Cisco Cache Application Basic WCCP Configuration

The Web Cache Communication Protocol (WCCP) is a Cisco-developed content-routing technology that allows you to deploy transparent caching using the Content Engines in your network. Cisco IOS Release 12.1 and later allows the use of Version 1 (WCCPv1) or Version 2 (WCCPv2) of the WCCP.

This chapter describes how to configure a router or cluster of routers and Content Engines using WCCPv2. WCCPv2 offers many enhancements over WCCPv1, such as support for many routers, multicasting and support for re-direction of non-HTTP traffic. With WCCPv1 only a single router can be configured to service either a single Content Engine or a cluster of Content Engines. Further information on WCCP Version 1 commands and router configuration examples are in the Cisco IOS software online documentation as well as in "Web Cache Communication Protocol Version 1."

To make a Content Engine running the Cache application software operational on the network, you must perform these tasks:

Use the Cisco Content Delivery Networking Products Getting Started Guide to configure your network settings.
Configure the Content Engine for transparent or proxy-server operation.
Configure the router or switch only if you are deploying a transparent caching operation.
Verify your configuration.

The procedures for these tasks are in the following sections:

Basic Cache Application Router Configurations for HTTP Traffic and WCCP Version 2
Verifying the Software Configuration
Removing or Replacing a Content Engine

For additional information on web caching concepts and network placement diagrams, refer to the Network Caching White Paper on the Cisco.com Content Networking website at the following URL:

http://www.cisco.com/warp/public/cc/pd/cxsr/500/tech/cds_wp.htm

To upgrade a Content Engine from earlier versions of the Cache software, use the upgrade procedures in the Cisco ACNS Software System Maintenance and Troubleshooting Guide.

See "Cisco Application and Content Networking Software Cache Application Features," for a list of the feature described in this guide.

Basic Cache Application Router Configurations for HTTP Traffic and WCCP Version 2

A router or switch with the proper configuration is required for transparent caching services. The router or switch must be running a version of Cisco IOS software that supports the Web Cache Communication Protocol (WCCP) Version 2.

When cache support is enabled on the router or switch, and WCCP support is enabled on the Content Engines, the devices can communicate and deliver the services for which they are configured. To suspend caching services, you can disable cache support on the router or switch rather than powering off or otherwise disabling individual Content Engines. (For instance, use the no ip wccp router or switch command to disable caching.)

Many WCCP Version 2 features also require a configuration of the appropriate Cache application wccp global configuration command. Refer to the Cisco Application and Content Networking Software Command Reference and release notes for more details.

If you do not know how to configure a router or a switch, refer to the software documentation supplied with the devices. Further information on WCCP Version 2 commands and router configuration examples are in the Cisco IOS software online documentation as well as in "Web Cache Communication Protocol Version 2."

Web Cache Service Configuration with Clients and Cache on Different Subnets

In this scenario, the Content Engine and the requesting clients are on different subnets, as shown in Figure 2-1.

A router running WCCP Version 2 transparently redirects client HTTP traffic bound for router interface s0/0 to the Content Engine. The web cache service redirects HTTP traffic on port 80 only.

Figure 2-1: Web Cache Service with Content Engine and Clients on Different Subnets

Configuring the Content Engine for Web Cache Service—Clients and Cache on Different Subnets

To configure the Content Engine for the web cache service, perform the following steps while logged in to the Cache software in global configuration mode:

	Command	Purpose
Step 1	contentengine(config)# wccp version 2	Ensures that the Content Engine is running WCCP Version 2.
Step 2	contentengine(config)# wccp router-list 1 10.10.20.1	Configures a router list.
Step 3	contentengine(config)# wccp web-cache router-list-num 1	Informs the routers in the specified router list that the Content Engine is accepting web cache service.
Step 4	contentengine(config)# exit	Exits global configuration mode.
Step 5	contentengine# write memory	Writes running configurations to nonvolatile memory.

