[j-nsp] OSPF Debug

[Scotty]

Im trying to debug an OSPF issue between an M20 (5.6R1.3), interface is
P-1GE-SX going to an M160 (6.2R1.5) and that interface is a PB-2GE-SX.

M20 side seems to be the problem.  Basic area 0.0.0.0 setup, textbook
example.  I;ve tried numbered and unnumbered interfaces.  The M20 side
always is in state "init" it see's the hello and gets the router-id of the
M160, but the M160 side always goes from "attempt" to  state "down" after
dead-timers expire.  A 'show ospf neighbor' shows the neighbor in state init
on the M20 side and "down" on the M160 side. 

I'm thinking that I am forgetting something really stupid or there is some
sort of compatibility issue.  It is clear that the M20 is not sending its
HELLO packets *or* the M160 is sending it's HELLO and not listening for the
other side.  If you came across this same issue, where would you look first?


So far I have not seen anything alarming in 'flag all details' on either
router in the traceoptions, further the interfaces do work fine, in fact I
have an iBGP session between these two routers using these exact same
interfaces.  I have verified that MTU is exactly the same, Ive tried
encaps/vlan-tagging, etc just to test things and I always end up with the
same result.  The M160 is a new router getting inserted into network, my M20
has been around for awhile now and working great with OSPF.  Im hoping it is
as simple as a 5.6/6.2 compatibility problem because that is easy to fix and
would explain all the hair sitting next to both boxes.

-Scotty