- Cisco IOS IP Application Services Configuration Guide, Release 12.4T
Table Of Contents
Layer 2 Forwarding, Redirection, and Return
WCCP Closed Services and Open Services
Registering a Router to a Multicast Address
Using Access Lists for a WCCP Service Group
Enabling the WCCP Outbound ACL Check
Verifying and Monitoring WCCP Configuration Settings
Configuration Examples for WCCP
Changing the Version of WCCP on a Router: Example
Configuring a General WCCPv2 Session: Example
Setting a Password for a Router and Content Engines: Example
Configuring a Web Cache Service: Example
Running a Reverse Proxy Service: Example
Registering a Router to a Multicast Address: Example
WCCP Outbound ACL Check Configuration: Example
Verifying WCCP Settings: Examples
Configuring WCCP
First Published: August 21, 2007Last Updated: November 20, 2009The Web Cache Communication Protocol (WCCP) is a Cisco-developed content-routing technology that intercepts IP packets and redirects those packets to a destination other than that specified in the IP packet. Typically the packets are redirected from their destination web server on the Internet to a content engine that is local to the client. In some WCCP deployment scenarios, redirection of traffic may also be required from the web server to the client. WCCP enables you to integrate content engines into your network infrastructure.
Cisco IOS Release 12.1 and later releases allow the use of either WCCP Version 1 (WCCPv1) or Version 2 (WCCPv2).
The tasks in this document assume that you have already configured content engines on your network. For specific information on hardware and network planning associated with Cisco Content Engines and WCCP, see the Cisco Content Engines documentation at the following URL:
http://www.cisco.com/univercd/cc/td/doc/product/webscale/content/index.htm
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Cisco Systems replaced the Cache Engine 500 series platforms with content engine platforms in July 2001. Cache engine products were the Cache Engine 505, 550, 570, and 550-DS3. Content engine products are the Content Engine 507, 560, 590, and 7320.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for WCCP" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
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Prerequisites for WCCP
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Restrictions for WCCP
General
The following limitations apply to WCCPv1 and WCCPv2:
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WCCPv1
The following limitations apply to WCCPv1:
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WCCPv2
The following limitations apply to WCCPv2:
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WCCP VRF Support
This feature is supported only on Cisco 7200 NPE-G2 and Cisco 7304-NPE-G100 routers.
Layer 2 Forwarding and Return
The following limitations apply to WCCP Layer 2 Forwarding and Return:
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Cisco ASR 1000 Series Aggregation Services Routers
The following limitations apply to Cisco ASR 1000 series aggregation services routers:
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Configure a loopback address and assign an IP address to it so that it is used as the routerID. It is unlikely that such a loopback IP address will get removed, but when removed, the source IP address of the GRE packet from the router to the cache engine will carry the removed IP address. Enter the shutdown command, followed by the no shutdown command on the cache engine interface that has the GRE redirect method configured to stop the interface from using the removed IP address.•
Cisco Catalyst 4500 Series Switches
The following limitations apply to Cisco Catalyst 4500 series switches:
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Cisco Catalyst 6500 Series Switches
The following limitation apply to Cisco Catalyst 6500 series switches:
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http://www.cisco.com/en/US/docs/app_ntwk_services/waas/acns/v42/configuration/guide/transprt.html
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Catalyst 6500 Series Switches and Cisco 7600 Series Routers Access Control Lists
When WCCP is using the mask assignment, any redirect list is merged with the mask information from the appliance and the resulting merged access control list (ACL) is passed down to the Catalyst 6500 series switch or Cisco 7600 series router hardware.
The following restrictions apply to the redirect-list ACL:
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If the redirect ACL does not meet the above restrictions, the system will log the following error message:
WCCP-3-BADACE: Service <service group>, invalid access-list entry (seq:<sequence>, reason:<reason>)WCCP continues to redirect packets, but the redirection is carried out in software (NetFlow Switching) until the access list is adjusted.
Information About WCCP
To configure WCCP, you should understand the following concepts:
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Understanding WCCP
WCCP uses Cisco Content Engines (or other content engines running WCCP) to localize web traffic patterns in the network, enabling content requests to be fulfilled locally. Traffic localization reduces transmission costs and download time.
