Network Working Group M. Day
Internet-Draft Cisco
Expires: March 27, 2001 D. Gilletti
Entera
September 26, 2000
Content Distribution Network Peering Scenarios
draft-day-cdnp-scenarios-00.txt
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Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Abstract
This document sets forth several logical and detailed scenarios to
be considered when evaluating systems and protocols for CDN peering.
Pre IETF Submission Draft
This ID is an interim product of work in progress within the Content
Alliance. For information about the Content Alliance, see
www.content-peering.org.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Logical Peering Scenarios . . . . . . . . . . . . . . . . . 5
2.1 Fundamental Concepts . . . . . . . . . . . . . . . . . . . . 5
2.2 Expanding Existing CDN Footprint . . . . . . . . . . . . . . 5
2.3 ACCOUNTING and REDIRECTION PEERING Across Multiple
DISTIBUTING CDNs . . . . . . . . . . . . . . . . . . . . . . 6
2.4 ACCOUNTING PEERING Across Multiple DISTRIBUTING CDNs . . . . 6
2.5 PUBLISHER peers w/multiple DISTRIBUTING CDNs . . . . . . . . 6
3. Detailed Peering Scenarios . . . . . . . . . . . . . . . . . 7
3.1 Peering Establishment and Termination Scenarios . . . . . . 7
3.1.1 Peering Establishment . . . . . . . . . . . . . . . . . . . 7
3.1.2 Peering Termination . . . . . . . . . . . . . . . . . . . . 7
3.2 Distributing Content . . . . . . . . . . . . . . . . . . . . 8
3.2.1 Content Is Valuable . . . . . . . . . . . . . . . . . . . . 8
3.2.2 Distribution is Valuable . . . . . . . . . . . . . . . . . . 9
3.3 Redirecting Requests . . . . . . . . . . . . . . . . . . . . 11
3.4 Billing and Settling . . . . . . . . . . . . . . . . . . . . 11
4. Security Considerations . . . . . . . . . . . . . . . . . . 13
5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 14
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
References . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 16
Full Copyright Statement . . . . . . . . . . . . . . . . . . 17
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1. Introduction
This document presents several logical and detailed scenarios which
are intended to describe the potential configurations that can be
realized when peering CDNs. The logical scenarios describe how
various entities may combine to provide a complete CDN solution. The
detailed scenarios describe the actual peering interactions between
the various peered entities. These scenarios answer two distinct
needs:
1. To provide some concrete examples of what CDN peering is, and
2. To provide a basis for evaluating CDN peering proposals.
Each of the logical peering scenarios gives an indication of how the
various CDN elements are combined. From [2] these elements are:
1. REDIRECTION PEERING SYSTEM
2. DISTRIBUTION PEERING SYSTEM
3. ACCOUNTING PEERING SYSTEM
The peering scenarios presented in this document are also framed by
the following concepts:
1. Content Has Value
2. Distribution Has Value
3. Users Have Value
At present, the references to the above concepts are only employed
when they directly affect the nature of the peering scenario. A
reader who is interested in a detailed description of these concepts
is referred to [3].
Terms in ALL CAPS are defined in [1].
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2. Logical Peering Scenarios
This section provides several logical peering scenarios that may
arise in peered CDN implementations.
2.1 Fundamental Concepts
There are many potential peering configurations that can be imagined
for peered CDNs. All of these configurations MUST adhere to the
following concepts:
There is only one FIRST-REDIRECTION system for a given set of
CONTENT:
In order to prevent potential conflicts this document assumes
that there is one and only one FIRST-REDIRECTION SYSTEM. All
other REDIRECTION SYSTEMs MUST honor this relationship.
There may be more than one ACCOUNTING ENTITY:
These scenarios assume that multiple ACCOUNTING ENTITIES may
coexist. These entities may require specific ACCOUNTING
information or they may share this information depending upon the
function that they provide.
There may be more than one DISTRIBUTING CDN:
These scenarios assume that multiple DISTRIBUTING CDNs may
coexist. They further assume that these CDNs may have peering
relationships that are outside the scope of the scenario being
discussed.
2.2 Expanding Existing CDN Footprint
This scenario considers the case where two or more existing CDNs
wish to peer in order to provide an increased scale and reach. It
assumes that both of them already provide REDIRECTION, DISTRIBUTION,
and ACCOUNTING services and that they will continue to provide these
services to existing customers.
