEF2E1D">BGP NSF Restrictions</a></li> <li class="link ulchildlink"><a href="#GUID-CE0E561B-17A5-43A8-A3D3-BD50661A28AE">EIGRP NSF Restrictions</a></li> <li class="link ulchildlink"><a href="#GUID-A06F7B62-95B8-4DC7-84E8-85A268EBBA01">OSPF NSF Restrictions</a></li> </ul> </nav>  <article class="topic concept nested2 restrictions" aria-labelledby="GUID-3FE0FFC5-F67D-42CD-B0CF-5FBBAA85ACF0__GUID-6608718C-45B7-4D45-BDBA-A32E3CCE1327" lang="en-US" id="GUID-3FE0FFC5-F67D-42CD-B0CF-5FBBAA85ACF0"> <h3 class="title topictitle3" id="GUID-3FE0FFC5-F67D-42CD-B0CF-5FBBAA85ACF0__GUID-6608718C-45B7-4D45-BDBA-A32E3CCE1327">General Restrictions</h3> <section class="body conbody"> <p class="p"> NSF capability is not enabled by default for OSPF, ISIS, or BGP. NSF capability is enabled by default for EIGRP only. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested2 restrictions" aria-labelledby="GUID-1CA8BA39-3D64-4735-A7F9-A7A39DEF2E1D__GUID-E05FB23F-98FC-4EAB-A9F1-D587B1BB6551" lang="en-US" id="GUID-1CA8BA39-3D64-4735-A7F9-A7A39DEF2E1D"> <h3 class="title topictitle3" id="GUID-1CA8BA39-3D64-4735-A7F9-A7A39DEF2E1D__GUID-E05FB23F-98FC-4EAB-A9F1-D587B1BB6551">BGP NSF Restrictions</h3> <section class="body conbody"> <ul class="ul"> <li class="li"> <p class="p"> BGP support in NSF requires that neighbor networking devices be NSF-aware. If an NSF-capable device discovers that a particular BGP neighbor does not have graceful restart capability, it will not establish an NSF-capable session with that neighbor. All other neighbors that have graceful restart capability will continue to have NSF-capable sessions with this NSF-capable networking device. </p> </li> <li class="li"> <p class="p"> All devices must be configured with the same type of NSF helper mode, either IETF graceful restart or Cisco NSF. </p> </li> </ul> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested2 restrictions" aria-labelledby="GUID-CE0E561B-17A5-43A8-A3D3-BD50661A28AE__GUID-C7A8E681-F945-421E-A889-34515C5BB9C0" lang="en-US" id="GUID-CE0E561B-17A5-43A8-A3D3-BD50661A28AE"> <h3 class="title topictitle3" id="GUID-CE0E561B-17A5-43A8-A3D3-BD50661A28AE__GUID-C7A8E681-F945-421E-A889-34515C5BB9C0">EIGRP NSF Restrictions</h3> <section class="body conbody"> <ul class="ul"> <li class="li"> <p class="p"> An NSF-aware device cannot support two NSF-capable peers performing an NSF restart operation at the same time. However, both neighbors will reestablish peering sessions after the NSF restart operation is complete. </p> </li> <li class="li"> <p class="p"> Distributed platforms that run a supporting version of Cisco software can support full NSF capabilities. These devices can perform a restart operation and can support other NSF capable peers. </p> </li> <li class="li"> <p class="p"> Single processor platforms that run a supporting version of Cisco software support only NSF awareness. These devices maintain adjacency and hold known routes for the NSF-capable neighbor until it signals that it is ready for the NSF-aware device to send its topology table or the route-hold timer expires. </p> </li> </ul> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested2 restrictions" aria-labelledby="GUID-A06F7B62-95B8-4DC7-84E8-85A268EBBA01__GUID-1DF8FD12-CF60-4E8D-AACC-206105298C8D" lang="en-US" id="GUID-A06F7B62-95B8-4DC7-84E8-85A268EBBA01"> <h3 class="title topictitle3" id="GUID-A06F7B62-95B8-4DC7-84E8-85A268EBBA01__GUID-1DF8FD12-CF60-4E8D-AACC-206105298C8D">OSPF NSF Restrictions</h3> <section class="body conbody"> <ul class="ul" id="GUID-A06F7B62-95B8-4DC7-84E8-85A268EBBA01__GUID-27433700-F314-49EC-9AE3-30C030633AEA"> <li class="li"> <p class="p"> OSPF NSF for virtual links is not supported. </p> </li> <li class="li"> <p class="p"> OSPF NSF for sham links is not supported. </p> </li> <li class="li"> <p class="p"> OSPF NSF supports NSF/SSO for IPv4 traffic only. </p> </li> <li class="li"> <p class="p"> OSPFv3 is not supported with NSF/SSO. Only OSPFv2 is supported with NSF/SSO. </p> </li> <li class="li"> <p class="p"> All neighbor networking devices must be NSF-aware. If an NSF-capable device discovers that it has non-NSF-aware neighbors on a particular network segment, it will disable NSF capabilities for that segment. Other network segments composed entirely of NSF-capable or NSF-aware devices will continue to provide NSF capabilities. </p> </li> <li class="li"> <p class="p"> You can configure strict link state advertisement (LSA) checking on both NSF-aware and NSF-capable devices; however, it is effective only when the device is in helper mode. </p> </li> </ul> </section>  <nav role="navigation" class="related-links"></nav>  </article> </article> <article class="topic concept nested1" aria-labelledby="GUID-ABC26FEE-E0CC-4FCC-9D02-7D76E1A03594__GUID-CCF6F371-588A-4B97-8367-64A5CC649FE4" lang="en-US" id="GUID-ABC26FEE-E0CC-4FCC-9D02-7D76E1A03594"> <h2 class="title topictitle2" id="GUID-ABC26FEE-E0CC-4FCC-9D02-7D76E1A03594__GUID-CCF6F371-588A-4B97-8367-64A5CC649FE4">Information About Nonstop Forwarding</h2> <section class="body conbody"></section>  <nav role="navigation" class="related-links"> <ul class="ullinks"> <li class="link ulchildlink"><a href="#GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8">Nonstop Forwarding</a></li> <li class="link ulchildlink"><a href="#GUID-EC89C83D-FBC9-4DD8-908E-96CD3227208B">Cisco NSF Routing and Forwarding</a></li> <li class="link ulchildlink"><a href="#GUID-E8C73C05-5FBA-4D7C-A864-B7EC1855A9B7">Cisco Express Forwarding and NSF</a></li> <li class="link ulchildlink"><a href="#GUID-3FF82CF4-CDB1-4C42-8FC4-569B83155BCF">BGP NSF Operations</a></li> <li class="link ulchildlink"><a href="#GUID-CCDE4394-3390-4C7A-905F-D63D4939247E">EIGRP NSF Operations</a></li> <li class="link ulchildlink"><a href="#GUID-3FC93CEB-564F-40A0-8D76-8C26E08CACB6">IPv6 support for NSF Operations</a></li> <li class="link ulchildlink"><a href="#GUID-53E2A6DF-3323-4CEC-B0BC-C186EBC4DFBD">IS-IS NSF Operations</a></li> <li class="link ulchildlink"><a href="#GUID-C56A2BB8-2860-4EFD-9BA6-B314684F3126">NSF-OSPF Operations</a></li> </ul> </nav>  <article class="topic concept nested2" aria-labelledby="GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8__GUID-9433A099-89AE-4CC5-9E5F-0A982F4B7E47" lang="en-US" id="GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8"> <h3 class="title topictitle3" id="GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8__GUID-9433A099-89AE-4CC5-9E5F-0A982F4B7E47">Nonstop Forwarding</h3> <section class="body conbody"> <table class="olh_note" border="0" role="note"> <tr> <td width="1%" class="olh_note" role="heading" border="0"><img src="https://www.cisco.com/content/dam/en/us/td/i/templates/note.gif"><br><p><b>Note</b></p> </td> <td border="0" class="olh_note"> <section class="note__content"> <hr> <p class="p"> In the following content, the term Route Processor (RP) is used to describe the route processing engine on all networking devices, regardless of the platform designation, unless otherwise noted. </p> <hr> </section> </td> </tr> </table> <p class="p"> NSF works with the SSO feature in Cisco software to minimize the amount of time a network is unavailable to its users following a switchover. The main objective of NSF is to continue forwarding IP packets following an RP switchover. </p> <p class="p"> Usually, when a networking device restarts, all routing peers of that device detect that the device went down and then came back up. This transition results in what is called a routing flap, which could spread across multiple routing domains. Routing flaps caused by routing restarts create routing instabilities, which are detrimental to the overall network performance. NSF helps to suppress routing flaps in SSO-enabled devices, thus reducing network instability. </p> <p class="p"> NSF allows for the forwarding of data packets to continue along known routes while the routing protocol information is being restored following a switchover. With NSF, peer networking devices do not experience routing flaps. Data traffic is forwarded through intelligent line cards or dual forwarding processors (FPs) while the standby RP assumes control from the failed active RP during a switchover. The ability of line cards and FPs to remain up through a switchover and to be kept current with the Forwarding Information Base (FIB) on the active RP is key to NSF operation. </p> <p class="p"> The NSF feature provides the following benefits: </p> <ul class="ul" id="GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8__GUID-08CAF8B0-B19D-450A-BF11-7ADE31948AEE"> <li class="li" id="GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8__LI_E2AED67BED9646978B5C0749F927381C"> <p class="p"> Improved network availability—NSF continues forwarding network traffic and application state information so that user session information is maintained after a switchover. </p> </li> <li class="li" id="GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8__LI_E2ED2915682449038EA3450EDBC51806"> <p class="p"> Overall network stability—Network stability may be improved with the reduction in the number of route flaps that had been created when devices in the network failed and lost their routing tables. </p> </li> <li class="li" id="GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8__LI_513624F9DF0C4E7F88B746D4FEA7FA2A"> <p class="p"> Neighboring devices do not detect link flapping—Because the interfaces remain up across a switchover, neighboring devices do not detect a link flap (that is, the link does not go down and come back up). </p> </li> <li class="li" id="GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8__LI_F76C35E96FD14C2CBF7BAC28677BFC29"> <p class="p"> Prevention of routing flaps—Because SSO continues forwarding network traffic in the event of a switchover, routing flaps are avoided. </p> </li> <li class="li" id="GUID-2FB4DCBA-1264-4265-9D8C-C0A27D41B4C8__LI_5DE1A2D09F1C4939B94BC61E94B75641"> <p class="p"> No loss of user sessions—User sessions established prior to the switchover are maintained. </p> </li> </ul> <p class="p"> NSF always runs together with SSO. SSO supported protocols and applications must be high-availability (HA)-aware. A feature or protocol is HA-aware if it maintains, either partially or completely, undisturbed operation during an RP switchover. For some HA-aware protocols and applications, state information is synchronized from the active to the standby processor. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested2" aria-labelledby="GUID-EC89C83D-FBC9-4DD8-908E-96CD3227208B__GUID-F9DC153F-DCD1-4112-83E0-B45BDA8B74FC" lang="en-US" id="GUID-EC89C83D-FBC9-4DD8-908E-96CD3227208B"> <h3 class="title topictitle3" id="GUID-EC89C83D-FBC9-4DD8-908E-96CD3227208B__GUID-F9DC153F-DCD1-4112-83E0-B45BDA8B74FC">Cisco NSF Routing and Forwarding</h3> <section class="body conbody"> <p class="p"> Cisco NSF is supported by the BGP, EIGRP, IPv6, IS-IS, and OSPF protocols for routing and by CEF for forwarding. Of the routing protocols, BGP, EIGRP, IPv6, IS-IS, and OSPF have been enhanced with NSF-capability and awareness, which means that devices running these protocols can detect a switchover and take the necessary actions to continue forwarding network traffic and to recover route information from the peer devices. The IS-IS protocol can be configured to use state information that has been synchronized between the active and the standby RP to recover route information following a switchover instead of information received from peer devices. </p> <p class="p"> Each protocol depends on CEF to continue forwarding packets during switchover while the routing protocols rebuild the Routing Information Base (RIB) tables. Once the routing protocols have converged, CEF updates the FIB table and removes stale route entries. CEF, in turn, updates the line cards with the new FIB information. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested2" aria-labelledby="GUID-E8C73C05-5FBA-4D7C-A864-B7EC1855A9B7__GUID-94E1BD26-9660-4F44-900F-2F59B99FFF31" lang="en-US" id="GUID-E8C73C05-5FBA-4D7C-A864-B7EC1855A9B7"> <h3 class="title topictitle3" id="GUID-E8C73C05-5FBA-4D7C-A864-B7EC1855A9B7__GUID-94E1BD26-9660-4F44-900F-2F59B99FFF31">Cisco Express Forwarding and NSF</h3> <section class="body conbody"> <p class="p"> A key element of NSF is packet forwarding. In a Cisco networking device, packet forwarding is provided by CEF. CEF maintains the FIB, and uses the FIB information that was current at the time of the switchover to continue forwarding packets during a switchover. This feature reduces traffic interruption during the switchover. </p> <p class="p"> During normal NSF operation, CEF on the active RP synchronizes its current FIB and adjacency databases with the FIB and adjacency databases on the standby RP. Upon switchover of the active RP, the standby RP initially has FIB and adjacency databases that are mirror images of those that were current on the active RP. For platforms with intelligent line cards, the line cards will maintain the current forwarding information over a switchover; for platforms with forwarding engines, CEF will keep the forwarding engine on the standby RP current with changes that are sent to it by CEF on the active RP. In this way, the line cards or forwarding engines will be able to continue forwarding after a switchover as soon as the interfaces and a data path are available. </p> <p class="p"> As the routing protocols start to repopulate the RIB on a prefix-by-prefix basis, the updates in turn cause prefix-by-prefix updates to CEF, which it uses to update the FIB and adjacency databases. Existing and new entries will receive the new version (“epoch”) number, indicating that they have been refreshed. The forwarding information is updated on the line cards or forwarding engine during convergence. The RP signals when the RIB has converged. The software removes all FIB and adjacency entries that have an epoch older than the current switchover epoch. The FIB now represents the newest routing protocol forwarding information. </p> <p class="p"> The routing protocols run only on the active RP, and they receive routing updates from their neighbor devices. Routing protocols do not run on the standby RP. Following a switchover, the routing protocols request that the NSF-aware neighbor devices send state information to help rebuild the routing tables. Alternately, the IS-IS protocol can be configured to synchronize state information from the active to the standby RP to help rebuild the routing table on the NSF-capable device in environments where neighbor devices are not NSF-aware. </p> <p class="p"> For NSF operation, the routing protocols depend on CEF to continue forwarding packets while the routing protocols rebuild the routing information. The CEF NSF feature operates by default while the networking device is running in SSO mode. No configuration is necessary. