ASDM Book 1: Cisco ASA Series General Operations ASDM Configuration Guide, 7.2

Web Cache Services Using WCCP

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This chapter describes how to configure web caching services using WCCP, and includes the following sections:

• Information About WCCP
• Guidelines and Limitations
• Licensing Requirements for WCCP
• Adding or Editing WCCP Service Groups
• Configuring Packet Redirection
• WCCP Monitoring
• Feature History for WCCP

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.

ASA Implementation of WCCP

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.

Failover Guidelines

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.

Firewall Mode Guidelines

Supported in routed and transparent firewall modes.

Context Mode Guidelines

Supported in single mode and multiple context mode.

IPv6 Guidelines

Does not support IPv6 traffic for redirection.

Additional Guidelines

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

Configuring WCCP Service Groups

To allocate space and enable support of the specified WCCP service group, perform the following steps:

Step 1 In the ASDM main application window, choose Configuration > Device Management > Advanced > WCCP > Service Groups.

Step 2 To add a new service group, click Add to display the A dd Service Group dialog box.

Step 3 To modify an existing service group, click Edit to display the Edit Service Group dialog box.

Step 4 To remove a selected service group, click Delete.

Step 5 To continue, see Adding or Editing WCCP Service Groups.

Step 6 Click Apply to save your changes, or click Reset to discard them and enter new ones.

Configuring Packet Redirection

To configure packet redirection on the ingress of an interface using WCCP, perform the following steps:

Step 1 In the ASDM main application window, choose Configuration > Device Management > Advanced > WCCP > Redirection.

Step 2 To add a new WCCP packet redirection, click Add to display the Add WCCP Redirection dialog box.

Step 3 To modify an existing WCCP packet redirection, click Edit to display the Edit WCCP Redirection dialog box.

Step 4 To remove a selected WCCP packet redirection, click Delete.

Step 5 To continue, see Adding or Editing Packet Redirection.

WCCP Monitoring

To monitor WCCP, perform the following steps:

Feature History for WCCP

Table 20-1 lists the release history for this feature. ASDM is backwards-compatible with multiple platform releases, so the specific ASDM release in which support was added is not listed.