This section describes some of the communication between SteelHead Mobile clients and the Mobile Controller. For more information about the terminology used in this section such as packages, policies, group assignments, and so on, see the SteelCentral Controller for SteelHead Mobile User’s Guide.

A client machine with the SteelHead Mobile client software installed and enabled begins optimizing traffic after it has completed some initial interaction with a Mobile Controller. This initial contact with the Mobile Controller is triggered by the SteelHead Mobile client when it intercepts the first connection that is to be optimized.

The SteelHead Mobile begins by contacting a Mobile Controller that is already included on the list of controllers defined in the policy of the client. In a small deployment, there is probably only one Mobile Controller on the list. In a larger deployment, there might be more than one Mobile Controller. In such a case, the first Mobile Controller contacted is either the one at the top of the list (depending on the endpoint settings in the policy) or one that is chosen at random.

Contact is made through a TCP connection on port 7870. If there are no problems, the Mobile Controller issues a license. If the Mobile Controller does not have a license available, it instructs the client to contact the next Mobile Controller on its list. The SteelHead Mobile client continues through its list of Mobile Controllers, contacting each one in turn, until it receives a license. If no licenses are available, the client continues to try and contact Mobile Controllers every 20 seconds until it receives a license. After a license has been issued, the SteelHead Mobile client can continue to optimize any new connections that it intercepts that match relevant in-path rules in the client policy.

During this initial interaction after a license has been issued, the Mobile Controller takes the opportunity to check the policy that the client already has, and if a newer one exists, the controller automatically downloads it to the client. If a newer policy is downloaded, it takes immediate effect.

The Mobile Controller also checks the current version of the SteelHead Mobile client software, and if a newer version is available for the client, it might prompt the client to update its software. This step can occur differently depending on the way you have configured the endpoint settings for the client policy: for example, if you have a manual update process.

The connection on TCP port 7870 to the Mobile Controller from the SteelHead Mobile client is kept open to allow the client to send updates for reporting purposes (for example, optimized connections, data reduction, and so on). These updates are typically sent every 5 minutes.

If the end user logs off the client machine but there are still optimized connections in the background, the SteelHead Mobile client remains licensed and the connections continue to be optimized.

The Mobile Controller releases the client license under one of the following circumstances:

In this last case, the client instantly requests a license once more if a new connection is intercepted for optimization.

Location awareness enables the SteelHead Mobile client to enter branch mode and may use branch warming. To learn more about these features and how it affects whether licenses are issued, see Location Awareness.