Multicasting Applications Across Inter-Domain Peering Points
draft-tarapore-mboned-multicast-cdni-03

MBONED Working Group                                  Percy S. Tarapore
Internet Draft                                             Robert Sayko
Intended status: BCP                                               AT&T
Expires: January 15, 2014                                 Greg Shepherd
                                                        Toerless Eckert
                                                                  Cisco
                                                           Ram Krishnan
                                                                 Brocade
                                                           July 15, 2013

       Multicasting Applications Across Inter-Domain Peering Points
                draft-tarapore-mboned-multicast-cdni-03.txt

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Abstract

   This document examines the process of transporting applications via
   multicast across inter-domain peering points. The objective is to
   describe the setup process for multicast-based delivery across
   administrative domains and document supporting functionality to
   enable this process.

Table of Contents

   1. Introduction...................................................2
   2. Overview of Inter-domain Multicast Application Transport.......3
   3. Inter-domain Peering Point Requirements for Multicast..........4
      3.1. Native Multicast..........................................4
      3.2. Peering Point Enabled with GRE Tunnel.....................6
      3.3. Peering Point Enabled with an AMT - Both Domains Multicast
      Enabled........................................................7
      3.4. Peering Point Enabled with an AMT - AD-2 Not Multicast
      Enabled........................................................9
   4. Supporting Functionality......................................11
      4.1. Network Transport and Security Guidelines................11
      4.2. Routing Aspects and Related Guidelines...................11
      4.3. Back Office Functions - Billing and Logging Guidelines...11
      4.4. Operations - Service Performance and Monitoring Guidelines12
      4.5. Reliability Models/Service Assurance Guidelines..........12
      4.6. Provisioning Guidelines..................................12
      4.7. Client Models............................................12
      4.8. Addressing Guidelines....................................12
   5. Security Considerations.......................................12
   6. IANA Considerations...........................................12
   7. Conclusions...................................................13
   8. References....................................................13
      8.1. Normative References.....................................13
      8.2. Informative References...................................13
   9. Acknowledgments...............................................13

   1. Introduction

   Several types of applications (e.g., live video streaming, software
   downloads) are well suited for delivery via multicast means. The use
   of multicast for delivering such applications offers significant

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   savings for utilization of resources in any given administrative
   domain. End user demand for such applications is growing. Often,
   this requires transporting such applications across administrative
   domains via inter-domain peering points.

   The objective of this Best Current Practices document is twofold:
     o Describe the process and establish guidelines for setting up
        multicast-based delivery of applications across inter-domain
        peering points, and
     o Catalog  all  required  information  exchange  between  the
        administrative domains to support multicast-based delivery.

   While there are several multicast protocols available for use, this
   BCP will focus the discussion to those that are applicable and
   recommended for the peering requirements of today's service model,
   including:

     o Protocol  Independent  Multicast  -  Source  Specific  Multicast
        (PIM-SSM) [RFC4607]
     o Internet Group Management Protocol (IGMP) v3 [RFC4604]
     o Multicast Listener Discovery (MLD) [RFC4604]

   This document therefore serves the purpose of a "Gap Analysis"
   exercise for this process. The rectification of any gaps identified
   - whether they involve protocol extension development or otherwise -
   is beyond the scope of this document and is for further study.

   2. Overview of Inter-domain Multicast Application Transport

   A multicast-based application delivery scenario is as follows:
     o Two independent administrative domains are interconnected via a
        peering point.
     o The peering point is either multicast enabled (end-to-end
        native multicast across the two domains) or it is connected by
        one of two possible tunnel types:
       o A Generic Routing Encapsulation (GRE) Tunnel [RFC2784]
          allowing multicast tunneling across the peering point, or
       o An Automatic Multicast Tunnel (AMT) [IETF-ID-AMT].
     o The application stream originates at a source in Domain 1.

