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MBONED Working Group                                  Percy S. Tarapore
Internet Draft                                             Robert Sayko
Intended status: BCP                                               AT&T
Expires: January 9, 2013                                   Ram Krishnan
                                                                 Brocade
                                                            July 9, 2012


               Multicast Considerations in Support of CDN-I
                draft-tarapore-mboned-multicast-cdni-00.txt


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   the Trust Legal Provisions and are provided without warranty as
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Abstract

   This document examines the current capabilities of multicast to
   support content distribution in an environment involving multiple
   Service Providers joining together to form a Content Distribution
   Network Interconnection (CDN-I) Federation.

Table of Contents


   1. Introduction...................................................2
   2. CDN Nomenclature...............................................3
   3. Multicast Use Cases for a CDN-I Federation.....................4
      3.1. Native Multicast Use Case.................................5
      3.2. Automatic Multicast Tunneling Use Cases...................5
         3.2.1. AMT Interconnection Between P-CDN and S-CDN..........6
         3.2.2. AMT Tunnel Connecting S-CDN and EU...................7
         3.2.3. AMT Tunnel Connecting EU to P-CDN Through Non-Multicast
         S-CDN.......................................................7
   4. Content Types Suitable for Multicast-based CDN.................8
      4.1. Live Content..............................................8
      4.2. "Delayed-Play" Download...................................8
      4.3. "Instant-Play" Download...................................8
   5. Evaluation of Native Multicast for CDN.........................9
   6. Evaluation of AMT for CDN......................................9
   7. Security Considerations.......................................10
   8. IANA Considerations...........................................10
   TBD..............................................................10
   9. Conclusions...................................................10
   10. References...................................................11
      10.1. Normative References....................................11
      10.2. Informative References..................................11
   11. Acknowledgments..............................................11

   1. Introduction

   Content Providers (CP) are experiencing significant growth in demand
   for all types of internet-based content. A single "over-the-top" CP
   would require significant resources to deliver content that could be
   requested from anywhere in the world. Service Providers (SP) are
   taking advantage of this situation by forming Content Distribution
   Network (CDN) Federations for the purpose of distributing content on
   behalf of Content Providers (CP). There are several advantages to
   such CDN Federations:


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   o  CPs can simply contract with one or more SPs in a CDN Federation
      for delivery of their content. This enables CPs to concentrate on
      their main objective - creation of content.

   o  SPs can expand their geographic reach via distribution agreements
      with Federation members without developing costly resources
      outside their local territories.

   Multicast-based delivery mechanisms are a natural fit for content
   distribution in the proposed CDN Federations. The scope of this
   document is strictly focused on the interactions between CDN
   Federation members to support multicast-based content distribution.
   The purpose of this document is the detailed examination of
   applicable multicast techniques and the identification of detailed
   data/metadata/parameters that will have to be exchanged by CDN
   Federation members to enable multicast-based content distribution.

   2. CDN Nomenclature

   Terminology utilized to describe end-to-end user requests is
   described as follows.

   There are many entities involved in distribution of the content from
   the CP all the way to the End User (EU). Figure 1 is a diagram
   depicting the basic logical relationships among the various roles
   involved in content delivery. Besides the CP and EU, the two
   remaining major entities are the two members of a CDN Federation -
   the Primary CDN Provider (P-CDN) and the Supporting CDN Provider (S-
   CDN) [A-0200003]. The relationships between these entities are as
   follows - see Figure 1.

   1. The Content Provider owns the content and specifies conditions of
      delivery and use. The End User interacts with the CP (link 1 in
      the figure) for authentication and authorization, and to reach an
      agreement to obtain specific content (content selection, content
      purchase, acknowledgement of conditions of use). The CP has the
      legal right to distribute content and specify conditions for
      distribution.

   2. The CP has an agreement and interacts with the P-CDN for deploying
      content (link 2).

   3. The P-CDN in turn has an agreement with an S-CDN for deploying and
      distributing content (link 3).




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   4. The End User is attached to S-CDN for access and obtains the
      content from the S-CDN (link 4). The End User also interacts with
      the CP (link 1) as indicated above.


               -----------------------------------------------
               |                     (1)                     |
               v                                             |
         +---------+     +---------+     +---------+     +---------+
         |         |     |         |     |         |     |         |
         | Content |     | Primary |     | Suppor- |     |  End    |
         | Provider| --> |   CDN   | --> | -ting   | --> |  User   |
         |         | (2) |         | (3) |  CDN    | (4) |         |
         |         |     |         |     |         |     |         |
         +---------+     +---------+     +---------+     +---------+

               Figure 1 - Relationships in a CDN Federation

   Note that all SPs in the CDN Federation can play the role of P-CDN
   (active relationship with a CP) as well as an S-CDN (attach EUs and
   distribute content from P-CDN to EUs).

   3. Multicast Use Cases for a CDN-I Federation

   Use cases involving multicast methods for distributing content in a
   CDN Federation have been described in [A-0200004].























