Subject: Re: [Ice] ICE-bis: Question for clarification on frozen candidates and multiple media streams

From: Ari Keränen <[email-masked]>
Date: Sun, 13 Mar 2016 13:37:24 -0700

Hi,

I didn't see answer to this e-mail, so let me try to clarify.

On 22/02/16 02:31, Christer Holmberg wrote:
> Section 2.4 (Frozen Candidates) of draft-5245bis, talking about
> establishing multiple flows, says:
>
> “The network properties are likely to be very similar for each
>
>                component (especially because RTP and RTCP are sent and
> received from
>
>                the same IP address).”
>
> I think this text is unclear.
>
> It could mean that the same IP address is used for all RTP/RTCP flows,
> which does not have to be the case.

That is indeed not the case. Maybe it should say "for each component of 
a media stream" to make it more clear.

> It could mean that RTP and RTCP is sent from the same IP address as the
> associated STUN requests. While that is true, I don’t understand what it
> has to do with multiple flows.

Which flow do you refer to? I assume multiple components (not media 
streams).

> It could mean that, for a given flow, RTP and RTCP are sent from the
> same IP address. Is that always true? And, even if it is, I don’t
> understand what it has to do with multiple flows.

Since RTP and RTCP use different ports but same IP addresses (for the 
same RTP media stream), these two components are most likely treated by 
middleboxes in identical way. Hence, if the first one works, the second 
does too.

Cheers,
Ari