[c-nsp] OSPF / FRR(rLFA) + Non FRR links

CiscoNSP List CiscoNSP_list at hotmail.com
Tue Oct 18 00:28:41 EDT 2016


Hi,

Have an interesting(unexpected) situation on an ASR920 that is running ospf / frr(rLFA) to a number of other ASR920's (All running sopf / frr(rLFA)....but it also has a non-frr(rLFA) link to a 7200, which also has a non-frr(rLFA) link back to the other ASR920's (So bascially a triangle topology)


ASR920's link to the 7200 has a very high OSPF cost (As I dont want it used, unless all other links fail)


Unexpectadly, the ASR920 only creates a single rLFA tunnel to one of the other ASR920's (All the other ASR920's create 2)


Also, not expected, the ASR920 chooses to use the link to the 7200 as a repair path to the directly connected ASR920's even though the links to the other(directly connected) ASR920's have a much lower cost?


If I shutdown the link on the ASR920->7200, the ASR920 creates a second tunnel, and starts using the rLFA tunnels as repair paths? (This is the behavior I expected, even with the link to the 7200 operational)


I have a TAC case open (For 2 weeks now!), and they are stumped...so Im hoping someone on the list may know why this is occurring (Or if it is expected behavior?)


Cheers




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