Web Cache Communication 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 255 service groups (0-254)
• Adds MD5 shared secret security

• Accelerator or Engine is a WCCP client
• Registers WCCP services (0-254) 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 (0-254)
• 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

• Selects an engine in the cluster
• Hash 256 buckets
• Mask 128 buckets represented by 7 bit mask of the source or destination IP/Port

• Redirect list allows router to permit/deny traffic to intercept
• Two methods of redirection:
• WCCP L2: Local subnet only, little overhead. Rewrites packet MAC address to that of the local Engine
• WCCP GRE: Any IP-Subnet, more overhead. Creates tunnel from router to local or remote Engine.

• WCCP GRE return.
• WCCP L2 return.
• Engine can optionally return traffic any other way including routing.

{{Refimprove section|date=February 2013}}

Whilst originally designed for Cisco's Content Cache appliance they have since added support to other products, including:

• ASR 1000 Routers {{cite web | url=http://www.cisco.com/en/US/prod/collateral/routers/ps9343/white_paper_c11_502351.html | title=Unified-wan-services }}
• Application & Content Networking System (ACNS)
• Wide Area Application Services (WAAS)
• ASA/PIX Firewalls
• Some IOS versions
• IronPort S-Series Web Security Appliance
• Nexus 7000 Switches

Other vendors have also implemented WCCP support into their products, as it allows clustering and transparent deployment on networks using Cisco routers/switches without additional hardware. WCCP is of particular use to vendors of web cache/proxy/security appliances for redirection of web traffic.

Please note that some vendors did not follow the standards when implementing WCCP and this could result in intercompatibility problems.

A list includes:

• Cisco
• Section [http://docwiki.cisco.com/wiki/Network_Caching_Technologies#WCCP_Network_Caching WCCP Network Caching] in the Cisco DocWiki (formerly known as the "Internetworking Technology Handbook")
• Section [http://www.cisco.com/en/US/docs/ios/12_2/configfun/configuration/guide/fcf018_ps1835_TSD_Products_Configuration_Guide_Chapter.html Configuring Web Cache Services Using WCCP] in the "Cisco IOS Configuration Fundamentals Configuration Guide, Release 12.2"
• Section [http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/12s_wccp.html WCCPv2 and WCCP Enhancements] in the feature guide for "Cisco IOS Software Releases 12.0 S"
• [http://www.techrepublic.com/article/configure-wccp-on-your-cisco-ios-router Configure WCCP on your Cisco IOS router] on TechRepublic
• [http://tools.ietf.org/html/draft-mclaggan-wccp-v2rev1-00 Web Cache Communication Protocol V2, revision 1] on IETF Web Site
• [https://www.barracuda.com/support/knowledgebase/50160000000H9bT How to set up WCCP on your Barracuda Web Filter] in Barracuda Networks Knowledgebase

Category:Cisco protocols

Category:Web caching protocol