Table Of Contents
Changes for Release 11.1(18)CA and Release 11.2(13)P
Enable the Web Cache Control Protocol on the Router
Monitor the Web Cache Control Protocol
Web Cache Control Protocol
Description
The Web Cache Control Protocol (WCCP) feature allows you to use a Cisco Cache Engine to handle web traffic, thus reducing transmission costs and downloading time. This traffic includes user requests to view pages and graphics on World Wide Web servers, whether internal or external to your network, and the replies to those requests. shows a sample WCCP network configuration.
Figure 1 Sample Cisco Cache Engine Network Configuration
When a user (client) requests a page from a web server (located in the Internet, in this case), the router sends the request to a Cisco Cache Engine (Cache 1, Cache 2, or Cache 3). If the cache engine has a copy of the requested page in storage, the engine sends the user that page. Otherwise, the engine gets the requested page and the objects on that page from the web server, stores a copy of the page and its objects (caches them), and forwards the page and objects to the user.
WCCP transparently redirects HTTP requests from the intended server to a Cisco Cache Engine. End users do not know that the page came from the cache engine rather than the originally requested web server.
The Using the Cisco Cache Engine publication contains detailed information about the Cisco Cache Engine and discusses alternative network configurations.
Benefits
Web caches reduce transmissions costs and the amount of time required to download web files. If a client requests a web page that is already cached, the request and data only have to travel between the Cisco Cache Engine and the client. Without a web cache, the request and reply must travel over the Internet or wide-area network. Cached pages can be loaded faster than non-cached pages and do not have to be transmitted from the Internet to your network.
Cisco IOS support of WCCP provides a transparent web cache solution. Users can benefit from web proxy caches without having to configure clients to contact a specific proxy server in order to access web resources. Many web proxy caches require clients to access web resources through a specific proxy web server rather than using the originally requested web server URL. With WCCP, the clients send web requests to the desired web server URL. Cisco IOS routers intelligently intercept HTTP requests and transparently redirect them to a Cisco Cache Engine.
Redirection Process
When a Web Cache Control Protocol-enabled router receives an IP packet, the router determines if the packet is a request that should be directed to a Cisco Cache Engine. The router looks for TCP as the protocol field in the IP header and for 80 as the destination port in the TCP header. If the packet meets these criteria, it is redirected to a Cisco Cache Engine.
Through communication with the Cisco Cache Engines, the routers running WCCP are aware of available cache engines.
Changes for Release 11.1(18)CA and Release 11.2(13)P
In Cisco IOS Release 11.1(18)CA and Release 11.2(13)P, the following changes were made:
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The ip wccp redirect-list command was added.
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Platforms
In Release 11.1 CA, this feature is supported on these platforms:
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In Release 11.2 P, this feature is supported on these platforms:
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Prerequisites
To use the Web Cache Control Protocol, IP must be configured on the interface connected to the Internet and the interface connected to the Cisco Cache Engine.
The interface connected to the Cisco Cache Engine must be an Ethernet or Fast Ethernet interface.
Configuration Tasks
To configure the Web Cache Control Protocol on the router, you must perform the following tasks. The first task is required, while the second is optional.
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Enable the Web Cache Control Protocol on the Router
To enable an interface to redirect web traffic to the Cisco Cache Engine using the Web Cache Control Protocol, perform the following tasks beginning in global configuration mode:
Monitor the Web Cache Control Protocol
To monitor the Web Cache Control Protocol, perform any of the following tasks in EXEC mode:
The show ip wccp and show ip wccp web-caches commands display a count of the number of packets redirected. Use the clear ip wccp EXEC command to clear this counter.
Configuration Example
The following example configures a router to support the Web Cache Control Protocol and to redirect web-related packets from Ethernet interface 0 to the Cisco Cache Engine:
Router# configure terminalRouter(config)# ip wccp enableRouter(config)# interface Ethernet 0Router(config-if)# ip web-cache redirectRouter(config-if)# endRouter#%SYS-5-CONFIG_I: Configured from console by console.Router# copy running-config startup-configAfter the router has been configured, use the show ip wccp web-cache command to verify that Web Cache Control Protocol is enabled and aware of Cisco Cache Engines. In this example, the show ip wccp web-cache command is entered immediately after the router has been configured. After a few seconds, the cache engine becomes usable, as seen in the second output.
