From: George Spahl (g.spahl@xxxxxxxxxxxxx)
Date: Tue Mar 05 2002 - 09:40:48 GMT-3
Stefano,
There are a couple of things to investigate when you're having ospf
demand circuit problems. First of all, as obvious as it seems, make
sure the two sides are neighbors (this has bitten me more than once).
Once you're certain the neighborship exists, you can use the debug
dialer commands in concert with the debup ip packet detail command to
see what it is that is causing the one side to dial the other. This
might be a broadcast from another routing protocol or some other thing
you can easily fix. Sometimes it's a packet with a destination of
224.0.0.5. I used to always think this was a hello packet violating the
spirit of the demand circuit, but later I found out this is usually an
OSPF LSA of some type that is being generated due to a topology change
somewhere that involves the OSPF network. It could be a change due to
the ISDN interfaces going down and a /32 route being withdrawn from the
routing table (the archives can tell you how to fix this with the "no
peer neighbor-route" command) or it could be a problem with a flapping
route somewhere else, or maybe something else entirely. The secret to
finding out exactly which route is changing so that you can fix the
problem is to use the undocumented command that someone on the list
mentioned a while back "debug ip ospf monitor". It's the only way I
know of to pinpoint the route and once you've done that you've got it by
the short hairs. Hopefully, if there are other clever or undocumented
ways of identifying the changing routes someone will let us know.
Hope this helps!
George
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Stefano Andrello
Sent: Tuesday, March 05, 2002 4:04 AM
To: ccielab@groupstudy.com
Subject: demand circuit
i've configured 2 routers running ospf demand circuit on dialer
interface.
evry time there is a change in the topology the two routers brig up the
line
even if it not necessary ( I think ). any suggestion?
thanks
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