Table Of Contents

Web Cache Communication Protocol Version 1

Feature Overview

Benefits

Redirection Process

Related Documents

Prerequisites

Configuration Tasks

Configuring the Content Engine

Configuring the Router

Enabling WCCP on the Router

Monitoring WCCP Version 1

Configuration Example

Command Reference

clear ip wccp

ip wccp enable

ip wccp redirect-list

ip web-cache redirect

show ip interface

show ip wccp

show ip wccp web-caches

Debug Commands

debug ip wccp events

debug ip wccp packets

Web Cache Communication Protocol Version 1

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This appendix describes the Web Cache Communication Protocol (WCCP) Version 1 feature. (WCCP is also known as Web Cache Control Protocol and Web Cache Coordination Protocol.) This appendix includes information on the benefits of this feature, and other information you may need to work with WCCP Version 1. This appendix includes the following sections:

•Feature Overview

•Related Documents

•Prerequisites

•Configuration Tasks

•Configuration Example

•Command Reference

•Debug Commands

Feature Overview

The WCCP feature allows you to use a Content 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. Figure A-1 shows a sample WCCP network configuration.

Figure A-1 Content Engine Network Configuration Using WCCP Version 1

When a user (client) requests a page from a web server (located on the Internet, in this case), the router sends the request to a Content Engine (Content Engine 1, Content Engine 2, or Content Engine 3). If the Content Engine has a copy of the requested page in storage, the Content Engine sends the user that page. Otherwise, the Content Engine obtains 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 Content Engine. End users do not know that the page came from the Content Engine rather than from the originally requested web server.

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 Content 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 noncached 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 Content Engine.

Redirection Process

When a WCCP-enabled router receives an IP packet, the router determines whether the packet is a request that should be directed to a Content 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 Content Engine.

Through communication with the Content Engines, the routers running WCCP are aware of available Content Engines.

Related Documents

Refer to the following Cisco IOS documentation for further information on WCCP.

•Cisco IOS Configuration Fundamentals Configuration Guide

•Cisco IOS Configuration Fundamentals Command Reference

Prerequisites

To use a WCCP-enabled router, an IP address must be configured on the interface connected to the Internet, and the interface must be connected to the Content Engine.

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Note A Content Engine and a WCCP-enabled router cannot be separated by a firewall. The firewall handles only packet traffic toward the origin web server and does not handle packet traffic sent to the client by the Content Engine on behalf of the server.

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Configuration Tasks

You can configure a single router to run the web cache associated with WCCP Version 1. Perform the following tasks to configure a Content Engine with a single WCCP-enabled router.

•Configuring the Content Engine

•Configuring the Router

•Enabling WCCP on the Router

Configuring the Content Engine

To use WCCP, the Content Engine must be properly configured. Keep these important points in mind:

•The IP address of the router must be configured as the home router for the Content Engine.

•Versions of software on the Content Engines must be compatible with those installed on the router.

•The Content Engines must not have their packets encrypted or compressed and should be part of the "inside" Network Address Translation if one is present.

•Placing a Content Engine beyond a web cache redirect-enabled interface and along the route to the server will not cause the IP route cache to be populated with an entry.

Configuring the Router

To configure WCCP on the router, you must perform the following tasks. The first task is required, whereas the second is optional.

•Enabling WCCP on the Router

•Monitoring WCCP

Enabling WCCP on the Router

To enable an interface to redirect web traffic to the Content Engine using WCCP Version 1, perform the following tasks beginning in global configuration mode:

	Command	Purpose
Step 1	ip wccp version 1	Enables the router to use WCCP Version 1.
Step 2	ip wccp redirect-list {number | name}	(Optional) Specifies the redirect access list. Only packets that match this access list are redirected. If you do not configure this command, all web-based packets are redirected.
Step 3	interface type number	Enters interface configuration mode.
Step 4	ip web-cache redirect	Configures the interface connected to the Internet to redirect web traffic to the Content Engine.
Step 5	ip route-cache same-interface	(Optional) If the client and a Content Engine are located on the same network, configures the router to use the fast switching path on the interface.
Step 6	end	Exits configuration mode.
Step 7	copy running-config startup-config	Saves the configuration.

