[Asterisk-Dev] SIP/IAX repacking cpu cost?

[Kevin P. Fleming]

Roy Sigurd Karlsbakk wrote:

> someone (zoa?) at #asterisk mentioned that SIP/IAX repacking (no 
> transcoding) might be CPU consuming due to lack of tuning. Can this be 
> fact?

That was me, and it had nothing to do with "lack of tuning". You asked 
how many simultaneous channels Asterisk could support in your situation, 
and I asked if it was SIP-SIP or SIP-something else.

SIP-SIP induces very little load on the CPU when the media path is not 
going through Asterisk, and even when it is it is a very simple code 
path (all inside rtp.c).

SIP-IAX on the other hand requires queuing and dequeueing frames between 
two different channel drivers. There is no way this can be as efficient 
as the frames staying inside a single channel driver (or protocol 
driver, in this case), no matter how much "tuning" may be done.