[Asterisk-Users] Distortion/crackling/skipping problems on outgoing calls -- please help!!!

[Robert Geller]

Rich Adamson wrote:

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>>Thank you very much for your response. I do acknowledge that my previous 
>>posts did not contain much technical information to speak of, but it was 
>>mainly because I wasn't/am not familiar with the Asterisk CLI and 
>>troubleshooting Asterisk problems, so I apologize for that.
>>
>>I did get the idea early this morning to try to analyze packets with 
>>ethereal, and I captured packets when I was made an internal IAX call to 
>>the Asterisk system (voicemail). I don't really know what to look for, 
>>but I will learn (again, I'm not very familiar with ethereal). Do you 
>>hapeople say ve any suggestions for filters to use, to evaluate possible 
>>packet loss or resending of data?
>>    
>>
>
>An important item to look at in each packet is the timestamp. In sip
>packets, the timestamp should be increasing by 160 for each conseq pkt.
>In iax packets, the timestamp should be increasing by 20 for each pkt.
>
>So if you see a timestamp of 3290 in one pkt and 3310 in the next (a diff
>of 20), that's good. Notice the increasing timestamp value and the diff.
>If pkt 3310 arrives before 3290, then something in the network is delaying
>the delivery of packets so as to cause them to not arrive in the proper
>order.
>
>If there are missing packets, then you'll see timestamps jumping by 40,
>60, 80 or some other value (diff) for iax packets, or, similar for sip
>packets.
>
>  
>
>>Regarding the command that you suggested in the CLI, iax2 show netstats, 
>>it doesn't recognize that command or anything similar, and 'help' 
>>doesn't return anything similar that I can see (I'm using 1.0.7 if that 
>>helps).
>>    
>>
>
>Since 1.0.7 is rather old (in the scheme of things), I'd suggest you
>install something newer to play with. There has been a ton of stuff
>that has changed since 1.0.7, but I don't recall if those changes would
>have anything to do with your problem. (I use nothing but cvs head, but
>I kind of keep an eye on how many changes are happening (and for what
>reason), and upgrade when the number of problems seem to be at a low.
>The 'iax2 show netstats' would have been added in a later version.
> 
>  
>
>>At this point, I'm thinking that it could be a matter of bad cabling or 
>>something. The Cat5 cable that's running the 8 or so feet from my PC to 
>>my router is homemade by me, and many people do report problems with 
>>homemade cables. I may not have made it exactly right, or the untwisted 
>>segment may be longer than 1/2", which supposedly causes distortion and 
>>interference. Perhaps I ought to run out and buy a couple factory-made 
>>cables to test the difference, if any, between them.
>>    
>>
>
>Replacing the cable would probably be a good start since they are
>relatively cheap. Go buy a new one so there's no question about its
>quality. Also, keep the cable at least a little distance away from
>transformers, ballasts, and other things that tend to generate tons
>of electical noise. (Some desk lamps even have extremely noisy transformers
>or ballasts in them.)
>
>
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>
Your advice was *extremely* helpful. It seems that I learn something new 
each time I read you all's posts. To me, it looked like each packet was 
correctly sent at the right interval each time, but I didn't evaluate 
each one. However, the general trend is that there seems to be no packet 
loss or resending.

I could buy another cable as well, just to be safe, but it seems to me 
the potential IRQ conflict is more the more likely problem--of course, 
even when I "ifconfig eth2 down"ed the interface, it still showed up in 
/proc/interrupts -- does bringing the interface down not completely 
bring it down? Should I permanently disable it and reboot?

Again, thank you very much for your ongoing help; I feel like I'm paying 
(or ought to) for professional support here. :-)

Regards,
Robert Geller