Monitoring WCCP Version 1

To monitor WCCP, perform any of the following tasks in EXEC mode:

Command	Purpose
show ip wccp	Displays global WCCP statistics.
show ip wccp web-caches	Displays information about all known Content Engines.
show ip interface	Shows whether web cache redirecting is enabled on an interface.

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 WCCP Version 1 and to redirect web-related packets from Ethernet interface 0 to the Content Engine:

Router# configure terminal

Router(config)# ip wccp enable

Router(config)# interface Ethernet 0

Router(config-if)# ip web-cache redirect

Router(config-if)# end

Router#

%SYS-5-CONFIG_I: Configured from console by console.

Router# copy running-config startup-config

After the router has been configured, use the show ip wccp web-caches command to verify that WCCP is enabled and aware of Content Engines. In this example, the show ip wccp web-caches command is entered immediately after the router has been configured. After a few seconds, the Content Engine becomes usable, as seen in the second output.

Router# show ip wccp web-caches

WCCP Web-Cache information:

        IP Address:            192.168.51.102

        Protocol Version:      1.0

        State:                 NOT Usable

        Initial Hash Info:     FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

                               FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

        Assigned Hash Info:    00000000000000000000000000000000

                               00000000000000000000000000000000

        Hash Allotment:        0 (0.00%)

        Packets Redirected:    0

        Connect Time:          00:00:06

Router# show ip wccp web-caches

WCCP Web-Cache information:

        IP Address             192.168.51.102

        Protocol Version:      0.3

        State:                 Usable

        Initial Hash Info:     FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

                               FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

        Assigned Hash Info:    FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

                               FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

        Hash Allotment:        256 (100.00%)

        Packets Redirected:    0

        Connect Time:          00:00:31

Command 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

•ip wccp enable

•ip wccp redirect-list

•ip web-cache redirect

•show ip interface

•show ip wccp

•show ip wccp web-caches

clear ip wccp

To clear the counter for packets redirected by the Web Cache Communication Protocol, use the
clear ip wccp EXEC command.

clear ip wccp

Syntax Description

This command has no arguments or keywords.

Defaults

No default behavior or values

Command Modes

EXEC

Command History

This command first appeared in Cisco IOS Release 11.2 P and IOS Release 11.1 CA.

Usage Guidelines

The "Packets Redirected" count is displayed by the show ip wccp and show ip wccp web-caches commands.

Examples

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-caches

WCCP Web-Cache information:

        IP Address:            192.168.88.11

        Protocol Version:      1.0

        State:                 Usable

        Initial Hash Info:     AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

                               AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

        Assigned Hash Info:    FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

                               FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

        Hash Allotment:        256 (100.00%)

        Packets Redirected:    21345

        Connect Time:          00:13:46

Router# clear ip wccp

Router# show ip wccp web-caches

WCCP Web-Cache information:

        IP Address:            192.168.88.11

        Protocol Version:      1.0

        State:                 Usable

        Initial Hash Info:     AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

                               AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

        Assigned Hash Info:    FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

                               FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

        Hash Allotment:        256 (100.00%)

        Packets Redirected:    0

        Connect Time:          00:13:46

Related Commands

show ip wccp

show ip wccp web-caches

ip wccp enable

To enable the router to support WCCP, use the ip wccp enable global configuration command. The no form of this command disables support for WCCP.

ip wccp enable

no ip wccp enable

Syntax Description

This command has no arguments or keywords.

Defaults

WCCP is disabled on the router.

Command Modes

Global configuration

Command History

This command first appeared in Cisco IOS Release 11.2 P and Release 11.1 CA.

Usage Guidelines

This command and the ip web-cache redirect interface configuration command are the only commands required to start redirecting requests to the Content Engine using WCCP. To see whether WCCP 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 Content Engines but does not use them.

Use the ip wccp redirect-list command to limit the redirection of packets to those matching an access list.

