BFD for Pseudowires
Load base.ipv4.and.ipv6.cfg
#IOS-XE (R1-R6)
config replace flash:ospfv2.cfg
Enable LDP on all routers.
Configure a pseudowire between R2-R6 on their loopbacks.
Create a VPWS using Gi2 service-instance 10 on each router. (This will not actually be operational).
Configure the pseudowire to use BFD.
Answer
Explanation
Using BFD with pseudowires is essentially just the process of creating a multi-hop BFD session like normal, and then telling the router to monitor the pseudowire peer via BFD.
First we create a multi-hop BFD template and map the remote pseudowire peer to the BFD template:
Next, we create a pseduowire template and configure BFD monitoring:
Finally, the template is applied to the pseudowire peer in the xconnect config:
Verification
We can verify the multi-hop session just like any other BFD multi-hop session. Notice that xconnect is the registered protocol, and that, as usual, echos cannot be used for multi-hop sessions.
Let’s now simulate failure a new way. We’ll apply an ACL to all of R6’s interfaces that block BFD control packets. This simulates a scenario in which OSPF is still up (somehow), or hasn’t yet hit the dead timer.
Within just a few seconds, BFD goes down on R2 and informs the xconnect process. The AToM VC is now down:
Personally, I don’t really see the use case for this. It is much more complex than just running BFD for the IGP, and relying on the IGP for reachability to the pseudowire peer.
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