< draft-ietf-wrec-taxonomy-04.txt		draft-ietf-wrec-taxonomy-05.txt >
	Network Working Group I. Cooper		Network Working Group I. Cooper
	Internet-Draft Mirror Image		Internet-Draft Mirror Image
	Expires: December 22, 2000 I. Melve		Expires: January 2, 2001 I. Melve
	UNINETT		UNINETT
	G. Tomlinson		G. Tomlinson
	Novell		Novell
	June 23, 2000		July 4, 2000
	Internet Web Replication and Caching Taxonomy		Internet Web Replication and Caching Taxonomy
	draft-ietf-wrec-taxonomy-04.txt		draft-ietf-wrec-taxonomy-05.txt
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is in full conformance with		This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026.		all provisions of Section 10 of RFC2026.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	other groups may also distribute working documents as		other groups may also distribute working documents as
	Internet-Drafts.		Internet-Drafts.
	skipping to change at page 1, line 35 ¶		skipping to change at page 1, line 35 ¶
	months and may be updated, replaced, or obsoleted by other documents		months and may be updated, replaced, or obsoleted by other documents
	at any time. It is inappropriate to use Internet-Drafts as reference		at any time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt.		http://www.ietf.org/ietf/1id-abstracts.txt.
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	This Internet-Draft will expire on December 22, 2000.		This Internet-Draft will expire on January 2, 2001.
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2000). All Rights Reserved.		Copyright (C) The Internet Society (2000). All Rights Reserved.
	Abstract		Abstract
	This memo specifies standard terminology and the current taxonomy of		This memo specifies standard terminology and the current taxonomy of
	web replication and caching infrastructure deployed today. It		web replication and caching infrastructure deployed today. It
	introduces standard concepts and protocols used today within this		introduces standard concepts and protocols used today within this
	skipping to change at page 2, line 11 ¶		skipping to change at page 2, line 11 ¶
	document[23], and are not part of this document. This document		document[23], and are not part of this document. This document
	presents open protocols and points to published material for each		presents open protocols and points to published material for each
	protocol.		protocol.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 4
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
	2.1 Base Terms . . . . . . . . . . . . . . . . . . . . . . . . 5		2.1 Base Terms . . . . . . . . . . . . . . . . . . . . . . . . 5
	2.2 First order derivative terms . . . . . . . . . . . . . . . 7		2.2 First order derivative terms . . . . . . . . . . . . . . . 7
	2.3 Second order derivatives . . . . . . . . . . . . . . . . . 7		2.3 Second order derivatives . . . . . . . . . . . . . . . . . 8
	2.4 Topological terms . . . . . . . . . . . . . . . . . . . . 8		2.4 Topological terms . . . . . . . . . . . . . . . . . . . . 8
	2.5 Automatic use of proxies . . . . . . . . . . . . . . . . . 8		2.5 Automatic use of proxies . . . . . . . . . . . . . . . . . 9
	3. Distributed System Relationships . . . . . . . . . . . . . 10		3. Distributed System Relationships . . . . . . . . . . . . . 11
	3.1 Replication Relationships . . . . . . . . . . . . . . . . 10		3.1 Replication Relationships . . . . . . . . . . . . . . . . 11
	3.1.1 Client to Replica . . . . . . . . . . . . . . . . . . . . 10		3.1.1 Client to Replica . . . . . . . . . . . . . . . . . . . . 11
	3.1.2 Inter-Replica . . . . . . . . . . . . . . . . . . . . . . 10		3.1.2 Inter-Replica . . . . . . . . . . . . . . . . . . . . . . 11
	3.2 Proxy Relationships . . . . . . . . . . . . . . . . . . . 11		3.2 Proxy Relationships . . . . . . . . . . . . . . . . . . . 12
	3.2.1 Client to Non-Interception Proxy . . . . . . . . . . . . . 11		3.2.1 Client to Non-Interception Proxy . . . . . . . . . . . . . 12
