Hello !
I have seen this exact same situation on an E3 here
in Norway. One side up/up, the other up/up(looped).
I even raised a TAC case on it, as our telco insisted it
had to be a router issue.
Working with TAC and the telco in a conference call, what
finally solved it was having the telco doing a bit test from
the looped side towards the "OK" side. When tests were
switched off in the network, the circuit magically worked.
The telco people mentioned that the circuit had been
running in "SDH protection path" (the SDH backup mechanism)
for some time, and been switched back to the normal path.
Not sure whether that had anything to do with the problem though.
I for one will insist that the telco does every test possible,
the next time I see this special situation. Then I will
wait for the magic to happen again :-)
One interesting observation :
In our case, it was the local side that was up/up, and the remote side
was up/up(looped). This meant that we had some traffic flowing in
to us, for instance SYSLOG messages from the remote router.
Anything flowing out from us went to some big bit bucket
at the telco.
We use OSPF on the link, and SYSLOG messages immediately came in
from the remote site, complaining about duplicate router id
seen on the link (%OSPF-4-DUP_RTRID_NBR).
Next time, I will try to correlate local up/up and remote
duplicate router id on link to pinpoint the problem faster...
jgh
---Jan Gunnik Hope, ID Comnet AS, Norway, www.idcomnet.no jan.gunnik.hope@idcomnet.no, +47 53 05 11 00
-----Opprinnelig melding----- Fra: jlewis@lewis.org [mailto:jlewis@lewis.org] Sendt: 28. desember 2001 18:41 Til: Jim Warner Kopi: cisco-nsp@puck.nether.net Emne: Re: Odd T1 problem
On Fri, 28 Dec 2001, Jim Warner wrote:
> > I've never seen this happen,... so the circuit is simultaneously > > up and looped towards the customer. > > I once had a video conferencing point to point T1 where the far > side saw themselves (i.e. looped) but the near side saw the far > side. I told the trouble desk that the line was half looped and > they indicated that this was something they could straighten out > in software. And they did. > > I don't think I would know how to do this with a "conventional" > DSX-1 jack panel. But with computers, you can do anything.
I don't know what was going on, and I'm sure I never will, but it seems while our tech was on the road between the Z end and A end, after replacing everything at the Z end, The circuit magically fixed itself.
He arrived at the A end, and without making any changes, we went from A end up/up, Z end up/up(looped) to everything normal and the circuit able to pass traffic again.
I just know if I call Bell back and ask them what's going on, they'll say they haven't even looked at this circuit since yesterday.
-- ---------------------------------------------------------------------- Jon Lewis *jlewis@lewis.org*| I route System Administrator | therefore you are Atlantic Net | _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
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