Examples

The following example configures a router to support WCCP and redirects web-related packets from Ethernet interface 0 to the Content Engine:

Router# configure terminal

Router(config)# ip wccp enable

Router(config)# interface Ethernet 0

Router(config-if)# ip web-cache redirect

Router(config-if)# end

Router#

%SYS-5-CONFIG_I: Configured from console by console.

Related CommandsRelated Commands

ip wccp redirect-list

ip web-cache redirect

show ip wccp

show ip wccp web-caches

ip wccp redirect-list

To specify which packets are redirected to a Content 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 Cisco IOS Release 11.2 P.

Defaults

All HTTP packets are redirected to the Content Engine.

Command Modes

Global configuration

Command History

This command first appeared in Cisco IOS Release 11.2 P and Release 11.1 CA.

Usage Guidelines

Use this command to specify which packets should be redirected to the Content Engine. When WCCP is enabled but this command is not configured, all web-related packets are redirected to the Content Engine. When you enter this command, only packets that match the access list are redirected.

Some websites use the source IP address of packets for authentication. The Content Engine uses its own IP address when sending requests to websites. Thus, the requests from the Content Engine may not be authenticated. Use this command to bypass the Content Engine in these cases.

Use the ip wccp enable and ip web-cache redirect commands to configure WCCP.

Examples

The following example configures a router to redirect web-related packets without a destination of 192.168.196.51 to the Content Engine:

Router# configure terminal

Router(config)# access-list 100 deny ip any host 192.168.196.51

Router(config)# access-list 100 permit ip any any

Router(config)# ip wccp enable

Router(config)# ip wccp redirect-list 100

Router(config)# interface Ethernet 0

Router(config-if)# ip web-cache redirect

Router(config-if)# end

Router#

%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 Content Engine, use the ip web-cache redirect interface configuration command. The no form of this command disables the redirection of messages to the Content Engine.

ip web-cache redirect

no ip web-cache redirect

Syntax Description

This command has no arguments or keywords.

Defaults

The interface does not redirect messages to the Content Engine.

Command Modes

Interface configuration

Command History

This command first appeared in Cisco IOS Release 11.2 P and Release 11.1 CA.

Usage Guidelines

This command and the ip wccp enable interface command are the only commands required to start redirecting requests to the Content Engine using WCCP.

Examples

The following example configures a router to support WCCP and redirects web-related packets from Ethernet interface 0 to the Content Engine:

Router# configure terminal

Router(config)# ip wccp enable

Router(config)# interface Ethernet 0

Router(config-if)# ip web-cache redirect

Router(config-if)# end

Router#

%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-caches

show 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

type	(Optional) Interface type.
number	(Optional) Interface number.

Defaults

No default behavior or values

Command Modes

EXEC

Command History

This command first appeared in Cisco IOS Release 10.0.

Usage Guidelines

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 information about that specific interface only.

If you specify no optional arguments, you will see information about all of the interfaces.

When an asynchronous interface is encapsulated with Point-to-Point Protocol (PPP) or Serial Line Internet Protocol (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.

Examples

The following is sample output from the show ip interface command:

Router# show ip interface

Ethernet0 is up, line protocol is up

  Internet address is 172.168.78.24, subnet mask is 255.255.255.240

  Broadcast address is 255.255.255.255

  Address determined by non-volatile memory

  MTU is 1500 bytes

  Helper address is not set

  Secondary address 172.31.255.255, subnet mask 255.255.255.0

  Directed broadcast forwarding is enabled

  Multicast groups joined: 224.0.0.1 224.0.0.2

  Outgoing access list is not set

  Inbound  access list is not set

  Proxy ARP is enabled

  Security level is default

  Split horizon is enabled

  ICMP redirects are always sent

  ICMP unreachables are always sent

  ICMP mask replies are never sent

  IP fast switching is enabled

  IP fast switching on the same interface is disabled

  IP SSE switching is disabled

  Router Discovery is disabled

  IP output packet accounting is disabled

  IP access violation accounting is disabled

  TCP/IP header compression is disabled

  Probe proxy name replies are disabled

  Web Cache Redirect is enabled

Table A-1 describes the fields shown in the display.