	3.2.2 Client to Surrogate to Origin Server . . . . . . . . . . . 11		3.2.2 Client to Surrogate to Origin Server . . . . . . . . . . . 12
	3.2.3 Inter-Proxy . . . . . . . . . . . . . . . . . . . . . . . 12		3.2.3 Inter-Proxy . . . . . . . . . . . . . . . . . . . . . . . 13
	3.2.3.1 (Caching) Proxy Meshes . . . . . . . . . . . . . . . . . . 12		3.2.3.1 (Caching) Proxy Meshes . . . . . . . . . . . . . . . . . . 13
	3.2.3.2 (Caching) Proxy Arrays . . . . . . . . . . . . . . . . . . 13		3.2.3.2 (Caching) Proxy Arrays . . . . . . . . . . . . . . . . . . 14
	3.2.4 Network Element to Caching Proxy . . . . . . . . . . . . . 13		3.2.4 Network Element to Caching Proxy . . . . . . . . . . . . . 14
	4. Replica Selection . . . . . . . . . . . . . . . . . . . . 15		4. Replica Selection . . . . . . . . . . . . . . . . . . . . 16
	4.1 Navigation Hyperlinks . . . . . . . . . . . . . . . . . . 15		4.1 Navigation Hyperlinks . . . . . . . . . . . . . . . . . . 16
	4.2 HTTP Redirection . . . . . . . . . . . . . . . . . . . . . 15		4.2 HTTP Redirection . . . . . . . . . . . . . . . . . . . . . 16
	4.3 DNS Redirection . . . . . . . . . . . . . . . . . . . . . 16		4.3 DNS Redirection . . . . . . . . . . . . . . . . . . . . . 17
	5. Inter-Replica Communication . . . . . . . . . . . . . . . 17		5. Inter-Replica Communication . . . . . . . . . . . . . . . 18
	5.1 Batch Driven Replication . . . . . . . . . . . . . . . . . 17		5.1 Batch Driven Replication . . . . . . . . . . . . . . . . . 18
	5.2 Demand Driven Replication . . . . . . . . . . . . . . . . 17		5.2 Demand Driven Replication . . . . . . . . . . . . . . . . 18
	5.3 Synchronized Replication . . . . . . . . . . . . . . . . . 18		5.3 Synchronized Replication . . . . . . . . . . . . . . . . . 19
	6. User Agent to Proxy Configuration . . . . . . . . . . . . 19		6. User Agent to Proxy Configuration . . . . . . . . . . . . 20
	6.1 Manual Proxy Configuration . . . . . . . . . . . . . . . . 19		6.1 Manual Proxy Configuration . . . . . . . . . . . . . . . . 20
	6.2 Proxy Auto Configuration (PAC) . . . . . . . . . . . . . . 19		6.2 Proxy Auto Configuration (PAC) . . . . . . . . . . . . . . 20
	6.3 Cache Array Routing Protocol (CARP) v1.0 . . . . . . . . . 20		6.3 Cache Array Routing Protocol (CARP) v1.0 . . . . . . . . . 21
	6.4 Web Proxy Auto-Discovery Protocol (WPAD) . . . . . . . . . 20		6.4 Web Proxy Auto-Discovery Protocol (WPAD) . . . . . . . . . 21
	7. Inter-Proxy Communication . . . . . . . . . . . . . . . . 22		7. Inter-Proxy Communication . . . . . . . . . . . . . . . . 23
	7.1 Loosely coupled Inter-Proxy Communication . . . . . . . . 22		7.1 Loosely coupled Inter-Proxy Communication . . . . . . . . 23
	7.1.1 Internet Cache Protocol (ICP) . . . . . . . . . . . . . . 22		7.1.1 Internet Cache Protocol (ICP) . . . . . . . . . . . . . . 23
	7.1.2 Hyper Text Caching Protocol . . . . . . . . . . . . . . . 22		7.1.2 Hyper Text Caching Protocol . . . . . . . . . . . . . . . 23
	7.1.3 Cache Digest . . . . . . . . . . . . . . . . . . . . . . . 23		7.1.3 Cache Digest . . . . . . . . . . . . . . . . . . . . . . . 24
	7.1.4 Cache Pre-filling . . . . . . . . . . . . . . . . . . . . 24		7.1.4 Cache Pre-filling . . . . . . . . . . . . . . . . . . . . 25
	7.2 Tightly Coupled Inter-Cache Communication . . . . . . . . 25		7.2 Tightly Coupled Inter-Cache Communication . . . . . . . . 26
	7.2.1 Cache Array Routing Protocol (CARP) v1.0 . . . . . . . . . 25		7.2.1 Cache Array Routing Protocol (CARP) v1.0 . . . . . . . . . 26
	8. Network Element Communication . . . . . . . . . . . . . . 26		8. Network Element Communication . . . . . . . . . . . . . . 27
	8.1 Web Cache Control Protocol (WCCP) . . . . . . . . . . . . 26		8.1 Web Cache Control Protocol (WCCP) . . . . . . . . . . . . 27
	8.2 Network Element Control Protocol (NECP) . . . . . . . . . 26		8.2 Network Element Control Protocol (NECP) . . . . . . . . . 27
