Using Transparent Web Cache Balancing (TWCB) on Your Network

Transparent Web Caching is a means of transparently redirecting a client's IPv4 or IPv6 HTTP traffic to a cache server that will service the client's HTTP requests. The cache stores HTTP information and tries to service the client's requests with the information it has stored. For most networks, web services are the primary consumer of network bandwidth. Web caching reduces network traffic and aides in optimizing bandwidth usage by localizing web traffic patterns, allowing content requests to be fulfilled locally. Web caching allows end-users to access web objects stored on local cache servers with a much faster response time than accessing the same objects over an internet connection or through a default gateway. This can also result in substantial cost savings by reducing the internet bandwidth usage.

Transparent Web Cache Balancing (TWCB) provides a means of load balancing HTTP requests over a server farm (a group of servers) or web caches.

TWCB adds three important elements to standard web caching: transparency, load balancing, and scalability:

• In standard web caching, network users must set their browsers to cache web traffic. Because web caching is highly sensitive to user preference, users sometimes balk at this requirement, and the inability to control user behavior can be a problem for the network administrator. TWCB is said to be transparent to the user because web traffic is automatically rerouted, and the ability to configure caching is removed from the user and resides instead in the hands of the network administrator. With TWCB the user can not by-pass web caching once set up by the network administrator. On the other hand, the network administrator can add users for whom web caching is not desired to a host redirection list, denying these users access to TWCB functionality.
• In standard web caching, a user-cache is configured and assigned to a single cache server. TWCB provides for load balancing across all cache servers of a given server farm that can be configured for heavy web-users using a predictor round-robin algorithm.
• Scalability is provided by the ability to associate multiple cache servers with the web cache. This scalability is further refined by the ability to logically associate cache servers with multiple server farms.