Unified Communications

Recently I went through the trouble of trying to determine why my Lync 2010 client was showing an Exchange Integration error. I knew EWS was working correctly. None of the configuration had been changed, yet somehow something had changed.  I went through most of the available solutions such as these

http://www.confusedamused.com/notebook/lync-claims-ews-not-deployed/

http://sparesomeexchange.com/how-lync-2010-obtains-exchange-web-services-ews-url-via-autodiscover-in-exchange-2010/

 

http://lyncuc.blogspot.com/2013/01/lync-and-exchange-web-services-ews-and.html

One of the things I noted while troubleshooting this was that Lync clients were behaving differently than they did since the last time I experienced a problem like this which was a few years ago. Back then, The Lync client would fall back to UCMapi and connect directly to the configured outlook mailbox. But this did not work for every EWS case I experienced.

 

This time around in almost all cases, this was the case, Lync client fails on EWS and falls back to EWS. Why worry about this? Because my users Lync availability is broken. When EWS is broken, Lync client does not automatically display presence status based on Outlook. Lync uses EWS to display presence status.

Iam not wireshark or Microsoft Netmon guru, but I gathered some traces and tried as best as I could to follow them through. Wireshark showed me that DNS resolution was working correctly, the Lync client was getting to the Auto Discovery for Exchange as per design and requesting Autodiscover.xml file correctly. However the response from the exchange server was a redirect to the /owa virtual directory. 

The highlighted entry shows that we got a redirect to some location in response to our request

Examining the redirect, we have been redirected to the login page for outlook web access

This immediately rang a bell, either my F5 HLB Loadbalancer  or Exchange Servers were redirecting all exchange Virtual Directory to the Outlook Web Access. I quickly ruled out F5 and zoomed in on Exchange and yes there it was. Exchange was configured to redirectly all subdirectory to Outlook Web Access.   Upon removing the redirection from the AutoDiscover and EWS Virtual Directory, Lync was happy again to connect to EWS.

 

Who has been here?