	8.3 SOCKS . . . . . . . . . . . . . . . . . . . . . . . . . . 27		8.3 SOCKS . . . . . . . . . . . . . . . . . . . . . . . . . . 28
	9. Security Considerations . . . . . . . . . . . . . . . . . 28		9. Security Considerations . . . . . . . . . . . . . . . . . 29
	9.1 Authentication . . . . . . . . . . . . . . . . . . . . . . 28		9.1 Authentication . . . . . . . . . . . . . . . . . . . . . . 29
	9.1.1 Man in the middle attacks . . . . . . . . . . . . . . . . 28		9.1.1 Man in the middle attacks . . . . . . . . . . . . . . . . 29
	9.1.2 Trusted third party . . . . . . . . . . . . . . . . . . . 28		9.1.2 Trusted third party . . . . . . . . . . . . . . . . . . . 29
	9.1.3 Authentication based on IP number . . . . . . . . . . . . 28		9.1.3 Authentication based on IP number . . . . . . . . . . . . 29
	9.2 Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 29		9.2 Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 30
	9.2.1 Trusted third party . . . . . . . . . . . . . . . . . . . 29		9.2.1 Trusted third party . . . . . . . . . . . . . . . . . . . 30
	9.2.2 Logs and legal implications . . . . . . . . . . . . . . . 29		9.2.2 Logs and legal implications . . . . . . . . . . . . . . . 30
	9.3 Service security . . . . . . . . . . . . . . . . . . . . . 29		9.3 Service security . . . . . . . . . . . . . . . . . . . . . 30
	9.3.1 Denial of service . . . . . . . . . . . . . . . . . . . . 30		9.3.1 Denial of service . . . . . . . . . . . . . . . . . . . . 31
	9.3.2 Replay attack . . . . . . . . . . . . . . . . . . . . . . 30		9.3.2 Replay attack . . . . . . . . . . . . . . . . . . . . . . 31
	9.3.3 Stupid configuration of proxies . . . . . . . . . . . . . 30		9.3.3 Stupid configuration of proxies . . . . . . . . . . . . . 31
	9.3.4 Copyrighted transient copies . . . . . . . . . . . . . . . 30		9.3.4 Copyrighted transient copies . . . . . . . . . . . . . . . 31
	9.3.5 Application level access . . . . . . . . . . . . . . . . . 30		9.3.5 Application level access . . . . . . . . . . . . . . . . . 31
	10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 31		10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 32
	References . . . . . . . . . . . . . . . . . . . . . . . . 32		References . . . . . . . . . . . . . . . . . . . . . . . . 33
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . 34		Authors' Addresses . . . . . . . . . . . . . . . . . . . . 35
	Full Copyright Statement . . . . . . . . . . . . . . . . . 36		Full Copyright Statement . . . . . . . . . . . . . . . . . 37
	1. Introduction		1. Introduction
	Since its introduction in 1990, the World-Wide Web has evolved from		Since its introduction in 1990, the World-Wide Web has evolved from
	a simple client server model into a sophisticated distributed		a simple client server model into a sophisticated distributed
	architecture. This evolution has been driven largely due to the		architecture. This evolution has been driven largely due to the
	scaling problems associated with exponential growth. Distinct		scaling problems associated with exponential growth. Distinct
	paradigms and solutions have emerged to satisfy specific		paradigms and solutions have emerged to satisfy specific
	requirements. Two core infrastructure components being employed to		requirements. Two core infrastructure components being employed to
	meet the demands of this growth are replication and caching. In many		meet the demands of this growth are replication and caching. In many
	skipping to change at page 5, line 19 ¶		skipping to change at page 5, line 19 ¶
	taken, where possible, from the HTTP/1.1 specification[1] and are		taken, where possible, from the HTTP/1.1 specification[1] and are
	included here for reference. First- and second-order derivatives are		included here for reference. First- and second-order derivatives are
	constructed from these base terms to help define the relationships		constructed from these base terms to help define the relationships
	that exist within this area.		that exist within this area.
