Stickiness

Stickiness refers to the ability of a virtual server to associate some set of IP network tuple information to a real server.

A virtual server using stickiness will create a sticky entry when it creates a binding. The sticky entry contains a mapping of client source IP address, and optionally, destination IP and destination UDP/TCP port number, and the real server that was selected. The bindings can come and go but the sticky entries persist using a separate idle timer. When a new request is processed by a virtual server, the sticky table is checked for an entry matching the virtual server's sticky type. If an entry is found, then the load balancing algorithm is skipped and the request is mapped to the sticky entry‘s indicated real server.

In this way a virtual server associates particular clients to a real server for as long as the sticky entry remains in the table.

A sticky entry will only start aging when it has no associated bindings.