ITU Telecommunication Standardization Sector        Document AVC-1142
Study Group 16                                              Version 0
Former Q.2&3/15 Rapporteur Meeting                    7 February 1997
Boston, 18-21 February 1997

Source:  Lucent Technologies
	 Terry Lyons			Tel: +1 908 957 5644
	 Room MT-3K407			Fax: +1 908 957 5403
	 200 Laurel Avenue
	 Middletown NJ 07748 USA	terry.g.lyons@lucent.com

Title:   Need for coordination of H.320 over AAL 5

Purpose: Discussion

                   ------------------------------

H.320 audiovisual communication is an important application of N-ISDN
services, but it is not the only thing one would like to transport over
AAL 5.  Voice and facsimile are at least as significant today, and other
purely digital applications may increase.

We believe that the transport of H.320 streams over B-ISDN and ATM LANs
should not be studied in isolation but as part of the general need to
transport N-ISDN services over an AAL:

    - H.321, which treats the transport of H.320 over AAL 1,
     already pays attention to what Q.2931 and I.580 say about
     using AAL 1 for N-ISDN equivalent services.

    - H.321 Annex A, which will treat transport over AAL 5,
     should anticipate what they will say (some day) about using
     AAL 5 for N-ISDN equivalent services

Although Q.2931 and I.580 do not yet specify AAL 5 for such purposes,
intense interest in AAL 5 within both Q12/16 and the ATM Forum suggests
that market pressures will force an evolution in that direction.  Q12/16
and the ATM Forum will have major influence on the technical content of
N-ISDN over AAL 5.

When a (hypothetical) I.36x.y is written to specify the details of N-ISDN
over AAL 5, H.321 Annex A should be in harmony with it.  This will allow
H.321 to benefit automatically from I.580 (evolved to AAL 5) interworking
to N-ISDN and will eliminate the need to maintain special-purpose H.320/
H.321 Annex A gateways different from I.580.

These contributions to the ATM Forum are a basis for its discussions of
N-ISDN over AAL 5:

    [1] ATMF/96-1556 VTOA, Lucent Technologies (Terry Lyons),
     "Industrial strength AAL 5 to the desktop", December 1996.

    [2] ATMF/96-1679 VTOA, Nortel (Francois Audet),
     "AAL 5 for rates higher than 64 kbit/s", December 1996.

    [3] ATMF/97-0021 SAA+VTOA, France Telecom (Christian Wipliez),
     "AAL 5 packing options for Nx64k frame based videoconference",
     February 1997.

In light of the concurrent work, Q12/16 should seek to maintain a liaison
with the ATM Forum and to ensure an aligned solution (Technical Committee
working groups VTOA and SAA; chair: George Dubrowski, Bellcore NVC 1F-249,
331 Newman Springs Road, Red Bank NJ 07701, ghd@cc.bellcore.com).

It is suggested that SG 16 submit draft H.321 Annex A for comment to the
next ATM Forum meeting, 28 April - 2 May 1997 in Chicago.