	Terms that are in common usage and which are contrary to definitions		Terms that are in common usage and which are contrary to definitions
	in RFC2616 and this document are highlighted.		in RFC2616 and this document are highlighted.
	2.1 Base Terms		2.1 Base Terms
	The majority of these terms are taken as-is from RFC 2616[1], and		The majority of these terms are taken as-is from RFC2616[1], and are
	are included here for reference.		included here for reference.
	client (taken from [1])		client (taken from [1])
	A program that establishes connections for the purpose of sending		A program that establishes connections for the purpose of sending
	requests.		requests.
	server (taken from [1])		server (taken from [1])
	An application program that accepts connections in order to		An application program that accepts connections in order to
	service requests by sending back responses. Any given program may		service requests by sending back responses. Any given program may
	be capable of being both a client and a server; our use of these		be capable of being both a client and a server; our use of these
	terms refers only to the role being performed by the program for		terms refers only to the role being performed by the program for
	skipping to change at page 7, line 31 ¶		skipping to change at page 7, line 31 ¶
	editors, spiders (web-traversing robots), or other end user tools.		editors, spiders (web-traversing robots), or other end user tools.
	caching proxy		caching proxy
	A proxy with a cache, acting as a server to clients, and a client		A proxy with a cache, acting as a server to clients, and a client
	to servers.		to servers.
	Caching proxies are often referred to as "proxy caches" or simply		Caching proxies are often referred to as "proxy caches" or simply
	"caches". The term "proxy" is also frequently misused when		"caches". The term "proxy" is also frequently misused when
	referring to caching proxies.		referring to caching proxies.
	surrogate (a.k.a. "reverse proxies", "web server accelerators")		surrogate
	An intermediary program which acts on behalf of one or more		A gateway co-located with an origin server, or at a different
	origin servers by serving the original resource from a different		point in the network, delegated the authority to operate on
	part of the network. Requests are typically serviced from an		behalf of, and typically working in close co-operation with, one
	internal cache or by acting as a gateway or tunnel to the origin		or more origin servers. Responses are typically delivered from an
	server. The implementation requirements of surrogates with		internal cache.
	respect to handling cache directives from [1] have not been
	standardized. Surrogates are also known as "reverse proxies" and		Surrogates may derive cache entries from the origin server or
	"(origin) server accelerators".		from another of the origin server's delegates. In some cases a
			surrogate may tunnel such requests.
			Where close co-operation between origin servers and surrogates
			exists, this enables modifications of some protocol requirements,
			including the Cache-Control directives in [1]. Such modifications
			have yet to be fully specified.
			Devices commonly known as "reverse proxies" and "(origin) server
			accelerators" are both more properly defined as surrogates.
			reverse proxy
			See "surrogate".
			server accelerator
			See "surrogate".
	2.3 Second order derivatives		2.3 Second order derivatives
	The following terms further build on first order derivatives:		The following terms further build on first order derivatives:
	master origin server		master origin server
	An origin server on which the definitive version of a resource		An origin server on which the definitive version of a resource
	resides.		resides.
	replica origin server		replica origin server
	skipping to change at page 22, line 15 ¶		skipping to change at page 23, line 15 ¶
	7. Inter-Proxy Communication		7. Inter-Proxy Communication
	7.1 Loosely coupled Inter-Proxy Communication		7.1 Loosely coupled Inter-Proxy Communication
	This section describes the cooperation and communication between		This section describes the cooperation and communication between
	caching proxies.		caching proxies.
