Re: [rtcweb] Transports questions on IPv6

On Wed, Mar 5, 2014 at 3:55 PM, Simon Perreault <simon.perreault@viagenie.ca
> wrote:

> Since you asked for more...
>
> Le 2014-03-05 14:56, Justin Uberti a écrit :
> > which path (v6-to-TURN or v6-from-TURN) should be prioritized?
>
> I'm sorry, I don't understand this question.
>

Imagine I am a v6-only endpoint. Via IPv6, I allocate 2 ports on the TURN
server, v4 and v6. The remote client is v4-only, and via IPv4 it also
allocates v4 and v6 on its TURN server. So we need to relay to connect v4
and v6. Which path should be preferred?

a) Caller -- TURN/v6 --> TURN Server(Caller, v4 alloc) <-- v4 -- Callee
[ Caller candidate is relay, Callee candidate is host ]
b) Caller -- v6 --> TURN Server(Callee, v6 alloc) <-- TURN/v4 -- Callee
[ Caller candidate is host, Callee candidate is relay ]

I worked this through and I think ICE will choose (b), due to the (G>D?1:0)
tiebreaker, which seems right to me. So no action needed :)

> > Note also that these v4->v6 or v6->v4 allocations will be dependent on
> the SSODA work being discussed in TRAM, since this is the only way to
> allocate v4 and v6 TURN from a single host candidate.
>
> I don't understand what you mean.
>

I was assuming that WebRTC endpoints will need to do cross-family
allocations, to handle the case where they are talking to a v4-only or
v6-only endpoint and they are not v4- or v6- capable. If so, the transports
draft will need to reference the SSODA work once it becomes a WG item,
since I don't think WebRTC endpoints should create additional sockets to do
cross-family allocations (we have enough sockets already, as shown below).

> > Also worth noting:
> >
> > With the current default settings, a single STUN and TURN server, and
> assuming a dual-stack host with two network interfaces, a PeerConnection
> with audio, video, and data will generate
> >
> > 5 (components) * 4 (local-udp+stun+turn+local-tcp) * 2 (interfaces) * 2
> (IP protocols) = 80 candidates
>
> It's....... it's beautiful!
>
> Simon
> --
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>
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