Table A-1 Field Descriptions—show ip interface Command 

Field	Description
Ethernet0 is up	If the interface hardware is usable, the interface is marked "up." For an interface to be usable, both the interface hardware and the line protocol must be up.
Line protocol is up	If the interface can provide two-way communication, the line protocol is marked "up." For an interface to be usable, both the interface hardware and the line protocol must be up.
Internet address	Shows the IP address.
Subnet mask	Shows the subnet mask address.
Broadcast address	Shows the broadcast address.
Address determined by...	Indicates how the IP address of the interface was determined.
MTU	Shows the maximum transmission unit (MTU) value set on the interface.
Helper address	Shows a helper address, if one has been set.
Secondary address	Shows a secondary address, if one has been set.
Directed broadcast forwarding	Indicates whether directed broadcast forwarding is enabled.
Multicast groups joined	Indicates the multicast groups that this interface is a member of.
Outgoing access list	Indicates whether the interface has an outgoing access list set.
Inbound access list	Indicates whether the interface has an incoming access list set.
Proxy ARP	Indicates whether proxy Address Resolution Protocol (ARP) is enabled for the interface.
Security level	Specifies the IP Security Option (IPSO) security level set for this interface.
ICMP redirects	Specifies whether redirects will be sent on this interface.
ICMP unreachables	Specifies whether unreachable messages will be sent on this interface.
ICMP mask replies	Specifies whether mask replies will be sent on this interface.
IP fast switching	Specifies whether fast switching has been enabled for this interface. It is generally enabled on serial interfaces, such as this one.
IP SSE switching	Specifies whether IP silicon switching engine (SSE) switching is enabled.
Router Discovery	Specifies whether the discovery process has been enabled for this interface. It is generally disabled on serial interfaces.
IP output packet accounting	Specifies whether IP accounting is enabled for this interface and what the threshold (maximum number of entries) is.
TCP/IP header compression	Indicates whether compression is enabled or disabled.
Probe proxy name	Indicates whether HP probe proxy name replies are generated.
Web Cache Redirect	Indicates whether HTTP packets are redirected to a Content Engine.

show ip wccp

To display global statistics related to WCCP, use the show ip wccp EXEC command.

show ip wccp

Syntax Description

This command has no arguments or keywords.

Defaults

No default behavior or values

Command Modes

EXEC

Command History

This command first appeared in Cisco IOS Release 11.2 P and Release 11.1 CA.

Usage Guidelines

Use the clear ip wccp command to reset the counter for the "Total Packets Redirected" information.

Examples

The following example shows sample show ip wccp output:

Router# show ip wccp

Global WCCP information:

         Number of web-caches:                2

         Total Packets Redirected:            101

         Redirect access-list:                no_linux

         Total Packets Denied Redirect:       88

         Total Packets Unassigned:            0

Table A-2 describes the fields shown in this example.

Table A-2 Field Descriptions—show ip wccp Command

Field	Description
Number of web-caches	Number of Content Engines using the router as their home router.
Total Packets Redirected	Total number of packets redirected by the router.
Redirect access-list	Name or number of the redirect access list. Only packets matching the access list are redirected.
Total Packets Denied Redirect	Total number of packets that were not redirected because they did not match the access list.
Total Packets Unassigned	Number of packets that were not redirected because they were not assigned to any web cache. Packets are sometimes not assigned during initial discovery of Content Engines or when a Content Engine is dropped from a farm.

Related Commands

clear ip wccp

ip wccp enable

ip wccp redirect-list

ip web-cache redirect

show ip interface

show ip wccp web-caches

show ip wccp web-caches

To display information about the router's known Content Engines, use the show ip wccp web-caches EXEC command.

show ip wccp web-caches

Syntax Description

This command has no arguments or keywords.

Defaults

No default behavior or values

Command Modes

EXEC

Command History

This command first appeared in Cisco IOS Release 11.2 P and Release 11.1 CA.

