Subject: [Sigtran] IUA - SCTP: If SCTP goes down at SG...

From: "Dheepa Devadoss" <[email-masked]>
Date: Wed, 14 Jun 2006 12:21:14 +0530

Hi

I am beginner with IUA and SCTP ,so apologies if this question sounds too
lame.

Question is:

How is an association re-established in case the SCTP instance
crashes/restarts in the SG(IUA).

Looking at IUA , SCTP RFCs and Q.921 ,Q.931 spcifications this is what I
understand

1.Asscociation is always setup by the MGC (recommended in IUA RFC)
2.This asscociation is setup even before D-channel is brought into service
i.e even before Q.931 invokes a DL-ESTABLISH primitive in the MGC.(probably
by configuring the SCTP through IUA layer managemnt interface )
3.When Q.931 wants to activate D-channel it calls DL-ESTABLISH (and a
corresponding message gets sent on IUA/SCTP by mapping interface id to
stream id)

My question is if SCTP instance on SG restarts , How will the SCTP on MGC
re-establish the association without causing too much damage in the
Q.931call states maintained at MGC?

If I have the control on the IUA and SCTP layers on the SG side can I
control by invoking some (??) primitives(mgmt) on IUA/SCTP in SG to give an
indication to the peer SCTP on MGC?
i cannot setup a new association because I am on the SG side ...

Please let me know if my understanding is right/wrong and what should be
done in this scenario

Thanks a lot and appreciate ur input

cheers
Dheepa
"As I learn more I realize how less I know"
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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Wed, 14 Jun 2006 02:32:35 -0600

Dheepa,

Dheepa Devadoss wrote:                        (Wed, 14 Jun 2006 12:21:14)
>    My  question is if SCTP instance on SG restarts , How will the SCTP on
>    MGC  re-establish  the  association without causing too much damage in
>    the Q.931 call states maintained at MGC?

When the SG SCTP instance restarts, the SCTP at the MGC will issue
COMMUNICATION_DOWN indication to the local IUA, issuing an M-SCTP RELEASE
indication to management that can then issue a M-SCTP ESTABLISH request.
You don't really need to do anything special at the SG.  The ASPs in the
AS are responsible for the Q.931 call state.  Just because the SCTP
association restarted does not mean that the D-channel has been released:
meaning Q.931 does not necessarily get a DL-RELEASE indication and Q.931
call state will be undisturbed.

--brian

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/