Understanding Wccp; Wccp Message Exchange - Cisco Catalyst 3560-X Software Configuration Manual

Hide thumbs Also See for Catalyst 3560-X:

Table of Contents

Understanding WCCP

The WCCP and Cisco cache engines (or other application engines running WCCP) localize traffic

patterns in the network, enabling content requests to be fulfilled locally.

WCCP enables supported Cisco routers and switches to transparently redirect content requests. With

transparent redirection, users do not have to configure their browsers to use a web proxy. Instead, they

can use the target URL to request content, and their requests are automatically redirected to an

application engine. The word transparent means that the end user does not know that a requested file

(such as a web page) came from the application engine instead of from the originally specified server.

When an application engine receives a request, it attempts to service it from its own local cache. If the

requested information is not present, the application engine sends a separate request to the end server to

retrieve the requested information. After receiving the requested information, the application engine

forwards it to the requesting client and also caches it to fulfill future requests.

With WCCP, the application-engine cluster (a series of application engines) can service multiple routers

or switches, as shown

This sequence of events describes the WCCP message exchange:

Catalyst 3750-X and 3560-X Switch Software Configuration Guide

Cisco Cache Engine and WCCP Network Configuration

The application engines send their IP addresses to the WCCP-enabled switch by using WCCP,

signaling their presence through a Here I am message. The switch and application engines

communicate to each other through a control channel based on UDP port 2048.

The WCCP-enabled switch uses the application engine IP information to create a cluster view (a list

of application engines in the cluster). This view is sent through an I see you message to each

application engine in the cluster, essentially making all the application engines aware of each other.

A stable view is established after the membership of the cluster remains the same for a certain

amount of time.

When a stable view is established, the application engine in the cluster with the lowest IP address is

elected as the designated application engine.

Configuring Cache Services By Using WCCP

Catalyst 3750-x