Configuring the Router for Web Cache Service—Clients and Cache on Different Subnets

To configure the router for web cache service, perform the following steps while logged in to the router global configuration mode:

	Command	Purpose
Step 1	router(config)# ip wccp web-cache	Instructs the router to run the web cache service.
Step 2	router(config)# interface Serial0	Specifies which router interface to configure. In this scenario, Serial0 is the router interface to the Internet.
Step 3	router(config-if)# ip wccp web-cache redirect out	Instructs the router to redirect web cache traffic bound for the specified interface to Content Engines that accept web cache service. In this scenario there is only one router. Web cache traffic is defined as HTTP packets on port 80.
Step 4	router(config-if)# exit	Exits global configuration mode.

Configuration Examples—Web Cache Service with Clients and Cache on Different Subnets

This example shows a Content Engine and router configured for the web cache service with the topology illustrated in Figure 2-1:

Content Engine Configuration

. . .
hostname Content_engine_4.1
!
clock timezone pst -8 0
!
ip domain-name cisco.com
!
exec-timeout 20
!
interface FastEthernet 0
ip address 10.10.20.10 255.255.255.0
no autosense
bandwidth 100
full-duplex
exit
interface FastEthernet 1
shutdown
exit
!
ip default-gateway 10.10.20.1
!
ip name-server 10.10.10.100
!
!
wccp router-list 1 10.10.20.1

wccp web-cache router-list-num 1

wccp version 2

!
!
!
...

WCCP-Enabled Router Configuration

Building configuration...
 
Current configuration:
!
hostname WCCP-Router
!
!
ip subnet-zero
!
ip wccp web-cache         

!
interface Ethernet0
 ip address 10.10.10.1 255.255.255.0
!
interface Ethernet1
 ip address 10.10.20.1 255.255.255.0
!
interface Serial0
 ip address 192.168.1.2 255.255.255.252
 no ip directed-broadcast
 no ip mroute-cache
ip wccp web-cache redirect out

 !
end

Web Cache Service Configuration with Clients and Cache on Same Subnet

In this scenario, the Content Engine and the requesting clients are on the same subnet, as shown in Figure 2-2.

A router running WCCP Version 2 transparently redirects client HTTP traffic bound for router interface s0/0 to the Content Engine. The web cache service redirects HTTP traffic on port 80 only.

Figure 2-2: Web Cache Service with Clients and Content Engine on Same Subnet

Configuring the Content Engine for Web Cache Service—Clients and Cache on Same Subnet

To configure the Content Engine for the web cache service, perform the following steps while logged in to the Cache software in global configuration mode:

	Command	Purpose
Step 1	contentengine(config)# wccp version 2	Ensures that Content Engine is running WCCP Version 2.
Step 2	contentengine(config)# wccp router-list 1 10.10.10.1	Configures a router list.
Step 3	contentengine(config)# wccp web-cache router-list-num 1	Informs the routers in the specified router list that the Content Engine is accepting web cache service.
Step 4	contentengine(config)# exit	Exits global configuration mode.
Step 5	contentengine# write memory	Writes running configurations to nonvolatile memory.

Configuring the Router for Web Cache Service—Clients and Cache on Same Subnet

To configure the router for the web cache service, perform the following steps while logged in to the Cache software global configuration mode:

	Command	Purpose
Step 1	router(config)# ip wccp web-cache	Instructs the router to run the web cache service.
Step 2	router(config)# interface Ethernet0	Specifies which router interface to configure. In this scenario, Ethernet0 is the router interface to which the Content Engine and clients are connected.
Step 3	router(config-if)# ip route-cache same-interface	Enables fast switching of redirected packets back through the interface on which they were received. Without this command, the router does not use the high-speed switching cache, and the packets are process-switched, a much slower method.
Step 4	router(config)# interface Serial0	Specifies which router interface to configure. In this scenario, Serial0 is the router interface to the Internet.
Step 5	router(config-if)# ip wccp web-cache redirect out	Instructs the router to redirect web cache traffic bound for the specified interface to Content Engines that accept web cache service. In this scenario there is only one router. Web cache traffic is defined as TCP port 80 traffic.
Step 6	router(config-if)# exit	Exits global configuration mode.

