FLUTE SDP specification
Jani Peltotalo <[email protected]> Wed, 23 Jun 2010 20:29:51 +0300
| Newsgroups | gmane.ietf.rmt |
|---|---|
| Message-ID | <[email protected]> |
Dear RMTers, We are currently updating the FLUTE SDP specification and at this point we need to clarify three issues: 1. Our understanding is that ALC, LCT and FLUTE sessions must originate from a single sender and therefore from a single IP address. There is some confusing text of discussing ASM/SSM models in the ALC, LCT and FLUTE specifications. It is our understanding that ASM/SSM discussion only relates to IP level routing and (e.g., IGMP) joining of IP multicast groups. Does anyone disagree with this? (And more critically is anyone aware of implementation that is incompatible with our understanding.) 2. FLUTE SDP defines the Composite Session token so that multiple FLUTE sessions can be described in a single SDP object/instance/file (for efficiency and encapsulation). To enable this the 05-version of the specification promotes one media (channel) to be the Primary Media where things like source IP address are defined for all media / channel for a single FLUTE session. The specification currently says: "The first media line declared for a Composite Session group is the Primary Media.". However, we propose to change this to: "The first (leftmost) mid value declared for a Composite Session group is the Primary Media.". This should make reading and writing the SDP simpler and less prone to errors. Because of the convention of declaring the group's mid values in the same order as the media lines we anticipate no compatibility breakages. Does anyone disagree with this? 3. ALC, LCT and FLUTE specify: "Each TSI MUST uniquely identify a FLUTE session for a given source IP address during the time that the session is active and also for a large time before and after the active session time.". In SDP, the t-field is mandatory and this field is used to specify precise time. We would like to fully specify what is meant by large time. We propose 60 minutes. We will also clarify the best practise use of SDP session times (especially with unbounded and permanent sessions) in MMUSIC working group. Will this make anyone happy on unhappy? BR, Jani Peltotalo