I have the following topology:
On R3 I have a xconnect to R1 with a backup xconnect to R2. Something like this:
interface gigabitethernet 0/1
xconnect 10.1.1.1 1000 encapsulation mpls
backup peer 10.2.2.2 1000
R3 sees both neighbours, R1 & R2, over the same uplink interface.
Now R1 crashes and goes offline. What is the right/best mechanism, that R3 can detect this topology change in a fast way? There is no "port down" on R3, it must be some kind of timeout, that R3 switch over to the backup peer over R2.
Should I use BFD with OSPF? Is this enough, that R3 will switch to the backup peer? BFD with LDP neighbours don't exist, if I'm right. Or can I tune some LDP timers?
I also found BFDoVCCV, but this is not supported, when there is a backup peer configured.
I like to have something, that detects the issue in 3 seconds or less.
I don't think that is possible, from the same page:
"Bidirectional Forwarding Detection over Virtual Circuit Connection Verification (BFDoVCCV) with status signaling is supported only on static pseudowires that do not have a backup peer. Explicit configuration of backup peers that violates this restriction is rejected."
I have adjusted the LDP timers to 2/6 and used BFD with OSPF in my lab setup. Currently I have a failover time from around 6 seconds.
I will make some more tests, also with the new ISR1100 series, in the next weeks. Maybe It's different in the current IOS XE Releases or there is something else that I can do.