WCCP enables Cisco IOS routing platforms to transparently redirect content requests. The main benefit of transparent redirection is that users do not need to configure their browsers to use a web proxy. Instead, they can use the target URL to request content, and have their requests automatically redirected to a content engine. The word "transparent" in this case means that the end user does not know that a requested file (such as a web page) came from the content engine instead of from the originally specified server.
When a content engine receives a request, it attempts to service it from its own local cache. If the requested information is not present, the content engine issues its own request to the originally targeted server to get the required information. When the content engine retrieves the requested information, it forwards it to the requesting client and caches it to fulfill future requests, thus maximizing download performance and substantially reducing transmission costs.
WCCP enables a series of content engines, called a content engine cluster, to provide content to a router or multiple routers. Network administrators can easily scale their content engines to manage heavy traffic loads through these clustering capabilities. Cisco clustering technology enables each cluster member to work in parallel, resulting in linear scalability. Clustering content engines greatly improves the scalability, redundancy, and availability of your caching solution. You can cluster up to 32 content engines to scale to your desired capacity.
Layer 2 Forwarding, Redirection, and Return
WCCP uses either Generic Routing Encapsulation (GRE) or Layer 2 (L2) to redirect or return IP traffic. When WCCP forwards traffic via GRE, the redirected packets are encapsulated within a GRE header. The packets also have a WCCP redirect header. When WCCP forwards traffic using L2, the original MAC header of the IP packet is overwritten and replaced with the MAC header for the WCCP client.
Using L2 as a forwarding method allows direct forwarding to the content engine without further lookup. Layer 2 redirection requires that the router and content engines are directly connected, that is, on the same IP subnetwork.
When WCCP returns traffic via GRE, the returned packets are encapsulated within a GRE header. The destination IP address is the address of the router and the source address is the address of the WCCP client. When WCCP returns traffic via L2, the original IP packet is returned without any added header information. The router to which the packet is returned will recognize the source of the packet and prevent redirection.
The WCCP redirection method does not have to match the return method.
L2 forwarding, return, or redirection are typically used for hardware accelerated platforms. In Cisco IOS Release 12.4(20)T and later releases, L2 forwarding, return, and redirection can also be used for software switching platforms.
On Cisco ASR 1000 series aggregation services routers, both the GRE and L2 forward/return methods use the hardware, so there is not any significant performance degradation between them.
For content engines running Application and Content Networking System (ACNS) software, use the wccp custom-web-cache command with the l2-redirect keyword to configure L2 redirection. For content engines running Cisco Wide Area Application Services (WAAS) software, use the wccp tcp-promiscuous command with the l2-redirect keyword to configure L2 redirection.
For more information on Cisco ACNS commands used to configure Cisco Content Engines, see the Cisco ACNS Software Command Reference, Release 5.5, at the following URL:
http://www.cisco.com/en/US/docs/app_ntwk_services/waas/acns/v55/command/reference/55cref.html
For more information on WAAS commands used to configure Cisco Content Engines, see the Cisco Wide Area Application Services Command Reference (Software Versions 4.0.1 and 4.0.3) at the following URL:
http://www.cisco.com/en/US/docs/app_ntwk_services/waas/waas/v401_v403/command/reference/cmdref.html
WCCP Mask Assignment
The WCCP Mask Assignment feature enables mask assignment as the load-balancing method (instead of the default hash assignment method) for a WCCP service.
For content engines running Application and Content Networking System (ACNS) software, use the wccp custom-web-cache command with the mask-assign keywords to configure mask assignment. For content engines running Cisco Wide Area Application Services (WAAS) software, use the wccp tcp-promiscuous command with the mask-assign keyword to configure mask assignment.
For more information on Cisco ACNS commands used to configure Cisco Content Engines, see the Cisco ACNS Software Command Reference, Release 5.5, at the following URL:
http://www.cisco.com/en/US/docs/app_ntwk_services/waas/acns/v55/command/reference/55cref.html
For more information on WAAS commands used to configure Cisco Content Engines, see the Cisco Wide Area Application Services Command Reference (Software Versions 4.0.1 and 4.0.3) at the following URL:
http://www.cisco.com/univercd/cc/td/doc/product/webscale/waas/waas40/cmdref/index.htm
Hardware Acceleration
Catalyst 4500 series switches provide hardware acceleration for directly connected Cisco Content Engines.
