In an earlier blog post I wrote about Using an F5 LTM Load Balancer for Reverse Proxy with Lync 2013. This works fine for the domains that you have entered when configuring the Lync 2013 iApp in the F5.

If you have multiple SIP domains and thus multiple Simple URLs like meet.contoso.com, meet.fabrikam.com and meet.alpineskihouse.com it doesn’t work out-of-the-box and your Lync client will fail using these URL’s.

To get this working you have to manually configure the Lync Revese Proxy iRule in the F5. To do this you first have to disable Strict Updates, otherwise updating the iRule will fail (for security reasons this makes sense).

When Strict Updates is disabled navigate to the proper iRule as shown in the following figure:

You’ll notice that the initial FQDN’s are configured here, in our example for lyncweb, meet, dialin and lyncdiscover. To get this working for other URL’s just add the other domains and you’re done (and don’t forget the lyncdiscoverinternal name).

When done, don’t forget to enable Strict Updates again, just in case…