[Asterisk-Users] AArgh, * and the 7960

[Brian Cuthie]

brian k. west wrote:

>>You know, I'm not so sure this is limited to chan_capi. I have two
>>asterisk boxes running, with one connected to my PSTN gateway (also
>>using Asterisk).  1.0 stable works fine with my Cisco phone. CVS head
>>works if I comment out the offending lines. Without commenting them out,
>>the cisco phones drop packets like crazy. No chan_api is involved.
>>    
>>
>
>I use two 7960s daily with cvs-head out two cisco gateways and in and out
>via nufone IAX2 without issues.
>
>The question is what is diffrent about your setup vs mine?
>
>  
>
That's a good question. Let me describe my setup and when the problem 
occurs and when it doesn't and maybe it'll help in figuring out what's 
really going on here.

I have something that looks like this:

[PSTN Gateway *] <-- 100Mb Ethernet --> [Systemix * svr] <--  public 
Internet --> [local * server] <-- 100Mb Ethernet --> [Cisco 7960]

(All inter-Asterisk communication is done using IAX)

In this configuration with the cvs head from 5/9 the Cisco phone works 
horribly (dropped/repeated? packets) unless I comment out the timestamp 
check in rtp.c. Stable seems to work pretty well. Now if I change the 
config so that it looks like this:

[PSTN Gateway *] <-- 100Mb Ethernet --> [Systemix * svr] <--  public 
Internet --> [Cisco 7960]

Things seem to work ok without having to make changes to rtp.c. So I've 
had a suspicion that it has something to do with delay or jitter that's 
introduced in the IAX channel that goes over the public Internet. But, 
as you say, this works fine for you. Could it be the extra * in the 
middle? That's one difference between our setups.

Now the big unknown here is which version of * my PSTN provider is 
running. I've asked them. I'm hopeful I'll eventually get an answer.

>>And as far as 'fixing' it goes, I would love to. I'm not without the
>>skill. But, while Asterisk is almost unbelievable in its features set,
>>some of the code is damn hard to grok. Some source files have as many as
>>8000 lines with virtually *no* comments. I don't think I've seen a
>>single function with a preamble describing what it does, or how it works.
>>    
>>
>
>Look at the .h files in include/asterisk/
>  
>
I have, and while there is some documentation there, it's limited and 
does little to explain the actual code.

-brian