draft-ietf-cdi-model-00.txt   draft-ietf-cdi-model-01.txt 
Network Working Group M. Day Network Working Group M. Day
Internet-Draft Cisco Internet-Draft Cisco
Expires: August 23, 2002 B. Cain Expires: August 23, 2002 B. Cain
Cereva Storigen
G. Tomlinson G. Tomlinson
CacheFlow CacheFlow
P. Rzewski P. Rzewski
Inktomi Inktomi
February 22, 2002 February 22, 2002
A Model for Content Internetworking (CDI) A Model for Content Internetworking (CDI)
draft-ietf-cdi-model-00.txt draft-ietf-cdi-model-01.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 Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Content Networks . . . . . . . . . . . . . . . . . . . . . . 4 2. Content Networks . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Problem Description . . . . . . . . . . . . . . . . . . . . 4 2.1 Problem Description . . . . . . . . . . . . . . . . . . . . 4
2.2 Caching Proxies . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Caching Proxies . . . . . . . . . . . . . . . . . . . . . . 5
2.3 Server Farms . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 Server Farms . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4 Content Distribution Networks . . . . . . . . . . . . . . . 7 2.4 Content Distribution Networks . . . . . . . . . . . . . . . 7
2.4.1 Historic Evolution of CDNs . . . . . . . . . . . . . . . . . 9 2.4.1 Historic Evolution of CDNs . . . . . . . . . . . . . . . . . 9
2.4.2 Describing CDN Value: Reach and Scale . . . . . . . . . . . 9 2.4.2 Describing CDN Value: Scale and Reach . . . . . . . . . . . 9
3. Content Network Model Terms . . . . . . . . . . . . . . . . 11 3. Content Network Model Terms . . . . . . . . . . . . . . . . 11
4. Content Internetworking . . . . . . . . . . . . . . . . . . 14 4. Content Internetworking . . . . . . . . . . . . . . . . . . 14
5. Content Internetworking Model Terms . . . . . . . . . . . . 15 5. Content Internetworking Model Terms . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . 18 6. Security Considerations . . . . . . . . . . . . . . . . . . 18
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
References . . . . . . . . . . . . . . . . . . . . . . . . . 20 References . . . . . . . . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 21
Full Copyright Statement . . . . . . . . . . . . . . . . . . 22 Full Copyright Statement . . . . . . . . . . . . . . . . . . 22
1. Introduction 1. Introduction
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popular servers). However, both in principle and increasingly in popular servers). However, both in principle and increasingly in
practice, a CDN can support the delivery of any digital content -- practice, a CDN can support the delivery of any digital content --
including various forms of streaming media. For a streaming media including various forms of streaming media. For a streaming media
CDN (or media distribution network or MDN), the surrogates may be CDN (or media distribution network or MDN), the surrogates may be
operating as splitters (serving out multiple copies of a stream). operating as splitters (serving out multiple copies of a stream).
The splitter function may be instead of, or in addition to, a role as The splitter function may be instead of, or in addition to, a role as
a caching proxy. However, the basic elements defined in this model a caching proxy. However, the basic elements defined in this model
are still intended to apply to the interconnection of content are still intended to apply to the interconnection of content
networks that are distributing streaming media. networks that are distributing streaming media.
2.4.2 Describing CDN Value: Reach and Scale 2.4.2 Describing CDN Value: Scale and Reach
There are two fundamental elements that give a CDN value: outsourcing There are two fundamental elements that give a CDN value: outsourcing
infrastructure and improved content delivery. A CDN allows multiple infrastructure and improved content delivery. A CDN allows multiple
surrogates to act on behalf of an orgin server, therefore removing surrogates to act on behalf of an orgin server, therefore removing
the delivery of content from a centralized site to multiple and the delivery of content from a centralized site to multiple and
(usually) highly distributed sites. We refer to increased aggregate (usually) highly distributed sites. We refer to increased aggregate
infrastructure size as "scale." In addition, a CDN can be constructed infrastructure size as "scale." In addition, a CDN can be constructed
with copies of content near to end users, overcoming issues of with copies of content near to end users, overcoming issues of
network size, network congestion, and network failures. We refer to network size, network congestion, and network failures. We refer to
increased diversity of content locations as "reach." increased diversity of content locations as "reach."
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participant than they could otherwise achieve. By using commonly participant than they could otherwise achieve. By using commonly
defined protocols for content internetworking, each content network defined protocols for content internetworking, each content network
can treat neighboring content networks as "black boxes", allowing can treat neighboring content networks as "black boxes", allowing
them to hide internal details from each other. them to hide internal details from each other.
