MBONED Working Group                                    P. Tarapore, Ed.
Internet-Draft                                                  R. Sayko
Intended status: Best Current Practice                              AT&T
Expires: April 30, May 3, 2018                                         G. Shepherd
                                                          T. Eckert, Ed.
                                                             R. Krishnan
                                                        October 27, 30, 2017

          Use of Multicast Across Inter-Domain Peering Points


   This document examines the use of Source Specific Multicast (SSM)
   across inter-domain peering points for a specified set of deployment
   scenarios.  The objective is to describe the setup process for
   multicast-based delivery across administrative domains for these
   scenarios and document supporting functionality to enable this

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Overview of Inter-domain Multicast Application Transport  . .   5
   3.  Inter-domain Peering Point Requirements for Multicast . . . .   6
     3.1.  Native Multicast  . . . . . . . . . . . . . . . . . . . .   7
     3.2.  Peering Point Enabled with GRE Tunnel . . . . . . . . . .   8
     3.3.  Peering Point Enabled with an AMT - Both Domains
           Multicast Enabled . . . . . . . . . . . . . . . . . . . .  10
     3.4.  Peering Point Enabled with an AMT - AD-2 Not Multicast
           Enabled . . . . . . . . . . . . . . . . . . . . . . . . .  12
     3.5.  AD-2 Not Multicast Enabled - Multiple AMT Tunnels Through
           AD-2  . . . . . . . . . . . . . . . . . . . . . . . . . .  14
   4.  Functional Guidelines . . . . . . . . . . . . . . . . . . . .  16
     4.1.  Network Interconnection Transport Guidelines  . . . . . .  16
       4.1.1.  Bandwidth Management  . . . . . . . . . . . . . . . .  16
     4.2.  Routing Aspects and Related Guidelines  . . . . . . . . .  18
       4.2.1.  Native Multicast Routing Aspects  . . . . . . . . . .  19
       4.2.2.  GRE Tunnel over Interconnecting Peering Point . . . .  19
       4.2.3.  Routing Aspects with AMT Tunnels  . . . . . . . . . .  20
       4.2.4.  Public Peering Routing Aspects  . . . . . . . . . . .  22
     4.3.  Back Office Functions - Provisioning and Logging
           Guidelines  . . . . . . . . . . . . . . . . . . . . . . .  23
       4.3.1.  Provisioning Guidelines . . . . . . . . . . . . . . .  24
       4.3.2.  Interdomain Authentication Guidelines . . . . . . . .  25
       4.3.3.  Log Management Guidelines . . . . . . . . . . . . . .  26
     4.4.  Operations - Service Performance and Monitoring
           Guidelines  . . . . . . . . . . . . . . . . . . . . . . .  27
     4.5.  Client Reliability Models/Service Assurance Guidelines  .  29
     4.6.  Application Accounting Guidelines . . . . . . . . . . . .  29
   5.  Troubleshooting and Diagnostics . . . . . . . . . . . . . . .  29
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  30
     6.1.  DoS attacks (against state and bandwidth) . . . . . . . .  30
     6.2.  Content Security  . . . . . . . . . . . . . . . . . . . .  32
     6.3.  Peering Encryption  . . . . . . . . . . . . . . . . . . .  34
     6.4.  Operational Aspects . . . . . . . . . . . . . . . . . . .  34
   7.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  35
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  37
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  37
   10. Change log [RFC Editor: Please remove]  . . . . . . . . . . .  37
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  39
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  39
     11.2.  Informative References . . . . . . . . . . . . . . . . .  40
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  41

1.  Introduction

   Content and data from 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 content or
   other data offers significant savings of utilization of resources in
   any given administrative domain.  End user demand for such content or
   other data is growing.  Often, this requires transporting the content
   or other data across administrative domains via inter-domain peering

   The objective of this Best Current Practices document is twofold:

   o  Describe the technical process and establish guidelines for
      setting up multicast-based delivery of application content or
      other data across inter-domain peering points via a set of use

   o  Catalog all required information exchange between the
      administrative domains to support multicast-based delivery.  This
      enables operators to initiate necessary processes to support
      inter-domain peering with multicast.

   The scope and assumptions for this document are as follows:

   o  Administrative Domain 1 (AD-1) sources content to one or more End
      Users (EUs) in one or more Administrative Domain 2 (AD-2).  AD-1
      and AD-2 want to use IP multicast to allow supporting large and
      growing EU populations with minimum amount of duplicated traffic
      to send across network links.

      o  This document does not detail the case where EUs are
         originating content.  To support that additional service, it is
         recommended to use some method (outside the scope of this
         document) by which the content from EUs is transmitted to the
         application in AD-1 that this document refers to as the
         multicast source and let it send out the traffic as IP
         multicast.  From that point on, the descriptions in this
         document apply, except that they are not complete because they
         do not cover the transport or operational aspects of the leg
         from EU to AD-1.