Catalyst 6500 series switches and Cisco 7600 series routers provide WCCP Layer 2 Policy Feature Card (PFC) redirection hardware acceleration. Hardware acceleration allows Cisco Content Engines to perform a L2 MAC address rewrite redirection method when directly connected to a compatible switch or router.
Redirection processing is accelerated in the switching or routing hardware, which is more efficient than L3 redirection with Generic Routing Encapsulation (GRE). L2 redirection takes place on the switch or router, and is not visible to the Multilayer Switch Feature Card (MSFC). The WCCP L2 PFC redirection feature requires no configuration on the MSFC. The show ip wccp {service-number | web-cache} detail command displays which redirection method is in use for each content engine.
In order for the router or switch to make complete use of hardware redirection, the content engine must be configured with L2 redirection and mask assignment as discussed in the "Layer 2 Forwarding, Redirection, and Return" section.
Use the ip wccp web-cache accelerated command on hardware-based platforms to enforce the use of L2 redirection and mask assignment. Using this command configures the router to form a service group and redirect packets with an appliance only if the appliance is configured for L2 and mask assignment.
The following guidelines apply to WCCP Layer 2 PFC redirection:
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Cisco ASR 1000 Series Aggregation Services Routers
WCCP implementation on the Cisco ASR 1000 series aggregation services routers is hardware accelerated by default. You do not need to configure the ip wccp web-cache accelerated command on Cisco ASR routers to enable hardware acceleration.
WCCPv1 Configuration
With WCCPv1, only a single router services a cluster. In this scenario, this router is the device that performs all the IP packet redirection. Figure 1 illustrates the WCCPv1 configuration.
Figure 1 WCCPv1 Configuration
Content is not duplicated on the content engines. The benefit of using multiple content engines is that you can scale a caching solution by clustering multiple physical content engines to appear as one logical cache.
The following sequence of events details how WCCPv1 configuration works:
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WCCPv2 Configuration
Multiple routers can use WCCPv2 to service a content engine cluster. This configuration is in contrast to WCCPv1, in which only one router could redirect content requests to a cluster. Figure 2 illustrates a sample configuration using multiple routers.
Figure 2 Cisco Cache Engine Network Configuration Using WCCPv2
The subset of content engines within a cluster and routers connected to the cluster that are running the same service is known as a service group. Available services include TCP and User Datagram Protocol (UDP) redirection.
Using WCCPv1, the content engines were configured with the address of the single router. WCCPv2 requires that each content engine be aware of all the routers in the service group. To specify the addresses of all the routers in a service group, you must choose one of the following methods:
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The multicast option is easier to configure because you need only specify a single address on each content engine. This option also allows you to add and remove routers from a service group dynamically, without needing to reconfigure the content engines with a different list of addresses each time.
The following sequence of events details how WCCPv2 configuration works:
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WCCP VRF Support
The WCCP VRF Support feature enhances the existing WCCPv2 protocol by implementing support for virtual routing and forwarding (VRF).
The WCCP VRF Support feature allows service groups to be configured on a per VRF basis in addition to those defined globally.
Along with the service identifier, the VRF of WCCP protocol packets arriving at the router is used to associated cache-engines with a configured service group.
This feature is supported only on Cisco 7200 NPE-G2 and Cisco 7304-NPE-G100 routers.
Support for Services Other Than HTTP
WCCPv2 allows redirection of traffic other than HTTP (TCP port 80 traffic), including a variety of UDP and TCP traffic. WCCPv1 supported the redirection of HTTP (TCP port 80) traffic only. WCCPv2 supports the redirection of packets intended for other ports, including those used for proxy-web cache handling, File Transfer Protocol (FTP) caching, FTP proxy handling, web caching for ports other than 80, and Real Audio, video, and telephony applications.
To accommodate the various types of services available, WCCPv2 introduces the concept of multiple service groups. Service information is specified in the WCCP configuration commands using dynamic services identification numbers (such as 98) or a predefined service keyword (such as web-cache). This information is used to validate that service group members are all using or providing the same service.
