Minutes of the Megaco/H.gcp conference call held June 16th/99, 11amET to 1:50pmET
Number of participants: about 30, including Megaco, SG16, and Megaco/SG16 participants
The meeting was structured around the following agenda points - they are each addressed below.
1) Termination naming - hierarchical or logical, or a combination with TerminationId + Bearer? 2) handling multplexing terminations - as in H.gcp? or as a new context type? 3) allowing one BearerDescriptor, and multiple MediaDescriptors per termination - acceptable? 4) decision on transport 5) proposal for tagging the MediaDescriptor with its encoding: SDP or H.GCP 6) proposal for text vs binary encoding of the protocol (draft-huitema-megaco-sdp-discuss-01.txt) 7) multimedia vs monomedia contexts (related to #3) 8) code points process 9) naming an editor team for a combined IETF/SG16 document, document format
***NOTE, if you wish to start a new discussion thread on any of the topics below, PLEASE put a relevant subject on your msg (e.g. Subject: Issue #1) , and do not simply reply to this email.
***Another NOTE: all internet-drafts relevant to Megaco are at available at: ftp://standards.nortelnetworks.com/megaco/docs/Oslo99/ , as well as at ftp://ftp.ietf.org/internet-drafts
Issue #1) Termination naming - hierarchical or logical, or a combination with TerminationId + Bearer? & Issue #2) handling multplexing terminations - as in H.gcp? or as a new context type? ------------- - Question: Is a circuit that is outside a context a kind of termination, or a separate construct? Much discussion from Brian Rosen, Paul Sijben, John Segers, Mike Buckley, Fernando Cuervo, Tom Taylor. There seemed to be consensus that a circuit is a kind of termination. However, it was brought up by Fernando Cuervo that if we consider the concept of resources for function keys, indicators, displays, softkeys, and dialpads, that are outside a context, as described in the IP Phone draft (draft-blatherwick-megaco-ipphone-00.txt), then perhaps we could consider a circuit as a resource when it is outside a context.
- note that an issue had come up on the list that management issues may be out of scope of Megaco. In fact, COT cannot be considered management - it is part of ISUP call control and setup, so we need a way of expressing COT across the Megaco boundary.
- it was agreed that the definition of an MG is: an MG does media adaptation and connections, nothing more - There was discussion on whether an MG knows about the concept of "users".
Conclusion: a) We need better definitions of Termination and Context, and THEN define how to create a multiplex using terminations and contexts.
b) Brian Rosen and Paul Sijben agreed to talk about Issues #1 and #2 tommorrow (June 17th) and post a msg to the Megaco mailing list. If there is consensus on the outcome of their conversation, this issue is closed, if not, Tom Taylor will appoint a design team to come up with a solution within a week.
Issue #3) allowing one BearerDescriptor, and multiple MediaDescriptors per termination - acceptable?
- related to #1 and #2 - not discussed - wait to see output from Brian Rosen and Paul Sijben.
Issue #4) decision on transport ------------- Conclusion: - agreed that the Megaco protocol must define something for transport. We need something for fragmentation, and need to define the timers that the MGC and MG will use, how they will use them (i.e. what will the retry mechanism be), and be able to suggest default values for them. The transport solution itself could be in a separate document.
- agreed that both MGC and MG "must" implement some kind of "UDP + timers" mechanism. We need to choose one. There are two proposals on the table: 1) the UDP + timers method in the Telcordia/Cisco MGCP - draft-huitema-megaco-mgcp-v0r1-05.txt, and 2) Transaction UDP + Timers (TUDP) - draft-cuervo-megaco-tudp-00.txt - This one has just come out, and addresses the needs of Megaco - people are invited to read it and comment on it.
- agreed that the MGC and MG both "may" implement TCP.
Issue #5) proposal for tagging the MediaDescriptor with its encoding: SDP or H.GCP & Issue #6) proposal for text vs binary encoding of the protocol (draft-huitema-megaco-sdp-discuss-01.txt) ------------- - as with the transport issue, we need to nail down this issue asap, so that the protocol can begin to be implemented
- there was a desire to go with what we have already, which means SDP, but there is still the issue of and/or capability syntax to be added to the SDP
- it was mentioned that we need to be able to express all codec parameters in SDP and in H.245 - Christian Huitema has built comparison tables for this already - see draft-huitema-megaco-sdp-discuss-01.txt
Conclusion: - agreed that we will wait a week for Joerg Ott and Gur Kimchi to put a proposal on the table that allows us to express and/or syntax for stating codec capabilities - for example an MG can support both G.723 and GSM, but not both at the same time.
- Tom Taylor will probably pull together a small design team to bring this issue to conclusion within the next week and a half.
Issue #7) multimedia vs monomedia contexts (related to #3) ------------- - not discussed, although there seems to be consensus for multimedia contexts.
Issue #8) code points process ------------- - Tom Taylor brought up the issue of having a registry to define code points for Megaco.
- discussed that if we had a single registry, say IANA, then we could possibly modify H.245 to use code points coming out of IANA
- there is a precedent for this: H.245 refers to IANA-defined RTP payload types.
Conclusion: - look at new object oriented extension for defining codepoints in H.245 (in the H.245 coming out of Santiago)
- if this is used, then IANA could define the codepoints, and it would be possible to add them to H.245 using the object oriented extension mechanism without having to change H.245 (NOTE: not sure if I got this right...)
Issue #9) naming an editor team for a combined IETF/SG16 document, document format ------------- - addressed in Tom's email - see below:
From: Taylor, Tom-PT [CAR:5V00-I:EXCH] Sent: Wednesday, June 16, 1999 2:23 PM To: megaco@standards.nortelnetworks.com Subject: Working Methods For Our Protocol Document
We came to several conclusions on the Megaco/H.GCP conference call today regarding the mechanics of developing the protocol draft:
Brian Rosen and Bryan Hill are officially co-editors of thedocument, from both the IETF and the ITU point of view. (There may be ITU legalities to be fulfilled before that is fully so).
We are going with a single document from here on. That is, thenext document merges the Megaco and H.GCP drafts.
Our working documentation will be in the form of PDF files postedon the web site. Of course, when it is time to create an RFC, this will be turned into text and Postscript.
I have to ask: will this final point cause anyone major difficulties? Is anyone in a position where they cannot read Adobe PDF? One drawback I can think of is the inability to cut and paste quotations from the document when suggesting changes. Is this a major hangup, and if so, what suggestions for work-arounds?
Tom Taylor
----------- Once again, if I have made any errors or omissions in these minutes, please let me know. Thanks to those who joined the call.
Nancy -------------------------------------------------------------------------- Nancy M. Greene Internet & Service Provider Networks, Nortel Networks T:514-271-7221 (internal:ESN853-1077) E:ngreene@nortelnetworks.com