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested2" aria-labelledby="GUID-3FF82CF4-CDB1-4C42-8FC4-569B83155BCF__GUID-AEC4CEA4-F0E3-48F6-A9C6-B38BED555548" lang="en-US" id="GUID-3FF82CF4-CDB1-4C42-8FC4-569B83155BCF"> <h3 class="title topictitle3" id="GUID-3FF82CF4-CDB1-4C42-8FC4-569B83155BCF__GUID-AEC4CEA4-F0E3-48F6-A9C6-B38BED555548">BGP NSF Operations</h3> <section class="body conbody"> <p class="p"> When a NSF-capable device begins a BGP session with a BGP peer, it sends an OPEN message to the peer. Included in the message is a declaration that the NSF-capable device has “graceful restart capability.” Graceful restart is the mechanism by which BGP routing peers avoid a routing flap following a switchover. If the BGP peer has received this capability, it is aware that the device sending the message is NSF-capable. Both the NSF-capable device and its BGP peers need to exchange the graceful restart capability in their OPEN messages, at the time of session establishment. If both the peers do not exchange the graceful restart capability, the session will not be graceful restart capable. </p> <p class="p"> If the BGP session is lost during the RP switchover, the NSF-aware BGP peer marks all the routes associated with the NSF-capable device as stale; however, it continues to use these routes to make forwarding decisions for a set period of time. This functionality means that no packets are lost while the newly active RP is waiting for convergence of the routing information with the BGP peers. </p> <p class="p"> After an RP switchover occurs, the NSF-capable device reestablishes the session with the BGP peer. In establishing the new session, it sends a new graceful restart message that identifies the NSF-capable device as having restarted. </p> <p class="p"> At this point, the routing information is exchanged between the two BGP peers. Once this exchange is complete, the NSF-capable device uses the routing information to update the RIB and the FIB with the new forwarding information. The NSF-aware device uses the network information to remove stale routes from its BGP table. Following that, the BGP protocol is fully converged. </p> <p class="p"> If a BGP peer does not support the graceful restart capability, it will ignore the graceful-restart capability in an OPEN message but will establish a BGP session with the NSF-capable device. This function will allow interoperability with non-NSF-aware BGP peers (and without NSF functionality), but the BGP session with non-NSF-aware BGP peers will not be graceful restart-capable. </p> <p class="p"> BGP support in NSF requires that neighbor networking devices be NSF-aware; that is, the devices must have the graceful restart capability and advertise that capability in their OPEN message during session establishment. If an NSF-capable device discovers that a particular BGP neighbor does not have graceful restart capability, it will not establish an NSF-capable session with that neighbor. All other neighbors that have graceful restart capability will continue to have NSF-capable sessions with this NSF-capable networking device. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested2" aria-labelledby="GUID-CCDE4394-3390-4C7A-905F-D63D4939247E__GUID-9C77FDB9-9C3A-4FBA-914A-194155726DEA" lang="en-US" id="GUID-CCDE4394-3390-4C7A-905F-D63D4939247E"> <h3 class="title topictitle3" id="GUID-CCDE4394-3390-4C7A-905F-D63D4939247E__GUID-9C77FDB9-9C3A-4FBA-914A-194155726DEA">EIGRP NSF Operations</h3> <section class="body conbody"> <p class="p">Cisco NSF is supported by the EIGRP protocol for routing and by CEF for forwarding. EIGRP depends on CEF to continue forwarding packets during switchover while the routing protocols rebuild the Routing Information Base (RIB) tables. Once the routing protocols have converged, CEF updates the FIB table and removes stale route entries. CEF, in turn, updates the line cards with the new FIB information. </p> <p class="p"> EIGRP nonstop forwarding (NSF) capabilities are exchanged by EIGRP peers in hello packets. The NSF-capable device notifies its neighbors that an NSF restart operation has started by setting the restart (RS) bit in a hello packet. When an NSF-aware device receives notification from an NSF-capable neighbor that an NSF-restart operation is in progress, the NSF-capable and NSF-aware devices immediately exchange their topology tables. The NSF-aware device sends an end-of-table (EOT) update packet when the transmission of its topology table is complete. The NSF-aware device then performs the following actions to assist the NSF-capable device: </p> <ul class="ul" id="GUID-CCDE4394-3390-4C7A-905F-D63D4939247E__GUID-123329A0-F6D9-4B7B-9565-17F3E3353A91"> <li class="li" id="GUID-CCDE4394-3390-4C7A-905F-D63D4939247E__LI_319072CE45E442A38ABCDEF3DAD3460C"> <p class="p"> The EIGRP hello hold timer is expired to reduce the time interval set for hello packet generation and transmission. This allows the NSF-aware device to reply to the NSF-capable device more quickly reducing the amount of time required for the NSF-capable device to rediscover neighbors and rebuild the topology table. </p> </li> <li class="li" id="GUID-CCDE4394-3390-4C7A-905F-D63D4939247E__LI_10FD462D990F4B2492E27ED0E742BB04"> <p class="p"> The route-hold timer is started. This timer is used to set the period of time that the NSF-aware device will hold known routes for the NSF-capable neighbor. </p> </li> <li class="li" id="GUID-CCDE4394-3390-4C7A-905F-D63D4939247E__LI_E2FBDCD49C7A4911B7EFC312D8A3D0AC"> <p class="p"> The NSF-aware device notes in the peer list that the NSF-capable neighbor is restarting, maintains adjacency, and holds known routes for the NSF-capable neighbor until the neighbor signals that it is ready for the NSF-aware device to send its topology table or the route-hold timer expires. If the route-hold timer expires on the NSF-aware device, the NSF-aware device will discard held routes and treat the NSF-capable device as a new device joining the network and reestablishing adjacency accordingly. </p> </li> <li class="li" id="GUID-CCDE4394-3390-4C7A-905F-D63D4939247E__LI_E450BB62ECD647448F8F807714982622"> <p class="p"> The NSF-aware device will continue to send queries to the NSF-capable device that is still converging after switchover, effectively extending the time before a stuck-in-active (SIA) condition can occur. </p> </li> </ul> <p class="p"> When the switchover operation is complete, the NSF-capable device notifies its neighbors that it has reconverged and has received all of their topology tables by sending an EOT update packet to the assisting devices. The NSF-capable device then returns to normal operation. The NSF-aware device will look for alternate paths (go active) for any routes that are not refreshed by the NSF-capable (restarting device). The NSF-aware device will then return to normal operation. If all paths are refreshed by the NSF-capable device, the NSF-aware device will immediately return to normal operation. </p> <p class="p"> NSF-aware devices are completely compatible with non-NSF-aware or non-NSF-capable neighbors in an EIGRP network. A non-NSF-aware neighbor will ignore NSF capabilities and reset adjacencies and otherwise maintain the peering sessions normally. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested2" aria-labelledby="GUID-3FC93CEB-564F-40A0-8D76-8C26E08CACB6__GUID-6F3403CD-5AAD-408C-B3F6-5AC5E215546B" lang="en-US" id="GUID-3FC93CEB-564F-40A0-8D76-8C26E08CACB6"> <h3 class="title topictitle3" id="GUID-3FC93CEB-564F-40A0-8D76-8C26E08CACB6__GUID-6F3403CD-5AAD-408C-B3F6-5AC5E215546B">IPv6 support for NSF Operations</h3> <section class="body conbody"></section>  <nav role="navigation" class="related-links"> <ul class="ullinks"> <li class="link ulchildlink"><a href="#GUID-BEC37ED8-5AE0-4A49-BA4C-B9BBA06A3065">Nonstop Forwarding and Graceful Restart for MP-BGP IPv6 Address Family</a></li> <li class="link ulchildlink"><a href="#GUID-9F897034-EA06-4FB9-8E08-91F954C0E09B">Nonstop Forwarding for IPv6 RIP</a></li> <li class="link ulchildlink"><a href="#GUID-B75B97C9-3A7B-4C77-8492-14AF9BDF3CA1">Nonstop Forwarding for Static Routes</a></li> </ul> </nav>  <article class="topic concept nested3" aria-labelledby="GUID-BEC37ED8-5AE0-4A49-BA4C-B9BBA06A3065__GUID-0CF19287-B537-46F1-94F9-D14D916156D3" lang="en-US" id="GUID-BEC37ED8-5AE0-4A49-BA4C-B9BBA06A3065"> <h4 class="title topictitle4" id="GUID-BEC37ED8-5AE0-4A49-BA4C-B9BBA06A3065__GUID-0CF19287-B537-46F1-94F9-D14D916156D3">Nonstop Forwarding and Graceful Restart for MP-BGP IPv6 Address Family</h4> <section class="body conbody"> <p class="p"> The graceful restart capability is supported for IPv6 BGP unicast, multicast, and VPNv6 address families, enabling Cisco NSF functionality for BGP IPv6. The BGP graceful restart capability allows the BGP routing table to be recovered from peers without keeping the TCP state. </p> <p class="p"> NSF continues forwarding packets while routing protocols converge, therefore avoiding a route flap on switchover. Forwarding is maintained by synchronizing the FIB between the active and standby RP. On switchover, forwarding is maintained using the FIB. The RIB is not kept synchronized; therefore, the RIB is empty on switchover. The RIB is repopulated by the routing protocols and subsequently informs the FIB about RIB convergence by using the NSF_RIB_CONVERGED registry call. The FIB tables are updated from the RIB, removing any stale entries. The RIB starts a fail-safe timer during RP switchover, in case the routing protocols fail to notify the RIB of convergence. </p> <p class="p"> The Cisco BGP address family identifier (AFI) model is modular and scalable, and supports multiple AFIs and subsequent address family identifier (SAFI) configurations. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested3" aria-labelledby="GUID-9F897034-EA06-4FB9-8E08-91F954C0E09B__GUID-DD18A26F-33AF-4E8F-A4E5-7AB60FB6567C" lang="en-US" id="GUID-9F897034-EA06-4FB9-8E08-91F954C0E09B"> <h4 class="title topictitle4" id="GUID-9F897034-EA06-4FB9-8E08-91F954C0E09B__GUID-DD18A26F-33AF-4E8F-A4E5-7AB60FB6567C">Nonstop Forwarding for IPv6 RIP</h4> <section class="body conbody"> <p class="p"> RIP registers as an IPv6 NSF client. Doing so has the benefit of using RIP routes installed in the Cisco Express Forwarding table until RIP has converged on the standby. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested3" aria-labelledby="GUID-B75B97C9-3A7B-4C77-8492-14AF9BDF3CA1__GUID-F6D8B8D4-117A-48ED-A10A-DDC59D27D5AC" lang="en-US" id="GUID-B75B97C9-3A7B-4C77-8492-14AF9BDF3CA1"> <h4 class="title topictitle4" id="GUID-B75B97C9-3A7B-4C77-8492-14AF9BDF3CA1__GUID-F6D8B8D4-117A-48ED-A10A-DDC59D27D5AC">Nonstop Forwarding for Static Routes</h4> <section class="body conbody"> <p class="p"> Cisco NSF supports IPv6 static routes. