Relationship of H.323 and H.245 versions

Paul Long Plong at SMITHMICRO.COM
Fri Jan 29 13:21:07 EST 1999


Sorry, but I won't be in Monterey.

I agree with what you say, except that I would go further and state that there
is always a one-to-one mapping between H.225.0 and H.245 protocolIdentifiers
via H.323. For example,

    H.225.0v1 => H.323v1 => H.245v2 and H.245v2 => H.323v1 => H.225.0v1
    H.225.0v2 => H.323v2 => H.245v3 and H.245v3 => H.323v2 => H.225.0v2

This is already implied by the Summary section of H.323 starting with version
2. I think it's clear, but you could add clarification text if you like. IOW,
for example, an EP cannot use H.245v2 and H.225.0v2 in the same call.

Paul Long
Smith Micro Software, Inc.

                -----Original Message-----
                From:   Dave Walker [SMTP:dave_walker at Mitel.COM]
                Sent:   Friday, January 29, 1999 9:36 AM
                To:     ITU-SG16 at
                Subject:        Re: Relationship of H.323 and H.245 versions

                This thread seemed to be moving towards a consensus.  Is
                planning to submit a contribution at Monterey? Pete? Paul?

                Since the developing consensus seemed to be that H.225.0
                identifier also identifies the version of H.323, I would like
                add a provision that in the absence of any H.245 protocol
                that there be an implied linkage between H.323 version and

                That is, if any ASN.1 structure defined in H.245 is received
                to reception of an H.245 protocol identifier, the H.245
                used shall be that which is explicitly required by the H.323
                identified by the H.225.0 protocol identifier in use.  This
                apply to an OLC structure in fastStart for example.

                Dave Walker
                Mitel Corporation
                Ontario, CANADA

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