Usage Guidelines

Use the clear ip wccp command to reset the counter for the "Packets Redirected" information.

Examples

The following example shows sample show ip wccp web-caches output:

Router# show ip wccp web-caches

WCCP Web-Cache information:

        IP Address:            172.168.88.11

        Protocol Version:      1.0

        State:                 Usable

        Initial Hash Info:     AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

                               AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

        Assigned Hash Info:    FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

                               FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

        Hash Allotment:        256 (100.00%)

        Packets Redirected:    21345

        Connect Time:          00:13:46

Table A-3 explains the fields shown in this display.

Table A-3 Field Descriptions—show ip wccp web-caches Command 

Field	Description
IP Address	IP address of the Content Engine.
Protocol Version	Version of the Web Cache Communication Protocol that the Content Engine is running.
State	State of the Content Engine. Possible values are "Usable" and "NOT Usable."
Initial Hash Info	Initial contents of the hash field. The hash field contains information about how the router intends to use the Content Engine.
Assigned Hash Info	Current hash information of the Content Engine. The hash information field contains information about how the router intends to use the Content Engine.
Hash Allotment	Percentage of all possible web servers for which the router redirects HTTP requests to this web cache. In this example, there is only one Content Engine, so all HTTP requests are redirected to it.
Packets Redirected	Number of packets redirected to this Content Engine.
Connect Time	Indicates how long the Content Engine has used this router as its home router.

Related Commands

clear ip wccp

ip wccp enable

ip web-cache redirect

show ip interface

show ip wccp

Debug Commands

This section documents new or modified debug commands related to WCCP.

•debug ip wccp events

•debug ip wccp packets

debug ip wccp events

To display information about significant WCCP events, use the debug ip wccp events command. To disable debugging output, use the no form of this command.

debug ip wccp events

no debug ip wccp events

Syntax Description

This command has no arguments or keywords.

Defaults

No default behavior or values

Examples

The following example is sample output of the debug ip wccp events command when a Content Engine is added to the list of available web caches:

Router# debug ip wccp events

WCCP-EVNT: Built I_See_You msg body w/1 usable web caches, change # 0000000A

WCCP-EVNT: Web Cache 192.168.25.3 added

WCCP-EVNT: Built I_See_You msg body w/2 usable web caches, change # 0000000B

WCCP-EVNT: Built I_See_You msg body w/2 usable web caches, change # 0000000C

debug ip wccp packets

To display information about every WCCP packet received or sent by the router, use the debug ip wccp packets command. To disable debugging output, use the no form of this command.

debug ip wccp packets

no debug ip wccp packets

Syntax Description

This command has no arguments or keywords.

Defaults

No default behavior or values

Examples

The following example is sample output of the debug ip wccp packets command. The router is sending keepalive packets to the Content Engines at 192.168.25.4 and 192.168.25.3. Each keepalive packet has an identification number associated with it. When the Content Engine receives a keepalive packet from the router, it sends a reply with the identification number back to the router.

Router# debug ip wccp packets

WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.4 w/rcvd_id 00003532

WCCP-PKT: Sending I_See_You packet to 192.168.25.4 w/ rcvd_id 00003534

WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.3 w/rcvd_id 00003533

WCCP-PKT: Sending I_See_You packet to 192.168.25.3 w/ rcvd_id 00003535

WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.4 w/rcvd_id 00003534

WCCP-PKT: Sending I_See_You packet to 192.168.25.4 w/ rcvd_id 00003536

WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.3 w/rcvd_id 00003535

WCCP-PKT: Sending I_See_You packet to 192.168.25.3 w/ rcvd_id 00003537

WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.4 w/rcvd_id 00003536

WCCP-PKT: Sending I_See_You packet to 192.168.25.4 w/ rcvd_id 00003538

WCCP-PKT: Received valid Here_I_Am packet from 192.168.25.3 w/rcvd_id 00003537

WCCP-PKT: Sending I_See_You packet to 192.168.25.3 w/ rcvd_id 00003539