The WCCP—Fast Timers feature enables WCCP to establish redirection using a configurable message interval when a WCCP client is added to a service group or when a WCCP client fails. WCCP routers and WCCP clients exchange keepalive messages at a fixed interval. Prior to the introduction of the WCCP—Fast Timers feature, the WCCP message interval was fixed at 10 seconds. The WCCP—Fast Timers feature enables use of message intervals ranging from 0.5 seconds to 60 seconds and a timeout value scaling factor of 1 to 5. The default is 10 seconds. The timer interval is driven by the WCCP client which is being redirected to. The WCCP clients must support variable message interval timers in order for the WCCP—Fast Timers feature to function correctly.
The WCCP message interval capability introduced by the WCCP—Fast Timers feature defines the transmission interval that WCCP clients and WCCP routers use when sending keepalive messages and defines a scaling factor used when calculating the timeout value. The WCCP router uses the timeout value to determine if a WCCP client is no longer available and to redirect traffic as a result. The WCCP router enforces a single message interval per service group. WCCP clients with incompatible message intervals are prevented from joining a service group. If a default message interval that is smaller than the default 10 seconds is used, CPU usage will increase.
You can use the show ip wccp service service-number detail command to display information about the message interval.