5. Content Internetworking Model Terms 5. Content Internetworking Model Terms
This section consists of the definitions of a number of terms used to This section consists of the definitions of a number of terms used to
refer to roles, participants, and objects involved in internetworking refer to roles, participants, and objects involved in internetworking
content networks. The purpose of this section is to identify common content networks. The purpose of this section is to identify common
terms and provide short definitions. A more detailed technical terms and provide short definitions.
discussion of these terms and their relationships appears in "Content
Internetworking Architectural Overview" [4].
ACCOUNTING INTERNETWORKING ACCOUNTING INTERNETWORKING
Interconnection of two or more ACCOUNTING SYSTEMS so as to enable Interconnection of two or more ACCOUNTING SYSTEMS so as to enable
the exchange of information between them. The form of ACCOUNTING the exchange of information between them. The form of ACCOUNTING
INTERNETWORKING required may depend on the nature of the INTERNETWORKING required may depend on the nature of the
NEGOTIATED RELATIONSHIP between the peering parties -- in NEGOTIATED RELATIONSHIP between the peering parties -- in
particular, on the value of the economic exchanges anticipated. particular, on the value of the economic exchanges anticipated.
ADVERTISEMENT ADVERTISEMENT
Information about resources available to other CONTENT NETWORKS, Information about resources available to other CONTENT NETWORKS,
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An ADVERTISEMENT from a CONTENT NETWORK's DISTRIBUTION SYSTEM to An ADVERTISEMENT from a CONTENT NETWORK's DISTRIBUTION SYSTEM to
potential CONTENT SOURCES, describing the capabilities of one or potential CONTENT SOURCES, describing the capabilities of one or
more CONTENT DESTINATIONS. Contrast with AREA ADVERTISEMENT, more CONTENT DESTINATIONS. Contrast with AREA ADVERTISEMENT,
CONTENT ADVERTISEMENT. CONTENT ADVERTISEMENT.
DISTRIBUTION INTERNETWORKING DISTRIBUTION INTERNETWORKING
Interconnection of two or more DISTRIBUTION SYSTEMS so as to Interconnection of two or more DISTRIBUTION SYSTEMS so as to
propagate CONTENT SIGNALS and copies of CONTENT to groups of propagate CONTENT SIGNALS and copies of CONTENT to groups of
SURROGATES. SURROGATES.
ENLISTED
Describes a CONTENT NETWORK that, as part of a NEGOTIATED
RELATIONSHIP, has accepted a DISTRIBUTION task from another
CONTENT NETWORK, has agreed to perform REQUEST-ROUTING on behalf
of another CONTENT NETWORK, or has agreed to provide ACCOUNTING
data to another CONTENT NETWORK. Contrast with ORIGINATING.
INJECTION INJECTION
A "send-only" form of DISTRIBUTION INTERNETWORKING that takes A "send-only" form of DISTRIBUTION INTERNETWORKING that takes
place from an ORIGIN to a CONTENT DESTINATION. place from an ORIGIN to a CONTENT DESTINATION.
INTER- INTER-
Describes activity that involves more than one CONTENT NETWORK Describes activity that involves more than one CONTENT NETWORK
(e.g. INTER-CDN). Contrast with INTRA-. (e.g. INTER-CDN). Contrast with INTRA-.
INTRA- INTRA-
Describes activity within a single CONTENT NETWORK (e.g. INTRA- Describes activity within a single CONTENT NETWORK (e.g. INTRA-
CDN). Contrast with INTER-. CDN). Contrast with INTER-.
NEGOTIATED RELATIONSHIP NEGOTIATED RELATIONSHIP
A relationship whose terms and conditions are partially or A relationship whose terms and conditions are partially or
completely established outside the context of CONTENT NETWORK completely established outside the context of CONTENT NETWORK
internetworking protocols. internetworking protocols.
ORIGINATING
Describes a CONTENT NETWORK that, as part of a NEGOTIATED
RELATIONSHIP, submits a DISTRIBUTION task to another CONTENT
NETWORK, asks another CONTENT NETWORK to perform REQUEST-ROUTING
on its behalf, or asks another CONTENT NETWORK to provide
ACCOUNTING data. Contrast with ENLISTED.
REMOTE CONTENT NETWORK REMOTE CONTENT NETWORK
A CONTENT NETWORK able to deliver CONTENT for a particular REQUEST A CONTENT NETWORK able to deliver CONTENT for a particular REQUEST
that is not the AUTHORITATIVE REQUEST-ROUTING SYSTEM for that that is not the AUTHORITATIVE REQUEST-ROUTING SYSTEM for that
REQUEST. REQUEST.
