Re: [MMUSIC] Single SCTP usage per SDP session?

[Christer Holmberg <[e-mail]>]

Hi,

...

>> But, I also want to be sure that people are ok with such approach. So, 
>> if someone thinks we should use the setup attribute to negotiate which 
>> endpoint initiates the SCTP association, please speak up now :)
>
> <Raju>
> I see that the NAT traversal as a big advantage of both peers attempt to open SCTP association. 
> SCTP INIT chunk will punch holes in NAT box which will then allows incoming INIT CHUNK or INT 
> ACK. All this is possible because SCTP RFC http://tools.ietf.org/html/rfc4960#section-5.2.1 allows 
> such INIT collisions and converts them into a single SCTP association; however the 4-tuple 
> (+additional IPs) should match though.
> This is the issue with a=setup usage for TCP and SDP descriptions (without ICE) specifying only the server 
> port; though TCP allows simultaneous open, per a=setup only one side can initiate TCP conn which will
> not punch a hole in other end's NAT and results in TCP SYN being dropped. 

Not that, in case of 'DTLS/SCTP', the transport layer protocol will be UDP or TCP, and in case of TCP I assume the setup attribute WILL
be used as defined in RFC 4145 when establishing the TCP connection. 

> How about the concern of NATs and hosts not supporting simultaneous SCTP open? there by limiting the success rate?

I have no idea.

(In case of 'DTLS/SCTP' it doesn't matter, though, as the transport layer protocol will be UDP or TCP.)

Regards,

Christer