From: David Russell (drussell@xxxxxxxxxxx)
Date: Sat Mar 25 2000 - 18:58:14 GMT-3
Title: ISDN
As long as we are sharing ...
I used to have a problem with ISDN callback. I would set it up and
then use ping to test it. The ping would always seem to fail.
Looking at the debug I noticed that the callback is scheduled for
"Dialer enable-timeout" seconds after the call is dropped. By default
it is 15 secs which is longer than the standard ping. By dropping the
value to say 5 seconds (I am not very patient either) I can get the
much desired "..!!!" that tells us that life is good.
Dave
-----Original Message-----
From: Price, Jamie <jprice@isgteam.com>
To: 'Ccielab@Groupstudy.Com' <Ccielab@groupstudy.com>
Date: Saturday, March 25, 2000 4:12 PM
Subject: ISDN
Hi,
I've noticed that there have been a few queries/comments of late on
ISDN interfaces flapping when they shouldn't be.
I was recently having the same sort of problem and what I found may
be related to what a few other peoplemhave been dealing with so I
felt this was a good place to speak up.
Even in a straight BRI to BRI setup on 2 routers, no other
interfaces, no routing protocols etc, I found that when I was using
encap ppp the call would be made, then disconnect after the
idle-timeout only to reconnect again straight away. This wouldn't
happen using HDLC. Investigation using "sh dialer" and "debug ppp
neg" showed me that the ppp traffic was keeping the interface up -
even though my dialer list was set to define only IP as interesting
traffic.
The interface would flap anywhere between 2 and 6 times before it
would actually shutdown - sometimes it wouldn't shut down at all,
consistently ending the call and then setting it back up again.
Using "sh dialer" again I noticed that the "wait-for-carrier-time"
was 30 seconds. My idle-timeout was set at 10 (ok...I'm an
impatient guy!!!). Increasing the idle-timeout in excess of the
wait-for-carrier-time (i.e. >30 secs) took care of the problem
completely.
`Playing around a bit more I wondered if dropping the
wait-for-carrier-time to 20 and the idle-timeout to 25 would work.
Playing around with the wait-for-carrier-time though really started
messing things up.
End result is that as long as I have my idle-timeout in excess of
30 secs my ISDN configs work fine. As I said this may be related
to problems others have been having using demand-circuits etc.
Does anyone want to expand on this? I'm using 11.3, 2 x 2600's,
and a Teltone ISDN demonstrator. I'm keen to know if theres a
reason this happens (I have been looking but am at a loss so far),
if this is an IOS "feature", or if I have a flaky ISDN
demonstrator.
Thanks
Jamie
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