[Rmt] WEBRC session description questions

[<[e-mail]>]

Hi WEBRC folk

>From this text from the WEBRC RFC3738...

"Before joining a session the receiver MUST know the mapping between the
CNs and the channels. Upon joining the session or shortly thereafter, it
SHOULD have the values of LENP_B, BCR_P, TSD, P, N, L, Q and T. Some of
these values may be computed or measured once the receiver has joined
the session. For example, the receiver MAY obtain LENP_B and T from the
first packet received from the base channel, and the receiver MAY
measure BCR_P once it is joined to the base channel.  The values of P, Q
and TSD MAY be fixed to default values built into the receiver that do
not change from session to session, and the value of N MAY be computed
as T-Q.  The receiver SHOULD know whether the sender is employing a
technique to produce constant aggregate rate as described in [8]."

Does anyone have a perspective on how trivial/complex and rapid/stalling the in-band detection or calculation would be for:
1. LENP_B - calculated from from first packet. That's minimal effort - right?
2. T - calculated from from first packet. That's minimal effort - right?
3. BCR_P - measured after joining. What kind of delay and processing is introduced?
4. N - simple calculation, no problem.
5. TSD, P, Q - must be communicated out of band. Are these likely to be fixed for practically all cases?
6. L - must be communicated out of band - right?

We're thinking about a flag for "constant aggregate rate" - would the rate need communicating instead?

Also, we're figuring out the CN semantics and whether ordering (and not explicit labelling) is sufficient.

Cheers, Rod.