[Asterisk-Users] IAX2 Asymmetric Latency

[Zdik Kudrle]

> On Sat, 2005-01-29 at 15:48 +0100, Zdik Kudrle wrote:
> 
> > I'm running Asterisk with HFC-S card connected to HW PBX in my office.
> > When I make a call from home using iaxComm connected to Office
> > Asterisk, the outgoing latency is about 0.25 sec, which is quite OK.
> > But to incoming latency begins on 0.5 sec and in a minute it's about 5
> > seconds (!) and growing fast. 
> 
> Just curious: how did you measure that latency? Since I have constant
> trouble especially with iaxcomm <-> * configurations myself.
Well, it will sound funny, my way was kinda amateurish:

I called from my home thru Asterisk to my Cellphone. I've picked up the
phone and set up input channel instead of microphone my TV card. I started
the TV a listened to the latency cellphone<->TV. Then I said something to
phone and listened to the latency cellphone<->Speakers. Simple, but it
works for me. Today I did the same thing without cellphone - somebody was
sitting in the office and answered local call (no calling out, just intra
PBX call). He sent me a message using ICQ and that exact moment said
something to the phone and vice versa. The result was pretty same using
the cellphone...

I don't think my soundcard has latency problems (Live!5.1). The really
strange think is that latency is _increasing_. It means that somewhere all
the data must be stored but I've got no idea where. Maybe I'll run some
crashtest - one part or other will crash with out of memory... :-)

> E.g. currently I have a situation iaxcomm <-> * <-> NAT <-> public *
> with latency issues. If on the other hand I use gnomemeeting instead of
> iaxcomm, all works well.
This sounds promising, I'll give it a try.

> Finally, debugging this stuff, and especially the network traffic and
> protocol interaction, is pretty tedious, so if you could give a hint
> how to best measure network latencies I'd sure appreciate it.
Sorry to disappoint you, I'm not that kind of network magician..



--ZK

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