Web Cache Communication Protocol (WCCP) is a Cisco-developed content-routing protocol that provides a mechanism to redirect traffic flows in real-time. It has built-in load balancing, scaling, fault tolerance, and service-assurance (failsafe) mechanisms. Cisco IOS Release 12.1 and later releases allow the use of either Version 1 (WCCPv1) or Version 2 (WCCPv2) of the protocol.
WCCP allows utilization of Cisco Cache Engines (or other caches running WCCP) to localize web traffic patterns in the network, enabling content requests to be fulfilled locally. Traffic localization reduces transmission costs and download time.
WCCP allows utilization of Cisco Cache Engines (or other caches running WCCP) to localize web traffic patterns in the network, enabling content requests to be fulfilled locally. Traffic localization reduces transmission costs and download time.
Contents
1 Protocol Versions
2 Registration
3 Assignment
4 Redirect from Router to Cache Engine
5 Return from Cache Engine to Router
5.1 External links
Protocol
WCCPv1
Only a single router services a cluster of systems Supports HTTP (TCP port 80) traffic flows only Provides generic routing encapsulation (GRE) to prevent packet modification Routers and cache engines communicate to each other via a control channel based on UDP port 2048
WCCPv2
Allows for use across up to 32 routers (WCCP servers) Supports up to 32 engines/accelerators (WCCP clients) Supports any IP protocol including any TCP or UDP Supports up to 256 service groups (0-255) Adds MD5 shared secret security Primary WCCP functions
Registration
Accelerator or Engine is a WCCP client Registers WCCP services (0-255) with “Here I Am” if application is operational Registration announces WCCP client on service group, provides availability notification, requests interesting traffic Transmits “Here I Am” every 10 seconds Lead WCCP client (lowest IP address) instructs routers on protocol/port, assignment, forwarding, and return methods Router is a WCCP server Accepts service group registration (0-255) Acknowledges “Here I Am” with “I See You” Waits 30 (3x10) seconds before declaring engine failed Announce engines to other engines Router id is highest interface IP or highest loopback IP if one exists Redirects traffic to engine
Assignment
an engine in the cluster Hash 256 buckets Mask 128 buckets represented by 7 bit mask of the source or destionation IP/Por
Redirect from Router to Cache EngineWCCP GRE redirect creates tunnel from router to local or remote Engine WCCP L2 redirect rewrites packet MAC address to that of the local Engine Redirect list allows router to permit/deny traffic to intercept
Return from Cache Engine to RouterWCCP GRE return WCCP L2 return Engine can optionally return traffic any other way including routing
Redirect from Router to Cache EngineWCCP GRE redirect creates tunnel from router to local or remote Engine WCCP L2 redirect rewrites packet MAC address to that of the local Engine Redirect list allows router to permit/deny traffic to intercept
Return from Cache Engine to RouterWCCP GRE return WCCP L2 return Engine can optionally return traffic any other way including routing
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