	7.1.1 Internet Cache Protocol (ICP)		7.1.1 Internet Cache Protocol (ICP)
	Authoritative reference:		Authoritative reference:
	RFC 2186 Internet Cache Protocol (ICP), version 2[5]		RFC2186 Internet Cache Protocol (ICP), version 2[5]
	Description:		Description:
	ICP is used by proxies to query other (caching) proxies about web		ICP is used by proxies to query other (caching) proxies about web
	resources, to see if the requested resource is present on the		resources, to see if the requested resource is present on the
	other system.		other system.
	ICP uses UDP. Since UDP is an uncorrected network transport		ICP uses UDP. Since UDP is an uncorrected network transport
	protocol, an estimate of network congestion and availability may		protocol, an estimate of network congestion and availability may
	be calculated by ICP loss. This rudimentary loss measurement		be calculated by ICP loss. This rudimentary loss measurement
	provides, together with round trip times, a load balancing method		provides, together with round trip times, a load balancing method
	for caches.		for caches.
	Security:		Security:
	See RFC 2187[6]		See RFC2187[6]
	ICP does not convey information about HTTP headers associated		ICP does not convey information about HTTP headers associated
	with resources. HTTP headers may include access control and cache		with resources. HTTP headers may include access control and cache
	directives. Since proxies ask for the availability of resources,		directives. Since proxies ask for the availability of resources,
	and subsequently retrieve them using HTTP, false cache hits may		and subsequently retrieve them using HTTP, false cache hits may
	occur (object present in cache, but not accessible to a sibling		occur (object present in cache, but not accessible to a sibling
	is one example).		is one example).
	ICP suffers from all the security problems of UDP.		ICP suffers from all the security problems of UDP.
	skipping to change at page 22, line 53 ¶		skipping to change at page 23, line 53 ¶
	Submitter:		Submitter:
	Document editors.		Document editors.
	See also Internet-Draft draft-lovric-icp-ext-02.txt[7], ICP		See also Internet-Draft draft-lovric-icp-ext-02.txt[7], ICP
	development Web page[8], ICP1.4 specification[9].		development Web page[8], ICP1.4 specification[9].
	7.1.2 Hyper Text Caching Protocol		7.1.2 Hyper Text Caching Protocol
	Authoritative reference:		Authoritative reference:
	RFC 2756 Hyper Text Caching Protocol (HTCP/0.0)[18]		RFC2756 Hyper Text Caching Protocol (HTCP/0.0)[18]
	Description:		Description:
	HTCP is a protocol for discovering HTTP caching proxies and		HTCP is a protocol for discovering HTTP caching proxies and
	cached data, managing sets of HTTP caching proxies, and		cached data, managing sets of HTTP caching proxies, and
	monitoring cache activity.		monitoring cache activity.
	HTCP requests include HTTP header material, while ICPv2 does not,		HTCP requests include HTTP header material, while ICPv2 does not,
	enabling HTCP replies to more accurately describe the behaviour		enabling HTCP replies to more accurately describe the behaviour
	that would occur as a result of a subsequent HTTP request for the		that would occur as a result of a subsequent HTTP request for the
	same resource.		same resource.
	skipping to change at page 31, line 11 ¶		skipping to change at page 32, line 11 ¶
	world. Some network level equipment may have required physical		world. Some network level equipment may have required physical
	access to get sensitive information. Introduction of application		access to get sensitive information. Introduction of application
	level components may require additional system security.		level components may require additional system security.
	10. Acknowledgements		10. Acknowledgements
	The editors would like to thank the following for their assistance:		The editors would like to thank the following for their assistance:
	David Forster, Alex Rousskov, Josh Cohen, John Martin, John Dilley,		David Forster, Alex Rousskov, Josh Cohen, John Martin, John Dilley,
	Ivan Lovric, Joe Touch, Henrik Nordstrom, Patrick McManus, Duane		Ivan Lovric, Joe Touch, Henrik Nordstrom, Patrick McManus, Duane
	Wessels, Wojtek Sylwestrzak, Ted Hardie, Misha Rabinovich, Larry		Wessels, Wojtek Sylwestrzak, Ted Hardie, Misha Rabinovich, Larry
	Masinter, Keith Moore, Roy Fielding, and Patrick Faltstrom.		Masinter, Keith Moore, Roy Fielding, Patrick Faltstrom, Hilarie
			Orman, Mark Nottingham and Oskar Batuner.
