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This chapter describes how to configure web caching services using WCCP, and includes the following sections:
Web Cache Communication Protocol (WCCP) is a content routing protcol that allows utilization of Cisco Cache Engines (or other caches running WCCP) to localize web traffic patterns in the network, enabling content requests to be fulfilled locally. The purpose of web caching is to reduce latency and network traffic. Previously-accessed web pages are stored in a cache buffer, so if users need the page again, they can retrieve it from the cache instead of the web server.
WCCP specifies interactions between the ASA and external web caches. The feature transparently redirects selected types of traffic to a group of web cache engines to optimize resource usage and lower response times. The ASA only supports WCCP Version 2.
Using an ASA as an intermediary eliminates the need for a separate router to do the WCCP redirection, because the ASA redirects requests to cache engines. When the ASA determines that a packet needs redirection, it skips TCP state tracking, TCP sequence number randomization, and NAT on these traffic flows.
The following WCCPv2 features are supported for the ASA:
The following WCCPv2 features are not supported for the ASA:
In the ASA implementation of WCCP, the protocol interacts with other configurable features according to the following:
Supports Active/Active and Active/Standby failover. WCCP redirect tables are not replicated to standby units. After a failover, packets are not redirected until the tables are rebuilt. Sessions redirected before failover are probably reset by the web server.
Supported in routed and transparent firewall modes.
Supported in single mode and multiple context mode.
Does not support IPv6 traffic for redirection.
The ASA selects the highest IP address configured on any interface as the WCCP router ID. This address is used to establish a GRE tunnel with the cache engine.
WCCP does not support ACLs that include a user, user group, or a fully qualified domain name object.
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Note The ASA selects the highest IP address configured on any interface as the WCCP router ID. This address is used to establish a GRE tunnel with the cache engine.
WCCP redirection is supported only on the ingress of an interface. The only topology that the ASA supports is when client and cache engine are behind the same interface of the ASA and the cache engine can directly communicate with the client, without going through the ASA.
The following configuration tasks assume you have already installed and configured the cache engines that you want to include in your network.
To configure WCCP redirection, perform the following steps:
For example, to enable the standard web-cache service and redirect HTTP traffic that enters the inside interface to a web cache, enter the following commands:
hostname (config)#
wccp web-cache
hostname (config)#
wccp interface inside web-cache redirect in
To monitor WCCP, enter one of the following commands:
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Table 18-1 lists the release history for this feature.
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WCCP specifies interactions between the ASA and external web caches. We introduced the following commands: wccp and wccp interface |