Router# show ip wccp web-cacheWCCP Web-Cache information:IP Address: 192.168.51.102Protocol Version: 0.3State: NOT UsableInitial Hash Info: FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFAssigned Hash Info: 0000000000000000000000000000000000000000000000000000000000000000Hash Allotment: 0 (0.00%)Packets Redirected: 0Connect Time: 00:00:06Router# show ip wccp web-cacheWCCP Web-Cache information:IP Address 192.168.51.102Protocol Version: 0.3State: UsableInitial Hash Info: FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFAssigned Hash Info: FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFHash Allotment: 256 (100.00%)Packets Redirected: 0Connect Time: 00:00:31Command Reference
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 11.1 or Release 11.2 command references.
clear ip wccp
To clear the counter for packets redirected by the Web Cache Control Protocol, use the clear ip wccp EXEC command.
clear ip wccp
Syntax Description
This command has no arguments or keywords.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2 P and Cisco IOS Release 11.1 CA.
The "Packets Redirected" count is displayed by the show ip wccp and show ip wccp web-caches commands.
Sample Display
The following example shows output from the show ip wccp web-caches command before and after the clear ip wccp command is used:
Router# show ip wccp web-cachesWCCP Web-Cache information:IP Address: 192.168.88.11Protocol Version: 1.0State: UsableInitial Hash Info: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAssigned Hash Info: FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFHash Allotment: 256 (100.00%)Packets Redirected: 21345Connect Time: 00:13:46Router# clear ip wccpRouter# show ip wccp web-cachesWCCP Web-Cache information:IP Address: 192.168.88.11Protocol Version: 1.0State: UsableInitial Hash Info: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAssigned Hash Info: FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFHash Allotment: 256 (100.00%)Packets Redirected: 0Connect Time: 00:13:46Related Commands
show ip wccp
show ip wccp web-cachesip wccp enable
To enable the router to support the Web Cache Control Protocol, use the ip wccp enable global configuration command. The no form of this command disables support for the Web Cache Control Protocol.
ip wccp enable
no ip wccp enableSyntax Description
This command has no arguments or keywords.
Default
The Web Cache Control Protocol is disabled on the router.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2 P and Release 11.1 CA.
This command and the ip web-cache redirect interface command are the only commands required to start redirecting requests to the Cisco Cache Engine using the Web Cache Control Protocol. To see if the Web Cache Control Protocol is enabled on the router, use the show ip wccp command.
When this command is enabled but the ip web-cache redirect command is disabled, the router is aware of caches but does not use them.
Use the ip wccp redirect-list command to limit the redirection of packets to those matching an access list.
Example
The following example configures a router to support the Web Cache Control Protocol and redirects web-related packets from Ethernet interface 0 to the Cisco Cache Engine:
Router# configure terminalRouter(config)# ip wccp enableRouter(config)# interface Ethernet 0Router(config-if)# ip web-cache redirectRouter(config-if)# endRouter#%SYS-5-CONFIG_I: Configured from console by console.Related Commands
ip wccp redirect-list
ip web-cache redirect
show ip wccp
show ip wccp web-cachesip wccp redirect-list
To specify which packets are redirected to a Cisco Cache Engine, use the ip wccp redirect-list global configuration command. The no form of this command enables redirection of all packets.
ip wccp redirect-list {number | name}
Syntax Description
number
Standard or extended IP access list number from 1 to 199.
name
Standard or extended IP access list name. This argument is only available in Release 11.2 P.
Default
All HTTP packets are redirected to the Cisco Cache Engine.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2 P and Release 11.1 CA.
Use this command to specify which packets should be redirected to the Cisco Cache Engine. When WCCP is enabled but this command is not configured, all web-related packets are redirected to the Cisco Cache Engine. When you enter this command, only packets that match the access list are redirected.
