Content Switch Load Balancing Overview

This post provides a basic overview of content switching in the context of a load balancing switch. The basic idea behind the use of a content switch for load balancing is to add performance, scalability, high availability and resilience to a server farm (group or cluster of servers). This way there will be no one single point of failure or SPOF in your system. The users of your system only need to know one IP address - the VIP (virtual ip address) provided by the switch. The addresses of the servers behind the switch are only known to your content switch. The content switch then routes requests to individual servers by inspecting the contents of the requests and then forwarding them to specific servers based on the policies configured for the switch. There are many different load balancing policies that can be implemented by modern content switches. These include:

• sticky session - all requests from one user go to the same server
• load balancing based on file type, eg audio or video
• load balancing based on device type, eg different types of mobile phones
• load balancing can be done on a round robin basis
• the switch can be configured to distribute requests to the least loaded servers

An example of a content switch is the Cisco CSS 11500 Series Content Services Switch. This is a high-performance, high-availability switch used to build Web infrastructures. You can see details of this switch plus many more on the Cisco Website .

In addition a load balancing switch can monitor the health of each server and if a server fails it can exclude the server from receiving any more requests.