Re: [IPFIX] comments on draft-scholz-ipfix-rtp-msg-00

[Hadriel Kaplan <[e-mail]>]

On Mar 27, 2012, at 1:33 PM, Hendrik Scholz wrote:

>> 3) Some of the IEs imply there's a single SSRC for a flow - are you assuming a flow is by definition the 6-tuple of IP src/dest, port src/dest, transport type, and SSRC?  In other words, if there are two or more SSRCs in the same 5-tuple, would they be separate IPFIX flows? (they're only one "RTP" session from an RTP and SDP perspective)
> 
> Yes, a separate SSRC in between two nodes should be recorded
> in separate records. After all these streams would most likely
> belong to separate calls.

As much as I'd love for that to be the case, technically they might or might not.  For normal voice between two users it's always the case.  But RFC 3550 always supported separate SSRCs in the same RTP session and thus in the same 5-tuple, and RTCWeb and CLUE Working Groups have both been talking about using that ability. (so for example video from multiple cameras goes in the same RTP session, with separate SSRCs)  At least that's what I believe they're thinking of.  And of course even for a normal voice call there could be an SSRC collision, changing the SSRC mid-call.

I'm ok with assuming one, just wondering what we do if we get a second one.  I think you're saying we should treat is as a separate flow from an IPFIX reporting perspective, right?

-hadriel