	References		References
	[1] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter,		[1] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter,
	L., Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol		L., Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol
	-- HTTP/1.1", RFC 2616, June 1999,		-- HTTP/1.1", RFC 2616, June 1999,
	<http://www.rfc-editor.org/rfc/rfc2616.txt>.		<URL:http://www.ietf.org/rfc/rfc2616.txt>.
	[2] Netscape, Inc., "Navigator Proxy Auto-Config File Format",		[2] Netscape, Inc., "Navigator Proxy Auto-Config File Format",
	External reference http://www.netscape.com/eng/mozilla/2.0/		March 1996,
	relnotes/demo/proxy-live.html, March 1996,		<URL:http://www.netscape.com/eng/mozilla/2.0/relnotes/demo/prox
	<http://www.netscape.com/eng/mozilla/2.0/relnotes/demo/proxy-live.html>		y-live.html>.
	.
	[3] Gauthier, P., Cohen, J., Dunsmuir, M. and C. Perkins, "The Web		[3] Gauthier, P., Cohen, J., Dunsmuir, M. and C. Perkins, "The Web
	Proxy Auto-Discovery Protocol", Expired Internet Draft		Proxy Auto-Discovery Protocol", draft-ietf-wrec-wpad-01.txt
	draft-ietf-wrec-wpad-01.txt, July 1999,		(work in progress), July 1999,
	<http://www.ietf.org/internet-drafts/draft-ietf-wrec-wpad-01.txt>		<URL:http://www.wrec.org/Drafts/draft-ietf-wrec-wpad-01.txt>.
	.
	[4] Valloppillil, V. and K.W. Ross, "Cache Array Routing		[4] Valloppillil, V. and K.W. Ross, "Cache Array Routing
	Protocol", Expired Internet Draft draft-vinod-carp-v1-03.txt		Protocol", draft-vinod-carp-v1-03.txt (work in progress),
	available at http://ircache.nlanr.net/Cache/ICP/carp.txt,		February 1998,
	February 1998, <http://ircache.nlanr.net/Cache/ICP/carp.txt>.		<URL:http://www.wrec.org/Drafts/draft-vinod-carp-v1-03.txt>.
	[5] Wessels, D. and K. Claffy, "Internet Cache Protocol (ICP),		[5] Wessels, D. and K. Claffy, "Internet Cache Protocol (ICP),
	Version 2", RFC 2186, September 1997,		Version 2", RFC 2186, September 1997,
	<http://www.rfc-editor.org/rfc/rfc2186.txt>.		<URL:http://www.ietf.org/rfc/rfc2186.txt>.
	[6] Wessels, D. and K. Claffy, "Application of Internet Cache		[6] Wessels, D. and K. Claffy, "Application of Internet Cache
	Protocol (ICP), Version 2", RFC 2187, September 1997,		Protocol (ICP), Version 2", RFC 2187, September 1997,
	<http://www.rfc-editor.org/rfc/rfc2187.txt>.		<URL:http://www.ietf.org/rfc/rfc2187.txt>.
	[7] Lovric, I., "Internet Cache Protocol Extension", Expired		[7] Lovric, I., "Internet Cache Protocol Extension",
	Internet Draft draft-lovric-icp-ext-02.txt, October 1999,		draft-lovric-icp-ext-02.txt (work in progress), October 1999,
	<http://www.ietf.org/internet-drafts/draft-lovric-icp-ext-02.txt>		<URL:http://www.wrec.org/Drafts/draft-lovric-icp-ext-02.txt>.
	.
	[8] Wessels, D., "ICP Home Page", External reference		[8] Wessels, D., "ICP Home Page", July 1999,
	http://ircache.nlanr.net/Cache/ICP/, July 1999,		<URL:http://ircache.nlanr.net/Cache/ICP/>.
	<http://ircache.nlanr.net/Cache/ICP/>.
	[9] University of Southern California and University of		[9] University of Southern California and University of
	Colorado-Boulder, "Internet Cache Protocol Specification 1.4",		Colorado-Boulder, "Internet Cache Protocol Specification 1.4",
	External reference http://excalibur.usc.edu/icpdoc/icp.html,		September 1994,
	September 1994, <http://excalibur.usc.edu/icpdoc/icp.html>.		<URL:http://excalibur.usc.edu/icpdoc/icp.html>.