The content engines in a service group specify traffic to be redirected by protocol (TCP or UDP) and up to eight source or destination ports. Each service group has a priority status assigned to it. The priority of a dynamic service is assigned by the content engine. The priority value is in the range of 0 to 255 where 0 is the lowest priority. The predefined web-cache service has an assigned priority of 240.
Support for Multiple Routers
WCCPv2 allows multiple routers to be attached to a cluster of cache engines. The use of multiple routers in a service group allows for redundancy, interface aggregation, and distribution of the redirection load. WCCPv2 supports up to 32 routers per service group. Each service group is established and maintained independently.
MD5 Security
WCCPv2 provides optional authentication that enables you to control which routers and content engines become part of the service group using passwords and the HMAC MD5 standard. Shared-secret MD5 one-time authentication (set using the ip wccp [password [0-7] password] global configuration command) enables messages to be protected against interception, inspection, and replay.
Web Cache Packet Return
If a content engine is unable to provide a requested object it has cached due to error or overload, the content engine will return the request to the router for onward transmission to the originally specified destination server. WCCPv2 provides a check on packets that determines which requests have been returned from the content engine unserviced. Using this information, the router can then forward the request to the originally targeted server (rather than attempting to resend the request to the content engine cluster). This process provides error handling transparency to clients.
Typical reasons why a content engine would reject packets and initiate the packet return feature include the following:
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Load Distribution
WCCPv2 can be used to adjust the load being offered to individual content engines to provide an effective use of the available resources while helping to ensure high quality of service (QoS) to the clients. WCCPv2 allows the designated content engine to adjust the load on a particular content engine and balance the load across the content engines in a cluster. WCCPv2 uses three techniques to perform load distribution:
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The use of these hashing parameters prevents one content engine from being overloaded and reduces the potential for bottlenecking.
WCCP Bypass Packets
WCCP intercepts IP packets and redirects those packets to a destination other than the destination that is specified in the IP header. Typically the packets are redirected from a web server on the Internet to a web cache that is local to the destination.
Occasionally a web cache cannot manage the redirected packets appropriately and returns the packets unchanged to the originating router. These packets are called bypass packets and are returned to the originating router using either Layer 2 forwarding without encapsulation (L2) or encapsulated in generic routing encapsulation (GRE). The router decapsulates and forwards the packets normally. The VRF associated with the ingress interface (or the global table if there is no VRF associated) is used to route the packet to the destination.
GRE is a tunneling protocol developed by Cisco that encapsulates packet types from various protocols inside IP tunnels, creating a virtual point-to-point link over an IP network.
WCCP Closed Services and Open Services
In applications where packet flows are intercepted and redirected by a Cisco IOS router to external WCCP client devices, it may be necessary to block the packet flows for the application when a WCCP client device is not available. This blocking is achieved by configuring a WCCP closed service. When a WCCP service is configured as closed, WCCP discards packets that do not have a WCCP client registered to receive the redirected traffic.
By default, WCCP operates as an open service, wherein communication between clients and servers proceeds normally in the absence of an intermediary device.
The ip wccp service-list command can only be used for closed-mode services. Use the service-list keyword and service-access-list argument to register an application protocol type or port number.
When there is a conflict in service list definitions, the configured definition takes precedence over the external definition received via WCCP protocol messages.
WCCP Outbound ACL Check
WCCP operates by intercepting IP packets and redirecting those packets to a destination other than the destination that is specified in the IP header. Typically the packets are redirected from a web server on the Internet to a web cache that is local to the redirecting router.
Access control lists (ACLs) filter network traffic by controlling whether routed packets are forwarded or blocked at the router interface. Each packet is examined to determine whether it will be forwarded or dropped, according to the specified criteria within the ACL. ACL criteria can be the source address of the traffic, the destination address of the traffic, or the upper-layer protocol. An IP ACL is a sequential collection of permit and deny conditions that apply to an IP address. The router tests addresses against the conditions in the ACL one at a time. The first match determines whether the address is accepted or rejected. Because Cisco IOS software stops testing conditions after the first match, the order of the conditions is critical. If no conditions match, the router rejects the address, by virtue of an implicit "deny all" clause.
