If you get the packet capture into Wireshark, you can (in addition to checking for the DSCP == EF) measure the latency to see if QoS is doing its job.<br><br>From a router, though, you can check your policy maps with "show policy-map" or "show policy-map interface", it will tell you if a policy is applied and what it's doing. You're looking for a priority queue.<br>
<br>The Cisco QoS SRND is a good way to understand QoS. It's hefty, but most of the details are duplicated for every model of switch.<br><br>Sean<br><br><div class="gmail_quote">On Mon, Jan 5, 2009 at 4:07 PM, James Buchanan <span dir="ltr"><<a href="mailto:jbuchanan@ctiusa.com" target="_blank">jbuchanan@ctiusa.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div link="blue" vlink="purple" lang="EN-US">
<div>
<p><span style="color: rgb(31, 73, 125);">Hi John,</span></p>
<p><span style="color: rgb(31, 73, 125);"> </span></p>
<p><span style="color: rgb(31, 73, 125);">The biggest thing you are
looking for is that the voice traffic is being marked and that the marking is
being recognized throughout the network. A packet capture is the quickest way
to determine this. In the packet capture, you will see a field for
Differentiated Services. For traffic that is the actual audio payload, you
should see the Differentiated Services field as Expedited Forwarding. You will
want to check packets going in each direction. </span></p>
<p><span style="color: rgb(31, 73, 125);"> </span></p>
<p><span style="color: rgb(31, 73, 125);">On the switches, for ports that have
a phone plugged in you should see that the switchport is configured to trust
cos and is configured to trust based on the device being a cisco phone (mls qos
trust cos and mls qos trust cisco-phone). What these commands look like can
vary according to the model of switch. </span></p>
<p><span style="color: rgb(31, 73, 125);"> </span></p>
<p><span style="color: rgb(31, 73, 125);">For any connection that is a
voice server or voice gateway, the switchport should trust the dscp value (mls
qos trust dscp). This should also be true on uplinks from switch to switch and
from switch to WAN router.</span></p>
<p><span style="color: rgb(31, 73, 125);"> </span></p>
<p><span style="color: rgb(31, 73, 125);">On the WAN router, depending
upon the speed of your connection you should be using some sort of low latency
queuing and/or traffic shaping.</span></p>
<p><span style="color: rgb(31, 73, 125);"> </span></p>
<p><span style="color: rgb(31, 73, 125);">Thanks,</span></p>
<p><span style="color: rgb(31, 73, 125);"> </span></p>
<p><span style="color: rgb(31, 73, 125);">James</span></p>
<p><span style="color: rgb(31, 73, 125);"> </span></p>
<div>
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<p><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;"> <a href="mailto:cisco-voip-bounces@puck.nether.net" target="_blank">cisco-voip-bounces@puck.nether.net</a>
[mailto:<a href="mailto:cisco-voip-bounces@puck.nether.net" target="_blank">cisco-voip-bounces@puck.nether.net</a>] <b>On Behalf Of </b>Weigand, John
V.<br>
<b>Sent:</b> Monday, January 05, 2009 4:02 PM<br>
<b>To:</b> <a href="mailto:cisco-voip@puck.nether.net" target="_blank">cisco-voip@puck.nether.net</a><br>
<b>Subject:</b> [cisco-voip] How to check for QoS?</span></p>
</div>
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<p> </p>
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<p style="text-align: right;" align="right"><span style="color: navy;"><a href="http://www.medicineforthedefense.com/" target="_blank"><span style="font-size: 10pt; color: olive;">Serious
Medicine for the Defense ®</span></a></span><span style="font-size: 10pt; color: olive;"> </span></p>
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<p><span style="color: black;">I've been tasked with checking
to see if our VAR ever setup any QoS at all, and if so, what type and how
it's set. Unfortunately, although I've become fairly proficient at
CallManager itself, I'm pretty new to the inner workings of everything at
the actual network level.</span></p>
<p><span style="color: black;"> </span></p>
<p><span style="color: black;">I know there's a few different
ways to set it all up, and I've tried poking around, but I'm not really
even sure where to begin looking. Does anyone have any pointers as to how I
might be able to track down some of this info? Is there anything I can tell
from a packet capture of a call from between two of our sites? I do also
have read only access to the switches/routers on the network. </span></p>
<p><span style="color: black;"> </span></p>
<p><span style="color: black;">Thanks in advance!</span></p>
<p><span style="font-size: 12pt; color: navy;"> </span></p>
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<p style="margin-bottom: 12pt;"><b><span style="font-size: 10pt; color: navy;">John
V. Weigand</span></b><span style="font-size: 10pt; color: navy;"><br>
</span><span style="font-size: 7.5pt; color: navy;">Help Desk Support/Executive Support<br>
</span><span style="font-size: 7.5pt; color: black;"><br>
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300 Allen-Bradley Drive<br>
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<br>
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</span><span style="font-size: 7.5pt; color: black;">Tel:</span><span style="font-size: 7.5pt; color: navy;"> 440-484-2000</span><span style="font-size: 10pt; color: navy;"><br>
</span><span style="font-size: 7.5pt; color: black;">Fax: 440-484-2009<br>
Cell: <br>
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