The app cookie mode of persistence can be applied to any virtual service with an attached HTTP application profile. With this persistence method, the Avi Load Balancer does not insert its own cookie into HTTP responses for persistence. Instead, it relies on either an existing cookie that is inserted by the server, or a header. If the specified cookie does not exist in the client request, the Avi Load Balancer looks for a URI query of the same name and persists on that value. This persistence is performed on an ASP or a Java session ID.

Using session ID, servers do not have control over whether a client will accept a cookie. For this purpose, they can choose to embed the session ID in both a cookie and the URI. Older browsers or clients from Europe can skip the cookie and still include the session ID within the query of their requests. For this reason the Avi Load Balancer automatically checks both locations.

Once an identifier has been located in a server response and a client’s request, the Avi Load Balancer creates an entry in a local persistence table for future persistence like below:

www.avinetworks.com/index.html?jsessionid=a1b2c3d4e5

Note:

This method involves using an existing server cookie. For the Avi Load Balancer to use its own cookie for persistence, use the HTTP Cookie persistence mode, which is straightforward and more scalable.

See Persistence for descriptions of other persistence methods and options.

Persistence Table

Since app cookie persistence is stored locally on each SE, larger tables consume more memory. For very large persist tables, consider adding additional memory to the SEs through the SE Group properties for SE memory and the SE Group > Connection table setting.

The app cookie persistence table is automatically mirrored to all SEs supporting the virtual service using a pool configured with this persistence type.

Configuration Options

For details on fields for configuring App Cookie persistence profile, see Avi Load Balancer  UI Configuration Options under HTTP Cookie Persistence. Ensure that App Cookie is selected from the Type drop-down menu.