ITU-T H.248.72 PDF

This Recommendation defines ITU-T H.248 packages that allow a decomposed gateway to realize the media-oriented negotiation acceleration (MONA) negotiation procedures specified in Annex K of [ITU-T H.324].

During the MONA negotiation, terminals exchange their capabilities depending on which of the methods for establishing media channels are supported:

– signalling preconfigured channel (SPC);

– media preconfigured channel (MPC);

– accelerated ITU-T H.245 procedure (ACP).

The ACP method is supported in all terminals. The exchange of the MONA preference messages allows the determination of which of the three methods is used.

The "MONA Preference" package supports the sending and reception of MONA preference messages. It provides the following capabilities:

– Sending and reception of MONA preference messages including automatic retransmission.

– Sending and reception of media in preconfigured channels during the MONA negotiation procedures.

– Detection of legacy condition: this capability allows for a swift fallback to [ITU-T H.245] interworking.

– Completion of the MONA negotiation procedures.

The "MONA Preference" package is thus mandatory for any decomposed gateway that supports the ITU-T H.324, Annex K MONA procedures.

The "MONA Preference" package also includes the needed ITU-T H.248 capabilities for the use of the MPC method to establish media channels. These MPC related capabilities within the package only need to be supported by decomposed gateways supporting MPCs.

The "H.245 Transport for SPC Use" package allows the sending and reception of ITU-T H.245 messages using the SPC method during a MONA negotiation procedure. It also allows for the automatic retransmission of the messages to the remote end. This package is defined as an extension of the "H.245 Transport" package.

Decomposed gateways that support the SPC method for establishing media channels need to support the "H.245 Transport for SPC Use" package in addition to the "MONA Preference" package.

The ACP method is used when the terminals do not support another common method, SPC or MPC, or in order to establish missing channels when not all media channels have been already established with MPC. The ACP procedures are realized by exchanging ITU-T H.245 messages. The required ITU-T H.248 capabilities are provided by the [ITU-T H.248.12 Amd.2] H.245 transport package.