	[10] Postel, J. and J.K. Reynolds, "File Transfer Protocol (FTP)",		[10] Postel, J. and J.K. Reynolds, "File Transfer Protocol (FTP)",
	RFC 959, Oct 1985, <http://www.rfc-editor.org/rfc/rfc959.txt>.		RFC 959, Oct 1985,
			<URL:http://www.ietf.org/rfc/rfc0959.txt>.
	[11] Anklesaria, F., McCahill, M., Lindner, P., Johnson, D.,		[11] Anklesaria, F., McCahill, M., Lindner, P., Johnson, D.,
	Torrey, D. and B. Alberti, "The Internet Gopher Protocol", RFC		Torrey, D. and B. Alberti, "The Internet Gopher Protocol", RFC
	1436, Mar 1993, <http://www.rfc-editor.org/rfc/rfc1436.txt>.		1436, Mar 1993,
			<URL:http://www.ietf.org/rfc/rfc1436.txt>.
	[12] Berners-Lee, T., Fielding, R. and H. Frystyk, "Hypertext		[12] Berners-Lee, T., Fielding, R. and H. Frystyk, "Hypertext
	Transfer Protocol -- HTTP/1.0", RFC 1945, May 1996,		Transfer Protocol -- HTTP/1.0", RFC 1945, May 1996,
	<http://www.rfc-editor.org/rfc/rfc1945.txt>.		<URL:http://www.ietf.org/rfc/rfc1945.txt>.
	[13] Cisco Systems, "Cisco Web Cache Control Protocol V1.0",		[13] Cieslak, M. and D. Forster, "Cisco Web Cache Control Protocol
	Expired Internet Draft draft-ietf-wrec-web-pro-00.txt, June		V1.0", draft-ietf-wrec-web-pro-00.txt (work in progress), June
	1999,		1999,
	<http://www.ietf.org/internet-drafts/draft-ietf-wrec-web-pro-00.txt>		<URL:http://www.wrec.org/Drafts/draft-ietf-wrec-web-pro-00.txt>.
	.
	[14] Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D. and L.		[14] Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D. and L.
	Jones, "SOCKS Protocol Version 5", RFC 1928, March 1996,		Jones, "SOCKS Protocol Version 5", RFC 1928, March 1996,
	<http://www.rfc-editor.org/rfc/rfc1928.txt>.		<URL:http://www.ietf.org/rfc/rfc1928.txt>.
	[15] Brisco, T., "DNS Support for Load Balancing", RFC 1794, April		[15] Brisco, T., "DNS Support for Load Balancing", RFC 1794, April
	1995, <http://www.rfc-editor.org/rfc/rfc1794.txt>.		1995,
			<URL:http://www.ietf.org/rfc/rfc1794.txt>.
	[16] Goutard, C., Lovric, I. and E. Maschio-Esposito, "Pre-filling		[16] Goutard, C., Lovric, I. and E. Maschio-Esposito, "Pre-filling
	a cache - A satellite overview", Internet Draft		a cache - A satellite overview",
	draft-lovric-francetelecom-satellites-01.txt, February 2000,		draft-lovric-francetelecom-satellites-01.txt (work in
	<http://www.ietf.org/internet-drafts/draft-lovric-francetelecom-satellites-01.txt>		progress), February 2000,
	.		<URL:http://www.ietf.org/internet-drafts/draft-lovric-francetel
			ecom-satellites-01.txt>.
	[17] Hamilton, M., Rousskov, A. and D. Wessels, "Cache Digest		[17] Hamilton, M., Rousskov, A. and D. Wessels, "Cache Digest
	specification - version 5", External reference		specification - version 5", December 1998,
	http://squid.nlanr.net/CacheDigest/cache-digest-v5.txt,		<URL:http://www.squid-cache.org/CacheDigest/cache-digest-v5.txt
	December 1998,		>.
	<http://squid.nlanr.net/CacheDigest/cache-digest-v5.txt>.