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> </article> <article class="topic concept nested2" aria-labelledby="GUID-53E2A6DF-3323-4CEC-B0BC-C186EBC4DFBD__GUID-5E867125-648D-492D-8CB7-AD8F0351F822" lang="en-US" id="GUID-53E2A6DF-3323-4CEC-B0BC-C186EBC4DFBD"> <h3 class="title topictitle3" id="GUID-53E2A6DF-3323-4CEC-B0BC-C186EBC4DFBD__GUID-5E867125-648D-492D-8CB7-AD8F0351F822">IS-IS NSF Operations</h3> <section class="body conbody"> <p class="p"> When an IS-IS NSF-capable device performs an RP switchover, it must perform two tasks in order to resynchronize its Link State Database with its IS-IS neighbors. First, it must relearn the available IS-IS neighbors on the network without causing a reset of the neighbor relationship. Second, it must reacquire the contents of the Link State Database for the network. </p> <p class="p"> The IS-IS NSF feature offers two options when configuring NSF: </p> <ul class="ul" id="GUID-53E2A6DF-3323-4CEC-B0BC-C186EBC4DFBD__UL_9B547E92FAD542A9B70553882903EB1A"> <li class="li" id="GUID-53E2A6DF-3323-4CEC-B0BC-C186EBC4DFBD__LI_4F5AD213B3CA46D7BE6DB44889FB35F9"> <p class="p"> IETF IS-IS </p> </li> <li class="li" id="GUID-53E2A6DF-3323-4CEC-B0BC-C186EBC4DFBD__LI_4F51D9F3967B4CEA87EB8A2558FB0FF5"> <p class="p"> Cisco IS-IS </p> </li> </ul> <p class="p"> If neighbor devices on a network segment are NSF-aware, meaning that neighbor devices are running a software version that supports the IETF Internet draft for device restartability, they will assist an IETF NSF device that is restarting. With IETF, neighbor devices provide adjacency and link-state information to help rebuild the routing information following a switchover. A benefit of IETF IS-IS configuration is operation between peer devices based on a proposed standard. </p> <p class="p"> If you configure IETF on the networking device, but neighbor devices are not IETF-compatible, NSF will cancel following a switchover. </p> <p class="p"> If the neighbor devices on a network segment are not NSF-aware, you must use the Cisco configuration option. The Cisco IS-IS configuration transfers both protocol adjacency and link-state information from the active to the standby RP. A benefit of Cisco configuration is that it does not rely on NSF-aware neighbors. </p> </section>  <nav role="navigation" class="related-links"> <ul class="ullinks"> <li class="link ulchildlink"><a href="#GUID-FA2B8F35-C603-42B1-BA15-DD8D8C249DC8">IETF IS-IS Configuration</a></li> <li class="link ulchildlink"><a href="#GUID-90EFF3DA-BF68-418D-95D0-C5D472380D0C">Cisco IS-IS Configuration</a></li> </ul> </nav>  <article class="topic concept nested3" aria-labelledby="GUID-FA2B8F35-C603-42B1-BA15-DD8D8C249DC8__GUID-52E0ED30-F49E-4059-A4B5-4E3F5C5AF241" lang="en-US" id="GUID-FA2B8F35-C603-42B1-BA15-DD8D8C249DC8"> <h4 class="title topictitle4" id="GUID-FA2B8F35-C603-42B1-BA15-DD8D8C249DC8__GUID-52E0ED30-F49E-4059-A4B5-4E3F5C5AF241">IETF IS-IS Configuration</h4> <section class="body conbody"> <p class="p"> With the IETF IS-IS configuration, the NSF-capable device sends IS-IS NSF restart requests to neighboring NSF-aware devices as quickly as possible after an RP switchover. Neighbor networking devices recognize this restart request as a cue that the neighbor relationship with this device should not be reset, but that they should initiate database resynchronization with the restarting device. As the restarting device receives restart request responses from devices on the network, it can begin to rebuild its neighbor list. </p> <p class="p"> Once this exchange is complete, the NSF-capable device uses the link-state information to remove stale routes, update the RIB, and update the FIB with the new forwarding information. IS-IS is then fully converged. </p> <p class="p"> The switchover from one RP to the other happens within seconds. IS-IS reestablishes its routing table and resynchronizes with the network within a few additional seconds. At this point, IS-IS waits for a specified interval before it will attempt a second NSF restart. During this time, the new standby RP will boot up and synchronize its configuration with the active RP. The IS-IS NSF operation waits for a specified interval to ensure that connections are stable before attempting another restart of IS-IS NSF. This functionality prevents IS-IS from attempting back-to-back NSF restarts with stale information. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested3" aria-labelledby="GUID-90EFF3DA-BF68-418D-95D0-C5D472380D0C__GUID-8B602617-0343-44A7-9030-70B1B6B49F95" lang="en-US" id="GUID-90EFF3DA-BF68-418D-95D0-C5D472380D0C"> <h4 class="title topictitle4" id="GUID-90EFF3DA-BF68-418D-95D0-C5D472380D0C__GUID-8B602617-0343-44A7-9030-70B1B6B49F95">Cisco IS-IS Configuration</h4> <section class="body conbody"> <p class="p"> With the Cisco configuration option, full adjacency and link-state packet (LSP) information is saved, or “checkpointed,” to the standby RP. Following a switchover, the newly active RP maintains its adjacencies using the checkpointed data, and can quickly rebuild its routing tables. </p> <p class="p"> The switchover from one RP to the other happens within seconds. IS-IS reestablishes its routing table and resynchronizes with the network within a few additional seconds. At this point, IS-IS waits for a specified interval before it will attempt a second NSF restart. During this time, the new standby RP will boot up and synchronize its configuration with the active RP. Once this synchronization is completed, IS-IS adjacency and LSP data is checkpointed to the standby RP; however, a new NSF restart will not be attempted by IS-IS until the interval time expires. This functionality prevents IS-IS from attempting back-to-back NSF restarts. IS-IS NSF provides a command to extend the wait time for interfaces that, for whatever reason, do not come up in a timely fashion. </p> <p class="p"> Following a switchover, Cisco IS-IS NSF has complete neighbor adjacency and LSP information; however, it must wait for all interfaces that had adjacencies prior to the switchover to come up. If an interface does not come up within the allocated interface wait time, the routes learned from these neighbor devices are not considered in routing table recalculation. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> </article> <article class="topic concept nested2" aria-labelledby="GUID-C56A2BB8-2860-4EFD-9BA6-B314684F3126__GUID-C4ADE9F7-3163-4069-B29F-7AD9FFE61FC8" lang="en-US" id="GUID-C56A2BB8-2860-4EFD-9BA6-B314684F3126"> <h3 class="title topictitle3" id="GUID-C56A2BB8-2860-4EFD-9BA6-B314684F3126__GUID-C4ADE9F7-3163-4069-B29F-7AD9FFE61FC8">NSF-OSPF Operations</h3> <section class="body conbody"> <p class="p"> For Cisco Nonstop Forwarding (NSF), the Open Shortest Path First (OSPF) routing protocol has been enhanced to support high availability (HA) features in Stateful Switchover (SSO). Before an OSPF NSF-capable device can perform a Route Processor (RP) switchover, the device must be aware of the available OSPF neighbors on the network without resetting the neighbor relationship, and the device must acquire the contents of the link state database for the network. The NSF-capable device sends an OSPF NSF signal to neighboring NSF-aware devices to notify the devices that the neighbor relationship with the sending device must not be reset. The NSF-capable device uses the signals that it receives from other devices on the network to rebuild its neighbor list. </p> <p class="p"> The NSF-capable device synchronizes its database with all the NSF-aware neighbors on its neighbor list. After all neighbors exchange routing information, the NSF-capable device uses the routing information to remove stale routes and update the routing information base (RIB) and the forwarding information base (FIB) with the new forwarding information. The OSPF protocols are then fully converged. </p> <p class="p"> Prior to RFC 3623, Cisco implemented the proprietary Cisco NSF. The RFC 3623 Graceful OSPF Restart feature supports IETF NSF for OSPF processes in multivendor networks. The following are NSF device modes of operation common to Cisco and IETF NSF implementations: </p> <ul class="ul" id="GUID-C56A2BB8-2860-4EFD-9BA6-B314684F3126__GUID-9F099D00-DFF5-4AEE-91C0-CBDB543490BE"> <li class="li" id="GUID-C56A2BB8-2860-4EFD-9BA6-B314684F3126__LI_240AE88A24454EE0979A3F61D25F579E"> <p class="p"> Restarting mode—In this mode, the OSPF device performs nonstop forwarding recovery because of an RP switchover. </p> </li> <li class="li" id="GUID-C56A2BB8-2860-4EFD-9BA6-B314684F3126__LI_704BE23128DA45A9A897F4C0F0EF4306"> <p class="p"> Helper mode—Also known as NSF-awareness mode. In this mode, the neighboring device is in the restarting state and helps in NSF recovery. </p> </li> </ul> <p class="p"> The strict link state advertisement (LSA) checking feature allows a helper device to terminate the graceful restart process if the device detects a changed LSA that would cause flooding during the graceful restart process. Strict LSA checking is disabled by default. You can enable strict LSA checking when there is a change to an LSA that would be flooded to the restarting device. </p> </section>  <nav role="navigation" class="related-links"></nav>  </article> </article> <article class="topic concept nested1" aria-labelledby="GUID-0EFE26FF-30FB-47C5-864F-8F02167AE305__GUID-BC476634-0F8B-4C42-9474-7691C7FA8845" lang="en-US" id="GUID-0EFE26FF-30FB-47C5-864F-8F02167AE305"> <h2 class="title topictitle2" id="GUID-0EFE26FF-30FB-47C5-864F-8F02167AE305__GUID-BC476634-0F8B-4C42-9474-7691C7FA8845">How to Configure Nonstop Forwarding</h2> <section class="body conbody"></section>  <nav role="navigation" class="related-links"> <ul class="ullinks"> <li class="link ulchildlink"><a href="#GUID-4AA08479-0F33-46A4-A3DF-72987758A27A">Configuring and Verifying BGP NSF</a></li> <li class="link ulchildlink"><a href="#GUID-05853C5E-3576-46F6-AD42-BD97DFC949A8">Configuring and Verifying EIGRP NSF</a></li> <li class="link ulchildlink"><a href="#GUID-AC860E95-F8EE-4ED5-8130-4F5B6406D520">Configuring NSF-OSPF</a></li> <li class="link ulchildlink"><a href="#GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6">Configuring and Verifying IS-IS NSF</a></li> <li class="link ulchildlink"><a href="#GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF">Troubleshooting Nonstop Forwarding</a></li> </ul> </nav>  <article class="topic task nested2" aria-labelledby="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__GUID-98FB119A-D8C4-4058-B8FB-01CCB06E3C10" lang="en-US" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A"> <h3 class="title topictitle3" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__GUID-98FB119A-D8C4-4058-B8FB-01CCB06E3C10">Configuring and Verifying BGP NSF</h3> <section class="body taskbody"> <section class="section context" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__GUID-EC671F0B-30DE-4A05-B036-AEAA102DA285"> <p class="p"> Repeat this procedure on each peer device. </p> </section> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">SUMMARY STEPS</h3> <ol class="ol steps summary_steps" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__GUID-550E3C28-A5CA-4166-BD8B-E1545B67A742"> <li class="summary_indent"> <span> <span class="keyword kwd">enable</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">configure</span> </span> <span> <span class="keyword kwd">terminal</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">router</span> <span class="keyword kwd">bgp</span> </span> <span> <var>autonomous-system-number</var> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">bgp</span> <span class="keyword kwd">graceful-restart</span> </span> [<span><span class="keyword kwd">restart-time</span> </span> <span><var>seconds</var> </span> | <span><span class="keyword kwd">stalepath-time</span> </span> <span><var>seconds</var> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">end</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">bgp</span> <span class="keyword kwd">neighbors</span> </span> [<span><var>ip-address</var> </span> [<span><span class="keyword kwd">advertised-routes</span> </span> | <span><span class="keyword kwd">dampened-routes</span> </span> | <span><span class="keyword kwd">flap-statistics</span> </span> | <span><span class="keyword kwd">paths</span> </span> [<span><var>reg-exp</var> </span>] | <span><span class="keyword kwd">received</span> <span class="keyword kwd">prefix-filter</span> </span> | <span><span class="keyword kwd">received-routes</span> </span> | <span><span class="keyword kwd">routes</span> </span> | <span><span class="keyword kwd">policy</span> </span>[<span><span class="keyword kwd">detail</span> </span>]]] </li> </ol> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">DETAILED STEPS</h3> <table class="ol steps" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__GUID-550E3C28-A5CA-4166-BD8B-E1545B67A742"> <thead> <tr> <th align="left"> </th> <th font-weight="bold" align="left">Command or Action</th> <th font-weight="bold" align="left">Purpose</th> </tr> </thead> <tbody> <tr class="li step"> <td align="left" valign="top" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__STEP_043D0EA239FF4AF0967FA9E5A2DDAF78"> <p><b>Step 1</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">enable</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router> enable</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables privileged EXEC mode. </p> <ul class="ul" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__UL_A0C10DE73E7743F496F3B73879460A49"> <li class="li" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__LI_AE70F2BF19A84D71812043C1D4562BC8"> <p class="p"> Enter your password if prompted. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__STEP_14EDCFF0EA9A495581DE954750896469"> <p><b>Step 2</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">configure</span> </span> <span> <span class="keyword kwd">terminal</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router# configure terminal</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enters global configuration mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__STEP_E6F186682D9F4AF8A56D2917B99B024F"> <p><b>Step 3</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">router</span> <span class="keyword kwd">bgp</span> </span> <span> <var>autonomous-system-number</var> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config)# router bgp 120</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables a BGP routing process, and enters router configuration mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__STEP_08F2D4ECB7634278B1296098534ABC84"> <p><b>Step 4</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">bgp</span> <span class="keyword kwd">graceful-restart</span> </span> [<span><span class="keyword kwd">restart-time</span> </span> <span><var>seconds</var> </span> | <span><span class="keyword kwd">stalepath-time</span> </span> <span><var>seconds</var> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# bgp graceful-restart</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables the BGP graceful restart capability, which starts NSF for BGP. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__STEP_07B8636F77EF4D2DA624AA59F4606D6B"> <p><b>Step 5</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">end</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# end</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Exits to privileged EXEC mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-4AA08479-0F33-46A4-A3DF-72987758A27A__STEP_86A55569D1254B4284EE9C27D9941FED"> <p><b>Step 6</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">bgp</span> <span class="keyword kwd">neighbors</span> </span> [<span><var>ip-address</var> </span> [<span><span class="keyword kwd">advertised-routes</span> </span> | <span><span class="keyword kwd">dampened-routes</span> </span> | <span><span class="keyword kwd">flap-statistics</span> </span> | <span><span class="keyword kwd">paths</span> </span> [<span><var>reg-exp</var> </span>] | <span><span class="keyword kwd">received</span> <span class="keyword kwd">prefix-filter</span> </span> | <span><span class="keyword kwd">received-routes</span> </span> | <span><span class="keyword kwd">routes</span> </span> | <span><span class="keyword kwd">policy</span> </span>[<span><span class="keyword kwd">detail</span> </span>]]] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router# show ip bgp neighbors</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays information about BGP and TCP connections to neighbors. </p> </section> </td> </tr> </tbody> </table> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic task nested2" aria-labelledby="GUID-05853C5E-3576-46F6-AD42-BD97DFC949A8__GUID-463475FF-7CBC-4C04-9EBC-9DCFA881A4C3" lang="en-US" id="GUID-05853C5E-3576-46F6-AD42-BD97DFC949A8"> <h3 class="title topictitle3" id="GUID-05853C5E-3576-46F6-AD42-BD97DFC949A8__GUID-463475FF-7CBC-4C04-9EBC-9DCFA881A4C3">Configuring and Verifying EIGRP NSF</h3> <section class="body taskbody"> <section class="section context" id="GUID-05853C5E-3576-46F6-AD42-BD97DFC949A8__GUID-BEF7A20C-CA12-405B-9FE9-35052B33F668"> <p class="p"> Repeat this procedure on each peer device. </p> </section> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">SUMMARY STEPS</h3> <ol class="ol steps summary_steps" id="GUID-05853C5E-3576-46F6-AD42-BD97DFC949A8__GUID-4A052E97-D067-4319-8A38-3D09E9E262FB"> <li class="summary_indent"> <span> <span class="keyword kwd">enable</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">configure</span> </span> <span> <span class="keyword kwd">terminal</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">router</span> <span class="keyword kwd">eigrp</span> </span> <span> <var>as-number</var> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">nsf</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">timers</span> <span class="keyword kwd">nsf</span> <span class="keyword kwd">converge</span> </span> <span> <var>seconds</var> </span> <span> <span class="keyword kwd"> </span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">timers</span> <span class="keyword kwd">nsf</span> <span class="keyword kwd">signal</span> </span> <span> <var>seconds</var> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">timers</span> <span class="keyword kwd">nsf</span> <span class="keyword kwd">route-hold</span> </span> <span> <var>seconds</var> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">timers</span> <span class="keyword kwd">graceful-restart</span> </span> <span> <span class="keyword kwd">purge-time</span> </span> <span> <var>seconds</var> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">end</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">protocols</span> </span> </li> </ol> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">DETAILED STEPS</h3> <table class="ol steps" id="GUID-05853C5E-3576-46F6-AD42-BD97DFC949A8__GUID-4A052E97-D067-4319-8A38-3D09E9E262FB"> <thead> <tr> <th align="left"> </th> <th font-weight="bold" align="left">Command or Action</th> <th font-weight="bold" align="left">Purpose</th> </tr> </thead> <tbody> <tr class="li step"> <td align="left" valign="top"> <p><b>Step 1</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">enable</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router> enable</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables privileged EXEC mode. </p> <ul class="ul"> <li class="li"> <p class="p"> Enter your password if prompted. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top"> <p><b>Step 2</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">configure</span> </span> <span> <span class="keyword kwd">terminal</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router# configure terminal</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enters global configuration mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top"> <p><b>Step 3</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">router</span> <span class="keyword kwd">eigrp</span> </span> <span> <var>as-number</var> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config)# router eigrp 109</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables an EIGRP routing process, and enters router configuration mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top"> <p><b>Step 4</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">nsf</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config)# no nsf</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Enables NSF capabilities. </p> <ul class="ul"> <li class="li"> <p class="p"> This command is enabled by default. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top"> <p><b>Step 5</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">timers</span> <span class="keyword kwd">nsf</span> <span class="keyword kwd">converge</span> </span> <span> <var>seconds</var> </span> <span> <span class="keyword kwd"> </span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# timers nsf converge 120</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Adjusts the maximum time that the restarting device will wait for the EOT notification from an NSF-capable or NSF-aware peer. </p> <ul class="ul"> <li class="li"> <p class="p"> Enter this command on NSF-capable devices only. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top"> <p><b>Step 6</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">timers</span> <span class="keyword kwd">nsf</span> <span class="keyword kwd">signal</span> </span> <span> <var>seconds</var> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# timers nsf signal 20 </code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Adjusts the maximum time for the initial restart period. </p> <ul class="ul"> <li class="li"> <p class="p"> Enter this command on NSF-capable devices only. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top"> <p><b>Step 7</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">timers</span> <span class="keyword kwd">nsf</span> <span class="keyword kwd">route-hold</span> </span> <span> <var>seconds</var> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# timers nsf route-hold 240 </code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Sets the route-hold timer to determine how long an NSF-aware EIGRP device will hold routes for an inactive peer. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top"> <p><b>Step 8</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">timers</span> <span class="keyword kwd">graceful-restart</span> </span> <span> <span class="keyword kwd">purge-time</span> </span> <span> <var>seconds</var> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# timers graceful-restart purge-time 240</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Sets the route-hold timer to determine how long an NSF-aware EIGRP device will hold routes for an inactive peer. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top"> <p><b>Step 9</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">end</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# end</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Exits to privileged EXEC mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top"> <p><b>Step 10</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">protocols</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router# show ip protocols</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays the parameters and current state of the active routing protocol process. </p> </section> </td> </tr> </tbody> </table> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic concept nested2" aria-labelledby="GUID-AC860E95-F8EE-4ED5-8130-4F5B6406D520__GUID-1B6A7963-B53E-4ECA-89EC-FC64C21CA9C3" lang="en-US" id="GUID-AC860E95-F8EE-4ED5-8130-4F5B6406D520"> <h3 class="title topictitle3" id="GUID-AC860E95-F8EE-4ED5-8130-4F5B6406D520__GUID-1B6A7963-B53E-4ECA-89EC-FC64C21CA9C3">Configuring NSF-OSPF</h3> <section class="body conbody"> <p class="p"> Perform only one of the following tasks: </p> </section>  <nav role="navigation" class="related-links"> <ul class="ullinks"> <li class="link ulchildlink"><a href="#GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD">Configuring Cisco NSF-OSPF</a></li> <li class="link ulchildlink"><a href="#GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9">Configuring IETF NSF-OSPF</a></li> </ul> </nav>  <article class="topic task nested3" aria-labelledby="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__GUID-E057B0C9-1925-432E-8326-5370C07183BA" lang="en-US" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD"> <h4 class="title topictitle4" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__GUID-E057B0C9-1925-432E-8326-5370C07183BA">Configuring Cisco NSF-OSPF</h4> <section class="body taskbody"> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">SUMMARY STEPS</h3> <ol class="ol steps summary_steps" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__GUID-91FC0E38-84A5-4F6C-A5EE-E4A6E276741E"> <li class="summary_indent"> <span> <span class="keyword kwd">enable</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">configure</span> </span> <span> <span class="keyword kwd">terminal</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">router</span> <span class="keyword kwd">ospf</span> </span> <span> <var>process-id</var> </span> [<span><span class="keyword kwd">vrf</span> </span> <span><var>vpn-name</var> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">nsf</span> </span> <span><span class="keyword kwd">cisco</span> </span> [<span><span class="keyword kwd">enforce</span> <span class="keyword kwd">global</span> </span>] </li> <li class="summary_indent"> <span><span class="keyword kwd">nsf</span> </span> <span><span class="keyword kwd">cisco</span> <span class="keyword kwd">helper</span> </span> [<span><span class="keyword kwd">disable</span>] </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">ietf</span> </span><span><span class="keyword kwd">helper</span> </span> [<span><span class="keyword kwd">disable</span> </span> | <span><span class="keyword kwd">strict-lsa-checking</span> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">end</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">ospf</span> <span class="keyword kwd">nsf</span> </span> </li> </ol> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">DETAILED STEPS</h3> <table class="ol steps" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__GUID-91FC0E38-84A5-4F6C-A5EE-E4A6E276741E"> <thead> <tr> <th align="left"> </th> <th font-weight="bold" align="left">Command or Action</th> <th font-weight="bold" align="left">Purpose</th> </tr> </thead> <tbody> <tr class="li step"> <td align="left" valign="top" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__STEP_0587D08420294075902DF523B654994F"> <p><b>Step 1</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">enable</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device> enable</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables privileged EXEC mode. </p> <ul class="ul" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__GUID-A8DF2191-5841-4CF2-8C03-8CDFCAC373A1"> <li class="li" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__LI_9A85B290916242CB8A438EEC8AE3E0F1"> <p class="p"> Enter your password if prompted. