%CLNS-5-ADJCHANGE: ISIS (MTT): A

[mttciscoadmin]

I am currently getting topology mismatches and adjacency changes on a router, and it is happening quit frrequently.  There error messages that I am getting is 

Dec 4 10:39:31 cr01.brgn.monmouth.com 370: Dec 4 10:39:30: %CLNS-5-ADJCHANGE: ISIS (MTT): Adjacency to 2091.9101.4005 (GigabitEthernet0/3.551) Down, hold time expired
Dec 4 10:39:31 cr01.brgn.monmouth.com 371: Dec 4 10:39:30: %CLNS-5-ADJCHANGE: ISIS (MTT): Adjacency to 2091.9101.4005 (GigabitEthernet0/3.551) topology mismatched, TID (2) not in remote IIH
Dec 4 10:39:34 cr01.brgn.monmouth.com 372: Dec 4 10:39:33: %CLNS-5-ADJCHANGE: ISIS (MTT): Adjacency to 2091.9101.4005 (GigabitEthernet0/3.551) Up, new adjacency
Dec 4 10:40:07 cr01.brgn.monmouth.com 373: Dec 4 10:40:06: %CLNS-5-ADJCHANGE: ISIS (MTT): Adjacency to 2091.9101.4005 (GigabitEthernet0/3.551) Down, hold time expired
Dec 4 10:40:07 cr01.brgn.monmouth.com 374: Dec 4 10:40:06: %CLNS-5-ADJCHANGE: ISIS (MTT): Adjacency to 2091.9101.4005 (GigabitEthernet0/3.551) topology mismatched, TID (2) not in remote IIH
Dec 4 10:40:10 cr01.brgn.monmouth.com 375: Dec 4 10:40:09: %CLNS-5-ADJCHANGE: ISIS (MTT): Adjacency to 2091.9101.4005 (GigabitEthernet0/3.551) Up, new adjacency

The config has not been changed in over 3 years, and this just started happening a few days ago.  Also, the other router, has not had any isis changes as well in over 3 years.  Need help on solving this issue.

[kabeer]

I would suggest working on a TAC case to understand this further.. there can be a number of reasons that this can happen including the load on these routers etc.. Basically the error says that the router either did not receive the hello packet or the IS-IS process did not receive the hello packet.