Exam 350-501 topic 1 question 256 discussion

A. nsr process-failures switchover router ospf 100 nsf cisco B. router bgp 64512 nsr router ospf 100 nsr mpls ldp nsr C. nsr process-failures switchover router bgp 64512 nsr router ospf 100 nsr mpls ldp nsr D. nsr process-failures switchover router ospf 100 nsf ietf With NSF, both peers must be graceful restart capable/aware => neither A nor B To activate NSR, you have to enable the functionality in the global configuration "D. nsr process-failures switchover" and in the supported routing protocols (BGP, OSPF and LDP) with the command "nsr" Correct answer is C

If you reference this document: https://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k-r7-8/mpls/configuration/guide/b-mpls-cg-asr9000-78x/implementing-mpls-ldp-78x.html " Process failures of active TCP or LDP results in session loss and, as a result, NSR cannot be provided unless RP switchover is configured as a recovery action. For more information about how to configure switchover as a recovery action for NSR, see Configuring Transports module in IP Addresses and Services Configuration Guide for Cisco ASR 9000 Series Routers. " If you look up that document "Configuring Transports" that it asks you to refer to: https://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k-r7-7/configuration/guide/b-ip-addresses-cg-asr9000-77x/configuring-transports.html " You can use the nsr process-failures switchover command to let the RP failover be used as a recovery action when the active TCP or active LDP restarts. " So the "nsr process-failures switchover" command in global config does appear to be required, according to Cisco's documentation. Answer: C

Well, the command “nsr process-failures switchover” does exist on XR routers. It seems you only need this command to activate NSR without doing that on individual processes, but I could not check that. I tried in a lab and “C” is also valid: hostname XR11 nsr process-failures switchover router ospf 1 nsr router bgp 100 nsr mpls ldp nsr RP/0/0/CPU0:XR11(config)#nsr ? process-failures Recovery action for Process failures on active RP/DRP RP/0/0/CPU0:XR11(config)#nsr https://www.cisco.com/c/en/us/td/docs/iosxr/cisco8000/ip-addresses/710x/b-ip-addresses-cg-8k-710x/configuring-transports.html

This question is from the new Cisco SPCORE syllabus. There is a difference between "nsr" and "nsf.". For, "nsf," it requires peers to be "nsf-aware/capable.". However, the "nsr" router doesn't require anything from the peer. NSR-Related Commands Mandatory prerequisite is to have two redundant processors: RP/0/RSP0/CPU0:router# show redundancy Old syntax that allowed to enable NSR for OSPF, BGP, IS-IS, LDP: RP/0/RSP0/CPU0:router# show ospf process-id RP/0/RSP0/CPU0:router# show bgp nsr Use the show redundancy command to confirm that your IOS XR router has both Active and Standby RP cards. NSR feature had to be enabled manually in initial Cisco IOS XR releases, with the single command configured on global protocol level: router ospf 1 nsr …. router bgp 1 nsr … router isis 1 nsr …

This question is ridiculous. "nsr process-failures switchover" is not covered in the official SPCOR class. If you search google, the first two results are on Cisco's website, but give 404 errors. After that, the results are all brain dumps. The only way to learn about this command is by using Google cache for the removed pages on Cisco's website.