      o  This document does not detail the case where AD-1 and AD-2 are
         not directly connected to each other but only via one or more
         AD-3 (transit providers).  The cases described in this document
         where tunnels are used between AD-1 and AD-2 can be applied to
         such scenarios, but SLA ("Service Level Agreement") control for
         example would be different.  Other additional issues will
         likely exist as well in such scenarios.  This is for further

   o  For the purpose of this document, the term "peering point" refers
      to a network connection ("link") between two administrative
      network domains over which traffic is exchanged between them.
      This is also referred to as a Network-to-Network Interface (NNI).
      Unless otherwise noted, the peering point is assumed to be a
      private peering point, where the network connection is a
      physically or virtually isolated network connection solely between
      AD-1 and AD-2.  The other case is that of a broadcast peering
      point which is a common option in public Internet Exchange Points
      (IXP).  See Section 4.2.2 for more details about that option.

   o  Administrative Domain 1 (AD-1) is enabled with native multicast.
      A peering point exists between AD-1 and AD-2.

   o  It is understood that several protocols are available for this
      purpose including PIM-SM and Protocol Independent Multicast -
      Source Specific Multicast (PIM-SSM) [RFC7761], Internet Group
      Management Protocol (IGMP) [RFC3376], and Multicast Listener
      Discovery (MLD) [RFC3810].

   o  As described in Section 2, the source IP address of the multicast
      stream in the originating AD (AD-1) is known.  Under this
      condition, PIM-SSM use is beneficial as it allows the receiver's
      upstream router to directly send a JOIN message to the source
      without the need of invoking an intermediate Rendezvous Point
      (RP).  Use of SSM also presents an improved threat mitigation
      profile against attack, as described in [RFC4609].  Hence, in the
      case of inter-domain peering, it is recommended to use only SSM
      protocols; the setup of inter- domain peering for ASM (Any-Source
      Multicast) is not in scope for this document.

   o  The rest of the document assumes that PIM-SSM and BGP are used
      across the peering point plus AMT and/or GRE according to
      scenario.  The use of other protocols is beyond the scope of this

   o  An Automatic Multicast Tunnel (AMT) [RFC7450] is setup at the
      peering point if either the peering point or AD-2 is not multicast
      enabled.  It is assumed that an AMT Relay will be available to a
      client for multicast delivery.  The selection of an optimal AMT
      relay by a client is out of scope for this document.  Note that
      AMT use is necessary only when native multicast is unavailable in
      the peering point (Use Case 3.3) or in the downstream
      administrative domain (Use Cases 3.4, and 3.5).

   o  The collection of billing data is assumed to be done at the
      application level and is not considered to be a networking issue.
      The settlements process for end user billing and/or inter-provider
      billing is out of scope for this document.

   o  Inter-domain network connectivity troubleshooting is only
      considered within the context of a cooperative process between the
      two domains.

   This document also attempts to identify ways by which the peering
   process can be improved.  Development of new methods for improvement
   is beyond the scope of this document.

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) [RFC7450].

   o  A service provider controls one or more application sources in
      AD-1 which will send multicast IP packets via one or more (S,G)s
      (multicast traffic flows, see Section 4.2.1 if you are unfamiliar
      with IP multicast).  It is assumed that the service being provided
      is suitable for delivery via multicast (e.g. live video streaming
      of popular events, software downloads to many devices, etc.), and
      that the packet streams will carried by a suitable multicast
      transport protocol.

   o  An End User (EU) controls a device connected to AD-2, which runs
      an application client compatible with the service provider's
      application source.

   o  The application client joins appropriate (S,G)s in order to
      receive the data necessary to provide the service to the EU.  The
      mechanisms by which the application client learns the appropriate
      (S,G)s are an implementation detail of the application, and are
      out of scope for this document.

   The assumption here is that AD-1 has ultimate responsibility for
   delivering the multicast based service on behalf of the content
   source(s).  All relevant interactions between the two domains
   described in this document are based on this assumption.

   Note that domain 2 may be an independent network domain (e.g.: Tier 1
   network operator domain).  Alternately, domain 2 could also be an
   Enterprise network domain operated by a single customer of AD-1.  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.  Section 4
   contains a comprehensive list of pertinent information that needs to
   be exchanged between the two domains in order to support functions to
   enable the application transport.

   Note that domain 2 may be an independent network domain (e.g., Tier 1
   network operator domain).  Alternately, domain 2 could also be an
   Enterprise network domain operated by a single customer.

   The Use Cases describing various architectural configurations for the
   multicast distribution along with associated requirements is
   described in Section 3.  The peering point architecture and
   requirements may have some unique aspects associated with the
   Enterprise case.  These unique aspects will also be described in
   Section 3.  Section 4 contains a comprehensive list of pertinent
   information that needs to be exchanged between the two domains in
   order to support functions to enable the application transport.

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 five Use Cases for consideration in this document.

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 - see Figure 1.

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

   AD = Administrative Domain (Independent Autonomous System)
   AS = Application (e.g., Content) Multicast Source
   BR = Border Router
   I1 = AD-1 and AD-2 Multicast Interconnection (e.g., MBGP)
   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 an AMT enabled peering point.

