[Asterisk-Dev] IAX2 trunk really should send timestamps as part of iax2_meta_trunk_entry..

[Matt Riddell]

Andrew Kohlsmith wrote:
> On January 20, 2005 07:07 pm, Steve Kann wrote:
> 
>>To play devil's advocate against my own suggestion (I've thought about
>>this a bit since I wrote that), the problem is that you now have two
>>choices:
> 
> 
>>1) Put the timestamps at the beginning of the frame:
>>      This will likely end up meaning copying stuff around when we send,
>>because we won't know how big the timestamp stuff is.    But, it's easy
>>for the receiver to deal with..
> 
> 
>>This could be solved if there's a writev-equivalent way to send packets
>>from discontinuous areas of memory...
> 
> 
>>Or, we could just eat the memmove :)
> 
> 
> Well the entire basis behind Zaptel (and asterisk in general) is that CPU 
> power is cheap.  While we can't be flippant about it, I really don't think 
> that a simple memmove or few per trunk frame is going to be all that 
> terrible.
> 
> 
>>2) Put the timestamps at the end of the frame:
>>     This is easy to send, but then the receiver needs to walk through
>>all the meta entries to the end, to see _if_ there's timestamps there,
>>and then read them, before processing all the meta entries..
> 
> 
> My personal opinion is that #2 is better.  The receiver would copy the trunk 
> frame's "master" timestamp to each demuxed channel and then, upon finding the 
> meta entry could copy the "per channel" timestamp from the meta entry to the 
> appropriate channel's timestamp.  That should not be any different from the 
> normal operation unless a meta entry is detected.

Wouldn't this reduce the badwidth savings offered by a trunked connection?

-- 
Cheers,

Matt Riddell
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