Figure 1: Cisco Content Engine Network Configuration Using WCCPv2 The subset of content engines within a cluster and devices connected to the cluster that are running the same service is known as a service group. Available services include TCP and UDP redirection. WCCPv2 requires that each content engine be aware of all the devices in the service group. To specify the addresses of all the devices in a service group, choose one of the following methods: • Unicast—A list of device addresses for each of the devices in the group is configured on each content engine. In this case, the address of each device in the group must be explicitly specified for each content engine during configuration.
• Multicast—A single multicast address is configured on each content engine. In the multicast address method, the content engine sends a single-address notification that provides coverage for all switches in the service group. For example, a content engine could indicate that packets should be sent to a multicast address of 224.0.0.100, which would send a multicast packet to all devices in the service group configured for group listening using WCCP (see the ip wccp group-listen interface configuration command for details). 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: 1. Each content engine is configured with a list of devices. 2. Each content engine announces its presence and a list of all devices with which it has established communications. The routers reply with their view (list) of content engines in the group. 3.
When the view is consistent across all content engines in the cluster, one content engine is designated as the lead and sets the policy that the devices need to deploy in redirecting packets. Configuring WCCP WCCPv2 Configuration Configuring WCCP 4