Can't establish ISIS L1 link over ATM PVC

[dciapas]

Hello,

I' have C7507 and C7206VXR, both with PA-A3-OC3SMI. I've configured subinterfaces, vpi and vci, ip addresses. Ping works fine. EIGRP neighbors esablished fine.

But ISIS doesn't. I've entered "debug isis adj-packets" and found that both end system send IIH (ISIS hello), but one of them doesn't receive it.

Maybe it is a matter of "protocol clns ..." command ?

Thanks in advance

[ERIK LAWAETZ]

When you say you've configured subinterfaces I assume those are p2p and not p2m interfaces? IS-IS only works on p2p.

Have you mapped CLNS to the proper vpi/vci using "protocol clns ..."?

Although it's on Frame Relay and not ATM perhaps this page may help:

http://www.cisco.com/warp/customer/97/isis-frint.html

[dciapas]

Thanks for replay. Actually I've solved problem by myself - I've found the solution on :

<http://www.cisco.com/en/US/tech/tk365/tk381/technologies_white_paper09186a00800a3e6f.shtml>. It states:

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By default, IS-IS hellos are padded to the full maximum transmission unit (MTU) size

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The solution was to reduce MTU on subinterface. It is still not very clear which component - cisco routers or Alcatel ATM switches are tricky with MTU (it was 4470 - now 4400).