[Nice] Gracefull fallback, renegotiations?

Rémi Denis-Courmont remi.denis-courmont at nokia.com
Thu Jul 3 23:29:30 PDT 2008

On Thursday 03 July 2008 19:25:13 ext mikhail.zabaluev at nokia.com, you wrote:
> >Will there be always only one socket per component/transport/af? So
> >whichever local candidate we pick doesn't matter since they'll all be
> >sending the exact same packets?
> Don't you have to bind to every local interface, in order to send candidate
> checks properly? It might matter with VPN and IP migration.

Well, we _could_ sendmsg with IP_PKTINFO/IPV6_PKTINFO ancilliary data to set 
the source address per-packet. Also on Linux you can re-bind UDP sockets.

So we _could_ deal with multiple network interfaces with only one socket per 
component/transport/family. Considering that we only have one transport 
(UDP), and that (on Linux) you can send IPv4 datagrams on IPv6 socket, we 
could in principle do with a single socket per component.

Kai and I had been thinking it would be better to support multiple sockets 
because ICE-TCP would definitely require it, anyhow. But but... ICE-TCP does 
not seem to be going anywhere at the moment, due to poor support from the 
NATs. And we don't have a "customer" for TCP at the moment (file 
transfers??). And ICE-TCP is way more complicated than ICE-UDP (that tells 
something!), so I guess we'll skip that for the time being.

Rémi Denis-Courmont
Maemo Software, Nokia Devices R&D

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