- About This Guide
-
- Information about AAA
- Configuring the Local Database for AAA
- Configuring RADIUS Servers for AAA
- Configuring TACACS+ Servers for AAA
- Configuring LDAP Servers for AAA
- Configuring Windows NT Servers for AAA
- Configuring the Identity Firewall
- Configuring the ASA to Integrate with Cisco TrustSec
- Configuring Digital Certificates
- Index
Configuring Web Cache Services Using WCCP
This chapter describes how to configure web caching services using WCCP, and includes the following sections:
Information About WCCP
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.
Guidelines and Limitations
The following WCCPv2 features are supported for the ASA:
- Redirection of multiple TCP and UDP port-destined traffic.
- Authentication for cache engines in a service group.
- Multiple cache engines in a service group.
- GRE encapsulation.
The following WCCPv2 features are not supported for the ASA:
- Multiple routers in a service group.
- Multicast WCCP.
- The Layer 2 redirect method.
- WCCP source address spoofing.
- WAAS devices.
In the ASA implementation of WCCP, the protocol interacts with other configurable features according to the following:
- AAA for network access will not work in combination with WCCP.
- An inbound access rule always takes higher priority over WCCP. For example, if an ACL does not permit a client to communicate with a server, then traffic is not redirected to a cache engine.
- TCP intercept, authorization, URL filtering, inspect engines, and IPS features are not applied to a redirected flow of traffic.
- When a cache engine cannot service a request and a packet is returned, or when a cache miss happens on a cache engine and it requests data from a web server, then the contents of the traffic flow is subject to all the other configured features of the ASA.
- If you have two WCCP services and they use two different redirection ACLs that overlap and match the same packets (with a deny or a permit action), the packets behave according to the first service-group found and installed rules. The packets are not passed thorugh all service-groups.
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.
Licensing Requirements for WCCP
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Enabling WCCP Redirection
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:
Examples
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
WCCP Monitoring Commands
To monitor WCCP, enter one of the following commands:
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Feature History for WCCP
Table 16-1 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 |