Understanding Stateless Load Balancing for the AIS Server (Tools Release 9.2.5.2)

Overview

The Secure Session Balancing across AIS Servers feature (9.2.5.2) provides stateless load-balancing, which enables AIS servers to share sessions across multiple load-balanced AIS server instances.

Without Stateless Load Balancing, an established session can be used only by the AIS Server on which the session was established. The load balancer relies on configured session affinity to route requests to the same server every time when an established session is used. Sessions are retrieved using the AIS token and without Stateless Load Balancing, as you can see in the following image a single session is retrieved, which is represented here by “T”:

When Stateless Load Balancing is applied, a session is spread across all the participating nodes in the cluster. The same AIS token is used to retrieve the session on any of the participating nodes. Cookies or other mechanisms that provide session affinity must not be used or configured to ensure that the load balancer can balance requests across all the available nodes. As the session is already established and managed, user authentication is not required for each request, and this simplification improves the performance of each call compared with a traditional stateless call for which credentials have to be entered every time.