Load Balancing Methods

This document gives a brief explanation of the different load balancing methods. The SOURCE_IP load balancing method determines which server gets the traffic of a new session. The SOURCE_IP session persistence option determines the destination for an existing session, based solely on the source IP rather than based on a cookie.

Types of algorithms:

ROUND_ROBIN

• Each server is used in turn, according to their relative weights.

SOURCE_IP

• The source IP address is hashed and divided by the total weight of the running servers to designate which server will receive the request.

LEAST_CONNECTIONS

• The server with the lowest number of connections receives the connection.

Here’s a figure showing the Create Load Balancer menu, where you can select an option. In this view, the user is selecting from the SOURCE_IP options.

Here is an explanation of the session persistence options:

Types of session persistence:

SOURCE_IP

• All connections that originate from the same source IP address are handled by the same member of the pool.

HTTP_COOKIE

• The load-balancing function creates a cookie on the first request from a client. Subsequent requests that contain the same cookie value are handled by the same member of the pool.

APP_COOKIE

• The load-balancing function relies on a cookie established by the back-end application. All requests with the same cookie value are handled by the same member of the pool.

For further information, please see: http://docs.openstack.org/admin-guide/networking-introduction.html#load-balancer-as-a-service-lbaas-overview