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   3.1. Native Multicast Use Case

      -------------------               -------------------
     /       P-CDN       \             /       S-CDN       \
    / (Multicast Enabled) \           / (Multicast Enabled) \
   /                       \         /                       \
   | +----+                |         |                       |
   | |    |       +------+ |         |  +------+             |    +----+
   | | CS |------>|  BR  |-|---------|->|  BR  |-------------|--->| EU |
   | |    |       +------+ |   I1    |  +------+             | I2 +----+
   \ +----+                /         \                       /
    \                     /           \                     /
     \                   /             \                   /
      -------------------               -------------------

   CS = Content Server
   BR = Border Router
   I1 = P-CDN and S-CDN Multicast Interconnection (MBGP or BGMP)
   I2 = S-CDN and EU Multicast Connection

      Figure 1 - Content Distribution via End to End Native Multicast

   This case assumes that both CDN Providers as well as the
   interconnection between them and the connection between the EU and S-
   CDN are all multicast enabled.

   A variation of this "pure" Native Multicast case is when the
   interconnection I1 between the CDNs is multicast enabled via a
   Generic Routing Encapsulation Tunnel (GRE) [RFC2784] instead of
   utilizing MBGP or BGMP protocols.

   3.2. Automatic Multicast Tunneling Use Cases

   In reality, the initial introduction of multicast may not be fully
   multicast enabled resulting in "Multicast Islands" requiring
   Automatic Multicast Tunnels (AMT) for enabling multicast connections
   between them [IETF-ID-AMT].












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   3.2.1. AMT Interconnection Between P-CDN and S-CDN

      -------------------               -------------------
     /       P-CDN       \             /       S-CDN       \
    / (Multicast Enabled) \           / (Multicast Enabled) \
   /                       \         /                       \
   | +----+                |         |                       |
   | |    |       +------+ |         |  +------+             |    +----+
   | | CS |------>|  AR  |-|---------|->|  AG  |-------------|--->| EU |
   | |    |       +------+ |   I1    |  +------+             | I2 +----+
   \ +----+                /         \                       /
    \                     /           \                     /
     \                   /             \                   /
      -------------------               -------------------

   AR = AMT Relay
   AG = AMT Gateway
   I1 = AMT Interconnection between P-CDN and S-CDN
   I2 = S-CDN and EU Multicast Connection

          Figure 3 - AMT Interconnection between P-CDN and S-CDN

   This configuration assumes both CDN Providers are multicast enabled.
   Only the interconnection between them is not multicast enabled and
   hence, an AMT tunnel is established between them as shown in Figure
   3.























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   3.2.2. AMT Tunnel Connecting S-CDN and EU

      -------------------               -------------------
     /       P-CDN       \             /       S-CDN       \
    / (Multicast Enabled) \           / (Multicast Enabled) \
   /                       \         /                       \
   | +----+                |         |                       |
   | |    |       +------+ |         |  +------+    +------+ |    +----+
   | | CS |------>|  BR  |-|---------|->|  BR  |--->|  AR  |-|--->| EU |
   | |    |       +------+ |   I1    |  +------+    +------+ | I2 +----+
   \ +----+                /         \                       /
    \                     /           \                     /
     \                   /             \                   /
      -------------------               -------------------

   CS = Content Server
   BR = Border Router
   AR = AMT Relay
   I1 = P-CDN and S-CDN Multicast Interconnection (MBGP or BGMP)
   I2 = AMT Connection between S-CDN and EU

               Figure 4 - AMT Tunnel Connecting S-CDN and EU

   This case involves EU devices that are not multicast enabled. Hence
   an AMT Tunnel is established between the S-CDN AMT Relay and the EU
   device. This implies one tunnel per EU - potentially several AMT
   tunnels may need to be setup.
   Note that there could be configurations involving both situations
   described in 3.2.1 and 3.2.2.

   3.2.3. AMT Tunnel Connecting EU to P-CDN Through Non-Multicast S-CDN

   This Use Case assumes that EU attached to the non-multicast enabled
   S-CDN has a device populated with a client that establishes an AMT
   tunnel to the AMT Relay in the P-CDN.

   This configuration is needed when the S-CDN is not multicast-enabled.
   This is the most "extreme" AMT case as the length of the tunnels as
   well as the number of tunnels can be large.







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      -------------------               -------------------
     /       P-CDN       \             /       S-CDN       \
    / (Multicast Enabled) \           /   (Non-Multicast    \
   /                       \         /       Enabled)        \
   | +----+                |         |                       |
   | |    |       +------+ |         |                       |    +----+
   | | CS |------>|  AR  |-|---------|-----------------------|--->| EU |
   | |    |       +------+ |         |                       | I2 +----+
   \ +----+                /         \                       /
    \                     /           \                     /
     \                   /             \                   /
      -------------------               -------------------

   CS = Content Source
   AR = AMT Relay
   I2 = AMT Tunnel Connecting EU to P-CDN Relay through Non-Multicast
      Enabled S-CDN.