In this scenario it is assumed that the peering relationship between
all entities is comprised of; REDIRECTION PEERING, DISTRIBUTION
PEERING, and ACCOUNTING PEERING.
It is also worthwhile to consider that any one of these peered CDNs
may also have other peering arrangements which may or may not be
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transitive to peering relationships created for the above purpose.
2.3 ACCOUNTING and REDIRECTION PEERING Across Multiple DISTIBUTING CDNs
This scenario describes the case where a single entity performs
ACCOUNTING and REDIRECTION functions but has no inherent
DISTRIBUTION capabilities. The ACCOUNTING and REDIRECTION ENTITY
must therefore peer with one or more DISTRIBUTING CDNs in order to
provide a complete solution.
In this scenario the ACCOUNTING and REDIRECTION ENTITY, at a
minumum, would enter into REDIRECTION PEERING and ACCOUNTING PEERING
relationships with each of the DISTRIBUTING CDNs.
The ACCOUNTING and REDIRECTION ENTITY could also play an active role
in managing the DISTRIBUTION. In this case an additional
DISTRIBUTION PEERING relationships are required.
It is worth noting that the REDIRECTION ENTITY discussed here is
typically the FIRST-REDIRECTION SYSTEM although that is not a
requirement.
It is also worthwhile to consider that any one of these peered
ENTITIES may also have other peering arrangements which may or may
not be transitive to peering relationships created for the above
purpose.
2.4 ACCOUNTING PEERING Across Multiple DISTRIBUTING CDNs
This scenario describes the case where a single BILLING ENTITY which
provides a settlement/clearing-house function wishes to peer
w/mulitple DISTRIBUTING CDNs. For the purposes of this scenario it
is not necessary to consider the specifics of REDIRECTION PEERING.
In this scenario the BILLING ENTITY would enter into ACCOUNTING
PEERING relationships w/one or more DISTRIBUTING CDNs.
2.5 PUBLISHER peers w/multiple DISTRIBUTING CDNs
This scenario describes the case where a PUBLISHER wishes to
directly enter into peering relationships w/multiple DISTRIBUTING
CDNs. In this scenario it is assumed that the PUBLISHER operates as
the FIRST-REDIRECTION SYSTEM for its CONTENT although it is possible
that this function may be designated to one of the DISTRIBUTING CDNs.
In this scenario the PUBLISHER would enter into; DISTRIBUTION
PEERING, ACCOUNTING PEERING, and REDIRECTION peering with one or
more DISTRIBUTING CDNs.
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3. Detailed Peering Scenarios
The following text outlines what is intended to be a complete set of
detailed scenarios that can arise at when peering CDNs. It provides
additional detail around the following four areas:
1. Establishing/Terminating Peering
2. Distributing Content
3. Redirecting Requests
4. Billing/Settling
3.1 Peering Establishment and Termination Scenarios
These items describe the scenarios that occur when CDNs are
beginning or terminating some form of peering relationship.
In each case, we assume that the peering relationship is being
established between a BILLING ENTITY and a DISTRIBUTING CDN. The
BILLING ENTITY already has a NEGOTIATED RELATIONSHIP with the
relevant PUBLISHER(s), and so is already prepared to transfer money
in the appropriate direction, to the appropriate party. The
DISTRIBUTING CDN does not have such a connection to the relevant
PUBLISHER(s).
3.1.1 Peering Establishment
These items describe the situations in which CDNs are beginning some
form of peering.
1. BILLING ENTITY and DISTRIBUTING CDN agree to peer DISTRIBUTION
SYSTEMs for all PUBLISHERS of the BILLING ENTITY.
2. BILLING ENTITY and DISTRIBUTING CDN agree to peer DISTRIBUTION
SYSTEMs for some (specified) PUBLISHER(s) of the BILLING ENTITY.
3. BILLING ENTITY and REDIRECTION ENTITY agree to peer REDIRECTION
SYSTEMs for all PUBLISHERS of the BILLING CDN.
4. BILLING ENTITY and REDIRECTION ENTITY agree to peer REDIRECTION
SYSTEMs for some (specified) PUBLISHER(s) of the BILLING CDN.
3.1.2 Peering Termination
These items describe the situations in which CDNs are terminating
some or all content peering relationships.
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1. BILLING ENTITY ends DISTRIBUTION PEERING with specified
DISTRIBUTING CDN.