   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 guidelines for this configuration are as follows:

   a.  Dual homing for peering points between domains is recommended as
       a way to ensure reliability with full BGP table visibility.

   b.  If the peering point between AD-1 and AD-2 is a controlled
       network environment, then bandwidth can be allocated accordingly
       by the two domains to permit the transit of non- rate adaptive
       multicast traffic.  If this is not the case, then it is
       recommended that the multicast
       traffic should must support rate-
       adaption. rate-adaption (see [BCP145]).

   c.  The sending and receiving of multicast traffic between two
       domains is typically determined by local policies associated with
       each domain.  For example, if AD-1 is a service provider and AD-2
       is an enterprise, then AD-1 may support local policies for
       traffic delivery to, but not traffic reception from, AD-2.
       Another example is the use of a policy by which AD-1 delivers
       specified content to AD-2 only if such delivery has been accepted
       by contract.

   d.  Relevant information on multicast streams delivered to End Users
       in AD-2 is assumed to be collected by available capabilities in
       the application layer.  The precise nature and formats of the
       collected information will be determined by directives from 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.  See Figure 2.

       -------------------              -------------------
      /       AD-1        \            /        AD-2       \
     / (Multicast Enabled) \          / (Multicast Enabled) \
    /                       \        /                       \
    | +----+          +---+ |  (I1)  | +---+                 |
    | |    |   +--+   |uBR|-|--------|-|uBR|   +--+          |   +----+
    | | AS |-->|BR|   +---+-|        | +---+   |BR| -------->|-->| EU |
    | |    |   +--+ <.......|........|........>+--+          |I2 +----+
    \ +----+                /   I1   \                       /
     \                     /   GRE    \                     /
      \                   /   Tunnel   \                   /
       -------------------              -------------------

   AD = Administrative Domain (Independent Autonomous System)
   AS = Application (e.g., Content) Multicast Source
   uBR = unicast Border Router - not necessarily multicast enabled
         may be the same router as BR
   BR = Border Router - for multicast
   I1 = AD-1 and AD-2 Multicast Interconnection (e.g., MBGP)
   I2 = AD-2 and EU Multicast Connection

               Figure 2: Content Distribution via GRE Tunnel

   In this case, the interconnection I1 between AD-1 and AD-2 in
   Figure 2 is multicast enabled via a Generic Routing Encapsulation
   Tunnel (GRE) [RFC2784] between the two BR and encapsulating the
   multicast protocols across it.

   Normally, this approach is choosen if the uBR physcially connected to
   the peering link can or should not be enabled for IP multicast.  This
   approach may also be beneficial if BR and uBR are the same device,
   but the peering link is a broadcast domain (IXP), see Figure 6.

   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 an AMT enabled peering point.

   o  Ability to support partial and/or incremental IP multicast
      deployments in AD- 1 and/or AD-2: Only the path(s) between AS/BR
      (AD-1) and BR/EU (AD-2) need to be multicast enabled.  The uBRs
      may not support IP multicast or enabling it could be seen as
      operationally risky on that important edge node whereas dedicated
      BR nodes for IP multicast may be more acceptable at least
      initially.  BR can also be located such that only parts of the
      domain may need to support native IP multicast (e.g.: only the
      core in AD-1 but not edge networks towards uBR).

   o  GRE is an existing technology and is relatively simple to

   Disadvantages of this configuration:

   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  The GRE must be established prior to stream starting.

   o  The GRE tunnel is often left pinned up.

   Architectural guidelines for this configuration include the

   Guidelines (a) through (d) are the same as those described in Use
   Case 3.1.  Two additional guidelines are as follows:

   e. GRE tunnels are typically configured manually between peering
      points to support multicast delivery between domains.

   f. It is recommended that the GRE tunnel (tunnel server)
      configuration in the source network is such that it only
      advertises the routes to the application sources and not to the
      entire network.  This practice will prevent unauthorized delivery
      of applications through the tunnel (e.g., if application - e.g.,
      content - is not part of an agreed inter-domain 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.

       -------------------              -------------------
      /       AD-1        \            /        AD-2       \
     / (Multicast Enabled) \          / (Multicast Enabled) \
    /                       \        /                       \
    | +----+          +---+ |   I1   | +---+                 |
    | |    |   +--+   |uBR|-|--------|-|uBR|   +--+          |   +----+
    | | AS |-->|AR|   +---+-|        | +---+   |AG| -------->|-->| EU |
    | |    |   +--+ <.......|........|........>+--+          |I2 +----+
    \ +----+                /  AMT   \                       /
     \                     /  Tunnel  \                     /
      \                   /            \                   /
       -------------------              -------------------

   AD = Administrative Domain (Independent Autonomous System)
   AS = Application (e.g., Content) Multicast Source
   AR = AMT Relay
   AG = AMT Gateway
   uBR = unicast Border Router - not multicast enabled
         otherwise AR=uBR (AD-1), uBR=AG (AD-2)
   I1 = AMT Interconnection between AD-1 and AD-2
   I2 = AD-2 and EU Multicast Connection

           Figure 3: - 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 of
      bytes transmitted to all end users.

