When a Communicator Web Access user participates in an instant messaging (IM), audio conference, or a desktop sharing session, messages must be passed back and forth between Communicator Web Access and the user’s home server. This creates a problem for anonymous users because, by definition, anonymous users do not have a home server.
To accommodate anonymous users, Communicator Web Access lets you define a next hop server for each of your virtual servers. A next hop server can be any computer running Office Communications Server 2007 R2. The next hope server acts as a home server for anonymous users, giving Communicator Web Access a place to send messages to and receive messages from.
You must configure a next hop server when you create a virtual server. You can use the Communicator Web Access snap-in to change the next hop server at any time. When selecting a next hop server, keep in mind that if the next hop server fails, Communicator Web Access will fail as well. With this issue in mind, it is recommended that you select a server pool as your next hop server instead of an individual server. By choosing a server pool, you ensure that Communicator Web Access will continue to function even if an individual server in that pool fails.
To configure a next hop server
On a computer that is running the Communicator Web Access snap-in, log on as a member of the local Administrators group and the RTCUniversalServerAdmins group.
Click Start, point to Administrative Tools, and then click Microsoft Office Communications Server 2007 R2, Communicator Web Access.
In the console pane, expand the name of the computer that hosts the virtual server for which you want to specify a next hop server, right-click the name of the virtual server, and then click Properties.
In the Propertiesdialog box, on the Next Hoptab, select a server or server pool from the Next hop pooldropdown.
Type the listening port of the server or server pool in the Portbox and then click OK.
Note: Typically, Office Communications Server uses port 5061 as the listening port.