2. BILLING EMTITY ends REDIRECTION PEERING with specified
REDIRECTION ENTITY.
3. BILLING ENTITY ends all peering with specified CDN(s).
4. BILLING ENTITY ends all peering with all CDNs.
5. DISTRIBUTING CDN ends DISTRIBUTION PEERING with specified
BILLING ENTITY.
6. REDIRECTING CDN ends REDIRECTION PEERING with specified BILLING
ENTITY.
7. CDN ends all peering with specified BILLING ENTITY.
8. CDN ends all peering with all BILLING ENTITIES.
3.2 Distributing Content
These items describe situations in which content is being placed in
a CDN. Again, these descriptions are written in terms of a BILLING
ENTITY and a DISTRIBUTING CDN. We assume that any given CDN has its
own mechanisms for distributing content efficiently to an
appropriate set of SURROGATEs. The interactions in this situation
can only take place after some form of DISTRIBUTION PEERING has been
established, as described in the previous section. Interactions in
this section must take account of the possibility that one of the
parties may have terminated the peering relationship.
3.2.1 Content Is Valuable
These items describe situations in which payment is expected to flow
from the consumer of content back to the PUBLISHER via the BILLING
CDN. Included in valuable-content scenarios are business models such
as pay-per-view or subscriptions, but note that billing and
settlement issues are treated in greater detail in [3].
BILLING ENTITY initiates change in CONTENT distribution:
These items describe situations in which the BILLING ENTITY
initiates some change in the distribution of one or more CONTENT
objects.
1. BILLING ENTITY provides new CONTENT for distribution.
2. BILLING ENTITY signals currently distributed CONTENT has
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changed.
3. BILLING ENTITY withdraws CONTENT from distribution.
BILLING ENTITY initiates change in CONTINUOUS MEDIA distribution:
These items describe situations in which the BILLING ENTITY
initiates some change in the distribution of CONTINUOUS MEDIA.
1. BILLING ENTITY provides new CONTINUOUS MEDIA for distribution.
2. BILLING ENTITY signals currently distributed CONTINUOUS MEDIA
has changed.
3. BILLING ENTITY withdraws CONTINUOUS MEDIA from distribution.
DISTRIBUTING CDN initiates change in CONTENT distribution:
These items describe situations in which the DISTRIBUTING CDN
initiates some change in the distribution of CONTENT.
1. DISTRIBUTING CDN requests new CONTENT for distribution.
2. DISTRIBUTION CDN drops CONTENT from distribution.
DISTRIBUTING CDN initiates change in CONTINUOUS MEDIA distribution:
These items describe situations in which the DISTRIBUTING CDN
initiates some change in the distribution of CONTINUOUS MEDIA.
1. DISTRIBUTING CDN requests new CONTINUOUS MEDIA for
distribution.
2. DISTRIBUTING CDN drops CONTINUOUS MEDIA from distribution.
3.2.2 Distribution is Valuable
These items describe situations in which payment is expected to flow
from the PUBLISHER to the DISTRIBUTING CDN via the BILLING ENTITY.
These situations include most CDN revenue-sharing models, but note
that billing and settlement issues are treated in additional detail
in [3].
BILLING ENTITY initiates change in CONTENT distribution:
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These items describe situations in which the BILLING ENTITY
initiates some change in the distribution of CONTENT.
1. BILLING ENTITY provides new CONTENT for distribution.
2. BILLING ENTITY signals currently distributed CONTENT has
changed.
BILLING ENTITY withdraws CONTENT from distribution:
These items descrive the situations where the BILLING ENTITY
withdraws CONTENT from distribution.
BILLING ENTITY initiates change in CONTINUOUS MEDIA distribution:
These items describe situations in which the BILLING ENTITY
initiates some change in the distribution of CONTINUOUS MEDIA.
1. BILLING ENTITY provides new CONTINUOUS MEDIA for distribution.
2. BILLING ENTITY signals currently distributed CONTINUOUS MEDIA
has changed.
3. BILLING ENTITY withdraws CONTINUOUS MEDIA from distribution.
DISTRIBUTING CDN initiates change in CONTENT distribution:
These items describe situations in which the DISTRIBUTING CDN
initiates some change in the distribution of CONTENT.
