Requirements for WCCP transparent proxying

About WCCP

The Web Cache Communication Protocol (WCCP) provides a way for routers to redirect and distribute traffic among one or more proxy-cache servers (such as an appliance). WCCP has a built in load-balancing mechanism and provides redundancy.

WCCP can be used for both forward-proxy and reverse-proxy deployments. A WCCP router can redirect and distribute DNS, FTP, HTTP, NNTP, MMS, and RTSP requests across multiple appliances.

Note
You can also use a policy-based router to redirect traffic to the appliance. Contact your Network Appliance representative for more information.

Requirements for transparent proxying with a WCCP 2.0 router

To deploy transparent proxying with a WCCP router, you must meet the requirements listed in the following table.

Category	Requirements and recommendations
Appliance	A network interface is required for each router attached.
Network layout	The router must be in a location to detect all traffic for the clients it is expected to serve. See Router location for more information. If a firewall is between the WCCP router and the appliance, you must allow UDP port 2048. WCCP runs over UDP using port 2048.
Router configuration	You must meet the software requirements described in WCCP 2.0 software requirements. Configure WCCP service group information to correspond to service group configuration on the appliances. See Cisco documentation for information about setting up WCCP 2.0.
NetCache configuration	For each protocol for which you want to set up transparent proxying, enable the transparency feature. Configure service group information, which includes identifying traffic to be redirected to the appliances and the request distribution method to be used. NetCache can then send information to the router that the router can use to configure itself.

WCCP 2.0 software requirements

To implement transparent proxying with WCCP, your router or switch must meet the software requirements listed in the following table. See the Cisco Web site for more information about WCCP 2.0 requirements.

Hardware	Required software version
WCCP router	IOS 12.0(4) T images and later versions
WCCP switch	IOS 12.1(4) T images and later versions

Router location

The following table provides information about WCCP router location.

Router location in relation to...	Comments
NetCache appliances	When you have multiple subnets, the router and appliances can be on different subnets. However, Network Appliance recommends that, for efficiency, the router and appliances be on the same subnet. You can directly connect a WCCP router to an appliance. However, a direct connection is not a requirement or a best practice recommendation.
Clients	The router must be located so that it can view all network traffic for the clients that it is expected to serve.
Firewalls	Do not place the WCCP router in a location where a firewall that uses Network Address Translation (NAT) is located between it and the appliance. Firewall configuration for WCCP traffic can be difficult. Consult your Network Appliance service engineer for configuration help and deployment recommendations.

Router location in relation to...

Comments

NetCache appliances

When you have multiple subnets, the router and appliances can be on different subnets. However, Network Appliance recommends that, for efficiency, the router and appliances be on the same subnet.

You can directly connect a WCCP router to an appliance. However, a direct connection is not a requirement or a best practice recommendation.

Clients

The router must be located so that it can view all network traffic for the clients that it is expected to serve.

Firewalls

Do not place the WCCP router in a location where a firewall that uses Network Address Translation (NAT) is located between it and the appliance.
Firewall configuration for WCCP traffic can be difficult. Consult your Network Appliance service engineer for configuration help and deployment recommendations.