Ethereal-dev: RE: [Ethereal-dev] Re: [Ethereal-users] How to make ethereal reco gnise RTP,RTC
I'm almost sure the router works via pure RTP heuristics because they
claimed independence of the signaling protocol.
I don't know what heuristic they used but it worked quite well when I did
some tests in the lab. They certainly do not look deep into the signaling
messages like e.g. a packeteer box does.
Looking at the standard H.323 and SIP ports for presence of signalling
messages may also be used as an additional check for detecting RTP, but I
don't think that's really necessary.
> You can't count on the RTP odd port RTCP even port as part of a
> heuristic. There are a LOT of RTP implementations that have decided
> that RTCP isn't really necessary ( I happen to believe this
> means their
> broken, but it gets done a lot ).
If they claim standard compliancy they can only use even ports on RTP. I
know some of the old radvision stacks were not compliant. Probably you're
right that RTCP cannot be used because the standards give a lot of freedom
to when to send RTCP to the implementors. Some may indeed not even bother
about sending RTCP. If you want to use the presence of RCTP packets for the
heuristic it probably would be good to have a switch to disable this check.
Same probably applies for even RTP port numbers.
> Also I seem to recall discussion
> floating around about allowing the specification of port for RTCP
> which are not the next port after the RTP traffic.
>
>
>
