I wanted to lab up MPLS LDP session protection to reduce the time needed for LDP convergence in the event of a link failure. However, having targeted hellos is a prerequisite. So lets configure it.
Still working off the same topology, I’ll set up and test targeted hello sessions between PE_WEST and P1.
First I am going to shut down the link a P1 towards PE_WEST. The LDP neighbors drop as expected.
4d01h: %OSPF-5-ADJCHG: Process 1, Nbr 100.100.100.100 on FastEthernet1/0 from FULL to DOWN, Neighbor Down: Interface down or detached
4d01h: %LDP-5-NBRCHG: LDP Neighbor 100.100.100.100:0 is DOWN
3d22h: %LDP-5-NBRCHG: LDP Neighbor 18.104.22.168:0 is DOWN
Even though that link is down, connectivity between the loopbacks still work fine.
PE_WEST#ping 22.214.171.124 so lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 126.96.36.199, timeout is 2 seconds:
Packet sent with a source address of 100.100.100.100
I brought the link back up, and configured targeted hellos between PE_WEST and P1