Re: [MMUSIC] [Technical Errata Reported] RFC5576 (7544)

[Philipp Hancke <[e-mail]>]

>
> On 6/20/23 11:43, Christer Holmberg wrote:
>
> I am not sure I understand your comment, nor the comment from Philipp.
> They seem to be related to some implementation, because I have no idea
> what you refer to when you say "members", "set", "count" and "field"
> :)
>
> Are there implementations that add multiple instance of the same
> ssrc-id value to the sscr-group attribute?
>
> There was one implementation that crashed when someone sent it an
> ssrc-group
> with multiple occurences of the same SSRC, yes. Whether this was an attack
> or a mistake, I don't know.
>
> It would be nice to know WHY it was sent. Perhaps they think it is a valid
> case, which may also have to be dealt with.
>
> I came up with the idea of trying "what happens if" while debugging
unrelated SRTP issues where "is this trying to send RTX on the wrong SSRC"
was the hypothesis.

I do not think it is being used in production, in particular since for FID
https://www.rfc-editor.org/rfc/rfc4588#section-4
already says
   two different SSRC values MUST be used for the original stream and the
retransmission stream
I don't see the same explicit text in RFC 5956 (for FEC-FR) sadly.
cheers

Philipp
(with better quoting hopefully)