Re: [rtcweb] Unsupported PPID (Re: draft-ietf-rtcweb-data-channel failure handling description)

[Paul Kyzivat <[e-mail]>]

On 8/26/14 5:22 PM, Martin Thomson wrote:
> On 26 August 2014 13:36, Michael Tuexen
> <[e-mail]> wrote:
>> What I don't understand how ignoring gives you extensibility. If one sides sends a new PPID, and
>> the other sides ignores it, the sender (at the SCTP level) thinks that the message was received
>> without any problem, since SCTP doesn't take the PPID into account. So user messages are lost.
>
> I think that the use of a new PPID can be negotiated prior to use, so
> there aren't big problems with any action recommended here.  Resetting
> the stream might work, assuming that we can distinguish between an
> error and a graceful close correctly, that is.

There isn't currently any way to distinguish graceful close from a reset 
due to error is there?

PPID 50 is currently being used just for DATA_CHANNEL_OPEN and 
Data_CHANNEL_ACK. But the message format has made provision for 512 
different message types. Some others could be used, now or in the 
future, for other housekeeping, such as giving a reason for a reset.

One approach would be to define DATA_CHANNEL_CLOSE, and specify that it 
be used just before reset when the close is graceful.

	Thanks,
	Paul