Cisco Cisco IOS Software Release 12.0(11)S

WCCP Version 2 for Cisco IOS 12.0 S now contains the following new features:

WCCP Version 2 currently supports Cisco Express Forwarding (CEF), Fast, and Process forwarding 
paths. CEF is advanced Layer 3 IP switching technology. CEF optimizes network performance and 
scalability for networks with large and dynamic traffic patterns, such as the Internet, on networks 
characterized by intensive Web-based applications, or interactive sessions. Distributed CEF (dCEF) is 
one of two modes of CEF operation that enables line cards to perform the express forwarding between 
port adapters. 

The addition of support for distributed CEF (dCEF) improves performance and scalability by reducing 
processor load on the router. With dCEF packet classification and redirection takes place on the 
linecards. 

WCCP Version 2 was previously an output feature only, with packets classified by WCCP after a routing 
table lookup. CEF output features impose an overhead on packets arriving at all interfaces. You can now 
mark an interface for input redirection via the CLI. Also, you can now configure WCCP as an input 
feature to CEF, dCEF, Fast, and Process forwarding paths. When configured as an input feature WCCP 
classifies packets before the routing table reducing overhead time.

WCCP Version 2 can now classify packets by Border Gateway Protocol (BGP) attributes associated with 
the source or destination IP address of a packet. You can set a WCCP tag on one or more routes based 
on the route BGP attributes. WCCP tags are set using a route map. You can configure a WCCP service 
with a source or destination tag.

After you set a WCCP tag on a route or routes, you can configure a WCCP service with the same tag. 
WCCP then only redirects packets coming from or going to the tagged routes.When WCCP classifies a 
packet it matches the packet against a service description. If the packet matches the service description 
WCCP performs tag matching. If the tag is a source tag, the FIB entry matching the source address of 
the packet is retrieved and the WCCP tag is examined. If the WCCP tag is a destination tag, the FIB entry 
matching the packet destination IP address is retrieved. When the FIB tag does not match the WCCP 
service tag, the packet is not matched against the service.

At redirection time, when a packet has been matched against a service, WCCP performs a policy check. If a 
policy has been set on the service, WCCP inspects the Forwarding Information Base (FIB) entry associated 
with the source or destination address of the packet. If the FIB WCCP tag does not match the service tag the 
next service will be inspected. Both service and policy matches must occur before WCCP redirects packets 
to a service.