Some Web sites use the source IP address of packets for authentication. The Cisco Cache Engine uses its own IP address when sending requests to Web sites. Thus, the requests from the Cisco Cache Engine may not be authenticated. Use this command to bypass the Cisco Cache Engine in these cases.
Use the ip wccp enable and ip web-cache redirect commands to configure WCCP.
Example
The following example configures a router to redirect web-related packets without a destination of 192.168.196.51 to the Cisco Cache Engine:
Router# configure terminalRouter(config)# access-list 100 deny ip any host 192.168.196.51Router(config)# access-list 100 permit ip any anyRouter(config)# ip wccp enableRouter(config)# ip wccp redirect-list 100Router(config)# interface Ethernet 0Router(config-if)# ip web-cache redirectRouter(config-if)# endRouter#%SYS-5-CONFIG_I: Configured from console by console.Related Commands
clear ip wccp
ip wccp enable
ip web-cache redirect
show ip wccp
ip web-cache redirect
To instruct an interface to check for appropriate outgoing packets and redirect them to a Cisco Cache Engine, use the ip web-cache redirect interface configuration command. The no form of this command disables the redirection of messages to the Cisco Cache Engine.
ip web-cache redirect
no ip web-cache redirectSyntax Description
This command has no arguments or keywords.
Default
The interface does not redirect messages to the Cisco Cache Engine.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2 P and Release 11.1 CA.
This command and the ip wccp enable interface command are the only commands required to start redirecting requests to the Cisco Cache Engine using the Web Cache Control Protocol.
Example
The following example configures a router to support the Web Cache Control Protocol and redirects web-related packets from Ethernet interface 0 to the Cisco Cache Engine:
Router# configure terminalRouter(config)# ip wccp enableRouter(config)# interface Ethernet 0Router(config-if)# ip web-cache redirectRouter(config-if)# endRouter#%SYS-5-CONFIG_I: Configured from console by console.Related Commands
clear ip wccp
ip wccp enable
ip wccp redirect-list
show ip interface
show ip wccp
show ip wccp web-cachesshow ip interface
To display the usability status of interfaces configured for IP, use the show ip interface EXEC command.
show ip interface [type number]
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The Cisco IOS software automatically enters a directly connected route in the routing table if the interface is usable. A usable interface is one through which the software can send and receive packets. If the software determines that an interface is not usable, it removes the directly connected routing entry from the routing table. Removing the entry allows the software to use dynamic routing protocols to determine backup routes to the network (if any).
If the interface can provide two-way communication, the line protocol is marked "up." If the interface hardware is usable, the interface is marked "up."
If you specify an optional interface type, you will see only information on that specific interface.
If you specify no optional arguments, you will see information on all the interfaces.
When an asynchronous interface is encapsulated with PPP or SLIP, IP fast switching is enabled. A show ip interface command on an asynchronous interface encapsulated with PPP or SLIP displays a message indicating that IP fast switching is enabled.
Sample Display
The following is sample output from the show ip interface command:
Router# show ip interfaceEthernet0 is up, line protocol is upInternet address is 192.195.78.24, subnet mask is 255.255.255.240Broadcast address is 255.255.255.255Address determined by non-volatile memoryMTU is 1500 bytesHelper address is not setSecondary address 131.192.115.2, subnet mask 255.255.255.0Directed broadcast forwarding is enabledMulticast groups joined: 224.0.0.1 224.0.0.2Outgoing access list is not setInbound access list is not setProxy ARP is enabledSecurity level is defaultSplit horizon is enabledICMP redirects are always sentICMP unreachables are always sentICMP mask replies are never sentIP fast switching is enabledIP fast switching on the same interface is disabledIP SSE switching is disabledRouter Discovery is disabledIP output packet accounting is disabledIP access violation accounting is disabledTCP/IP header compression is disabledProbe proxy name replies are disabledWeb Cache Redirect is enableddescribes the fields shown in the display.
show ip wccp
To display global statistics related to the Web Cache Control Protocol, use the show ip wccp EXEC command.
show ip wccp
Syntax Description
This command has no arguments or keywords.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2 P and Release 11.1 CA.