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     o An End User associated with Domain 2 requests the application.
        It is assumed that the application is suitable for delivery via
        multicast means (e.g., live steaming of major events, software
        downloads to large numbers of end user devices, etc.)
     o The request is communicated to the application source which
        provides the relevant multicast delivery information to the EU
        device via a "manifest file". At a minimum, this file contains
        the {Source, Group} or (S,G) information relevant to the
        multicast stream.
     o The application client in the EU device then joins the
        multicast stream distributed by the application source in
        domain 1 utilizing the (S,G) information provided in the
        manifest file. The manifest file may also contain additional
        information that the application client can use to locate the
        source and join the stream.

   It should be noted that the second administrative domain - domain 2
   - may be an independent network domain (e.g., Tier 1 network
   operator domain) or it could also be an Enterprise network operated
   by a single customer. The peering point architecture and
   requirements may have some unique aspects associated with the
   Enterprise case.

   The Use Cases describing various architectural configurations for
   the multicast distribution along with associated requirements is
   described in section 3. Unique aspects related to the Enterprise
   network possibility will be described in this section. A
   comprehensive list of pertinent information that needs to be
   exchanged between the two domains to support various functions
   enabling the application transport is provided in section 4.

   3. Inter-domain Peering Point Requirements for Multicast

   The transport of applications using multicast requires that the
   inter-domain peering point is enabled to support such a process.
   There are three possible Use Cases for consideration.

   3.1. Native Multicast

   This Use Case involves end-to-end Native Multicast between the two
   administrative domains and the peering point is also native
   multicast enabled - Figure 1.

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      -------------------               -------------------
     /       AD-1        \             /        AD-2       \
    / (Multicast Enabled) \           / (Multicast Enabled) \
   /                       \         /                       \
   | +----+                |         |                       |
   | |    |       +------+ |         |  +------+             |   +----+
   | | CS |------>|  BR  |-|---------|->|  BR  |-------------|-->| EU |
   | |    |       +------+ |   I1    |  +------+             |I2 +----+
   \ +----+                /         \                       /
    \                     /           \                     /
     \                   /             \                   /
      -------------------               -------------------

   AD = Administrative Domain (Independent Autonomous System)
   CS = Content Multicast Source
   BR = Border Router
   I1 = AD-1 and AD-2 Multicast Interconnection (MBGP or BGMP)
   I2 = AD-2 and EU Multicast Connection

      Figure 1 - Content Distribution via End to End Native Multicast

   Advantages of this configuration are:

     o Most efficient use of bandwidth in both domains

     o Fewer devices in the path traversed by the multicast stream
        when compared to unicast transmissions.

   From the perspective of AD-1, the one disadvantage associated with
   native multicast into AD-2 instead of individual unicast to every EU
   in AD-2 is that it does not have the ability to count the number of
   End Users as well as the transmitted bytes delivered to them. This
   information is relevant from the perspective of customer billing and
   operational logs. It is assumed that such data will be collected by
   the application layer. The application layer mechanisms for
   generating this information need to be robust enough such that all
   pertinent requirements for the source provider and the AD operator
   are satisfactorily met. The specifics of these methods are beyond
   the scope of this document.

   Architectural Requirements for this Configuration:

   R3.1-1: Peering points between domains shall be at least dual homed
   for reliability with full BGP table visibility.

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   R3.1-2: If the peering point between AD-1 and AD-2 is a controlled
   network environment, then bandwidth can be allocated accordingly by
   AD-1 and AD-2 to permit the transit of non rate-adaptive multicast
   traffic, otherwise the multicast traffic should support rate-
   adaptation.

   R3.1-3: Each domain AD-1, AD-2 determines by local policy whether to
   permit sending and/or receiving of IP multicast traffic from the
   other domain. If AD-1 is for example a service provider and AD-2 an
   enterprise, then AD-1 may often only support traffic delivery to,
   but not traffic reception from AD-2.

   R3.1-4: Relevant information on the multicast streams delivered to
   End Users in AD-2 shall be collected at the application layer. The
   precise nature of the collected information will be driven by
   requirements set down by the source owner and the domain operators.