If there is an outbound ACL configured on the interface at which redirection takes place, it is possible, under some circumstances, that hosts whose traffic is redirected will gain access to destinations to which they would otherwise be blocked.
The WCCP Outbound ACL Check feature ensures that the outbound ACL checking is performed at the original interface so that the checking is secure and consistent across all platforms and Cisco IOS switching paths.
WCCP Service Groups
WCCP is a component of Cisco IOS software that redirects traffic with defined characteristics from its original destination to an alternative destination. The typical application of WCCP is to redirect traffic bound for a remote web server to a local web cache to improve response time and optimize network resource usage.
The nature of the selected traffic for redirection is defined by service groups specified on content engines and communicated to routers by using WCCP. The current implementation of WCCP in Cisco IOS releases prior to Cisco IOS Release 12.3(14)T allowed a maximum of eight service groups to be defined. This maximum restricted caching deployments. In Cisco IOS Release 12.3(14)T and later releases, the maximum number of service groups allowed is increased to 256.
WCCPv2 supports up to 32 routers per service group. Each service group is established and maintained independently.
WCCPv2 uses service groups based on logical redirection services, deployed for intercepting and redirecting traffic. The standard service is web cache, which intercepts TCP port 80 (HTTP) traffic and redirects that traffic to the content engines. This service is referred to as a well-known service, because the characteristics of the web cache service are known by both the router and content engines. A description of a well-known service is not required beyond a service identification. To specify the standard web cache service, use the ip wccp command with the web-cache keyword.
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Figure 3 WCCP Service Groups
The dynamic services are defined by the content engines; the content engine instructs the router which protocol or ports to intercept, and how to distribute the traffic. The router itself does not have information on the characteristics of the dynamic service group's traffic, because this information is provided by the first content engine to join the group. In a dynamic service, up to eight ports can be specified within a single protocol.
Cisco Content Engines, for example, use dynamic service 99 to specify a reverse-proxy service. However, other content engine devices may use this service number for some other service. The configuration information in this document describes how to enable general services on Cisco routers.
An interface may be configured with more than one WCCP service. When more than one WCCP service is configured on an interface, the precedence of a service depends on the relative priority of the service compared to the priority of the other configured services. Each WCCP service has a priority value as part of its definition. When an interface is configured with more than one WCCP service, the precedence of the packets is matched against service groups in priority order.
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With the ip wccp check services all command, WCCP can be configured to check all configured services for a match and perform redirection for those services if appropriate. The caches to which packets are redirected can be controlled by a redirect ACL as well as by the service priority.
If no WCCP services are configured with a redirect ACL, the services are considered in priority order until a service is found that matches the IP packet. If no services match the packet, the packet is not redirected. If a service matches the packet and the service has a redirect ACL configured, then the IP packet will be checked against the ACL. If the packet is rejected by the ACL, the packet will not be passed down to lower priority services unless the ip wccp check services all command is configured. When the ip wccp check services all command is configured, WCCP will continue to attempt to match the packet against any remaining lower priority services configured on the interface.
How to Configure WCCP
The following configuration tasks assume that you have already installed and configured the content engines you want to include in your network. You must configure the content engines in the cluster before configuring WCCP functionality on your routers or switches. Refer to the Cisco Cache Engine User Guide for content engine configuration and setup tasks.
Perform these tasks to configure WCCP on a router or switch:
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Configuring WCCP
Perform this task to configure WCCP.
Until you configure a WCCP service using the ip wccp {web-cache | service-number} global configuration command, WCCP is disabled on the router. The first use of a form of the ip wccp command enables WCCP. By default WCCPv2 is used for services, but you can use WCCPv1 functionality instead. To change the running version of WCCP from Version 2 to Version 1, or to return to WCCPv2 after an initial change, use the ip wccp version command in global configuration mode.
If a function is not allowed in WCCPv1, an error prompt will be printed to the screen. For example, if WCCPv1 is running on the router and you try to configure a dynamic service, the following message will be displayed: "WCCP V1 only supports the web-cache service." The show ip wccp EXEC command will display the WCCP protocol version number that is currently running on your router.
