[asterisk-users] Tired of dropouts and garbled phone calls - where to go next?

[Jules Agee]

iperf is great. Another essential troubleshooting tool is nfsen/nfdump 
(or any netflow/sflow monitoring utility that shows DSCP/TOS tag values).

On 10/28/2013 01:55 PM, Mike wrote:
> As stated in previous replies if you haven't already I would certainly 
> try to isolate the problem, e.g., are extension to extension calls 
> good, is the problem only on outside calls etc.
>
> We are starting our 4th year of VoIP service and have had two 
> seemingly similar episodes to yours during that time.  We are on a 
> non-symmetric cable connection, 20/4 (I believe).  After a few days of 
> "crappy" audio I started looking for some way to 
> characterize/correlate bad audio with something I could measure. I 
> found iperf (http://iperf.sourceforge.net/) to be a free and easy 
> starting point, which actually turned out to be all I needed.
>
> I simply ran a "server" instance on our "cloud" server roughly 1K 
> miles away and a "client" instance locally.  I used the command line 
> swithces that forced udp mode.  This allowed me to see jitter and 
> packet loss in both directions.  We had terrible packet loss in the 
> outbound direction. This didn't show up in normal browsing, emailing 
> etc., kinds of things as I suspect TCP retries masked the problem.  
> With a little persistence with the cable company the second tech found 
> a bad "tap" (I believe) outside at the cable drop.  Replacing that 
> solved our issue for almost two years.
>
> The next time this happened iperf showed a similar packet loss 
> problem. This time it turned out to be "noise in the system" according 
> to the cable tech.  He said it could be from any number of sources but 
> a different team would be out to hunt it down the next day.  In the 
> mean time he changed out our old Moto SB5101 modem for a more modern 
> DOCSIS 3.0 modem.  The multiple channel bonding that it offered was 
> much better at punching through the noise.  That change alone ended 
> crappy audio as well as packet loss as shown by iperf.
>
>

-- 
--
Jules Agee
Senior System Administrator
Pacific Coast Feather Co.
julesa at pcf.com       x284

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