   3.2. Peering Point Enabled with GRE Tunnel

   The peering point is not native multicast enabled in this Use Case.
   There is a Generic Routing Encapsulation Tunnel provisioned over the
   peering point. In this case, the interconnection I1 between AD-1 and
   AD-2 in Figure 1 is multicast enabled via a Generic Routing
   Encapsulation Tunnel (GRE) [RFC2784] and encapsulating the multicast
   protocols across the interface. The routing configuration is
   basically unchanged: Instead of BGP (SAFI2) across the native IP
   multicast link between AD-1 and AD-2, BGP (SAFI2) is now run across
   the GRE tunnel.

   Advantages of this configuration:

     o Highly efficient use of bandwidth in both domains although not
        as efficient as the fully native multicast Use Case.

     o Fewer devices in the path traversed by the multicast stream
        when compared to unicast transmissions.

     o Ability to support only partial IP multicast deployments in AD-
        1 and/or AD-2.

     o GRE is an existing technology and is relatively simple to
        implement.

   Disadvantages of this configuration:

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     o Per Use Case 3.1, current router technology cannot count the
        number of end users or the number bytes transmitted.

     o GRE tunnel requires manual configuration.

     o GRE must be in place prior to stream starting.

     o GRE is often left pinned up

   Architectural Requirements for this Configuration:

   R3.2-1 through R3.2-4 are the same as requirements R.3.1-1 through
   R.3.1-4 defined in Use Case 3.1.

   R3.2-5: GRE tunnels will be manually configured at peering points to
   support multicast delivery between domains.

   R3.1-6 The GRE tunnel (tunnel server) in source network must be
   configured to only advertise the routes to the Content Sources (not
   the entire network).  Otherwise content that should not be in tunnel
   may go through tunnel (e.g. content not part of an agreed CDN
   partnership).

   3.3. Peering Point Enabled with an AMT - Both Domains Multicast
      Enabled

   Both administrative domains in this Use Case are assumed to be
   native multicast enabled here; however the peering point is not. The
   peering point is enabled with an Automatic Multicast Tunnel. The
   basic configuration is depicted in Figure 2.

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      -------------------               -------------------
     /       AD-1        \             /       AD-2        \
    / (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 2 - AMT Interconnection between AD-1 and AD-2

   Advantages of this configuration:

     o Highly efficient use of bandwidth in AD-1.

     o AMT is an existing technology and is relatively simple to
        implement. Attractive properties of AMT include the following:

          o Dynamic interconnection between Gateway-Relay pair across
             the peering point.

          o Ability  to  serve  clients  and  servers  with  differing
             policies.

   Disadvantages of this configuration:

     o Per Use Case 3.1 (AD-2 is native multicast), current router
        technology cannot count the number of end users or the number
        bytes transmitted.

     o Additional  devices  (AMT  Gateway  and  Relay  pairs)  may  be
        introduced into the path if these services are not incorporated
        in the existing routing nodes.

     o Currently undefined mechanisms to select the AR from the AG
        automatically.

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   Architectural Requirements for this Configuration:

   R3.3-1 through R3.3-4 are the same as requirements R.3.1-1 through
   R.3.1-4 defined in Use Case 3.1.

   R3.3-5: AMT Relay and Gateway pair needs to be established at
   peering points to support multicast delivery between domains. The
   AMT tunnel will then configure dynamically across the peering point
   once the Gateway in AD-2 receives the (S,G) information from the EU.

   3.4. Peering Point Enabled with an AMT - AD-2 Not Multicast Enabled

   In this AMT Use Case, the second administrative domain AD-2 is not
   multicast enabled. This implies that the interconnection between AD-
   2 and the End User is also not multicast enabled as depicted in
   Figure 3.

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

   (Note: Diff-marks for the figure have been removed to improve
      viewing)

   CS = Content Source
   AR = AMT Relay
   EU/G = Gateway client embedded in EU device
   I2 = AMT Tunnel Connecting EU/G to AR in AD-1 through Non-Multicast
      Enabled AD-2.

      Figure 3 - AMT Tunnel Connecting AD-1 AMT Relay and EU Gateway

   This Use Case is equivalent to having unicast distribution of the
   application through AD-2. The total number of AMT tunnels would be
   equal to the total number of End Users requesting the application.
   The peering point thus needs to accommodate the total number of AMT

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   tunnels between the two domains. Each AMT tunnel can provide the
   data usage associated with each End User.