          Figure 5 - AMT Tunnel Connecting P-CDN AMT Relay and EU

   4. Content Types Suitable for Multicast-based CDN

   This section highlights applications and content types that are
   suitable for multicast-based delivery in a CDN Federation. Any unique
   aspects of specific applications/content types that require special
   attention are duly noted.

   4.1. Live Content

   Live events and presentations such as live radio an sporting events
   are examples. Delivery is via simple multicast means.

   Additional detail TBD

   4.2. "Delayed-Play" Download

   This includes download of movies and software updates. Delivery is
   via repeated multicasting of content.

   Additional detail TBD

   4.3. "Instant-Play" Download

   This includes Video-on-Demand (VoD) and on-demand streaming. Delivery
   is via simultaneous repeated multicast of content segments.



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   Additional detail TBD



   5. Evaluation of Native Multicast for CDN

   Use Case 3.1 describes Native Multicast configurations. This is the
   "simplest" multicast case in that a single standard set of protocols
   supports end-to-end content delivery from the CP to EU via two or
   more fully multicast-enabled CDN Providers. It also provides for
   efficient use of bandwidth and resources.

   Use Case 2a does deploy an AMT Tunnel for interconnecting two CDN
   Providers; the rest of the configuration is Native Multicast - this
   assumes that the EU devices are also multicast-enabled.

   Thus existing Native Multicast capabilities need to be examined to
   determine their ability to fully support content distribution in a
   CDN Federation. A list of issues requiring examination is as follows:

   o  Delivery - Identification and communication of {Source, Group}
      information and DNS information for provisioning across CDNs.
      Details to be provided.

   o  Routing/Peering - Identification and acknowledgement of external
      IP addresses particularly when utilizing a GRE Tunnel for
      interconnecting CDNs. Details to be provided.

   o  Back-Office Functions - Identification of appropriate
      data/metadata collected by Native Multicast to support usage of
      content for billing, settlements, logging, etc. Details to be
      provided.

   o  Security - Determine ability of Native Multicast to deal with
      security risks such as bot attacks, denial of service, etc.
      Details to be provided.

   o  Others - To Be Determined

   6. Evaluation of AMT for CDN

   Use Cases 3.2.1, 3.2.2, and 3.2.3 describe the possible
   configurations involving AMT Tunnels. The likeliest scenario is a
   combination of Use Cases 3.2.1 and 3.2.2.





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   Use Case 3.2.3 becomes problematic if the length of the AMT Tunnels
   connecting the EUs to the P-CDN AMT Gateway become prohibitively
   long.

   In all cases, there may be a concern if the total number of AMT
   Tunnels required is large. The list of issues that need to be
   examined for the AMT scenarios to support content distribution in a
   CDN Federation includes all identified issues in the Native Multicast
   case:

   o  Delivery - Identification and communication of {Source, Group}
      information and DNS information for provisioning across CDNs.
      Details to be provided.

   o  Routing/Peering - Identification and acknowledgement of external
      IP addresses when utilizing AMT Tunnels for interconnecting CDNs.
      Details to be provided.

   o  Back-Office Functions - Identification of appropriate
      data/metadata collected via AMT to support usage of content for
      billing, settlements, logging, etc. Details to be provided.

   o  Security - Determine ability of AMT to deal with security risks
      such as bot attacks, denial of service, etc. Details to be
      provided.

   o  Others - To Be Determined

   These have to be separately investigated for the AMT cases.
   In addition, there may be a need to examine the scope of additional
   resources in terms of bandwidth capacity and additional network
   elements particularly for Use Cases 3.2.2 and 3.2.3.


   7. Security Considerations

   TBD

   8. IANA Considerations

   TBD

   9. Conclusions

   TBD




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   10. References

   10.1. Normative References

   [RFC2784]   D. Farinacci, T. Li, S. Hanks, D. Meyer, P. Traina,
   "Generic Routing Encapsulation (GRE)", RFC 2784, March 2000

   [IETF-ID-AMT] G. Bumgardner, "Automatic Multicast Tunneling", draft-
   ietf-mboned-auto-multicast-13, April 2012, Work in progress

   10.2. Informative References

   [A-0200003] P. Tarapore, "CDN Interconnection Use Case Specifications
   and High Level Requirements", ATIS Standard A-0200003, June 2011
   (contact Nicole Butler at nbutler@atis.org using code IETF12 to
   receive a free copy before September 30, 2012)

   [A-0200004] P. Tarapore and R. Sayko, "CDN Interconnection Use Cases
   and Requirements for Multicast-Based Content Distribution", ATIS
   Standard A-0200004, January 2012 (contact Nicole Butler at
   nbutler@atis.org using code IETF12 to receive a free copy before
   September 30, 2012)

   11. Acknowledgments
























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   Authors' Addresses

   Percy S. Tarapore
   AT&T
   Phone: 1-732-420-4172
   Email: tarapore@att.com

   Robert Sayko
   AT&T
   Phone: 1-732-420-3292
   Email: rs1983@att.com

   Ram Krishnan
   Brocade
   Phone:
   Email: ramk@brocade.com

































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