Configuration Examples—Web Cache Service with Clients and Cache on the Same Subnet

This example shows a Content Engine and router configured for the web cache service with the topology illustrated in Figure 2-2:

Content Engine

hostname Content_engine_4.1
!
clock timezone pst -8 0
!
ip domain-name cu.net
!
interface FastEthernet 0
ip address 10.10.20.10 255.255.255.0
no autosense
bandwidth 100
full-duplex
exit
interface FastEthernet 1
shutdown
exit
!
ip default-gateway 10.10.20.1
!
ip name-server 10.10.10.100
!
!
!
wccp router-list 1 10.10.20.1

wccp web-cache router-list-num 1

wccp version 2

!
!
!
. . .

WCCP-Enabled Router

Building configuration...
 
Current configuration:
!
version 12.0
!
hostname WCCP-Router
!
!
ip wccp web-cache         
!
interface Ethernet0
 ip address 10.10.10.1 255.255.255.0
 ip route-cache same-interface

!
interface Serial0
ip address 192.168.1.2 255.255.255.252
no ip directed-broadcast
no ip mroute-cache
ip wccp web-cache redirect out

 !
end

Configuring Reverse Proxy Service

To ensure fast response times, maximized service availability, and the ability to withstand an excessive number of URL hits or an excess of bandwidth requested, Cisco Content Engines with Cache software can be deployed in front of a website server farm to offload traffic from busy firewalls and servers, helping to optimize the entire website infrastructure. This type of deployment is called web server acceleration, or reverse proxying.

The same Content Engine can provide a reverse proxy cache service while simultaneously providing a transparent network cache service.

In the deployment scenario shown in Figure 2-3, the Content Engine interoperates with a router running WCCP Version 2 to bring reverse proxy service within the web server environment. In this deployment, the router interface connected to the Internet has an IP address of 192.168.1.1. All HTTP requests destined for the web server are routed to the router interface of 172.16.21.1. Upon receiving the HTTP request at this interface, the router transparently intercepts and redirects the request to the Content Engine with an IP address of 172.16.20.23. Thus, the Content Engine is logically in front of the web server offloading web server HTTP traffic. The Content Engine sends a request to the web server only when it does not find the requested content in the cache.

Note A redirect list on the router or a static bypass list on the Content Engine can be used to allow flows to bypass interception. These lists use criteria based on source and destination IP addresses.

Figure 2-3: Reverse Proxy Service with WCCP-Enabled Router

Configuring the Content Engine for Reverse Proxy Service with Output Redirection

To configure reverse proxy on the Content Engine, perform the following steps starting from global configuration mode:

	Command	Purpose
Step 1	contentengine(config)# wccp version 2	Ensures that the Content Engine is running WCCP Version 2.
Step 2	contentengine(config)# wccp router-list 1 172.16.20.1	Configures a router list.
Step 3	contentengine(config )# wccp reverse-proxy router-list-num 1	Instructs the router to run the reverse proxy service.

Configuring the Router for Reverse Proxy Service with Output Redirection

To configure reverse proxy service on the router, perform the following steps starting in global configuration mode:

	Command	Purpose
Step 1	router(config)# ip wccp 99	Instructs the router to run the reverse proxy service. The reverse proxy service is indicated by a value of 99.
Step 2	router(config)# interface Ethernet 0/1	Specifies which router interface to configure. In this scenario, Ethernet 0/1 is the router interface to the web server.
Step 3	router(config-if)# ip wccp 99 redirect out	Instructs the router to redirect TCP port 80 traffic bound for the specified interface to Content Engines that accept reverse proxy service. In this scenario there is only one router.
Step 4	router(config)# exit	Exits global configuration mode.

Configuring the Router for Reverse Proxy Service with Input Redirection

	Command	Purpose
Step 1	router(config)# ip wccp 99	Instructs the router to run the reverse proxy service. The reverse proxy service is indicated by a value of 99.
Step 2	router(config)# interface s0/0	Specifies which router interface to configure. In this scenario, s0/0 is the router interface to the Internet.
Step 3	router(config-if)# ip wccp 99 redirect in	Instructs the router to redirect TCP port 80 traffic received on the specified interface to Content Engines that accept reverse proxy service.
Step 4	router(config-if)# exit	Exits interface configuration mode.

Note Input redirection is supported in Cisco IOS Release 12.1(3)T or 12.0(11)S and later versions of the same, or in Cisco IOS Release 12.2.

