[c-nsp] OSPF Loop-Free Alternate Fast Reroute and repair path

CiscoNSP List CiscoNSP_list at hotmail.com
Fri Sep 30 05:39:23 EDT 2016


Hi Everyone - Have some ASR920's that have just been deployed, and have just setup ospf+mpls on the Interpop links - One of the ASR920's has a link to a legacy 7200, that will be retired soon, and Ive set ospf cost very high on that link, as I dont want it used, unless all other interpop links fail....Ive tested about 50 destination prefixes, all have the correct primary + repair path (Being 10G link from ASR920->other POP ASR920, repair path being 1Gb cross-link to second ASR920, then its 10Gb link->other POP ASR920)....except one prefix....it for some reason has the correct primary path, but repair path it has chosen is via the 7200....why it is choosing this link as repair doesnt make sense (Based on ospf cost).....Is there anyway to check a destinations cost on the repair path? (I can manually work it out, which I have done(And it is way higher than the cost of the "correct" repair path)....but Im hoping I can interrogate the ASR to find out what it sees as the cost.....because even the loop of the 7200's best+repair path on the ASR920 is going via the paths of all the other prefixes Ive checked.


Thanks in advance.


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