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__STEP_0743FA7E1A344A38A84F5213CB121837"> <p><b>Step 2</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">configure</span> </span> <span> <span class="keyword kwd">terminal</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device# configure terminal</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enters global configuration mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__STEP_2945962620DC470FB009C7B530228402"> <p><b>Step 3</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">router</span> <span class="keyword kwd">ospf</span> </span> <span> <var>process-id</var> </span> [<span><span class="keyword kwd">vrf</span> </span> <span><var>vpn-name</var> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device(config)# router ospf 12 </code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables Open Shortest Path First (OSPF) routing process and enters router configuration mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__STEP_181EFE097438480F806CAEB32099B494"> <p><b>Step 4</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">nsf</span> </span> <span><span class="keyword kwd">cisco</span> </span> [<span><span class="keyword kwd">enforce</span> <span class="keyword kwd">global</span> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device(config-router)# nsf cisco </code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables Cisco Nonstop Forwarding (NSF) restarting mode. </p> <ul class="ul" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__GUID-C4433139-65F7-4801-9C88-145A3CEC3969"> <li class="li" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__LI_55C843BC27A64789A3744B8C81D0B47C"> <p class="p"> This command is not required on devices that operate only in NSF helper mode. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__STEP_4F8D27EF5D9E4FECB03EF8754B151CD4"> <p><b>Step 5</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span><span class="keyword kwd">nsf</span> </span> <span><span class="keyword kwd">cisco</span> <span class="keyword kwd">helper</span> </span> [<span><span class="keyword kwd">disable</span>] </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device(config-router)# nsf cisco helper</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables Cisco NSF helper support. </p> <ul class="ul" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__GUID-50A83711-8B85-4673-8278-CB6516BF8128"> <li class="li" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__LI_3CA4114275F34F33BD100387B75860AC"> <p class="p"> This command shows how to enable Cisco NSF helper mode. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__STEP_CF8E1C4E12684A99B63806F283671C2F"> <p><b>Step 6</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">ietf</span> </span><span><span class="keyword kwd">helper</span> </span> [<span><span class="keyword kwd">disable</span> </span> | <span><span class="keyword kwd">strict-lsa-checking</span> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device(config-router)# nsf ietf helper disable</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Disables IETF NSF helper mode on an NSF-aware device. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__STEP_1ACA846E20BB4BD68FB0CE77E0C8B747"> <p><b>Step 7</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">end</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device(config-router)# end</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Returns to privileged EXEC mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-D0B3014C-570A-4428-A9BF-EDBCD9BB7ADD__STEP_9422D489108B49149F5B89B87D78DFD6"> <p><b>Step 8</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">ospf</span> <span class="keyword kwd">nsf</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show ip ospf nsf</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays OSPF NSF state information. </p> </section> </td> </tr> </tbody> </table> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic task nested3" aria-labelledby="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__GUID-86A1A6F0-A8D6-4467-9826-C342F7D02245" lang="en-US" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9"> <h4 class="title topictitle4" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__GUID-86A1A6F0-A8D6-4467-9826-C342F7D02245">Configuring IETF NSF-OSPF</h4> <section class="body taskbody"> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">SUMMARY STEPS</h3> <ol class="ol steps summary_steps" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__GUID-F84F0533-CD95-41C4-98B4-48B6C6693FD9"> <li class="summary_indent"> <span> <span class="keyword kwd">enable</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">configure</span> </span> <span> <span class="keyword kwd">terminal</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">router</span> <span class="keyword kwd">ospf</span> </span> <span> <var>process-id</var> </span> [<span><span class="keyword kwd">vrf</span> </span> <span><var>vpn-name</var> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">ietf</span> </span> [<span><span class="keyword kwd">restart-interval</span> </span> <span><var>seconds</var> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">ietf</span> </span><span><span class="keyword kwd">helper</span> </span> [<span><span class="keyword kwd">disable</span> </span> | <span><span class="keyword kwd">strict-lsa-checking</span> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">cisco</span> <span class="keyword kwd">helper</span> <span class="keyword kwd">disable</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">end</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">ospf</span> <span class="keyword kwd">nsf</span> </span> </li> </ol> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">DETAILED STEPS</h3> <table class="ol steps" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__GUID-F84F0533-CD95-41C4-98B4-48B6C6693FD9"> <thead> <tr> <th align="left"> </th> <th font-weight="bold" align="left">Command or Action</th> <th font-weight="bold" align="left">Purpose</th> </tr> </thead> <tbody> <tr class="li step"> <td align="left" valign="top" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__STEP_8CE351A7DCBA4951AE62D240B9CA2858"> <p><b>Step 1</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">enable</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device> enable</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables privileged EXEC mode. </p> <ul class="ul" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__GUID-87C9EB86-23E2-4802-AE7B-32605623CE09"> <li class="li" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__LI_EE0F57936C4C4B44A336D1CF6DFB07AB"> <p class="p"> Enter your password if prompted. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__STEP_19704A86F66C434EB64383C63090F52D"> <p><b>Step 2</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">configure</span> </span> <span> <span class="keyword kwd">terminal</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device# configure terminal</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enters global configuration mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__STEP_EA26145F6DA1477282A8E3165B33BD77"> <p><b>Step 3</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">router</span> <span class="keyword kwd">ospf</span> </span> <span> <var>process-id</var> </span> [<span><span class="keyword kwd">vrf</span> </span> <span><var>vpn-name</var> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device(config)# router ospf 12 </code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables Open Shortest Path First (OSPF) routing process and enters router configuration mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__STEP_50404DBF73074AE1A23EC15B4079B459"> <p><b>Step 4</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">ietf</span> </span> [<span><span class="keyword kwd">restart-interval</span> </span> <span><var>seconds</var> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device(config-router)# nsf ietf restart-interval 180</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables IETF Nonstop Forwarding (NSF) restarting mode. </p> <ul class="ul" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__GUID-DECD9F0B-5DAD-481C-AA51-EB2574018BDE"> <li class="li" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__LI_A5C3D344DDD14BB78147735D5CC078CB"> <p class="p"> This command is not required on devices that operate only in helper mode. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__STEP_5DA26C98A9FC4DB3B51376511ECA6D7A"> <p><b>Step 5</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">ietf</span> </span><span><span class="keyword kwd">helper</span> </span> [<span><span class="keyword kwd">disable</span> </span> | <span><span class="keyword kwd">strict-lsa-checking</span> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device(config-router)# nsf ietf helper strict-lsa-checking</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Configures IETF NSF helper mode on neighbor devices that operate in helper mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__STEP_A9011984942C4E5B9662DFF4428008F4"> <p><b>Step 6</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">cisco</span> <span class="keyword kwd">helper</span> <span class="keyword kwd">disable</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device(config-router)# nsf cisco helper disable</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Disables Cisco NSF helper mode on an NSF-aware device. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__STEP_31B78C9E7E6A4646854AC05D85E604B3"> <p><b>Step 7</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">end</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device(config-router)# end</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p">Returns to privileged EXEC mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-5E810C0E-5621-4DE5-8278-00942C7B1EE9__STEP_EAE37ACDD14841FB97B7D52EF353C2BB"> <p><b>Step 8</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">ospf</span> <span class="keyword kwd">nsf</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h5 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h5> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show ip ospf nsf</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays OSPF NSF state information. </p> </section> </td> </tr> </tbody> </table> </section>  <nav role="navigation" class="related-links"></nav>  </article> </article> <article class="topic task nested2" aria-labelledby="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__GUID-A06D381D-71E9-426E-9DFA-401C63129DE0" lang="en-US" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6"> <h3 class="title topictitle3" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__GUID-A06D381D-71E9-426E-9DFA-401C63129DE0">Configuring and Verifying IS-IS NSF</h3> <section class="body taskbody"> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">SUMMARY STEPS</h3> <ol class="ol steps summary_steps" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__GUID-D2BC404A-88E6-4842-A993-FDA546EB2BC5"> <li class="summary_indent"> <span> <span class="keyword kwd">enable</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">configure</span> </span> <span> <span class="keyword kwd">terminal</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">router</span> <span class="keyword kwd">isis</span> </span> <span> <var>area-tag</var> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">nsf</span> </span> [<span><span class="keyword kwd">cisco</span> </span> | <span><span class="keyword kwd">ietf</span> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">interval</span> </span> <span> <var>minutes</var> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">t3</span> </span> {<span><span class="keyword kwd">manual</span> </span> <span><var>seconds</var> </span> | <span><span class="keyword kwd">adjacency</span> </span>} </li> <li class="summary_indent"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">interface</span> <span class="keyword kwd">wait</span> </span> <span> <var>seconds</var> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">end</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">isis</span> <span class="keyword kwd">nsf</span> </span> </li> </ol> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">DETAILED STEPS</h3> <table class="ol steps" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__GUID-D2BC404A-88E6-4842-A993-FDA546EB2BC5"> <thead> <tr> <th align="left"> </th> <th font-weight="bold" align="left">Command or Action</th> <th font-weight="bold" align="left">Purpose</th> </tr> </thead> <tbody> <tr class="li step"> <td align="left" valign="top" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__STEP_D373EB27B8DB4BA291BEDA248694AEBB"> <p><b>Step 1</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">enable</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router> enable</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables privileged EXEC mode. </p> <ul class="ul" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__UL_39CAF176B7EF46EFBA71B667BFE86E17"> <li class="li" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__LI_78F3C247BB3D4DE4A0F772247F196878"> <p class="p"> Enter your password if prompted. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__STEP_1962DAA120704FCAA452B1710EEA2E9F"> <p><b>Step 2</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">configure</span> </span> <span> <span class="keyword kwd">terminal</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router# configure terminal</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enters global configuration mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__STEP_D9E8847917FC4F8BA55C1AFB34A803FA"> <p><b>Step 3</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">router</span> <span class="keyword kwd">isis</span> </span> <span> <var>area-tag</var> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config)# router isis cisco1</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables the IS-IS routing protocol to specify an IS-IS process and enters router configuration mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__STEP_C6FB3BA2FF804FF9A40E865E2CD00C56"> <p><b>Step 4</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">nsf</span> </span> [<span><span class="keyword kwd">cisco</span> </span> | <span><span class="keyword kwd">ietf</span> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# nsf ietf</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables IS-IS NSF operations. