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Re: (ASCEND) ISDN cause code 31?
Our experience has been that the cause code 31 problem is an Ascend problem
and has nothing to do with Telco issues. There's been a TR opened on this
(87413) since back in March, which points to problems with the Max 4000
failing to assign HDLC sessions to calls it has answered.
Intermittent calls will fail going into the 4000, with the remote user
getting a cause code 31 error after about 7 seconds. The Max 4000 shows a
channel stuck in the 'r' state until another call comes in, at which point
the 4000 reports a Layer 1 change on that channel. According to Tech
Support, the 4000 tells the ISDN Switch that it will answer the call, but
never assigns an HDLC session to the B-channel once connected. The 'cause
31' is the Switch's way of saying "the call failed on the remote end, but I
don't know why".
We spent over 4 months trying to isolate this problem through Tech Support,
and finally got the TR opened in March. It doesn't seem to be purely load
related, since we've recreated this with only six active sessions on a fully
configured 4000. But we do definitely see it occur more frequently under
load (about 10% of all calls fail intermittently). Makes for really happy
customers.
We first saw this problem back in the early 4.5 releases, and it still
exists today in 5.0Ap16. We switched to a TNT back in June, and could not
recreate the problem there. Unfortunately there were so many other problems
that we had to go back to the 4000 again ... so we're patiently waiting
(what choice do we have?). This has not been seen on Max 2000s or the
1800s, just on both of the 4000s we currently have.
One last note is that this also shows up if you are running ISDN BRI cards
in the 4000 ... only the user sees a cause code of 18 since the 4000 never
really answers the call.
Sure wish we were getting paid by the hour to solve these issues ...
Jeff Altom
gofast.net Incorporated
St. Paul, Minnesota
>At 13:48 on 8/18, Kevin Smith wrote:
>>At 03:30 PM 8/15/97 -0400, Ascend-Users wrote:
>>Frequently but irregularly, one of my routers (a P50 running 5.0Ai17,
>>troublesome though it may be) is logging a "No connection -- cause code
>>031" error. I have looked this one up and all that I've seen is a
>>reason of "Normal return - unspecified" (or something to that effect) as
>>an explanation.
>>
>>Can anyone out there help me with this?
>>
>>I'm unsure at this time whether to complain to the Telco, complain to my
>>ISP, or look more closely at my own equipment.
>
>You might want to "discuss" it with Telco, rather than complain...they may
>need to do some investigation as to why they are getting/sending this
>code. Typically when I've seen it in the past, there was some kind of
>IXC connection to the LEC which didn't like the way the line was configured
>(something like that! - I think the call was hitting AT&T without a bill-to
>number ;)
>
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