   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 for the AG to automatically select
      the optimal AR.

   Architectural guidelines for this configuration are as follows:

   Guidelines (a) through (d) are the same as those described in Use
   Case 3.1.  In addition,

   e. It is recommended that AMT Relay and Gateway pairs be configured
      at the peering points to support multicast delivery between
      domains.  AMT tunnels will then configure dynamically across the
      peering points 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.  Hence, the interconnection between AD-2 and the
   End User is also not multicast enabled.  This Use Case is depicted in
   Figure 3.

      -------------------               -------------------
      /       AD-1        \            /        AD-2       \
     / (Multicast Enabled) \          / (Non Multicast      \
    /                       \        /              Enabled) \ N(large)
    | +----+          +---+ |        | +---+                 |  #EU
    | |    |   +--+   |uBR|-|--------|-|uBR|                 |   +----+
    | | AS |-->|AR|   +---+-|        | +---+    ................>|EU/G|
    | |    |   +--+ <.......|........|...........            |I2 +----+
    \ +----+                / N x AMT\                       /
     \                     /  Tunnel  \                     /
      \                   /            \                   /
       -------------------              -------------------

   AS = Application Multicast Source
   uBR = unicast Border Router - not multicast enabled,
         otherwise AR = uBR (in AD-1).
   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 4: 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
   tunnels between the two domains.  Each AMT tunnel can provide the
   data usage associated with each End User.

   Advantages of this configuration:

   o  Efficient use of bandwidth in AD-1 (The closer AR is to uBR, the
      more efficient).

   o  Ability for AD-1 to introduce IP multicast based content delivery
      without any support by network devices in AD-2: Only application
      side in the EU device needs to perform AMT gateway library
      functionality to receive traffic from AMT relay.

   o  Allows for AD-2 to "upgrade" to Use Case 3.5 (see below) at a
      later time without any change in AD-1 at that time.

   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 guidelines for this configuration are as follows:

   Guidelines (a) through (c) are the same as those described in Use
   Case 3.1.

   d. It is necessary that proper procedures are implemented such that
      the AMT Gateway at the End User device is able to find the correct
      AMT Relay for each (S,G) content stream.  Standard mechanisms for
      that selection are still subject to ongoing work.  This includes
      use of anycast gateway addresses, anycast DNS names, explicit
      configuration that is mapping (S,G) to a relay address or letting
      the application in the EU/G provide the relay address to the
      embedded AMT gateway function.

   e. The AMT tunnel capabilities are expected to be sufficient for the
      purpose of collecting relevant information on the multicast
      streams delivered to End Users in AD-2.

3.5.  AD-2 Not Multicast Enabled - Multiple AMT Tunnels Through AD-2

   This is a variation of Use Case 3.4 as follows:

      -------------------               -------------------
      /       AD-1        \            /        AD-2       \
     / (Multicast Enabled) \          / (Non Multicast      \
    /                 +---+ \  (I1)  / +---+        Enabled) \
    | +----+          |uBR|-|--------|-|uBR|                 |
    | |    |   +--+   +---+ |        | +---+           +---+ |   +----+
    | | AS |-->|AR|<........|....    | +---+           |AG/|....>|EU/G|
    | |    |   +--+         |  ......|.|AG/|..........>|AR2| |I3 +----+
    \ +----+                /   I1   \ |AR1|   I2      +---+ /
     \                     /  single  \+---+                /
      \                   / AMT Tunnel \                   /
       -------------------              -------------------

   uBR = unicast Border Router - not multicast enabled
         otherwise AR=uBR (AD-1) or ubr=AGAR1 (AD-2)
   AS = Application Source
   AR = AMT Relay in AD-1
   AGAR1 = AMT Gateway/Relay node in AD-2 across Peering Point
   I1 = AMT Tunnel Connecting AR in AD-1 to GW in AGAR1 in AD-2
   AGAR2 = AMT Gateway/Relay node at AD-2 Network Edge
   I2 = AMT Tunnel Connecting Relay in AGAR1 to GW in AGAR2
   EU/G = Gateway client embedded in EU device
   I3 = AMT Tunnel Connecting EU/G to AR in AGAR2

           Figure 5: AMT Tunnel Connecting AMT Relay and Relays

   Use Case 3.4 results in several long AMT tunnels crossing the entire
   network of AD-2 linking the EU device and the AMT Relay in AD-1
   through the peering point.  Depending on the number of End Users,
   there is a likelihood of an unacceptably high amount of traffic due
   to the large number of AMT tunnels - and unicast streams - through
   the peering point.  This situation can be alleviated as follows:

   o  Provisioning of strategically located AMT nodes in AD-2 AD-2.  An
      AMT node comprises co-location of an AMT Gateway and an AMT Relay.
      No change is required by AD-1 compared to 3.4.  This can be done
      whenever AD-2 seems fit (too much traffic across peering point.

   o  One such node is at the AD-2 side of the peering point (node AGAR1
      in above Figure).

   o  Single AMT tunnel established across peering point linking AMT
      Relay in AD-1 to the AMT Gateway in the AMT node AGAR1 in AD-2.

