User Manual

Web Caching
352 Enterasys X-Pedition User Reference Manual
Web Caching
Web caching provides a way to store frequently accessed Web objects on a cache of local servers.
Each HTTP request is transparently redirected by the X-Pedition to a configured cache server.
When a user first accesses a Web object, that object is stored on a cache server. Each subsequent
request for the object uses this cached object. Web caching allows multiple users to access Web
objects stored on local servers with a much faster response time than accessing the same objects
over a WAN connection. This can also result in substantial cost savings by reducing the WAN
bandwidth usage.
Note: The X-Pedition does not act as cache for web objects; rather, it redirects HTTP requests to
local servers on which web objects are cached. Implementing a Web Cache configuration
requires users to configure a “routed” network with IP interfaces that allow the router to
send requests for the Internet to the correct Web Caching Device.
Configuring Web Caching
The following are the steps in configuring Web caching on the X-Pedition:
1. Create the cache group (a list of cache servers) to cache Web objects.
2. Specify the hosts whose HTTP requests will be redirected to the cache servers. This step is
optional; if you do not explicitly define these hosts, then all HTTP requests are redirected.
3. Apply the caching policy to an outbound interface to redirect HTTP traffic on that interface to
the cache servers.
Creating the Cache Group
You can specify either a range of contiguous IP addresses or a list of up to four IP addresses to
define the servers when the cache group is created. If you specify multiple servers, load balancing
is based on the destination address of the request. If any cache server fails, traffic is redirected to
the other active servers.
To create the cache group, enter the following command in Configure mode:
Note: If a range of IP addresses is specified, the range must be contiguous and contain no more
than 256 IP addresses.
Create the cache group.
web-cache <cache-name> create server-list <server-list-
name>
range <ipaddr-range>|list <ipaddr-list>