Wireshark-users: Re: [Wireshark-users] advice on checking/comparing sent vs. received on two mach
From: Hansang Bae <hbae@xxxxxxxxxx>
Date: Thu, 06 Dec 2007 22:02:39 -0500
Trevor Tolk wrote:
I'm going to be testing the QoS of our WAN network.
I've done some user level testing, now I want to do some more in-depth testing. My plan is to saturate the network with non-QoS'd traffic, start running some QoS'd traffic over the wire, then monitor on both ends to verify that QoS'd traffic doesn't get dropped. I've not done a comparison of point A vs. point B before. Does anyone have any advice?

There are two ways you can do this. Method one. Capture on the sending and receiving computers while the link is saturated. It then becomes trivial to compare the sending and receiving side's packet traces. This will allow you to use UDP based testing to ensure QoS is working.

Method two: If you use tcp based testing program, or if your QoS protected traffic is TCP based, you can try the app with and without QoS protection. Since it's tcp based, you'll start to see retransmissions as packet loss occurs. If your QoS is working properly, you should not see any packet loss even when the link is saturated. You can quickly check for tcp events by using the "tcp.analysis.flags" filter. Hopefully, you should see a lot of retransmissions when QoS is turned off and none (or near zero) retransmissions with QoS turned on.

Have fun!