   o  AMT tunnels linking AMT node AGAR1 at peering point in AD-2 to
      other AMT nodes located at the edges of AD-2: e.g., AMT tunnel I2
      linking AMT Relay in AGAR1 to AMT Gateway in AMT node AGAR2 in
      Figure 4.

   o  AMT tunnels linking EU device (via Gateway client embedded in
      device) and AMT Relay in appropriate AMT node at edge of AD-2:
      e.g., I3 linking EU Gateway in device to AMT Relay in AMT node

   o  In the most simple option (not shown), AD-2 only deploys a single
      AGAR1 and lets EU/G build AMT tunnels directly to it.  This setup
      already solves the problem of replicated traffic across the
      peering point.  As soon as there is need to support more AMT
      tunnels to EU/G, then additional AGAR2 nodes can be deployed by

   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.  Additionally, there will be a single unicast
   stream across the peering point instead of possibly, an unacceptably
   large number of such streams per Use Case 3.4.  However, this implies
   that several AMT tunnels will need to be dynamically configured by
   the various AMT Gateways based solely on the (S,G) information
   received from the application client at the EU device.  A suitable
   mechanism for such dynamic configurations is therefore critical.

   Architectural guidelines for this configuration are as follows:

   Guidelines (a) through (c) are the same as those described in Use
   Case 3.1.

   d. It is necessary that proper procedures are implemented such that
      the various AMT Gateways (at the End User devices and the AMT
      nodes in AD-2) are able to find the correct AMT Relay in other AMT
      nodes as appropriate.  Standard mechanisms for that selection are
      still subject to ongoing work.  This includes use of anycast
      gateway addresses, anycast DNS names, or explicit configuration
      that is mapping (S,G) to a relay address.  On the EU/G, this
      mapping information may come from the application.

   e. The AMT tunnel capabilities are expected to be sufficient for the
      purpose of collecting relevant information on the multicast
      streams delivered to End Users in AD-2.

4.  Functional Guidelines

   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 Interconnection Transport Guidelines

   The term "Network Interconnection Transport" refers to the
   interconnection points between the two Administrative Domains.  The
   following is a representative set of attributes that will need to be
   agreed to between the two administrative domains to support multicast

   o  Number of Peering Points.

   o  Peering Point Addresses and Locations.

   o  Connection Type - Dedicated for Multicast delivery or shared with
      other services.

   o  Connection Mode - Direct connectivity between the two AD's or via
      another ISP.

   o  Peering Point Protocol Support - Multicast protocols that will be
      used for multicast delivery will need to be supported at these
      points.  Examples of protocols include eBGP [RFC4760] and MBGP

   o  Bandwidth Allocation - If shared with other services, then there
      needs to be a determination of the share of bandwidth reserved for
      multicast delivery.  See section 4.1.1 below for more details.

   o  QoS Requirements - Delay and/or latency specifications that need
      to be specified in an SLA.

   o  AD Roles and Responsibilities - the role played by each AD for
      provisioning and maintaining the set of peering points to support
      multicast delivery.

4.1.1.  Bandwidth Management

   Like IP unicast traffic, IP multicast traffic carried across non-
   controlled networks must comply to Congestion Control Principles as
   described in [BCP41] and explained in detail for UDP IP multicast in

   Non-controlled networks (such as the Internet) are those where there
   is no policy for managing bandwidth other than best effort with fair
   share of bandwidth under congestion.  As a simplified rule of thumb,
   complying to congestion control principles means to reduce bandwidth
   under congestion in a way that is fair to competing competing
   (typically TCP) flow ("rate adaptive").

   In many instances, multicast content delivery evolves from intra-
   domain deployments where it is handled as a controlled network
   service and of not complyng to congestion control principles.  It was
   given a reserved amount of bandwidth and admitted to the network so
   that congestion never occurs.  Therefore the congestion control issue
   should be given specific attention when evolving to an interdomain
   peering deployment.

   In the case where end-to-end IP multicast traffic passes across the
   network of two ADs (and their subsidiaries/customers), both ADs must
   agree on a consistent traffic management policy.  If for example AD-1
   sources non congestion aware IP multicast traffic and AD-2 carries it
   as best effort traffic across links shared with other Internet
   traffic and subject to congestion, this will not work: Under
   congestion, some amount of that traffic will be dropped, rendering
   the remaining packets often as undecodeable garbage clogging up the
   network in AD-2 and because this is not congestion aware, the loss
   does not reduce this rate.  Competing traffic will not get their fair
   share under congestion, and EUs will be frusted by extremely bad
   quality of both their IP multicast and other (e.g.: TCP) traffic.
   Note that this is not an IP multicast technology issue, but solely a
   transport/application layer issue: The problem would equally happen
   if AD-1 would send non-rate adaptive unicast traffic,, for example
   legacy IPTV video-on-demand traffic which typically is also non
   congestion aware.  Because rate adaption in IP unicast video is
   commonplace today because of ABR (Adaptive Bitrate Video), it is very
   unlikely for this to happen though in reality with IP unicast.

