Re: FW: New Version Notification - draft-mehta-rmt-flute-sdp-04.txt

Hi,

On 25 Nov 2005, at 12:49, Magnus Westerlund wrote:
...
>> Layering:
>> The layering with slash notation was our first consideration for
>> describing multiple channels some time ago (check out the  
>> discussion on
>> differentiating channels in the I-D). Using slash notation for one  
>> but
>> not the other is allowed (again check the I-D for reasons). However,
>> limiting all FLUTE sessions to only using conecutive numbers  
>> (addresses
>> for multicast; ports for unicast) is unecessary and potentailly  
>> harmful
>> as we do not yet a have a comprehensive set fo RMT CC RFCs for each
>> scheme which has been dicsussed. i.e. we need a means to group  
>> different
>> m-lines together: appearing in the same SDP without group:CS for  
>> single
>> FLUTE session SDPs; have a mid:# belonging to the same group:CS as  
>> other
>> media is for multiple FLUTE session SDPs. Use of port numbers to  
>> differentiate channels (with the same IP
>> destination/group address) is only useful where some other
>> application-based congestion control is introduced; indeed it is
>> recommended only for unicast applications. Differentiation of  
>> channels
>> based on IP destination/group address is appropriate for multicast
>> sessions with RMT congestion control. Note, the RMT family uses
>> layers/channels principally for congestion control. Using them for  
>> FEC
>> is allowed but if it messes with congestion control deployment on the
>> public Internet can not be assumed feasible.
>
> I think that using CS instead of the layering mechanism is the  
> right choice. However I think one should require the usage of CS  
> for all cases where a FLUTE session contains more than a single  
> channel. That way we are consistent with SDP usage.

I agree - my main concern with this draft is the implicit grouping of  
channels ("m=" lines) into a single session, unless otherwise  
signalled. I strongly prefer a solution where separate "m=" lines  
denote separate FLUTE sessions, unless the grouping framework is used.

Colin