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Re: (ASCEND) ISDN dial out problem/q.931 tracing
At 01:38 PM 1/29/98 +0100, Andre Beck wrote:
>On Thu, Jan 29, 1998 at 12:18:22AM -1000, Brian Uechi wrote:
>
>First of all, I've looked it up in Q.931 and the cause code table
>references to the B-channel-selection (5.1.2) where the statement
>is relatively clear: 44 means the B-channel exclusively requested
>was not available or, when non-exclusively requested (i.e. preferred)
>_no_ channel at all is available. Sounds pretty clear ;)
>
>> I used a combination of Andre Beck's (beck@ibh-dd.de) very useful
>> dtrace program and my own manual annotations based on the q.931 doc
>> to produce the following. I've also sent this to GTE for their
>> analysis. I ignored all the layer 2 stuff.
>>
>> PRI-XMIT-2/2: 25 octets @ B05B00E4 ;layer 3
>> [0000]: 08 02 04 5C 05 04 02 88 90 18 04 E1 80 83 17 70
>> 08 <proto DSS1>
>> 02 04 5C <callref caller 045c>
>> 05 <msgtype SETUP>
>> 04 <Bearer Capability,
>> 02 length 2,
>> 88 ccitt, cap Unrestricted digital,
>> 90 mode circuit, rate 64 kbps>
>> 18 <Channel ident,
>> 04 length 4,
>> E1 int identified, PRI/other, preferred, not D chan, chan
follows
>
>Ok, should mean "give me the channel which follows or, if unavailable, any
>one you can hand out".
>
>> 80 int id 00,
>
>That's the interesting point. You explicitely name an interface. Are you
>sure that this is the correct value here ? Q.931 makes no statements about
>how long this may be and what the content really means, i.e. leaves it
>to the carrier. IIRC this is called NFAS and is used to drive multiple
>E1/T1 PRIs with one D, but maybe the first interface is actually 01 or
>0005 or whatever. Your telco should be able to tell you ;)
I seem to recall that this is normal on the DMS. The AT&T switches work
differently - the way you said you would expect it.
I was confused by this too the first time I saw it, and was convinced that
the MAX was configured for NFAS! It would pay to ensure that Interface ID
of 0 is correct though.
Kevin
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