1. DISTRIBUTING CDN requests new CONTENT for distribution.
2. DISTRIBUTING CDN drops CONTENT from distribution.
DISTRIBUTING CDN initiates change in CONTINUOUS MEDIA distribution:
These items describe situations in which the DISTRIBUTING CDN
initiates some change in the distribution of CONTINUOUS MEDIA.
1. DISTRIBUTING CDN requests new CONTINUOUS MEDIA for
distribution.
2. DISTRIBUTING CDN drops CONTINUOUS MEDIA from distribution.
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3.3 Redirecting Requests
These items describe situations in which a REQUEST may need to be
redirected from the FIRST-REDIRECTION CDN to another CDN. The
FIRST-REDIRECTION CDN is the network that receives the request and
is able to redirect that request to a REMOTE CDN if appropriate.
Depending on the redirection technology involved, there may be zero,
one, or n redirections possible for a given REQUEST.
1. REQUEST is for CONTENT on the FIRST-REDIRECTION CDN
2. REQUEST is for CONTENT available from a single REMOTE CDN
3. REQUEST is for CONTENT available from multiple REMOTE CDNs
4. REQUEST is for CONTENT available on both the FIRST-REDIRECTION
CDN and a single REMOTE CDN
5. REQUEST is for CONTENT available on both the FIRST-REDIRECTION
CDN and multiple REMOTE CDNs
6. REQUEST is for CONTENT available on both the FIRST-REDIRECTION
CDN and a single REMOTE CDN, but the REMOTE CDN performance is
better.
3.4 Billing and Settling
This section enumerates some of the scenarios which result from
considering the concepts given in [3].
1. CONTENT is valuable and delivered by a CDN which is also the
BILLING ENTITY.
2. CONTENT is valuable and delivered by another CDN that has a
NEGOTIATED RELATIONSHIP with the BILLING ENTITY.
3. CONTENT is valuable and delivered by another network. The
BILLING ENTITY and other CDN each have a NEGOTIATED RELATIONSHIP
with a clearinghouse but have no direct relationship with each
other.
4. DISTRIBUTION is valuable and performed by a CDN which is also
the BILLING ENTITY.
5. DISTRIBUTION is valuable and performed by another CDN that has a
NEGOTIATED RELATIONSHIP with the BILLING ENTITY.
6. DISTRIBUTION is valuable and performed by another CDN. The
BILLING ENTITY and other CDN each have a NEGOTIATED RELATIONSHIP
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with a clearinghouse but have no direct relationship with each
other.
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4. Security Considerations
This document describes scenarios for use in evaluating CDN peering
proposals. As such, it does not propose any solutions which might
have security concerns.
This docment assumes that any peering solutions which are derived
within the context of Content Alliance effort will be compliant with
the trust model given in [4].
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5. Conclusion
[Conclusion goes here]
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6. Acknowledgements
The authors acknowledge the contributions and comments of Fred
Douglis (AT&T), Raj Nair (Cisco), Gary Tomlinson (Entera), and John
Scharber (Entera).
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References
[1] Day, M. and G. Tomlinson, "A Model for Content Peering",
draft-day-cdnp-model-00.txt, work in progress (work in
progress), September 2000,
<URL:http://www.ietf.org/internet-drafts/draft-day-cdnp-model-00
.txt>.
[2] Green, M., Cain, B. and G. Tomlinson, "Content Peering
Framework", draft-green-cdnp-framework-00.txt, work in progress
(work in progress), September 2000,
<URL:http://www.ietf.org/internet-drafts/draft-green-cdnp-framew
ork-00.txt>.
[3] Gilletti, D., Nair, R. and J. Scharber, "Billing Models for CDN
Peering", draft-gilletti-cdnp-billing-models-00.txt (work in
progress), September 2000,
<URL:http://www.ietf.org/internet-drafts/draft-gilletti-cdnp-bil
ling-models-00.txt>.
[4] Aboba, B., Arkko, J. and D. Harrington, "Introduction to
Accounting Management", draft-ietf-aaa-acct-06.txt (work in
progress), June 2000,
<URL:http://www.ietf.org/internet-drafts/draft-ietf-aaa-acct-06.
txt>.
Authors' Addresses
Mark S. Day
Cisco Systems
135 Beaver Street
Waltham, MA 02452
US
Phone: PHONE
EMail: markday@cisco.com
Don Gilletti
Entera, Inc.
40971 Encyclopedia Circle
Fremont, CA 94538
US
Phone: +1 510 770 5281
EMail: don@entera.com
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