Using the ip wccp web-cache password command, you can set a password for a router and the content engines in a service group. MD5 password security requires that each router and content engine that wants to join a service group be configured with the service group password. The password can consist of up to eight characters. Each content engine or router in the service group will authenticate the security component in a received WCCP packet immediately after validating the WCCP message header. Packets failing authentication will be discarded.
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Configuring Closed Services
Perform this task to specify the number of service groups for WCCP, to configure a service group as a closed or open service, and to optionally specify a check of all services.
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ip wccp [vrf vrf-name] web-cache mode {open | closed}
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Registering a Router to a Multicast Address
If you decide to use the multicast address option for your service group, you must configure the router to listen for the multicast broadcasts on an interface.
For network configurations where redirected traffic needs to traverse an intervening router, the router being traversed must be configured to perform IP multicast routing. You must configure the following two components to enable traversal over an intervening router:
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What to Do Next
For more information about configuring IP Multicast features, see the Cisco IOS IP Multicast Configuration Guide.
Using Access Lists for a WCCP Service Group
Perform this task to configure the router to use an access list to determine which traffic should be directed to which content engines.
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What to Do Next
For more information about configuring and using IP access lists, see "IP Access List Features Roadmap" in the Cisco IOS Security Configuration Guide.
Enabling the WCCP Outbound ACL Check
Perform this task to enable an outbound ACL check for WCCP.
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Verifying and Monitoring WCCP Configuration Settings
Use the following commands in EXEC mode to verify and monitor the configuration settings for WCCP.
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Troubleshooting Tips
Problems have been encountered because CPU usage is very high when WCCP is enabled. The counters enable a determination of the bypass traffic directly on the router and can indicate whether or not this is the cause. In some situations, 10 percent bypass traffic may be normal; in other situations, it may be high. However, any figure above 25 percent should prompt a closer investigation of what is occurring in the web cache.
If the counters suggest that the level of bypass traffic is high, the next step is to examine the bypass counters in the content engine and determine why the content engine is choosing to bypass the traffic. You can log in to the content engine console and use CLI to investigate further. The counters allow you to determine the percent of traffic being bypassed.
Configuration Examples for WCCP
This section provides the following configuration examples:
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Changing the Version of WCCP on a Router: Example
The following example shows how to change the WCCP version from the default of WCCPv2 to WCCPv1, and enabling the web-cache service in WCCPv1:
show ip wccp% WCCP version 2 is not enabledconfigure terminalip wccp version 1endshow ip wccp% WCCP version 1 is not enabledconfigure terminalEnter configuration commands, one per line. End with CNTL/Z.ip wccp web-cacheendshow ip wccpGlobal WCCP information:Router information:Router Identifier: 10.4.9.8Protocol Version: 1.0...Configuring a General WCCPv2 Session: Example
The following example shows how to configure a general WCCPv2 session:
configure terminalip wccp web-cache group-address 224.1.1.100 password password1interface ethernet0ip wccp web-cache redirect outexitip wccp check services all ! Configures a check of all WCCP services.Setting a Password for a Router and Content Engines: Example
The following example shows how to configure a WCCPv2 password where the password is password1:
configure terminalip wccp web-cache password password1Configuring a Web Cache Service: Example
The following example shows how to configure a web cache service:
configure terminalip wccp web-cacheinterface ethernet 0ip wccp web-cache redirect outexitcopy running-config startup-configThe following example shows how to configure a session in which redirection of HTTP traffic arriving on Ethernet interface 0/1 is enabled:
configure terminalinterface ethernet 0/1ip wccp web-cache redirect inexitshow ip interface ethernet 0/1...WCCP Redirect inbound is enabledWCCP Redirect exclude is disabled...Running a Reverse Proxy Service: Example
The following example assumes that you are configuring a service group using Cisco cache engines, which use dynamic service 99 to run a reverse proxy service:
configure terminalip wccp 99interface ethernet 0ip wccp 99 redirect outRegistering a Router to a Multicast Address: Example
