Re: [MMUSIC] Trickle ICE

[Bernard Aboba <[e-mail]>]

On Oct 10, 2012, at 11:18, "Christer Holmberg" <[e-mail]> wrote:

Q1: Remote endpoint support (SIP):
> --------------------------------------------
> 
> You say that, before the first offer is sent, one SHOULD determine whether the remote endpoint supports trickle ICE. 
> 
> For SIP, you give RFC 3840 as an example. I am not sure how that will work. Yes, you can use 3840 to request that the offer is sent to an entity which supports trickle ICE (for that, btw, you will also need to define an option tag, or something similar), but you cannot use it to determine whether the remote endpoint supports trickle ICE. In addition, you typically use 3840 at the same time when you send the initial offer.
> Of course, you could use SIP OPTIONS. But, there are a number of issues related to that, and I don't think we want to define a mechanism which relies on the usage of OPTIONS.

I think the idea originated from the RFC 5768 use of sip.ice, such as in a Require header in an INVITE request, Contact header in a REGISTER request or OPTIONS response. Some of the scenarios mentioned there include gateway scenarios in Section 3.1.