Cisco Content Engines, for example, use dynamic service 99 to specify a reverse-proxy service. However, other content engine devices may use this service number for some other service. WCCP: Check All Services An interface may be configured with more than one WCCP service. When more than one WCCP service is configured on an interface, the precedence of a service depends on the relative priority of the service compared to the priority of the other configured services. Each WCCP service has a priority value as part of its definition. When an interface is configured with more than one WCCP service, the precedence of the packets is matched against service groups in priority order.
The priority of a WCCP service group cannot be configured through Cisco IOS XE software. Note With the ip wccp check services all command, WCCP can be configured to check all configured services for a match and perform redirection for those services if appropriate. The caches to which packets are redirected can be controlled by a redirect ACL and by the service priority. The ip wccp check services all command must be configured at global level to support multiple WCCP services. If no WCCP services are configured with a redirect ACL, the services are considered in priority order until a service is found that matches the IP packet. If no services match the packet, the packet is not redirected.
If a service matches the packet and the service has a redirect ACL configured, then the IP packet will be checked against the ACL. If the packet is rejected by the ACL, the packet will not be passed down to lower priority services unless the ip wccp check services all command is configured. When the ip wccp check services all command is configured, WCCP will continue to attempt to match the packet against any remaining lower priority services configured on the interface. WCCP VRF WCCP VRF enhances the WCCPv2 protocol by adding support for virtual routing and forwarding (VRF). WCCP VRF allows service groups to be configured on a per-VRF basis in addition to being defined globally.
Along with the service identifier, the VRF of the WCCP packets arriving at the device is used to associate the cache engine with a configured service group. The same WCCP VRF must have the interface on which redirection is applied, the interface that is connected to the cache engine, and the interface on which the packet would have left if it had not been redirected. WCCP Troubleshooting Tips CPU usage may be very high when WCCP is enabled. The WCCP counters enable a determination of the bypass traffic directly on the switch and can indicate whether the cause is high CPU usage due to enablement of WCCP.
In some situations, 10 percent bypass traffic may be normal; in other situations, 10 percent may be high. However, any figure above 25 percent should prompt a closer investigation of what is occurring in the web cache. If the counters suggest that the level of bypass traffic is high, the next step is to examine the bypass counters in the content engine and determine why the content engine is choosing to bypass the traffic. You can log in to the content engine console and use the CLI to investigate further. The counters allow you to determine the percent of traffic being bypassed. Configuring WCCP WCCP: Check All Services Configuring WCCP 8