The following example shows how to register a router to a multicast address of 224.1.1.100:
ip wccp web-cache group-address 224.1.1.100interface ethernet 0ip wccp web cache group-listenThe following example shows a router configured to run a reverse proxy service, using the multicast address of 224.1.1.1. Redirection applies to packets outgoing via interface Ethernet interface 0:
ip wccp 99 group-address 224.1.1.1interface ethernet 0ip wccp 99 redirect outUsing Access Lists: Example
To achieve better security, you can use a standard access list to notify the router which IP addresses are valid addresses for a content engine attempting to register with the current router. The following example shows a standard access list configuration session where the access list number is 10 for some sample hosts:
access-list 10 permit host 11.1.1.1access-list 10 permit host 11.1.1.2access-list 10 permit host 11.1.1.3ip wccp web-cache group-list 10To disable caching for certain clients, servers, or client/server pairs, you can use WCCP access lists. The following example shows that any requests coming from 10.1.1.1 to 12.1.1.1 will bypass the cache, and that all other requests will be serviced normally:
ip wccp web-cache redirect-list 120access-list 120 deny tcp host 10.1.1.1 anyaccess-list 120 deny tcp any host 12.1.1.1access-list 120 permit ip any anyThe following example configures a router to redirect web-related packets received via interface ethernet 0/1, destined to any host except 209.165.200.224:
access-list 100 deny ip any host 209.165.200.224access-list 100 permit ip any anyip wccp web-cache redirect-list 100interface Ethernet 0/1ip wccp web-cache redirect inWCCP Outbound ACL Check Configuration: Example
The following configuration example shows that the access list prevents traffic from network 10.0.0.0 leaving Fast Ethernet interface 0/0. Because the outbound ACL check is enabled, WCCP does not redirect that traffic. WCCP checks packets against the ACL before they are redirected.
ip wccp web-cacheip wccp check acl outboundinterface fastethernet0/0ip access-group 10 outexitip wccp web-cache redirect-list redirect-outaccess-list 10 deny 10.0.0.0 0.255.255.255access-list 10 permit anyIf the outbound ACL check is disabled, the HTTP packets from network 10.0.0.0 would be redirected to a web cache. Users with that network address could retrieve web pages even though the network administrator wanted to prevent it.
Verifying WCCP Settings: Examples
The following example shows how to verify your configuration changes by using the more system:running-config command in privileged EXEC mode. The following example shows that both the web cache service and dynamic service 99 are enabled on the router:
Router# more system:running-configBuilding configuration...Current configuration:!version 12.0service timestamps debug uptimeservice timestamps log uptimeno service password-encryptionservice udp-small-serversservice tcp-small-servers!hostname router4!enable secret 5 $1$nSVy$faliJsVQXVPW.KuCxZNTh1enable password password1!ip subnet-zeroip wccp web-cacheip wccp 99ip domain-name cisco.comip name-server 10.1.1.1ip name-server 10.1.1.2ip name-server 10.1.1.3!!!interface Ethernet0ip address 10.3.1.2 255.255.255.0no ip directed-broadcastip wccp web-cache redirect outip wccp 99 redirect outno ip route-cacheno ip mroute-cache!interface Ethernet1ip address 10.4.1.1 255.255.255.0no ip directed-broadcastip wccp 99 redirect outno ip route-cacheno ip mroute-cache!interface Serial0no ip addressno ip directed-broadcastno ip route-cacheno ip mroute-cacheshutdown!interface Serial1no ip addressno ip directed-broadcastno ip route-cacheno ip mroute-cacheshutdown!ip default-gateway 10.3.1.1ip classlessip route 0.0.0.0 0.0.0.0 10.3.1.1no ip http server!!!line con 0transport input noneline aux 0transport input allline vty 0 4password alaska1login!endThe following example shows how to display information about bypassed packets for process, fast, and CEF that are switching paths in Cisco IOS.
Router# show ip wccp web-cache detailWCCP Client information:Web Client ID: 10.10.10.1Protocol Version: 2.0State: UsableInitial Hash Info: 0000000000000000000000000000000000000000000000000000000000000000Assigned Hash Info: FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFHash Allotment: 256 (100.00%)Packets Redirected: 4320Connect Time: 00:04:53Bypassed PacketsProcess: 0Fast: 0CEF: 250For more information about the show ip wccp web-cache command, see the Cisco IOS IP Application Services Command Reference.
Additional References
The following sections provide references related to WCCP.
Related Documents
Cisco IOS commands
WCCP commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples
Cisco ACNS software configuration information
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IP Access List overview, configuration tasks, and commands
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IP addressing and services commands and configuration tasks
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Standards
No new or modified standards are supported, and support for existing standards has not been modified.
