[Dart] Protocols and port numbers (Re: RTP and non-RTP traffic on same UDP 5-tuple)

[Harald Alvestrand <[e-mail]>]

On 06/13/2014 01:12 AM, Brian E Carpenter wrote:
>
> Subject to David's comment about AF "colour" possibly being preserved, yes.
>
> There is another little point though. We've been discussing port numbers
> as though they are transport-independent. Actually, a classifier needs to
> look at the protocol number (TCP, UDP, SCTP, DCCP etc) before it knows
> for sure where the port numbers are. So debating this point before
> draft-ietf-rtcweb-transports-05 is rock solid may be a little academic.
> I don't think generic classifiers are set up for "SCTP over DTLS over ICE"
> for example.

As far as anything at all in RTCWEB is rock solid, the decision to use
UDP is rock solid.
So we can take that as a given for RTCWEB.

(apart from the case where one uses TCP because the firewalls don't
allow UDP...)

Generic classifiers will detect the traffic as UDP, and may be able to
tell RTP from DTLS-encapsulated data in the same way as the DTLS/RTP
demultiplexing does it.

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