[j-nsp] ISIS and BFD

[Bit Gossip]

Experts,
rs2 is a IOS router and rc2 is Junos router and they have an established
ISIS adjacency with BFD; fine. Then with a fw filter I block BFD packets
reaching RC2; the ISIS session goes down as I would expect but then it
is re-established. How is that possible the session is re-established
when BFD packets are blocked?

This is the console of rc2.

rs2#show bfd neighbors

NeighAddr                         LD/RD    RH/RS     State     Int
1.1.6.53                        3/43    Up        Up        Te2/2


!!! Here I block BFD !!!

Dec 28 11:13:27.593 CET: %CLNS-5-ADJCHANGE: ISIS: Adjacency to rc2
(TenGigabitEthernet2/2) Down, BFD hold time expired
Dec 28 11:13:27.601 CET: %CLNS-5-ADJCHANGE: ISIS: Adjacency to rc2
(TenGigabitEthernet2/2) Up, new adjacency


rs2#show bfd neighbors

NeighAddr                         LD/RD    RH/RS     State     Int
1.1.6.53                        3/43    Down      Init      Te2/2
rs2#show isis neighbors

Tag null:
System Id      Type Interface   IP Address      State Holdtime Circuit
Id
rc2  L2   Te2/2       1.1.6.53     UP    26       01