I have two routers( a 7206 and a 7513) connected through 3 E1 links and they establish adjacency in only one link. The mtu is the same on both sides, there´s no phisical erros on the links, but two of them present the "INIT" state at the "sh clns neighboors" command. On the 7206 router, the holdtime is about 290, while on the 7513 it´s 26.
The only difference I have found is at "debug isis adj...":
ISIS-Adj: Sending serial IIH on Serial2/1/6:0, length 44
ISIS-Adj: Sending serial IIH on Serial2/1/5:0, length 1499
ISIS-Adj: Sending serial IIH on Serial2/1/4:0, length 1499
From your previous post it appears that "no hello padding" is not functioning properly due to IIH's being 1499 out of the interfaces that are not functioning properly. Have you tried applying this "no isis hello padding" on each of the interfaces just to try it.
There is not to much, as long as your capabilities (MTU,Wide Metric Support, etc) match that would keep these Adjacencies from coming up. If the SystemID's were duplicate it would stay in Init as well but you'd see this in your logs unless your logging level is set to something very high.
I am also assuming that other traffic (IP,CDP, etc) can pass through these curcuits and that there are no ACLs that would be limiting reception of these IIH's through them. If the no hello padding does not work you might send your router isis config as well just to see if there is something in there. Also your running IOS version might help out. Might be a bug.
Also here is a good link on whats all in a WAN IIH if your interested:
Looking carefully to this problem we detected some input erros on these interfaces that were counted as "abort frames". At the "show log" there were logs of "protocol up/down". So, we called up the Carrier Transmission area to look at SDH circuits and found sincronysm problems.
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