ASR903 17.6.5: BFD drops all ISIS adjacencies on same linecard

[MATTHIAS SCHAERER]

Hi 

On an ASR903 I see that the drop of one of four BFD sessions on a GigEth card leads to the drop of all ISIS adjacencies on the same card. Is that desired/normal behaviour? 

/Aug 10
filtering...
Aug 10 23:50:57.858: %BFDFSM-6-BFD_SESS_DOWN: BFD-SYSLOG: BFD session ld:14 handle:4,is going Down Reason: RX DOWN
Aug 10 23:50:57.878: %CLNS-5-ADJCHANGE: ISIS (ISIS_P40): Adjacency to router-a (GigabitEthernet0/4/1) Down, bfd neighbor down
Aug 10 23:50:57.879: %CLNS-5-ADJCHANGE: ISIS (ISIS_P40): Adjacency to router-b (GigabitEthernet0/4/3) Down, bfd neighbor down
Aug 10 23:50:57.879: %CLNS-5-ADJCHANGE: ISIS (ISIS_P40): Adjacency to router-c (GigabitEthernet0/4/0) Down, bfd neighbor down
Aug 10 23:50:57.880: %CLNS-5-ADJCHANGE: ISIS (ISIS_P40): Adjacency to router-d (GigabitEthernet0/4/4) Down, bfd neighbor down
Aug 10 23:50:58.882: %BFDFSM-6-BFD_SESS_UP: BFD-SYSLOG: BFD session ld:19 handle:8 is going UP
Aug 10 23:50:58.994: %CLNS-5-ADJCHANGE: ISIS (ISIS_P40): Adjacency to router-c (GigabitEthernet0/4/0) Up, new adjacency
Aug 10 23:50:59.003: %CLNS-5-ADJCHANGE: ISIS (ISIS_P40): Adjacency to router-b (GigabitEthernet0/4/3) Up, new adjacency
Aug 10 23:50:59.134: %CLNS-5-ADJCHANGE: ISIS (ISIS_P40): Adjacency to router-a (GigabitEthernet0/4/1) Up, new adjacency
Aug 10 23:50:59.894: %CLNS-5-ADJCHANGE: ISIS (ISIS_P40): Adjacency to router-d (GigabitEthernet0/4/4) Up, new adjacency

[marce1000]

       - Ref : https://www.cisco.com/c/en/us/support/docs/ip/ip-routing/220364-troubleshoot-bidirectional-forwarding-de.html
         >....
        >RX DOWN - The router receives notification from its neighbor that it has gone down.
        >....

       - If that is not considered as being coincidence then checkout the current software version being used on the ASR
         and or look into https://software.cisco.com/download/home/283780951/type/282046477/release/3.18.6SP
                                           if applicable

    M.

[Giuseppe Larosa · Accepted solution]

Hello @MATTHIAS SCHAERER ,

are the 4 Giga interfaces giga0/4/0 to giga0/4/3 connecting to the same IS-IS neighbor or to different IS-IS nodes?

in first case, as suggested by @marce1000  the reception of RX DOWN leads to tearing down all the sessions to the same neighbor.

In the second case, if the IS-IS neighbor nodes are different I agree with you that this should not happen.

Hope to help

Giuseppe

[MATTHIAS SCHAERER]

Thanks Giuseppe

The four connections indeed go to four different routers, so I probably open a case.

Cheers

Mat