	[18] Vixie, P. and D. Wessels, "Hyper Text Caching Protocol		[18] Vixie, P. and D. Wessels, "Hyper Text Caching Protocol
	(HTCP/0.0)", RFC 2756, January 2000,		(HTCP/0.0)", RFC 2756, January 2000,
	<http://www.rfc-editor.org/rfc/rfc2756.txt>.		<URL:http://www.ietf.org/rfc/rfc2756.txt>.
	[19] Fan, L., Cao, P., Almeida, J. and A. Broder, "Summary Cache: A		[19] Fan, L., Cao, P., Almeida, J. and A. Broder, "Summary Cache: A
	Scalable Wide-Area Web Cache Sharing Protocol", Proceedings of		Scalable Wide-Area Web Cache Sharing Protocol", Proceedings of
	ACM SIGCOMM'98 pp. 254-265, September 1998,		ACM SIGCOMM'98 pp. 254-265, September 1998,
	<http://www.cs.wisc.edu/~cao/papers/summarycache.html>.		<URL:http://www.cs.wisc.edu/~cao/papers/summarycache.html>.
	[20] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC: Keyed-Hashing		[20] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC: Keyed-Hashing
	for Message Authentication", RFC 2104, February 1997,		for Message Authentication", RFC 2104, February 1997,
	<http://www.rfc-editor.org/rfc/rfc2104.txt>.		<URL:http://www.ietf.org/rfc/rfc2104.txt>.
	[21] Cerpa, A., Elson, J., Beheshti, H., Chankhunthod, A., Danzig,		[21] Cerpa, A., Elson, J., Beheshti, H., Chankhunthod, A., Danzig,
	P., Jalan, R., Neerdaels, C., Shroeder, T. and G. Tomlinson,		P., Jalan, R., Neerdaels, C., Shroeder, T. and G. Tomlinson,
	"NECP: The Network Element Control Protocol", Internet Draft		"NECP: The Network Element Control Protocol",
	draft-cerpa-necp-02.txt, February 2000,		draft-cerpa-necp-02.txt (work in progress), February 2000,
	<http://www.ietf.org/internet-drafts/draft-cerpa-necp-02.txt>.		<URL:http://www.ietf.org/internet-drafts/draft-cerpa-necp-02.tx
			t>.
	[22] FOLDOC, "Free Online Dictionary of Computing: Replication",		[22] FOLDOC, "Free Online Dictionary of Computing: Replication",
	Online reference
	http://foldoc.doc.ic.ac.uk/foldoc/foldoc.cgi?replication,
	December 1997,		December 1997,
	<http://foldoc.doc.ic.ac.uk/foldoc/foldoc.cgi?replication>.		<URL:http://foldoc.doc.ic.ac.uk/foldoc/foldoc.cgi?replication>.
	[23] Dilley, J. and I. Cooper, "Known HTTP Proxy/Caching Problems",		[23] Cooper, I. and J. Dilley, "Known HTTP Proxy/Caching Problems",
	Internet Draft draft-ietf-wrec-known-prob-01.txt, February		draft-ietf-wrec-known-prob-02.txt (work in progress), July
	2000,		2000,
	<http://www.ietf.org/internet-drafts/draft-ietf-wrec-known-prob-01.txt>		<URL:http://www.ietf.org/internet-drafts/draft-ietf-wrec-known-
	.		prob-02.txt>.
	[24] http://www.squid-cache.org/		[24] <URL:http://www.squid-cache.org/>
	[25] http://www.vix.com/vix/wgi.html		[25] <URL:http://www.vix.com/vix/wgi.html>
	[26] http://ircache.nlanr.net/Cache/		[26] <URL:http://ircache.nlanr.net/Cache/>
	[27] http://www.terena.nl/task-force/tf-cache/		[27] <URL:http://www.terena.nl/task-force/tf-cache/>
	Authors' Addresses		Authors' Addresses
	Ian Cooper		Ian Cooper
	Mirror Image Internet, Inc.		Mirror Image Internet, Inc.
	49 Dragon Court		49 Dragon Court
	Woburn, MA 01801		Woburn, MA 01801
	USA		USA
	Phone: +1 781 376 1109		Phone: +1 781 376 1109
End of changes. 42 change blocks.
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