   While the rules for traffic management apply whether or not IP
   multicast is tunneled or not, the one feature that can make AMT
   tunnels more difficult is the unpredictability of bandwidth
   requirements across underlying links because of the way they can be
   used: With native IP multicast or GRE tunnels, the amount of
   bandwidth depends on the amount of content, not the number of EUs -
   and is therefore easier to plan for.  AMT tunnels terminating in EU/G
   on the other hand scale with the number of EUs.  In the vicinity of
   the AMT relay they can introduce very large amount of replicated
   traffic and it is not always feasible to provision enough bandwidth
   for all possible EU to get the highest quality for all their content
   during peak utilization in such setups - unless the AMT relays are
   very close to the EU edge.  Therefore it is also recommended to use
   IP multicast rate adaptation even inside controlled networks when
   using AMT tunnels directly to EU/G.

   Note that rate-adaptive IP multicast traffic in general does not mean
   that the sender is reducing the bitrate, but rather that the EUs that
   experience congestion are joining to a lower bitrate (S,G) stream of
   the content, similar to adaptive bitrate streaming over TCP.
   Migration from non rate-adaptive to rate adaptive bitrate in IP
   multicast does therefore also change the dynamic (S,G) join behavior
   in the network resulting in potentially higher performance
   requirement for IP multicast protocols (IGMP/PIM), especially on the
   last hops where dynamic changes occur (including AMT gateway/relays):
   In non rate-adaptive IP multicast, only "channel change" causes state
   change, in rate-adaptive also the congestion situation causes state

   Even though not fully specified in this document, peerings that rely
   on GRE/AMT tunnels may be across one or more transit ADs instead of
   an exclusive (non-shared, L1/L2) path.  Unless those transit ADs are
   explicitly contracted to provide other than "best effort" transit for
   the tunneled traffic, the IP multicast traffic tunneled must be rate
   adaptive to not violate BCP41 across those transit ADs.

4.2.  Routing Aspects and Related Guidelines

   The main objective for multicast delivery routing is to ensure that
   the End User receives the multicast stream from the "most optimal"
   source [INF_ATIS_10] which typically:

   o  Maximizes the multicast portion of the transport and minimizes any
      unicast portion of the delivery, and

   o  Minimizes the overall combined network(s) route distance.

   This routing objective applies to both Native and AMT; the actual
   methodology of the solution will be different for each.  Regardless,
   the routing solution is expected:

   o  To be scalable,

   o  To avoid or minimize new protocol development or modifications,

   o  To be robust enough to achieve high reliability and automatically
      adjust to changes and problems in the multicast infrastructure.

   For both Native and AMT environments, having a source as close as
   possible to the EU network is most desirable; therefore, in some
   cases, an AD may prefer to have multiple sources near different
   peering points.  However, that is entirely an implementation issue.

4.2.1.  Native Multicast Routing Aspects

   Native multicast simply requires that the Administrative Domains
   coordinate and advertise the correct source address(es) at their
   network interconnection peering points(i.e., border routers).  An
   example of multicast delivery via a Native Multicast process across
   two Administrative Domains is as follows assuming that the
   interconnecting peering points are also multicast enabled:

   o  Appropriate information is obtained by the EU client who is a
      subscriber to AD-2 (see Use Case 3.1).  This information is in the
      form of metadata and it contains instructions directing the EU
      client to launch an appropriate application if necessary, as well
      as additional information for the application about the source
      location and the group (or stream) id in the form of the "S,G"
      data.  The "S" portion provides the name or IP address of the
      source of the multicast stream.  The metadata may also contain
      alternate delivery information such as specifying the unicast
      address of the stream.

   o  The client uses the join message with S,G to join the multicast
      stream [RFC4604].  To facilitate this process, the two AD's need
      to do the following:

      o  Advertise the source id(s) over the Peering Points.

      o  Exchange relevant Peering Point information such as Capacity
         and Utilization.

      o  Implement compatible multicast protocols to ensure proper
         multicast delivery across the peering points.

4.2.2.  GRE Tunnel over Interconnecting Peering Point

   If the interconnecting peering point is not multicast enabled and
   both AD's are multicast enabled, then a simple solution is to
   provision a GRE tunnel between the two AD's - see Use Case 3.2.2.
   The termination points of the tunnel will usually be a network
   engineering decision, but generally will be between the border
   routers or even between the AD 2 border router and the AD 1 source
   (or source access router).  The GRE tunnel would allow end-to-end
   native multicast or AMT multicast to traverse the interface.
   Coordination and advertisement of the source IP is still required.

   The two AD's need to follow the same process as described in 4.2.1 to
   facilitate multicast delivery across the Peering Points.

4.2.3.  Routing Aspects with AMT Tunnels

   Unlike Native Multicast (with or without GRE), an AMT Multicast
   environment is more complex.  It presents a dual layered problem
   because there are two criteria that should be simultaneously met:

   o  Find the closest AMT relay to the end-user that also has multicast
      connectivity to the content source, and

   o  Minimize the AMT unicast tunnel distance.

