The patent does not cover all cookies. Entitled 'Cookie Persistence,' it covers a system that uses a cookie stored on a customer's computer to allow the customer to reconnect to the same server previously visited at a web site. This is relevant to large web sites that are operated from a pool of servers.
The system is important, for example, where a customer adds items to a shopping cart at a web site, then leaves the site before completing the transaction. When the customer returns, Cookie Persistence allows a traffic management device to direct the customer to the server that has stored the customer's shopping cart information, allowing the customer to complete the transaction.
Without Cookie Persistence, the traffic management device could direct the customer's request to a different server, which may not know about the customer and his shopping cart status.
F5 introduced its Cookie Persistence system to the traffic management market in 1999. It announced its patent grant on Wednesday and said that it has filed a patent infringement lawsuit against rivals Array Networks, NetScaler, and Radware in the US District Court in Seattle.
The patent is available on this page of the US Patent Office web site.