Re: francois' comments and why RFC4474 not used in the field
"Dan Wing" <[email protected]>
| Newsgroups | gmane.ietf.sip |
|---|---|
| Message-ID | <[email protected]> |
> > But if some service provider in the middle needs to drop the
> > call to <some spiffy codec> which isn't supported by Alice's
> > SP nor by Bob's SP -- what would that service provider do?
> > Not deploy that spiffy new codec, even though it would save
> > them thousands of dollars a day in satellite bandwidth fees?
>
> Well, no. You just can't do end-to-end media security in this
> case.
Ok. Then in that case a way to downgrade to RTP -- which we need
in any event -- would be needed.
> I don't understdand at all the claim that if transcoding is
> allowed, there would be any point in doing media security, or
> even Secure identity for that matter. I'm just saying if transcoding
> or media mucking-around is allowed, then just stick with P-AI.
So that the victim (user2) can distinguish between a service provider doing
transcoding for the legimate user1 versus the identity spoofing of user3
(diagram taken from
http://tools.ietf.org/html/draft-elwell-sip-e2e-identity-important-03):
user3/UA3
|
+------+------+
| enterprise3 |
+------+------+
|
+----------+ +----+-----+ +----------+
+---+ SBC SBC +---+ SBC SBC +---+ SBC SBC +---+
| +----------+ +----------+ +----------+ |
| ITSP-A ITSP-B ITSP-C |
| |
+------+------+ +------+------+
| enterprise1 | | enterprise2 |
+------+------+ +------+------+
| |
user1/UA1 user2/UA2
-d
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