Use the clear ip wccp command to reset the counter for the "Packets Redirected" information.
Sample Display
The following example shows sample show ip wccp output:
Router# show ip wccpGlobal WCCP information:Number of web-caches: 2Total Packets Redirected: 101Redirect access-list: no_linuxTotal Packets Denied Redirect: 88Total Packets Unassigned: 0describes fields shown in this example.
Related Commands
clear ip wccp
ip wccp enable
ip wccp redirect-list
ip web-cache redirect
show ip interface
show ip wccp web-cachesshow ip wccp web-caches
To display information about the router's known Cisco Cache Engines, use the show ip wccp web-caches EXEC command.
show ip wccp web-caches
Syntax Description
This command has no arguments or keywords.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2 P and Release 11.1 CA.
Use the clear ip wccp command to reset the counter for the "Packets Redirected" information.
Sample Display
The following example shows sample show ip wccp web-caches output:
Router# show ip wccp web-cachesWCCP Web-Cache information:IP Address: 192.168.88.11Protocol Version: 1.0State: UsableInitial Hash Info: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAssigned Hash Info: FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFHash Allotment: 256 (100.00%)Packets Redirected: 21345Connect Time: 00:13:46explains the fields shown in this display.
Related Commands
clear ip wccp
ip wccp enable
ip web-cache redirect
show ip interface
show ip wccpDebug Commands
This section documents the following new debug commands:
debug ip wccp events
Use the debug ip wccp events EXEC command to display information about significant Web Cache Control Protocol events. The no form of this command disables debugging output.
[no] debug ip wccp events
Sample Display
shows sample debug ip wccp events output when a Cisco Cache Engine is added to the list of available Web caches.
Figure 2 Sample Debug IP WCCP Events Output
Router# debug ip wccp eventsWCCP-EVNT: Built I_See_You msg body w/1 usable web caches, change # 0000000AWCCP-EVNT: Web Cache 192.168.25.3 addedWCCP-EVNT: Built I_See_You msg body w/2 usable web caches, change # 0000000BWCCP-EVNT: Built I_See_You msg body w/2 usable web caches, change # 0000000Cdebug ip wccp packets
Use the debug ip wccp packets EXEC command to display information about every Web Cache Control Protocol packet received or sent by the router. The no form of this command disables debugging output.
[no] debug ip wccp packets
Sample Display
shows sample debug ip wccp packets output. The router is sending keepalive packets to the Cisco Cache Engines at 192.168.25.4 and 192.168.25.3. Each keepalive packet has an identification number associated with it. When the Cisco Cache Engine receives a keepalive packet from the router, it sends a reply with the identification number back to the router.
Figure 3 Sample Debug IP WCCP Packets Output
Router# debug ip wccp packetsWCCP-PKT: Received valid Here_I_Am packet from 192.168.25.4 w/rcvd_id 00003532WCCP-PKT: Sending I_See_You packet to 192.168.25.4 w/ rcvd_id 00003534WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.3 w/rcvd_id 00003533WCCP-PKT: Sending I_See_You packet to 192.168.25.3 w/ rcvd_id 00003535WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.4 w/rcvd_id 00003534WCCP-PKT: Sending I_See_You packet to 192.168.25.4 w/ rcvd_id 00003536WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.3 w/rcvd_id 00003535WCCP-PKT: Sending I_See_You packet to 192.168.25.3 w/ rcvd_id 00003537WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.4 w/rcvd_id 00003536WCCP-PKT: Sending I_See_You packet to 192.168.25.4 w/ rcvd_id 00003538WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.3 w/rcvd_id 00003537WCCP-PKT: Sending I_See_You packet to 192.168.25.3 w/ rcvd_id 00003539What to Do Next
To use WCCP, the Cisco Cache Engine must be properly configured. Refer to the Using the Cisco Cache Engine publication for details on configuring the Cisco Cache Engine. Keep these important points in mind:
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