[Asterisk-Users] Maximum tollerable lag/jitter for IAX2w/ojitterbuffer enabled?

[Scott Laird]

On Sep 7, 2004, at 7:15 PM, Chris wrote:

>
>> Asterisk never ever uses TCP for IAX or IAX2.  It's ALWAYS UDP.  I 
>> don't
>> believe Asterisk supports SIP over TCP either.  Heck, the manager port
>> is the only thing that uses TCP that I know of with Asterisk.
>
> Hmmm I wonder why I had the impression that it was TCP... You're 
> right...
> Still, because UDP is connectionless and stateless it still won't 
> disconnect
> on a LAG spike. I've had UDP sit there and send packets at my machine 2
> hours after it had been shut down...

You *really* don't want it to be TCP.  Think about how TCP reacts to 
packet loss--it keeps retransmitting the dropped packet and delays 
everything after it until the dropped packet arrives.  Now imagine what 
that'd do to phone calls--among other things, you'd have 
ever-increasing delay times, and there's no way to catch back up--after 
even a small amount of packet loss, the call would be unusable.

TCP's a wonderful protocol, just not for real-time traffic.


Scott