On Fri, Sep 20, 2013 at 9:36 AM, Olle E. Johansson oej@edvina.net wrote:
20 sep 2013 kl. 15:16 skrev Kristian Kielhofner kris@kriskinc.com:
I've been spending some time looking at some of the significant changes Apple has made to Facetime in iOS 7. I'm far from an Apple fanboy but some of them are pretty interesting:
- multiplexing everything over a single UDP port
After reading your very good blog entry (thanks!) I suspect that they have gone the extra way and mixed SIP/RTP/RTCP due to carrier grade nats. There's a new RFC describing issues with those and one is a shortage of ports. Every customer gets only a few allocations and only one per common port. ONly one SIP phone on 5060 as an example.
Limiting the number of ports used will not only make firewall traversal easier, it will make CGN traversal easier. While waiting for the real stuff - IPv6.
Blog: http://blog.krisk.org/2013/09/apples-new-facetime-sip-perspective.html CGN RFC: http://www.rfc-editor.org/rfc/rfc7021.txt
/O
Olle,
Great point! I've updated my blog post with this information.
Thanks!