   There are essentially two components to the AMT specification

   AMT Relays:  These serve the purpose of tunneling UDP multicast
      traffic to the receivers (i.e., End-Points).  The AMT Relay will
      receive the traffic natively from the multicast media source and
      will replicate the stream on behalf of the downstream AMT
      Gateways, encapsulating the multicast packets into unicast packets
      and sending them over the tunnel toward the AMT Gateway.  In
      addition, the AMT Relay may perform various usage and activity
      statistics collection.  This results in moving the replication
      point closer to the end user, and cuts down on traffic across the
      network.  Thus, the linear costs of adding unicast subscribers can
      be avoided.  However, unicast replication is still required for
      each requesting End-Point within the unicast-only network.

   AMT Gateway (GW):  The Gateway will reside on an End-Point - this
      could be any type of IP host such as a Personal Computer (PC),
      mobile phone, Set Top Box (STB) or appliances.  The AMT Gateway
      receives join and leave requests from the Application via an
      Application Programming Interface (API).  In this manner, the
      Gateway allows the End-Point to conduct itself as a true Multicast
      End-Point.  The AMT Gateway will encapsulate AMT messages into UDP
      packets and send them through a tunnel (across the unicast-only
      infrastructure) to the AMT Relay.

   The simplest AMT Use Case (section 3.3) involves peering points that
   are not multicast enabled between two multicast enabled AD's.  An AMT
   tunnel is deployed between an AMT Relay on the AD 1 side of the
   peering point and an AMT Gateway on the AD 2 side of the peering
   point.  One advantage to this arrangement is that the tunnel is
   established on an as needed basis and need not be a provisioned
   element.  The two AD's can coordinate and advertise special AMT Relay
   Anycast addresses with each other.  Alternately, they may decide to
   simply provision Relay addresses, though this would not be an optimal
   solution in terms of scalability.

   Use Cases 3.4 and 3.5 describe more complicated AMT situations as
   AD-2 is not multicast enabled.  For these cases, the End User device
   needs to be able to setup an AMT tunnel in the most optimal manner.
   There are many methods by which relay selection can be done including
   the use of DNS based queries and static lookup tables [RFC7450].  The
   choice of the method is implementation dependent and is up to the
   network operators.  Comparison of various methods is out of scope for
   this document; it is for further study.

   An illustrative example of a relay selection based on DNS queries and
   Anycast IP addresses process for Use Cases 3.4 and 3.5 is described
   here.  Using an Anycast IP address for AMT Relays allows for all AMT
   Gateways to find the "closest" AMT Relay - the nearest edge of the
   multicast topology of the source.  Note that this is strictly
   illustrative; the choice of the method is up to the network
   operators.  The basic process is as follows:

   o  Appropriate metadata is obtained by the EU client application.
      The metadata contains instructions directing the EU client to an
      ordered list of particular destinations to seek the requested
      stream and, for multicast, specifies the source location and the
      group (or stream) ID in the form of the "S,G" data.  The "S"
      portion provides the URI (name or IP address) of the source of the
      multicast stream and the "G" identifies the particular stream
      originated by that source.  The metadata may also contain
      alternate delivery information such as the address of the unicast
      form of the content to be used, for example, if the multicast
      stream becomes unavailable.

   o  Using the information from the metadata, and possibly information
      provisioned directly in the EU client, a DNS query is initiated in
      order to connect the EU client/AMT Gateway to an AMT Relay.

   o  Query results are obtained, and may return an Anycast address or a
      specific unicast address of a relay.  Multiple relays will
      typically exist.  The Anycast address is a routable "pseudo-
      address" shared among the relays that can gain multicast access to
      the source.

   o  If a specific IP address unique to a relay was not obtained, the
      AMT Gateway then sends a message (e.g., the discovery message) to
      the Anycast address such that the network is making the routing
      choice of particular relay - e.g., closest relay to the EU.
      Details are outside the scope for this document.  See [RFC4786].

   o  The contacted AMT Relay then returns its specific unicast IP
      address (after which the Anycast address is no longer required).
      Variations may exist as well.

   o  The AMT Gateway uses that unicast IP address to initiate a three-
      way handshake with the AMT Relay.

   o  AMT Gateway provides "S,G" to the AMT Relay (embedded in AMT
      protocol messages).

   o  AMT Relay receives the "S,G" information and uses the S,G to join
      the appropriate multicast stream, if it has not already subscribed
      to that stream.

   o  AMT Relay encapsulates the multicast stream into the tunnel
      between the Relay and the Gateway, providing the requested content
      to the EU.

4.2.4.  Public Peering Routing Aspects

              AD-1a            AD-1b
              BR                BR
               |                 |
             --+-+---------------+-+-- broadcast peering point LAN
                 |                 |
                 BR               BR
                AD-2a            AD-2b

                     Figure 6: Broadcast Peering Point

   A broadcast peering point is an L2 subnet connecting 3 or more ADs.
   It is common in IXPs and usually consists of ethernet switch(es)
   operated by the IXP connecting to BRs operated by the ADs.

