Configuring LCS 2005 w/ SP1 for Multiple Domains

Automatic configuration allows Communicator to find and connect to the appropriate LCS server without manually entering a server name into its settings. Communicator has special requirements for DNS and certificates to make this work properly.  This bulletin details those requirements.  Manual configuration or using GPOs does not apply to this topic. Why all the fuss?  […]

Automatic configuration allows Communicator to find and connect to the appropriate LCS server without manually entering a server name into its settings. Communicator has special requirements for DNS and certificates to make this work properly.  This bulletin details those requirements.  Manual configuration or using GPOs does not apply to this topic.

Why all the fuss?  You might be asking yourself that question.  Basically, it boils down to how Office Communicator locates and connects to an LCS server or pool.  In simplest terms, Office Communicator is designed to make sure it connects to a server in the same domain as its logon ID or SIP URI.  If my logon id is chanb@consolidatedmessenger.com then Communicator expects to be able to logon to a server with a Full Qualified Domain Name (FQDN) in the same domain; ex. Lcspool01.consolidatedmessenger.com. 

So, you need to have DNS service records for each domain you are supporting and those service records need to point to FQDNs with matching domains.  This holds true for internal clients and external clients.  Below we take a look at both.

Supporting Internal Clients: To illustrate the requirements we will use a sample customer situation.  Consolidated Messenger is a large organization, requiring an Enterprise Pool.  Notice that the Pool name differs from the computer FQDN.  For an Enterprise Edition deployment we require a hardware load balancer using a Virtual IP (VIP) address for the Pool name. Here are the basic settings: 

Hosting Domain – na.consolidatedmesssenger.com
LCS Computer FQDN – server1.na.consolidatedmessenger.com
LCS Pool Name - Lcspool.na.consolidatedmessenger.com
LCS Pool IP address – 192.168.1.100
LCS Computer IP address – 192.168.1.101
Supported SIP Domains
Na.consolidatedmessenger.com (default inherited from AD)
Adataum.com
AlpineSkiHouse.com
Contoso.com
Fabrikam.com
Litwareinc.com
WingTipToys.com

NOTE: For this scenario the “hosting” domain (Consolidated Messenger) is not used for IM. This is common as the AD domain is inherited but not used for IM.

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OCS, Office Communications Server, LCS Server, Domains, FQDN, Virtual IP, Tips and Tricks, Knowledgebase