CLUSTERS

Setting up cluster access for mobile users
You can give mobile users the benefits of a cluster by setting them up to access the cluster through a passthru server. The passthru server can redirect the users to a different server in the cluster if the original server is busy or not available. Unless you use a passthru server, users will have to dial each cluster server individually and will not fail over if the server they call is not available.

The following figure shows a mobile client calling a passthru server and having access to any server in a cluster. When connecting to the cluster in this way, failover and workload balancing are available to the mobile client.

Routing a mobile client through a passthru server to a cluster

Because mobile clients can typically call only one server at a time, they cannot take advantage of a cluster of passthru servers. However, you can set up a hunt group of passthru servers to ensure that mobile clients have high availability to passthru servers.

If you do not have access to a passthru server, users can still use their Replicator page to simulate failover if a cluster server is down. To replicate a mail database, for example, set up the Replicator page to call and replicate with the user's mail server, and then call and replicate with the server that contains the user's replica mail database. That way, if either server is available, the user will have access to the mail database. The call to the second server will take very little time if the first call was successful.

The following figure shows a mobile client calling Server 1, which is the user's mail server, and then calling Server 2, which contains a replica of the user's mail database.

Simulating passthru for a mobile client