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__STEP_D5D72A60DDB3497EBB7350D315CCBECD"> <p><b>Step 5</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">interval</span> </span> <span> <var>minutes</var> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# nsf interval 2</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Configures the minimum time between NSF restart attempts. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__STEP_674C9D5DEF254725BA065D59E7B08C8E"> <p><b>Step 6</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">t3</span> </span> {<span><span class="keyword kwd">manual</span> </span> <span><var>seconds</var> </span> | <span><span class="keyword kwd">adjacency</span> </span>} </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# nsf t3 manual 40</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Specifies the methodology used to determine how long IETF NSF will wait for the link-state packet (LSP) database to synchronize before generating overloaded link-state information. </p> <ul class="ul" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__UL_9294B47D4F9842509C40064EDE88AACF"> <li class="li" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__LI_089015C879374897A1212933964E448F"> <p class="p"> This command is supported for IETF NSF only. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__STEP_4AAC5F80812A485D973B4EFB45EA9DEB"> <p><b>Step 7</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">nsf</span> </span> <span> <span class="keyword kwd">interface</span> <span class="keyword kwd">wait</span> </span> <span> <var>seconds</var> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# nsf interface wait 15</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> (Optional) Specifies how long a Cisco NSF restart will wait for all interfaces with IS-IS adjacencies to come up before completing the restart. </p> <ul class="ul" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__UL_F1BDBE4E55CE43CFA2765060712D4FCD"> <li class="li" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__LI_B9052BC2D8564D0E81FDB845D7CD1D6C"> <p class="p"> This command is supported for Cisco NSF only. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__STEP_859322175135474491B8AFDF4957C061"> <p><b>Step 8</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">end</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router(config-router)# end</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Exits to privileged EXEC mode. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-EC45A4DD-3C81-4913-BCC4-DB60823BFDF6__STEP_066F0C52AA7F4F8A97137E7B160375BD"> <p><b>Step 9</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">isis</span> <span class="keyword kwd">nsf</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Router# show isis nsf</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays current state information regarding IS-IS NSF. </p> </section> </td> </tr> </tbody> </table> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic task nested2" aria-labelledby="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__GUID-1820BC40-348E-4A22-B139-E9E7643C09E2" lang="en-US" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF"> <h3 class="title topictitle3" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__GUID-1820BC40-348E-4A22-B139-E9E7643C09E2">Troubleshooting Nonstop Forwarding</h3> <section class="body taskbody"> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">SUMMARY STEPS</h3> <ol class="ol steps summary_steps" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__GUID-B2058DC1-6947-499A-A805-B19A59BC7E28"> <li class="summary_indent"> <span> <span class="keyword kwd">enable</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">debug</span> <span class="keyword kwd">eigrp</span> <span class="keyword kwd">nsf</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">debug</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">eigrp</span> <span class="keyword kwd">notifications</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">debug</span> <span class="keyword kwd">isis</span> <span class="keyword kwd">nsf</span> </span> [<span><span class="keyword kwd">detail</span> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">debug</span> <span class="keyword kwd">ospf</span> <span class="keyword kwd">nsf</span> </span>[<span><span class="keyword kwd">detail</span> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">cef</span> <span class="keyword kwd">nsf</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">cef</span> <span class="keyword kwd">state</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">clns</span> <span class="keyword kwd">neighbors</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">bgp</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">bgp</span> <span class="keyword kwd">neighbor</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">cef</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">eigrp</span> <span class="keyword kwd">neighbors</span> </span> [<span><var>interface-type</var> | <var>as-number</var> | <span class="keyword kwd">static</span> | <span class="keyword kwd">detail</span> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">ospf</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">ospf</span> <span class="keyword kwd">neighbor</span> </span> [<span><span class="keyword kwd">detail</span> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">protocols</span> </span> </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">isis</span> <span class="keyword kwd">database</span> </span> [<span><span class="keyword kwd">detail</span> </span>] </li> <li class="summary_indent"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">isis</span> <span class="keyword kwd">nsf</span> </span> </li> </ol> <h3 font-weight="bold" class="sectiontitle tasklabel summary_steps cB_Bold">DETAILED STEPS</h3> <table class="ol steps" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__GUID-B2058DC1-6947-499A-A805-B19A59BC7E28"> <thead> <tr> <th align="left"> </th> <th font-weight="bold" align="left">Command or Action</th> <th font-weight="bold" align="left">Purpose</th> </tr> </thead> <tbody> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_8A6B5E597A5E4797A96554E427A1B209"> <p><b>Step 1</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">enable</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device> enable</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Enables privileged EXEC mode. </p> <ul class="ul" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__UL_CE086EF05ED54A62B1FBD68FA95DCF5B"> <li class="li" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__LI_31294A7A31404ECDBFF2A6AF704796F6"> <p class="p"> Enter your password if prompted. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_67D12223B2DD416A82EF4AB7E03AC160"> <p><b>Step 2</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">debug</span> <span class="keyword kwd">eigrp</span> <span class="keyword kwd">nsf</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# debug eigrp nsf</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays notifications and information about NSF events for an EIGRP routing process. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_FCA3ADB121154CC99E1017A794209D15"> <p><b>Step 3</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">debug</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">eigrp</span> <span class="keyword kwd">notifications</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# debug ip eigrp notifications</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays information and notifications for an EIGRP routing process. This output includes NSF notifications and events. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_2F86973BC3204D7CABDC6640C4932155"> <p><b>Step 4</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">debug</span> <span class="keyword kwd">isis</span> <span class="keyword kwd">nsf</span> </span> [<span><span class="keyword kwd">detail</span> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# debug isis nsf [detail]</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays information about the IS-IS state during a Cisco NSF restart. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_6A00D007790C4A23918A7E3B65B96B27"> <p><b>Step 5</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">debug</span> <span class="keyword kwd">ospf</span> <span class="keyword kwd">nsf</span> </span>[<span><span class="keyword kwd">detail</span> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# debug ospf nsf [detail]</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays debugging messages related to OSPF Cisco NSF commands. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_0FAAAE8CFC7940589A0DF90267D20D9B"> <p><b>Step 6</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">cef</span> <span class="keyword kwd">nsf</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show cef nsf</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays the current NSF state of CEF on both the active and standby RPs. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_79D4D58B261742C6998FD5A854952409"> <p><b>Step 7</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">cef</span> <span class="keyword kwd">state</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show cef state</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays the CEF state on a networking device. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_227E61126B464FC09F04E4A4657ACC0B"> <p><b>Step 8</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">clns</span> <span class="keyword kwd">neighbors</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show clns neighbors</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays both end system and intermediate system neighbors. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_67CAD3FD8BC045AB862A4CDF0341C312"> <p><b>Step 9</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">bgp</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show ip bgp</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays entries in the BGP routing table. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_EE68647F116F4658A4EC06D8A4694120"> <p><b>Step 10</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">bgp</span> <span class="keyword kwd">neighbor</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show ip bgp neighbor</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays information about the TCP and BGP connections to neighbor devices. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_A169D53B5BCD48CEB86CBCCC56CCE4E1"> <p><b>Step 11</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">cef</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show ip cef</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays entries in the FIB that are unresolved, or displays FIB summary. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_3B7F050B1D1B4079967E6799ABF1BB50"> <p><b>Step 12</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">eigrp</span> <span class="keyword kwd">neighbors</span> </span> [<span><var>interface-type</var> | <var>as-number</var> | <span class="keyword kwd">static</span> | <span class="keyword kwd">detail</span> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show ip eigrp neighbors detail</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays displayed information about neighbors discovered by EIGRP. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_19F92CF31EBE4EC187C5993E4A7F66CA"> <p><b>Step 13</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">ospf</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show ip ospf</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays general information about OSPF routing processes. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_CB0CC9481EB14449BAC7FEAAFE999054"> <p><b>Step 14</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">ospf</span> <span class="keyword kwd">neighbor</span> </span> [<span><span class="keyword kwd">detail</span> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show ip ospf neighbor [detail]</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays OSPF-neighbor information on a per-interface basis. