<?xml version='1.0'?>

<reference anchor='RFC2186'>

<front>
<title abbrev='ICP'>Internet Cache Protocol (ICP), version 2</title>
<author initials='D.' surname='Wessels' fullname='Duane Wessels'>
<organization>National Laboratory for Applied Network Research</organization>
<address>
<postal>
<street>10100 Hopkins Drive</street>
<street>La Jolla</street>
<street>CA 92093</street></postal>
<email>wessels@nlanr.net</email></address></author>
<author initials='K.' surname='Claffy' fullname='K. Claffy'>
<organization>National Laboratory for Applied Network Research</organization>
<address>
<postal>
<street>10100 Hopkins Drive</street>
<street>La Jolla</street>
<street>CA 92093</street></postal>
<email>kc@nlanr.net</email></address></author>
<date month='September' year='1997' />
<area>Applications</area>
<keyword>proxy</keyword>
<keyword>world wide web</keyword>
<abstract>
<t>
   This document describes version 2 of the Internet Cache Protocol
   (ICPv2) as currently implemented in two World-Wide Web proxy cache
   packages[3,5].  ICP is a lightweight message format used for
   communicating among Web caches.  ICP is used to exchange hints about
   the existence of URLs in neighbor caches.  Caches exchange ICP
   queries and replies to gather information to use in selecting the
   most appropriate location from which to retrieve an object.
</t>
<t>
   This document describes only the format and fields of ICP messages.
   A companion document (RFC2187) describes the application of ICP to
   Web caches.  Several independent caching implementations now use ICP,
   and we consider it important to codify the existing practical uses of
   ICP for those trying to implement, deploy, and extend its use for
   their own purposes.
</t></abstract></front>

<seriesInfo name='RFC' value='2186' />
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</reference>
