DSCP QoS & Microsoft Office Live Meeting

Today I've double checked the QoS situation with Live Meeting, with the help of my colleague Michael Melling, and here are our conclusions:

DSCP QosEnabled works fine with Office Communication 2007 R2 on Windows XP, Vista and Windows 7, provided you use the latest updated 3.5.6907.37 version. You can use WireShark to confirm the correct DSCP values are being used, as per my earlier blog post. The audio packets and the video packets will have a different DSCP value, so you can give them a appropriate priority over your network.

Now what about Office Live Meeting? We are using the 8.0.6362.128 version, which AFAIK is the latest. If you are running Window XP, then no problem. If you are trying to use Vista or Window 7, then there is a problem, as with those operating systems, Live Meeting fails to set a DCSP code on the packets.

In our tests today, we started a video call in Office Communicator, then switched into 'Share Information Using Live Meeting' mode. This opens the Live Meeting window, but leaves audio & video going through Office Communicator. But as we are in conference mode, all A/V packets are
now going via the OCS server. At this stage DSCP is still working fine. (We also have DCSP enabled on our OCS 2007 R2 server).

Now by clicking the WebCam icon in Live Meeting, you can flip the Video into a separate windows called 'Voice & Video'. (Don't forget you also need to click the 'Join Audio' button). Now Live Meeting is handling the Video, and that's fine if you are using Windows XP. But if you use Vista or Windows 7, a check with WireShark will show none of the UDP packets being sent by Live Meeting have a DSCP value - they are all marked 0x00.

To me that looks like a bug in Live Meeting.

There is a partial work around. Using Group Policy on Vista and Window 7, you can force all packets generated by a particular application to use a DSCP value that you specify. Unfortunately this does not allow you to differentiate between Audio and Video.

Here are a couple of screen-shots were I setup a local group policy on a Vista PC, so that any UDP packets sent by Live Meeting are given a DSCP value of 56'd. I used that value just while testing, to differentiate then from the A/V packets from Office Communicator.