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iperf is great. Another essential troubleshooting tool is
nfsen/nfdump (or any netflow/sflow monitoring utility that shows
DSCP/TOS tag values).<br>
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On 10/28/2013 01:55 PM, Mike wrote:<br>
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cite="mid:alpine.LRH.2.02.1310281353070.28842@arjlbqn.zvpebqry.yna"
type="cite">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.
<br>
<br>
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 (<a class="moz-txt-link-freetext" href="http://iperf.sourceforge.net/">http://iperf.sourceforge.net/</a>) to be a free and
easy starting point, which actually turned out to be all I needed.
<br>
<br>
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.
<br>
<br>
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.<br>
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<pre class="moz-signature" cols="72">--
--
Jules Agee
Senior System Administrator
Pacific Coast Feather Co.
<a class="moz-txt-link-abbreviated" href="mailto:julesa@pcf.com">julesa@pcf.com</a> x284</pre>
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