   Advantages of this configuration:

     o Highly efficient use of bandwidth in AD-1.

     o AMT is an existing technology and is relatively simple to
        implement. Attractive properties of AMT include the following:

          o Dynamic interconnection between Gateway-Relay pair across
             the peering point.

          o Ability  to  serve  clients  and  servers  with  differing
             policies.

     o Each AMT tunnel serves as a count for each End User and is also
        able to track data usage (bytes) delivered to the EU.

   Disadvantages of this configuration:

     o Additional devices (AMT Gateway and Relay pairs) are introduced
        into the transport path.

     o Assuming multiple peering points between the domains, the EU
        Gateway needs to be able to find the "correct" AMT Relay in AD-
        1.

   Architectural Requirements for this Configuration:

   R3.4-1 through R3.4-3 are the same as requirements R.3.1-1 through
   R.3.1-3 defined in Use Case 3.1.

   R3.4-4: Proper procedures shall exist to enable the AMT Gateway at
   End User device to find the correct AMT Relay in AD-1 across the
   peering points. At a minimum, the application client in the EU
   device will supply the (S,G) information to the Gateway for this
   purpose.

   R3.3-5: Relevant information on the multicast streams delivered to
   End Users in AD-2 via AMT tunnels shall be collected by the tunnels
   per existing AMT capabilities.

   A variation of this Use Case can be constructed as follows:

     o Single AMT tunnel across peering point.

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     o Strategic location of AMT Gateways at Exit Routers in AD-2 and
        an AMT Relay at AD-2 side of Peering Point. This reduces the
        total number of unicast streams across AD-2 equal to the total
        number of exit routers in AD-2.

     o Co-Location of AMT Relays with the AMT Gateways at the Exit
        Routers. This permits the AMT Gateway at the End User device
        application client to establish a shorter AMT tunnel with the
        AMT Relay at the appropriate Exit Router.

   The advantage for such a chained set of AMT tunnels is that the
   total number of unicast streams across AD-2 is significantly reduced
   thus freeing up bandwidth. The negative aspect is that several AMT
   tunnels will need to dynamically configure by the various AMT
   Gateways based solely on the (S,G) information received from the
   application client at the EU device.

   The requirements for this scenario are the same as the simpler case
   defined in this section. Only the dynamic configurations will become
   more complicated for setting up the correct set of tunnel chains.

   4. Supporting Functionality

   Supporting functions and related interfaces over the peering point
   that enable the multicast transport of the application are listed in
   this section. Critical information parameters that need to be
   exchanged in support of these functions are enumerated along with
   guidelines as appropriate. Specific interface functions for
   consideration are as follows.

   4.1. Network Transport and Security Guidelines

   4.2. Routing Aspects and Related Guidelines

   4.3. Back Office Functions - Billing and Logging Guidelines

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   4.4. Operations - Service Performance and Monitoring Guidelines

   4.5. Reliability Models/Service Assurance Guidelines

   4.6. Provisioning Guidelines

   In order to find right relay there is a need for a small/light
   implementation of an AMT DNS in source network.

   4.7. Client Models

   4.8. Addressing Guidelines

   5. Security Considerations

   (Include discussion on DRM, AAA, Network Security)

   6. IANA Considerations

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   7. Conclusions

   8. References

   8.1. 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

   [RFC4604] H. Holbrook, et al, "Using Internet Group Management
   Protocol Version 3 (IGMPv3) and Multicast Listener Discovery
   Protocol Version 2 (MLDv2) for Source Specific Multicast", RFC 4604,
   August 2006

   [RFC4607] H. Holbrook, et al, "Source Specific Multicast", RFC 4607,
   August 2006

   8.2. Informative References

   9. 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

   Greg Shepherd
   Cisco
   Phone:
   Email: shep@cisco.com

   Toerless Eckert
   Cisco
   Phone:
   Email: eckert@cisco.com

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

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