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_C08C5FC20CE54680A52E5CCC38446A19"> <p><b>Step 15</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">protocols</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show ip protocols</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays the parameters and current state of the active routing protocol process. </p> <ul class="ul" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__UL_D66F64A166304546B6C341DE9E80507C"> <li class="li" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__LI_DC9E15A3754749008655F2F334A9A6DA"> <p class="p"> The status of EIGRP NSF configuration and support is displayed in the output. </p> </li> </ul> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_6445AC39BD3A46EBBB38CBAF2FB4B9D4"> <p><b>Step 16</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">isis</span> <span class="keyword kwd">database</span> </span> [<span><span class="keyword kwd">detail</span> </span>] </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show isis database [detail]</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays the IS-IS link-state database. </p> </section> </td> </tr> <tr class="li step"> <td align="left" valign="top" id="GUID-C97EF833-E1C8-4E02-ABFE-FB671CE118CF__STEP_0A307550FEC14671965A0635F5A39BD0"> <p><b>Step 17</b></p> </td> <td align="left" valign="top" class="step--command"> <p class="ph cmd"> <span> <span class="keyword kwd">show</span> <span class="keyword kwd">isis</span> <span class="keyword kwd">nsf</span> </span> </p> <section class="itemgroup stepxmp"> <section class="tasklabel"> <h4 font-weight="bold" class="sectiontitle tasklabel cB_Bold">Example:</h4> </section> <section class="p"> <pre class="pre codeblock"><code> Device# show isis nsf</code></pre> </section> </section> </td> <td align="left" valign="top" class="step--purpose"> <section class="itemgroup info"> <p class="p"> Displays the current state information regarding IS-IS NSF. </p> </section> </td> </tr> </tbody> </table> </section>  <nav role="navigation" class="related-links"></nav>  </article> </article> <article class="topic reference nested1" aria-labelledby="GUID-4103D75F-A60C-443F-B7E6-BF7A3CB98684__GUID-05FC8DF2-C4F4-456F-92A0-AFD5BBD08D01" lang="en-US" id="GUID-4103D75F-A60C-443F-B7E6-BF7A3CB98684"> <h2 class="title topictitle2" id="GUID-4103D75F-A60C-443F-B7E6-BF7A3CB98684__GUID-05FC8DF2-C4F4-456F-92A0-AFD5BBD08D01">Configuration Examples for Nonstop Forwarding</h2> <section class="body refbody"> </section>  <nav role="navigation" class="related-links"> <ul class="ullinks"> <li class="link ulchildlink"><a href="#GUID-0F182D6B-ED73-4892-8754-2BA9845B7D68">Example NSF-Capable CEF</a></li> <li class="link ulchildlink"><a href="#GUID-0DCC9858-BFDE-4B09-B347-52CE02FDEA76">Example BGP NSF</a></li> <li class="link ulchildlink"><a href="#GUID-B2D2628D-4B8E-4F48-85F5-F554667C033B">Example: EIGRP NSF</a></li> <li class="link ulchildlink"><a href="#GUID-65684839-CAFD-498A-B70B-1D396AA1097A">Example: Configuring Cisco NSF-OSPF</a></li> <li class="link ulchildlink"><a href="#GUID-57D3DD5C-852B-4437-AB55-2A2665E81424">Example: Configuring IETF NSF-OSPF</a></li> <li class="link ulchildlink"><a href="#GUID-AC1C0F79-56EA-4B32-B63E-CFD00B66C277">Example IS-ISNSF</a></li> </ul> </nav>  <article class="topic reference nested2" aria-labelledby="GUID-0F182D6B-ED73-4892-8754-2BA9845B7D68__GUID-957B647E-3DAE-4CE6-BF71-5BD622D039F0" lang="en-US" id="GUID-0F182D6B-ED73-4892-8754-2BA9845B7D68"> <h3 class="title topictitle3" id="GUID-0F182D6B-ED73-4892-8754-2BA9845B7D68__GUID-957B647E-3DAE-4CE6-BF71-5BD622D039F0">Example NSF-Capable CEF</h3> <section class="body refbody"> <section class="section" id="GUID-0F182D6B-ED73-4892-8754-2BA9845B7D68__GUID-40C802F0-FBB9-4B9F-A54C-6DB9CD11B9E8"> <p class="p"> The CEF NSF feature operates by default while the networking device is running in SSO mode. No configuration is necessary. The following sample output shows that CEF is NSF capable: </p> <pre class="pre codeblock"><code> Router# <kbd class="userinput"><b class="ph userinput">show cef state</b></kbd> CEF Status [RP] CEF enabled/running dCEF enabled/running CEF switching enabled/running CEF default capabilities: Always FIB switching: yes Default CEF switching: yes Default dCEF switching: yes Update HWIDB counters: no Drop multicast packets: no <kbd class="userinput"><b class="ph userinput">CEF NSF capable: yes</b></kbd> IPC delayed func on SSO: no RRP state: I am standby RRP: no My logical slot: 0 RF PeerComm: no</code></pre> </section> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic reference nested2" aria-labelledby="GUID-0DCC9858-BFDE-4B09-B347-52CE02FDEA76__GUID-AC96E048-3551-494E-97A7-34AB7973068C" lang="en-US" id="GUID-0DCC9858-BFDE-4B09-B347-52CE02FDEA76"> <h3 class="title topictitle3" id="GUID-0DCC9858-BFDE-4B09-B347-52CE02FDEA76__GUID-AC96E048-3551-494E-97A7-34AB7973068C">Example BGP NSF</h3> <section class="body refbody"> <section class="section" id="GUID-0DCC9858-BFDE-4B09-B347-52CE02FDEA76__GUID-F5EC0BF2-3E85-4A5D-82B7-040AEB2F3CAD"> <p class="p"> The following partial output shows the BGP configuration on the SSO-enabled device: </p> <pre class="pre codeblock"><code> Router# <kbd class="userinput"><b class="ph userinput">show running-config</b></kbd> router bgp 120 bgp graceful-restart neighbor 10.2.2.2 remote-as 300 </code></pre> <p class="p"> The following sample output shows that the graceful restart function is both advertised and received and that the address families have the graceful restart capability. If no address families were listed, then BGP NSF will not occur. </p> <pre class="pre codeblock"><code> Router# <kbd class="userinput"><b class="ph userinput">show ip bgp neighbors</b></kbd> <kbd class="userinput"><b class="ph userinput">192.168.2.2</b></kbd> BGP neighbor is 192.168.2.2, remote AS YY, external link BGP version 4, remote router ID 192.168.2.2 BGP state = Established, up for 00:01:18 Last read 00:00:17, hold time is 180, keepalive interval is 60 seconds Neighbor capabilities: Route refresh:advertised and received(new) Address family IPv4 Unicast:advertised and received Address family IPv4 Multicast:advertised and received Graceful Restart Capabilty:advertised and received Remote Restart timer is 120 seconds Address families preserved by peer: IPv4 Unicast, IPv4 Multicast Received 1539 messages, 0 notifications, 0 in queue Sent 1544 messages, 0 notifications, 0 in queue Default minimum time between advertisement runs is 30 seconds</code></pre> </section> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic reference nested2" aria-labelledby="GUID-B2D2628D-4B8E-4F48-85F5-F554667C033B__GUID-FD48967D-F12E-481F-90C8-E6DEC9F1F1E3" lang="en-US" id="GUID-B2D2628D-4B8E-4F48-85F5-F554667C033B"> <h3 class="title topictitle3" id="GUID-B2D2628D-4B8E-4F48-85F5-F554667C033B__GUID-FD48967D-F12E-481F-90C8-E6DEC9F1F1E3">Example: EIGRP NSF</h3> <section class="body refbody"> <section class="section" id="GUID-B2D2628D-4B8E-4F48-85F5-F554667C033B__GUID-B2CE86A8-390A-4AFC-B38D-82D99DAA3653"> <p class="p"> The following sample output shows that EIGRP NSF support is present in the installed software image. </p> <ul class="ul" id="GUID-B2D2628D-4B8E-4F48-85F5-F554667C033B__GUID-8F44153C-CDB2-46D9-B3EA-DD60FA116B45"> <li class="li" id="GUID-B2D2628D-4B8E-4F48-85F5-F554667C033B__LI_79C52641927143A4BBA751B5ED07833B"> <p class="p"> “EIGRP NSF-aware route hold timer is . . .” is displayed in the output for either NSF-aware or NSF-capable devices, and the default or user-defined value for the route-hold timer is displayed. </p> </li> <li class="li" id="GUID-B2D2628D-4B8E-4F48-85F5-F554667C033B__LI_8DB8E77DD5DD4903A97E60B52E9EC0AB"> <p class="p"> “EIGRP NSF enabled” or “EIGRP NSF disabled” appears in the output only when the NSF capability is supported by the device. </p> </li> </ul> <pre class="pre codeblock"><code> Device#<kbd class="userinput"><b class="ph userinput"> show ip protocols</b></kbd> Routing Protocol is "eigrp 100" Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set Default networks flagged in outgoing updates Default networks accepted from incoming updates EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0 EIGRP maximum hopcount 100 EIGRP maximum metric variance 1 Redistributing: eigrp 100 EIGRP NSF-aware route hold timer is 240s EIGRP NSF enabled NSF signal timer is 20s NSF converge timer is 120s Automatic network summarization is in effect Maximum path: 4 Routing for Networks: 10.4.9.0/24 Routing Information Sources: Gateway Distance Last Update Distance: internal 90 external 170</code></pre> </section> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic reference nested2" aria-labelledby="GUID-65684839-CAFD-498A-B70B-1D396AA1097A__GUID-A33CA36C-F923-4779-923A-DF7264855CF5" lang="en-US" id="GUID-65684839-CAFD-498A-B70B-1D396AA1097A"> <h3 class="title topictitle3" id="GUID-65684839-CAFD-498A-B70B-1D396AA1097A__GUID-A33CA36C-F923-4779-923A-DF7264855CF5">Example: Configuring Cisco NSF-OSPF</h3> <section class="body refbody"> <section class="section" id="GUID-65684839-CAFD-498A-B70B-1D396AA1097A__GUID-A967E2D8-5E8D-47C1-8E52-70034595505E"> <p class="p">The following example shows how to enable Cisco Nonstop Forwarding (NSF) helper support in the router configuration mode: </p> <pre class="pre codeblock"><code> Device> <kbd class="userinput"><b class="ph userinput">enable</b></kbd> Device# <kbd class="userinput"><b class="ph userinput">configure terminal</b></kbd> Device(config)# <kbd class="userinput"><b class="ph userinput">router ospf 400</b></kbd> Device(config-router)# <kbd class="userinput"><b class="ph userinput">nsf cisco helper</b></kbd> Device(config-router)# <kbd class="userinput"><b class="ph userinput">nsf ietf helper disable</b></kbd> Device(config-router)# <kbd class="userinput"><b class="ph userinput">end</b></kbd> </code></pre> <p class="p"> The following sample output from the <span><span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">ospf</span> <span class="keyword kwd">nsf</span> </span> command shows that NSF is enabled for Open Shortest Path First (OSPF) process 400. NSF helper mode is enabled by default on devices running NSF-compatible software. In this configuration, IETF helper mode is disabled for process 400. </p> <pre class="pre codeblock"><code> Device> <kbd class="userinput"><b class="ph userinput">show ip ospf nsf</b></kbd> Routing Process "ospf 400" Non-Stop Forwarding enabled IETF NSF helper support disabled Cisco NSF helper support enabled OSPF restart state is NO_RESTART Handle 2162698, Router ID 192.168.2.155, checkpoint Router ID 0.0.0.0 Config wait timer interval 10, timer not running Dbase wait timer interval 120, timer not running</code></pre> </section> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic reference nested2" aria-labelledby="GUID-57D3DD5C-852B-4437-AB55-2A2665E81424__GUID-A682DFFC-9B10-41E3-A7C9-8FAF26122245" lang="en-US" id="GUID-57D3DD5C-852B-4437-AB55-2A2665E81424"> <h3 class="title topictitle3" id="GUID-57D3DD5C-852B-4437-AB55-2A2665E81424__GUID-A682DFFC-9B10-41E3-A7C9-8FAF26122245">Example: Configuring IETF NSF-OSPF</h3> <section class="body refbody"> <section class="section" id="GUID-57D3DD5C-852B-4437-AB55-2A2665E81424__GUID-9CF43A61-94F8-4C8A-B46D-58B2610779FA"> The following example shows how to enable IETF Nonstop Forwarding (NSF) helper support in the router configuration mode: <pre class="pre codeblock"><code> Device> <kbd class="userinput"><b class="ph userinput">enable</b></kbd> Device# <kbd class="userinput"><b class="ph userinput">configure terminal</b></kbd> Device(config)# <kbd class="userinput"><b class="ph userinput">router ospf 500</b></kbd> Device(config-router)# <kbd class="userinput"><b class="ph userinput">nsf ietf helper strict-lsa-checking</b></kbd> Device(config-router)# <kbd class="userinput"><b class="ph userinput">nsf cisco helper disable</b></kbd> Device(config-router)# <kbd class="userinput"><b class="ph userinput">end</b></kbd></code></pre> <p class="p"> The following sample output from the <span><span class="keyword kwd">show</span> <span class="keyword kwd">ip</span> <span class="keyword kwd">ospf</span> <span class="keyword kwd">nsf</span> </span> command shows that NSF is enabled for Open Shortest Path First (OSPF) process 500. NSF helper mode is enabled by default on devices running NSF-compatible software. In this configuration, Cisco helper mode is disabled. </p> <pre class="pre codeblock"><code> Device> <kbd class="userinput"><b class="ph userinput">show ip ospf nsf</b></kbd> Routing Process "ospf 500" Non-Stop Forwarding enabled IETF NSF helper support enabled Cisco NSF helper support disabled OSPF restart state is NO_RESTART Handle 1786466333, Router ID 10.1.1.1, checkpoint Router ID 0.0.0.0 Config wait timer interval 10, timer not running Dbase wait timer interval 120, timer not running</code></pre> </section> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic reference nested2" aria-labelledby="GUID-AC1C0F79-56EA-4B32-B63E-CFD00B66C277__GUID-4B6EC3DF-F0AC-4030-AAEA-4BD30D775BBF" lang="en-US" id="GUID-AC1C0F79-56EA-4B32-B63E-CFD00B66C277"> <h3 class="title topictitle3" id="GUID-AC1C0F79-56EA-4B32-B63E-CFD00B66C277__GUID-4B6EC3DF-F0AC-4030-AAEA-4BD30D775BBF">Example IS-ISNSF</h3> <section class="body refbody"> <section class="section" id="GUID-AC1C0F79-56EA-4B32-B63E-CFD00B66C277__GUID-B7BDE22E-A225-44E2-9832-DB1E37CC3F54"> <p class="p"> The following partial output shows that this device uses the Cisco implementation of IS-IS NSF. The display will show either Cisco IS-IS or IETF IS-IS configuration. </p> <pre class="pre codeblock"><code> Router# <kbd class="userinput"><b class="ph userinput">show running-config</b></kbd> router isis nsf cisco </code></pre> <p class="p"> In a Cisco NSF configuration, the display output is different on the active and the standby RPs. </p> <p class="p"> The following sample output on the active RP shows that Cisco NSF is enabled on the device: </p> <pre class="pre codeblock"><code> Router# <kbd class="userinput"><b class="ph userinput">show isis nsf </b></kbd> NSF is ENABLED, mode 'cisco' RP is ACTIVE, standby ready, bulk sync complete NSF interval timer expired (NSF restart enabled) Checkpointing enabled, no errors Local state:ACTIVE, Peer state:STANDBY HOT, Mode:SSO </code></pre> <p class="p"> The following sample output on the standby RP shows that NSF is enabled on the device (NSF restart enabled): </p> <pre class="pre codeblock"><code> Router# <kbd class="userinput"><b class="ph userinput">show isis nsf </b></kbd> NSF enabled, mode 'cisco' RP is STANDBY, chkpt msg receive count:ADJ 2, LSP 7 NSF interval timer notification received (NSF restart enabled) Checkpointing enabled, no errors Local state:STANDBY HOT, Peer state:ACTIVE, Mode:SSO </code></pre> <p class="p"> The following sample output shows that IETF NSF is configured for the IS-IS networking device: </p> <pre class="pre codeblock"><code> Router# <kbd class="userinput"><b class="ph userinput">show isis nsf </b></kbd> NSF is ENABLED, mode IETF NSF pdb state:Inactive NSF L1 active interfaces:0 NSF L1 active LSPs:0 NSF interfaces awaiting L1 CSNP:0 Awaiting L1 LSPs: NSF L2 active interfaces:0 NSF L2 active LSPs:0 NSF interfaces awaiting L2 CSNP:0 Awaiting L2 LSPs: Interface:Serial3/0/2 NSF L1 Restart state:Running NSF p2p Restart retransmissions:0 Maximum L1 NSF Restart retransmissions:3 L1 NSF ACK requested:FALSE L1 NSF CSNP requested:FALSE NSF L2 Restart state:Running NSF p2p Restart retransmissions:0 Maximum L2 NSF Restart retransmissions:3 L2 NSF ACK requested:FALSE Interface:GigabitEthernet2/0/0 NSF L1 Restart state:Running NSF L1 Restart retransmissions:0 Maximum L1 NSF Restart retransmissions:3 L1 NSF ACK requested:FALSE L1 NSF CSNP requested:FALSE NSF L2 Restart state:Running NSF L2 Restart retransmissions:0 Maximum L2 NSF Restart retransmissions:3 L2 NSF ACK requested:FALSE L2 NSF CSNP requested:FALSE Interface:Loopback1 NSF L1 Restart state:Running NSF L1 Restart retransmissions:0 Maximum L1 NSF Restart retransmissions:3 L1 NSF ACK requested:FALSE L1 NSF CSNP requested:FALSE NSF L2 Restart state:Running NSF L2 Restart retransmissions:0 Maximum L2 NSF Restart retransmissions:3 L2 NSF ACK requested:FALSE L2 NSF CSNP requested:FALSE</code></pre> </section> </section>  <nav role="navigation" class="related-links"></nav>  </article> </article> <article class="topic reference nested1" aria-labelledby="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__GUID-572E1FEC-EFCA-4B53-8D4E-7AA0ED95F50B" lang="en-US" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015"> <h2 class="title topictitle2" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__GUID-572E1FEC-EFCA-4B53-8D4E-7AA0ED95F50B">Additional References</h2> <section class="body refbody"> <section class="section" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__GUID-4810BFF2-DDBD-41FF-8D0F-DA4CA219DEA5"> <h3 class="title sectiontitle">Related Documents</h3> <table width="100%" border="1" class="table" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81"> <caption></caption> <colgroup> <col> <col> </colgroup> <thead class="thead"> <tr> <th font-weight="bold" class="entry" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1"> <p class="p"> Related Topic </p> </th> <th font-weight="bold" class="entry" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2"> <p class="p"> Document Title </p> </th> </tr> </thead> <tbody class="tbody"> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> Cisco IOS commands </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> <a class="xref" href="http://www.cisco.com/en/US/docs/ios/mcl/allreleasemcl/all_book.html" target="_blank">Cisco IOS Master Commands List, All Releases</a> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> Cisco debug commands </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> <em class="ph i">Cisco IOS Debug Command Reference</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> Cisco IOS High Availability commands </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> <em class="ph i">Cisco IOS High Availability Command Reference</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> BGP support for NSF </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> BGP Support for Nonstop Routing (NSR) with Stateful Switchover (SSO) module in the <em class="ph i">Cisco IOS IP Routing: BGP Configuration Guide</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> EIGRP NSF awareness </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> EIGRP Nonstop Awareness module in the <em class="ph i">Cisco IOS IP Routing: EIGRP Configuration Guide</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> IPv6 BGP graceful restart </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> Implementing Multiprotocol BGP for IPv6 module in the <em class="ph i">Cisco IOS IPv6 Configuration Guide</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> IPv6 RIP </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> Implementing RIP for IPv6 module in the <em class="ph i">Cisco IOS IPv6 Configuration Guide</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> IPv6 static routes </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> Implementing Static Routes for IPv6 module in the <em class="ph i">Cisco IOS IPv6 Configuration Guide</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> NSF/SSO--802.3ah OAM Support </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> Using Ethernet Operations, Administration, and Maintenance module in the <em class="ph i">Cisco IOS Carrier Ethernet Configuration Guide</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> NSF/SSO--Any Transport over MPLS (AToM) </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> Any Transport over MPLS and AToM Graceful Restart module in the <em class="ph i">Cisco IOS Multiprotocol Label Switching Configuration Guide</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> NSF/SSO--E-LMI Support </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> Configuring Ethernet Local Management Interface at a Provider Edge module in the <em class="ph i">Cisco IOS Carrier Ethernet Configuration Guide</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> NSF/SSO--MPLS VPN </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> Configuring NSF/SSO--MPLS VPN module in the <em class="ph i">MPLS Configuration Guide</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__1 "> <p class="p"> Virtual Private LAN Services </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_3E58B736B6D24416A2FE24556FC31E81__entry__2 "> <p class="p"> NSF/SSO/ISSU Support for VPLS module in the <em class="ph i">Cisco IOS Multiprotocol Label Switching Configuration Guide</em> </p> </td> </tr> </tbody> </table> </section> <section class="section" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__GUID-478C69E0-CE13-46CE-80EF-9B72CFFE1D46"> <h3 class="title sectiontitle">Standards</h3> <table width="100%" border="1" class="table" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_9133E1688059425C8F24A21F83EA13AB"> <caption></caption> <colgroup> <col> <col> </colgroup> <thead class="thead"> <tr> <th font-weight="bold" class="entry" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_9133E1688059425C8F24A21F83EA13AB__entry__1"> <p class="p"> Standard </p> </th> <th font-weight="bold" class="entry" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_9133E1688059425C8F24A21F83EA13AB__entry__2"> <p class="p"> Title </p> </th> </tr> </thead> <tbody class="tbody"> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_9133E1688059425C8F24A21F83EA13AB__entry__1 "> <p class="p"> No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_9133E1688059425C8F24A21F83EA13AB__entry__2 "> <p class="p"> -- </p> </td> </tr> </tbody> </table> </section> <section class="section" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__GUID-13A7E50D-F1FF-4E4C-B3DA-7C9E104D1164"> <h3 class="title sectiontitle">MIBs</h3> <table width="100%" border="1" class="table" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_A38CF6F41710494B81815E51798EB977"> <caption></caption> <colgroup> <col> <col> </colgroup> <thead class="thead"> <tr> <th font-weight="bold" class="entry" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_A38CF6F41710494B81815E51798EB977__entry__1"> <p class="p"> MIB </p> </th> <th font-weight="bold" class="entry" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_A38CF6F41710494B81815E51798EB977__entry__2"> <p class="p"> MIBs Link </p> </th> </tr> </thead> <tbody class="tbody"> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_A38CF6F41710494B81815E51798EB977__entry__1 "> <p class="p"> No new or modified MIBs are supported, and support for existing MIBs has not been modified. </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_A38CF6F41710494B81815E51798EB977__entry__2 "> <p class="p"> To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: </p> <p class="p"> <a class="xref" href="http://www.cisco.com/go/mibs" target="_blank">http://www.cisco.com/go/mibs</a> </p> </td> </tr> </tbody> </table> </section> <section class="section" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__GUID-119E5AFA-A15E-4995-8808-F558F7A8B419"> <h3 class="title sectiontitle">RFCs</h3> <table width="100%" border="1" class="table" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_84C09EEEDB5C4561BD99AF079AEC1EDE"> <caption></caption> <colgroup> <col> <col> </colgroup> <thead class="thead"> <tr> <th font-weight="bold" class="entry" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_84C09EEEDB5C4561BD99AF079AEC1EDE__entry__1"> <p class="p"> RFC </p> </th> <th font-weight="bold" class="entry" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_84C09EEEDB5C4561BD99AF079AEC1EDE__entry__2"> <p class="p"> Title </p> </th> </tr> </thead> <tbody class="tbody"> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_84C09EEEDB5C4561BD99AF079AEC1EDE__entry__1 "> <p class="p"> RFC 3623 </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_84C09EEEDB5C4561BD99AF079AEC1EDE__entry__2 "> <p class="p"> <em class="ph i">Graceful OSPF Restart</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_84C09EEEDB5C4561BD99AF079AEC1EDE__entry__1 "> <p class="p"> RFC 3847 </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_84C09EEEDB5C4561BD99AF079AEC1EDE__entry__2 "> <p class="p"> <em class="ph i">Restart Signaling for Intermediate System to Intermediate System (IS-IS)</em> </p> </td> </tr> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_84C09EEEDB5C4561BD99AF079AEC1EDE__entry__1 "> <p class="p"> RFC 4781 </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_84C09EEEDB5C4561BD99AF079AEC1EDE__entry__2 "> <p class="p"> <em class="ph i">Graceful Restart Mechanism for BGP</em> </p> </td> </tr> </tbody> </table> </section> <section class="section" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__GUID-E4D7595E-59F2-4ED8-BE4C-5BE9F6E905DF"> <h3 class="title sectiontitle">Technical Assistance</h3> <table width="100%" border="1" class="table" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_D5404B0DE7F547E193399FF036CAB65C"> <caption></caption> <colgroup> <col> <col> </colgroup> <thead class="thead"> <tr> <th font-weight="bold" class="entry" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_D5404B0DE7F547E193399FF036CAB65C__entry__1"> <p class="p"> Description </p> </th> <th font-weight="bold" class="entry" id="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_D5404B0DE7F547E193399FF036CAB65C__entry__2"> <p class="p"> Link </p> </th> </tr> </thead> <tbody class="tbody"> <tr> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_D5404B0DE7F547E193399FF036CAB65C__entry__1 "> <p class="p"> The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. </p> </td> <td class="entry" headers="GUID-F216276F-864E-4061-B4B5-9A67DE29D015__TABLE_D5404B0DE7F547E193399FF036CAB65C__entry__2 "> <p class="p"> <a class="xref" href="http://www.cisco.com/cisco/web/support/index.html" target="_blank">http://www.cisco.com/cisco/web/support/index.html</a> </p> </td> </tr> </tbody> </table> </section> </section>  <nav role="navigation" class="related-links"></nav>  </article> <article class="topic reference nested1" aria-labelledby="GUID-00848F77-D98A-45D5-986C-31F354790EB9__GUID-E2FC34C3-B1AA-41D6-9E4A-A82FBB63F059" lang="en-US" id="GUID-00848F77-D98A-45D5-986C-31F354790EB9"> <h2 class="title topictitle2" id="GUID-00848F77-D98A-45D5-986C-31F354790EB9__GUID-E2FC34C3-B1AA-41D6-9E4A-A82FBB63F059">Feature Information for Nonstop Forwarding</h2> <section class="body refbody"> <section class="section" id="GUID-00848F77-D98A-45D5-986C-31F354790EB9__d54e4623"> <p class="p">The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature. </p> Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to <a class="xref" href="http://www.cisco.com/go/cfn" target="_blank">www.cisco.com/go/cfn</a>. An account on Cisco.com is not required. </section> </section>  <nav role="navigation" class="related-links"></nav>  </article> <p class="topictitle1" id=""></p> </article> </article> </main> </div> </div> <div class="col narrow-v2"> <div class="rightRailComponent noprint base-blowout"> <div class="eotPersonalization"> <section id="eotTDCampaign"></section> </div> <div class="eot-feedback-container"> <div class="eot-feedback"> <h3>Was this Document Helpful?</h3> <span class="eot-feedback-btnwrap"> <button class="eot-feedback-btn eot-feedback-btn-yes" aria-label="Was this Document Helpful?? Yes">Yes</button> <button class="eot-feedback-btn eot-feedback-btn-no" aria-label="Was this Document Helpful?? 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High Availability Configuration Guide, Cisco IOS XE 17.x - Configuring Nonstop Forwarding [Cisco IOS XE 17] - Cisco