Citrix is expected to add WAN optimization to its products with the planned purchase of Orbital Data for $50 million.

The acquisition will give Citrix the ability to tinker with how data is sent over WAN connections so it is transferred more efficiently, giving users the feel that the link is faster. The technology can be deployed either as two appliances, one at each end of a connection, or as an appliance that is contacted by an individual computer running an Orbital Data WAN-optimization software client.

When the purchase is complete later this year, Citrix will start selling Orbital Data gear under the new name - Citrix WANScaler.

The deal makes the fourth major purchase by Citrix in the past year, which includes application firewall vendor Teros, SSL VPN maker Net6, and application acceleration company NetScaler. The common thread of all these acquisitions is that the companies involved sell gear to speed or secure remote access to applications, which is the main thrust of Citrix's light-client remote server technology, MetaFrame.

Citrix had been interested in this type of technology, and had an alliance with WAN optimization vendor Expand until last month when it refused the company admittance to a Citrix conference, saying that Expand's Compass WAN optimization devices compete too closely with the NetScaler range. Citrix currently has a partnership with Packeteer.

Citrix says Orbital Data's gear supports the best performance of Citrix applications over wide area connections. WAN optimization vendors use a variety of means in combination - compression, TCP multiplexing, caching - and some mixes work better than others depending on the types of traffic sent over the connection. So one vendor's gear might speed up transaction performance by 50% while another's might improve it by only 35%, for example.

Orbital Data also has software that optimizes the transfer of specific data types by anticipating the next application request and reducing the amount of traffic that must cross the WAN. For instance, it has software that can reduce the WAN chattiness of Microsoft Common Internet File System (CIFS) traffic.

Orbital Data makes an appliance for branch offices and a larger appliance for data centers as well as client software for individual machines trying to connect to central servers.