REQUEST-ROUTING INTERNETWORKING REQUEST-ROUTING INTERNETWORKING
Interconnection of two or more REQUEST-ROUTING SYSTEMS so as to Interconnection of two or more REQUEST-ROUTING SYSTEMS so as to
increase the number of REACHABLE SURROGATES for at least one of increase the number of REACHABLE SURROGATES for at least one of
the interconnected systems. the interconnected systems.
6. Security Considerations 6. Security Considerations
There are no security-related issues related to the terms defined in This document defines terminology and concepts for content
this document. The technology of content internetworking does raise internetworking. The terminology itself does not introduce any
some security-related issues, and a detailed discussion of those security-related issues. The implementation of content
issues appears in "Content Internetworking Architectural Overview" internetworking concepts does raise some security-related issues,
[4]. which we identify in broad categories below. Other CDI documents
will address their specific security-related issues in more detail.
Secure relationship establishment: content internetworking must
provide means to ensure that content networks are internetworking
only with other content networks as intended. It must be possible to
prevent unauthorized internetworking or spoofing of another network's
identity.
Secure content transfer: content internetworking must support
content-network mechanisms that ensure both the integrity of content
and the integrity of the delivery process, even when the delivering
network is not the originating network. Content internetworking must
allow for mechanisms to prevent theft or corruption of content.
Secure meta-content transfer: content internetworking must support
the movement of accurate, reliable, auditable information about costs
and performance between content networks. Content internetworking
must allow for mechanisms to prevent the diversion or corruption of
accounting data and similar meta-content.
7. Acknowledgements 7. Acknowledgements
The authors acknowledge the contributions and comments of Fred The authors acknowledge the contributions and comments of Fred
Douglis (AT&T), Don Gilletti (CacheFlow), Markus Hoffmann (Lucent), Douglis (AT&T), Don Gilletti (CacheFlow), Markus Hoffmann (Lucent),
Barron Housel (Cisco), Barbara Liskov (Cisco), John Martin (Network Barron Housel (Cisco), Barbara Liskov (Cisco), John Martin (Network
Appliance), Nalin Mistry (Nortel Networks) Raj Nair (Cisco), Hilarie Appliance), Nalin Mistry (Nortel Networks) Raj Nair (Cisco), Hilarie
Orman (Volera), Doug Potter (Cisco), and Oliver Spatscheck (AT&T). Orman (Volera), Doug Potter (Cisco), and Oliver Spatscheck (AT&T).
[Note to RFC Editor: The last normative reference is [4], all [Note to RFC Editor: The last normative reference is [3], all
subsequent references starting with [5] can be deleted.] subsequent references starting with [4] can be deleted.]
References References
[1] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., [1] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,
Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol -- Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol --
HTTP/1.1", RFC 2616, June 1999, <http://www.rfc-editor.org/rfc/ HTTP/1.1", RFC 2616, June 1999, <http://www.rfc-editor.org/rfc/
rfc2616.txt>. rfc2616.txt>.
[2] Schulzrinne, H., Rao, A. and R. Lanphier, "Real Time Streaming [2] Schulzrinne, H., Rao, A. and R. Lanphier, "Real Time Streaming
Protocol", RFC 2326, April 1998, <http://www.rfc-editor.org/rfc/ Protocol", RFC 2326, April 1998, <http://www.rfc-editor.org/rfc/
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Mark Stuart Day Mark Stuart Day
Cisco Systems Cisco Systems
1414 Massachusetts Avenue 1414 Massachusetts Avenue
Boxborough, MA 01719 Boxborough, MA 01719
US US
Phone: +1 978 936 1089 Phone: +1 978 936 1089
EMail: markday@cisco.com EMail: markday@cisco.com
Brad Cain Brad Cain
Cereva Networks Storigen Systems
3 Network Drive 650 Suffolk Street
Marlborough, MA 01752 Lowell, MA 01854
US US
Phone: +1 508-787-5000 Phone: +1 978-323-4454
EMail: bcain@cereva.com EMail: bcain@storigen.com
Gary Tomlinson Gary Tomlinson
CacheFlow, Inc. CacheFlow, Inc.
12034 134th Ct. NE Suite 201 12034 134th Ct. NE Suite 201
Redmond, WA 98052 Redmond, WA 98052
US US
Phone: +1 425 820 3009 Phone: +1 425 820 3009
EMail: garyt@cacheflow.com EMail: garyt@cacheflow.com
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