Configuration Examples—Reverse Proxy with Output Redirection

This section shows configurations of the Content Engine and the router for the deployment scenario in Figure 2-3. The reverse proxy related commands are in bold:

Content Engine

 !
 hostname ContentEngine
 !
 interface ethernet 0
  ip address 172.16.20.23 255.255.255.224
  ip broadcast-address 10.0.0.255
 exit
 !
 interface ethernet 1
 exit
 !
 ip default-gateway 172.16.20.1
 ip name-server 172.16.20.238
 ip domain-name cisco.com
 ip route 0.0.0.0 0.0.0.0 172.16.20.1
 !
 wccp router-list 1 172.16.20.1

 wccp 99 reverse-proxy router-list-num 1

 wccp version 2

 !
 end

WCCP-Enabled Router

Current configuration:
 !
 version 12.1
 service timestamps debug uptime
 service timestamps log uptime
 no service password-encryption
 !
 hostname 2611-5
 !
 enable secret 5 $1$9VQ.$BTPbq8xlE2dsKwKPDDmpL/
 !
 !
 ip subnet-zero
 ip wccp 99

 !
 !
 interface Ethernet0/0
  no ip address 
  no ip redirects
  !
 interface Serial0/0
  ip address 192.168.1.1 255.255.255.224
  !
 interface Ethernet0/1
  ip address 172.16.21.1 255.255.255.224
  ip wccp 99 redirect out

!
 interface Ethernet1/0
  ip address 172.16.20.1 255.255.255.224
  !
 interface Ethernet1/1
  no ip address
  shutdown
  full-duplex
 !
 interface Ethernet1/2
  no ip address
  shutdown
 !
. . .
 ip classless
 !
 !
 line con 0
  transport input none
 line aux 0
 line vty 0 4
  login
 !
 end

Disabling Transparent Caching Services on the Content Engine

To disable transparent caching on a Content Engine in a WCCP environment without powering it down, disable the running version of WCCP on the Content Engine by issuing the Cache software
no wccp version 2 global configuration command. The Content Engine will still service proxy-style requests, if so configured, and preserve its configuration settings.

Further information about the Content Engine commands used to configure the Content Engine for the deployment scenarios provided in this chapter can be found in the Cisco Application and Content Networking Software Command Reference. Refer to this document for more information about the Content Engine commands.

Verifying the Software Configuration

Once you have installed and configured the Content Engine and enabled WCCP caching services on the router, verify that the Cache application is working properly.

Step 1 Start a web browser and open various web pages on the Internet or your intranet. The web servers you connect to must be on a different subnet, so that the request goes through either a home router running WCCP Version 1 or Version 2, or a cluster of routers running WCCP Version 2. Request the same pages more than once, to ensure that pages you request are in the cache. For more information on WCCP, see "Web Cache Communication Protocol Version 1," and "Web Cache Communication Protocol Version 2."

Step 2 From the CLI, enter the following command to display the Content Engine HTTP caching saving statistics:

show statistics http savings

Step 3 Open a console or Telnet session on the home router or routers, and enter the show ip wccp commands to display statistics and status information about the Content Engine.

The statistics should show a number greater than 0 for packets redirected. Also, check for hash assignments, which indicate at the very least that the Content Engines are registered and communicating with the routers.

If the router shows that no packets are being redirected to the Content Engine, you must troubleshoot your setup.

Removing or Replacing a Content Engine

Refer to the Content Engine hardware documentation for instructions on physically removing a Content Engine from an active network.

The router and the Content Engine are in constant communication when WCCP is enabled; thus, when the router notices that the engine is no longer responding to it, the router stops sending requests to the engine. This is transparent to users. If other Content Engines are attached to the router, the router continues sending requests to the other engines.

When you remove a Content Engine, the pages that were cached on its hard disks are no longer available to the router or other Content Engines. Thus, you might see an increase in outgoing web traffic that might have otherwise been fulfilled by the Content Engine you are removing. However, after a time, the router and other Content Engines will redistribute the load of web traffic.

If you remove the last Content Engine from a router, you can also disable cache support on the router. However, this is not necessary; having cache support enabled when there are no Content Engines attached has no effect on the router's performance.

To replace a Content Engine, remove the old one from the network. Then, add the new Content Engine and configure it using the same startup configuration parameters that you used for the removed one.