If your LMI doesn't match, it just plain won't come up. Both the router and
the switch must agree on their link management packet details, or they won't
be able to communicate.
Now, what could cause things to bounce is if there is a physical layer
circuit problem and you're droping LMI packets. Take a look at show int on
your serial and you will see how many LMI packets were sent and received.
If they don't match, you had a problem at some point. clear the counters
and take a look at it a bit later.
Missing one every now and again won't kill you. You have to miss 3 to drop
and get 3 to come back on line (if I remember right). You can also debug
the LMI packets if you want to see what is inside of them. Mostly, it's
just DLCI information.
The other reason why you might drop is because (no office to any telco
folks) but the telco tends to jack things up on their frame relay networks.
We have thousands of frame relay links and every now and again, they will
just drop and come back on line. 99.9% of the time, it is because a DLCI
went inactive or deleted.
If a DLCI goes inactive, it means that you do not have end to end
connectivity for that PVC, however, your router and the switch both agree
that the thing really does exist.
If a DLCI goes DELETED, it means that you probably have an interface dlci
command in there, or a static dlci defined, and the switch doesn't agree
that it really exists.
Either of these two cases can be caused by a misconfiguration on the switch
while they're bringing up someone elses frame circuit and can knock you down.
Mike
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=14605&t=14490
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