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MIBs
RFCs
No new or modified RFCs are supported, and support for existing RFCs has not been modified.
Technical Assistance
Feature Information for WCCP
Table 1 lists the features in this module and provides links to specific configuration information. Only features that were introduced or modified in Cisco IOS Release 12.2(1) or a later release appear in the table.
Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
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Table 1 Feature Information for WCCP
WCCP Bypass Counters
12.3(7)T 12.2(25)S
The WCCP Bypass Counters feature allows you to display a count of packets that have been bypassed by a web cache and returned to the originating router to be forwarded normally.
The following sections provide information about this feature:
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The show ip wccp command was modified by this feature.
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WCCP Closed Services
12.4(11)T
The WCCP Closed Services feature permits WCCP services to be configured so that WCCP always intercepts traffic for such services but, if no WCCP client (such as a content engine) has registered to receive this traffic, packets are discarded.
This new behavior supports AONS (Application-Oriented Network Services) applications, which require traffic to be transparently intercepted using WCCP but do not want the packets to be forwarded to their destination if the WCCP client is unavailable to perform its processing. (This is contrary to the traditional use of WCCP to assist caches where the absence of a cache does not change the behavior as observed by the user.)
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The ip wccp command was modified by this feature.
WCCP Increased Services
12.3(14)T 12.2(33)SRA
12.2(33)SXHThe WCCP Increased Services feature increases the number of services supported by WCCP to a maximum of 256.
The following sections provide information about this feature:
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The following commands were modified by this feature: ip wccp, ip wccp check services all, show ip wccp.
WCCP Layer 2 Redirection / Forwarding
12.4(20)T
The WCCP Layer 2 Redirection/Forwarding feature allows directly connected Cisco content engines to use Layer 2 redirection, which is more efficient than Layer 3 redirection via GRE encapsulation. You can configure a directly connected Cache Engine to negotiate use of the WCCP Layer 2 Redirection/Forwarding feature. The WCCP Layer 2 Redirection/Forwarding feature requires no configuration on the router or switch.
The following sections provide information about this feature:
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There are no new or modified commands associated with this feature.
WCCP L2 Return
12.4(20)T
The following sections provide information about this feature:
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There are no new or modified commands associated with this feature.
WCCP Mask Assignment
12.4(20)T
The WCCP Mask Assignment feature introduces support for ACNS/WAAS devices using mask assignment as a cache engine assignment method.
The following section provides information about this feature:
There are no new or modified commands associated with this feature.
WCCP Outbound ACL Check
12.3(7)T
12.2(25)SThe WCCP Outbound ACL Check feature enables you to ensure that traffic redirected by WCCP at an input interface is subjected to the outbound ACL checks that may be configured on the output interface prior to redirection.
This feature is supported by Web Cache Communication Protocol (WCCP) Version 1 and Version 2.
The following sections provide information about this feature:
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The following commands were introduced or modified by this feature: ip wccp, ip wccp check acl outbound
WCCP Redirection on Inbound Interfaces
12.1(3)T
The WCCP Redirection on Inbound Interfaces feature enables interfaces to be configured for input redirection for a particular WCCP service. When this feature is enabled on an interface, all packets arriving at that interface are compared against the specified WCCP service. If the packets match, they will be redirected.
The following sections provide information about this feature:
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The following commands were introduced or modified by this feature: ip wccp redirect-list
WCCP Version 2
12.0(3)T
The WCCP Version 2 feature provides several enhancements and features to the WCCP protocol, including:
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The following sections provide information about this feature:
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The following commands were introduced or modified by this feature: clear ip wccp, ip wccp, ip wccp group-listen, ip wccp redirect, ip wccp redirect exclude in, ip wccp version, show ip wccp
WCCP VRF Support
15.0(1)M, 12.2(33)SRE
The WCCP VRF Support feature provides enhancements to the existing WCCPv2 protocol which support VRF awareness.
The following sections provide information about this feature:
The following commands were introduced or modified by this feature: clear ip wccp, debug ip wccp, ip wccp, ip wccp group-listen, ip wccp redirect, show ip wccp
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