nanog mailing list archives

Re: sanity check frame question


From: "Stephen Sprunk" <ssprunk () cisco com>
Date: Thu, 22 Aug 2002 09:06:12 -0500


Thus spake <Brennan_Murphy () NAI com>
I have a Frame connection between two sites, A and B. If the router
crashes at B, wouldn't A still see the DLCI for
B?  Is there any scenario where this wouldn't be the case?  If
B gets blown off the map, shouldnt A's frame interface be
in at least an up/down scenario?

In theory, when the remote LMI goes down, or any part of the PVC internal to the
carrier goes down, the local LMI should go INACTIVE.  In practice, this is
unreliable at best; for some carriers, you will always get ACTIVE status no
matter what.

ATM has a similar feature/problem with ILMI.  The only solution is to ignore the
carrier and do it yourself end-to-end (gosh, where have we heard that before?).

End-to-End Keepalives for FR:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/wan_r/wr
dfrely.htm#xtocid18

OAM Loopback for ATM:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/wan_r/wro
ampvc.htm#xtocid0

If the DLCI disappeared, doesn't that suggest that someone
deleted the PVC?

Distinguish between INACTIVE and DELETED; those represent very different things
in LMI.

S


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