Archana,

I should preface my reply with a personal comment: people should seriously consider discontinuing support for H.323v1 devices within a few years-- the sooner the better, in my opinion. H.323v1 devices seem to be rare these days (from what I have seen) and they do introduce a number of issues that complicate the development of newer H.323 entities. While I am generally not in favor of deprecating (and, arguably, one cannot deprecate) a standard, we as implementers would be much better off :-)

The destination address is not so important, but the source address is. The scenario you describe is, indeed, a problem and it is the reason why the sourceCallSignalAddress field was added.

The Gatekeeper can populate that address with a unique port number for every call that it places outbound. It can then use that information coming in via the ARQ to match the outbound call with the incoming ARQ.

Paul

----- Original Message ----- From: "Nehru, Archana" archie@TRILLIUM.COM To: ITU-SG16@mailbag.cps.INTEL.COM Sent: Thursday, April 12, 2001 8:34 PM Subject: H.323 v1 problem

hi all,

I have a doubt about ARQ message in H.323 -V1. The H.323 specs for V1 say that "srcCallSignalAddress" and "destCallSignalAddress" are optional. But there were some mails exchanged somtime back on the mailing list which

said

that these two fields are MANDATORY for v1, since without these fields it

is

not possible to identify a call in H.323 V1.

E.g: Let us say we have an endpoint EP1, and EP2 and a GK and a call is Gk-routed. When EP1 wants to make a connection to EP2, it finishes RAS with GK and

then

sends a SETUP to GK. When EP2 receives the incoming SETUP from the GK, it send an ARQ to the GK. At this point the Gk needs to identify the "call " associated with the incoming ARQ. As there was no "callId" in V1, the only parameters that can give the GK a clue are the "srcCallSignalAddress" and "destCallSignalAddress" tuple. But if these are treated optional, then

what

parameters can the GK use to find the "associated call"?

I believe for this reason it was suggested that "srcCallSignalAddress"

and

"destCallSignalAddress" would always be present in ARQ from a V1. Can someone please confirm this?.

Many thanks, -Archana

Archana Nehru, Engineering Project Manager, Trillium Digital Systems Inc., an Intel Company. http://www.trillium.com Ph:310-481-5525

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