Chances are that, if you live in one of the green countries from the picture below (courtesy of Wikipedia), and if you tried to setup the OCS 2007 R2 Edge server role, you probably felt the frustration, combined with a little bit of despair and asked yourself at some time: “Am I going nuts?”, “Did I suddenly lose my skills?” or “Did I fell into a wormhole and I am now living in a parallel Universe?”.
Why only the green countries? I will explain in detail shortly, but in order not to create too much suspense, let me just say that these countries use a comma "," as the decimal separator and not a period ".".
I've been planning on blogging about this issue for some months now, but for one reason or another, I didn't manage to do it until now. Meanwhile, some other people decide to share their experiences about the very same issue, writing them in some blog posts that I would like to recommend:
I would also like to add that there is now a permanent fix for the problem I'm about to describe.
Imagine the perfect installation of OCS 2007 R2, where all the requirements were met, where every single detail was taken care of, where every step of the official deployment guide was followed. But, at the very end, in the test phase, you taste the bitter taste of failure as some errors emerge:
A/V Authentication Edge Server: Could not contact A/V Authentication Edge Server. To resolve this error, check for the following 1. The outbound proxy is reachable. 2. The outbound proxy and A/V Authentication Edge Server are in trusted server list of each other. 3. The outbound proxy and A/V Authentication Edge Server have valid certificates. 4. Conference Server certificate is valid. 5. A/V Authentication Edge Server Gruu is correct.
Although OCS has lots and lots of (good) troubleshooting tools, sometimes it's not easy to spot the error, even when it is right in front of your eyes.
Analyzing the Communicator log from the external user, revealed the "Version Mismatch" error. The error has to do with localization (decimal separator), which caused a string comparison to fail: "2,0" with a comma it's different from "2.0" with a period! I must confess I would never get there without the help from a Microsoft colleague.
Here's the relevant excerpt from the communicator log and a glance of the Snooper Tool:
<?xml version="1.0"?> <response xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" requestID="37875240" version="2,0" serverVersion="2.0" to="sip:firstname.lastname@example.org; gruu;opaque=srvr:MRAS:TIS6zHHx10mnGGNqE01JjwAA" from="sip:email@example.com" reasonPhrase="Version Mismatch" xmlns="http://schemas.microsoft.com/2006/09/sip/mrasp" />
To workaround this problem, change the locale setting to English/US for the local account that the A/V Edge service and the A/V Edge Authentication service use (RTCProxyService).
Fortunately, the April updates for Communications Server 2007 R2 include a patch for this specific problem. Read the following KB article for more information: The Communications Server 2007 R2 - A/V Edge Authentication Server does not recognize a token request if the locale for RTCProxyService is not en-US/409 (and then apply the KB967831 hotfix).
When you apparently reached a dead-end and start doubting about yourself, you usually start trying some silly things. One of the approaches I took was to add the OCS Edge server to the list of authorized hosts. Don’t do this!!! The Edge server should never be placed in the Host Authorization tab, doing so will break the communication workflow.
At the beginning of the troubleshoot process, my prime suspect was NAT, since I was using for the first time one of the coolest features of OCS 2007 R2 (the A/V Edge interface can now be NAT'ed) and the symptoms were typical of NAT'ed A/V Edge interface.
There are some requirements for this particular configuration to work, I strongly recommend the reading of the excellent post by Rick Varvel: Configuring R2 A/V Edge Service for NAT.
At the end, NAT had nothing to do with the problem, I can assure you this features works perfectly.
The Butterfly Effect has origin in chaos theory and describes how small variations of the initial condition of a dynamical system may produce large variations in the long term behavior of the system. The phrase refers to the idea that a butterfly's wings might create tiny changes in the atmosphere that may ultimately create a tornado in a certain location.
In other words, sometimes a comma makes all the difference!
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