Use of GIT instead of B-HLI in H.310 and H.323 Annex C

Sakae OKUBO okubo at GITI.OR.JP
Sat Jul 3 23:10:09 EDT 1999


Dear Mr. Hedayat,
Dear Mr. Audet,

FA> I'd support this as well: some additional text regarding backward
FA> compatibility (use of GIT instead of B-HLI) is required. Along the
FA> lines of what was done for H.310 which went throught the same
FA> change.

What happened to H.310 as I recollect are as follows:

1. H.310 Version 1 (approved in November 1996)

Use of GIT was included in the Q.2931 SETUP message table for the H.245
resource/correlation number to associate the logical channel and ATM VC. But
GIT was noted as "under development".

2. H.310 V1 Implementors Guide approved in March 1997

As part of detailing and clarifying the use of DSS2 call signalling, it was
specified that H.310 correlation ID (H.245 resourceID in the
H222LogicalChannelParameters) shall be coded according to Q.2941.1 (GIT) in
the Q.2931 SETUP message.

At the same time, it was also specified that "Optionally, the H.310
correlationID may also be sent in the Broadband High Layer IE (B-HLI) as
follows. ... In the case where either of the terminals do not support the
GIT information element, the B-HLI information element shall be used to
convey the H.310 correlationID." Appendix II for extended use of Q.2931
Release 1 describes how to use B-HLI for the H.310 Correlation ID with the
note "These accommodations are provisional, the Generic Identifier Transport
Information Element should be used to convey the H.310 correlation ID when
the relevant Q.2931 specifications have been implemented."

3. H.310 Version 2, determined in February 1998

At this meeting, SG16 received a liaison statement from SG11 advising that
the use of B-HLI for the purpose of conveying the H.310 Correlation ID was
inappropriate. Hence in the process of integrating the H.310 V1 Impelmentors
Guide into draft H.310 V2, the option of B-HLI use was totally deleted.
Instead, according to the SG11 suggestion, the following one line sentence
was added: "Optionally, the H.310 correlationID may also be sent in the
user-to-user information IE." However, there is no description of how to use
the user-to-user information IE for this purpose.

4. H.310 Version 2, decided in September 1998

Compared to Version 1, the following were added:

- H.310 V1 IG except for the above mentioned optional B-HLI use for H.310
Correlation ID
- Correction approved in February 1998 for the H.320/H.321 stack for the
RAST-5 terminal
- Procedures for the interworking procedures between RAST-1 and RAST-5
terminals which were developed in the experts group work.

I hope this information may be of some use for considering the text for
H.323 Annex C regarding the use of GIT instead of B-HLI, though the
situations appears to be not completely the same between H.310 and H.323
Annex C.

KH> If the additional text is approved in Berlin will it
KH> be possible to add it to H.323 V3?

We should respect the guideline that officially the Rapporteur meeting
cannot re-address the matters in the White Contribution for decision (in the
spirit of determination based on maturity). However, the rule allows that
based on written contributions SG16 meeting in September may modify the
draft Recommendation submitted as White Contribution. Once the consensus is
obtained at the Berlin meeting, a delayed contribution should be submitted
by Administration(s) or ITU-T Sector member organization(s).

Best regards,

Sakae OKUBO (Mr.)
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