   In an example setup domain AD-2a peers with AD-1a and wants to
   receive IP multicast from it.  Likewise AD-2b peers with AD-1b and
   wants to receive IP multicast from it.

   Assume one or more IP multicast (S,G) traffic streams can be served
   by both AD-1a and AD-1b, for example because both AD-1a and AD-1b do
   contract this content from the same content source.

   In this case, AD-2a and AD-2b can not control anymore which upstream
   domain, AD-1a or AD-1b will forward this (S,G) into the LAN.  AD-2a
   BR requests the (S,G) from AD-1a BR and AD-2b BR requests the same
   (S,G) from AD-1b BR.  To avoid duplicate packets, an (S,G) can be
   forwarded by only one router onto the LAN, and PIM-SM/PIM-SSM detects
   requests for duplicate transmission and resolve it via the so-called
   "assert" protocol operation which results in only one BR forwarding
   the traffic.  Assume this is AD-1a BR.  AD-2b will then receive the
   multicast traffic unexpectedly from a provider with whom it does not
   have a mutual agreement for the traffic.  Quality issues in EUs
   behind AD-2b caused by AD-1a will cause a lot of responsiblity and
   troubleshooting issues.

   In face of this technical issues, we describe the following options
   how IP multicast can be carried across broadcast peering point LANs:

   1.  IP multicast is tunneled across the LAN.  Any of the GRE/AMT
       tunneling solutions mentioned in this document are applicable.
       This is the one case where specifically a GRE tunnel between the
       upstream BR (e.g.: AD-1a) and downstream BR (e.g.: AD-2a) is
       recommended as opposed to tunneling across uBRs which are not the
       actual BRs.

   2.  The LAN has only one upstream AD that is sourcing IP multicast
       and native IP multicast is used.  This is an efficient way to
       distribute the same IP multicast content to multiple downstream
       ADs.  Misbehaving downstream BRs can still disrupt the delivery
       of IP multicast from the upstream BR to other downstream BRs,
       therefore strict rules must be follow to prohibit that case.  The
       downstream BRs must ensure that they will always consider only
       the upstream BR as a source for multicast traffic: e.g.: no BGP
       SAFI-2 peerings between the downstream ADs across the peering
       point LAN, so that only the upstream BR is the only possible
       next-hop reachable across this LAN.  And routing policies
       configured to avoid fall back to the use of SAFI-1 (unicast)
       routes for IP multicast if unicast BGP peering is not limited in
       the same way.

   3.  The LAN has multiple upstreams, but they are federated and agree
       on a consistent policy for IP multicast traffic across the LAN.
       One policy is that each possible source is only announced by one
       upstream BR.  Another policy is that sources are redundantly
       announced (problematic case mentioned in above example), but the
       upstream domains also provide mutual operational insight to help
       troubleshooting (outside the scope of this document).

4.3.  Back Office Functions - Provisioning and Logging Guidelines

   Back Office refers to the following:

   o  Servers and Content Management systems that support the delivery
      of applications via multicast and interactions between AD's.

   o  Functionality associated with logging, reporting, ordering,
      provisioning, maintenance, service assurance, settlement, etc.

4.3.1.  Provisioning Guidelines

   Resources for basic connectivity between AD's Providers need to be
   provisioned as follows:

   o  Sufficient capacity must be provisioned to support multicast-based
      delivery across AD's.

   o  Sufficient capacity must be provisioned for connectivity between
      all supporting back-offices of the AD's as appropriate.  This
      includes activating proper security treatment for these back-
      office connections (gateways, firewalls, etc) as appropriate.

   o  Routing protocols as needed, e.g. configuring routers to support

   Provisioning aspects related to Multicast-Based inter-domain delivery
   are as follows.

   The ability to receive requested application via multicast is
   triggered via receipt of the necessary metadata.  Hence, this
   metadata must be provided to the EU regarding multicast URL - and
   unicast fallback if applicable.  AD-2 must enable the delivery of
   this metadata to the EU and provision appropriate resources for this

   Native multicast functionality is assumed to be available across many
   ISP backbones, peering and access networks.  If, however, native
   multicast is not an option (Use Cases 3.4 and 3.5), then:

   o  EU must have multicast client to use AMT multicast obtained either
      from Application Source (per agreement with AD-1) or from AD-1 or
      AD-2 (if delegated by the Application Source).

   o  If provided by AD-1/AD-2, then the EU could be redirected to a
      client download site (note: this could be an Application Source
      site).  If provided by the Application Source, then this Source
      would have to coordinate with AD-1 to ensure the proper client is
      provided (assuming multiple possible clients).

   o  Where AMT Gateways support different application sets, all AD-2
      AMT Relays need to be provisioned with all source & group
      addresses for streams it is allowed to join.

   o  DNS across each AD must be provisioned to enable a client GW to
      locate the optimal AMT Relay (i.e. longest multicast path and
      shortest unicast tunnel) with connectivity to the content's
      multicast source.

   Provisioning Aspects Related to Operations and Customer Care are
   stated as follows.

   Each AD provider is assumed to provision operations and customer care
   access to their own systems.

   AD-1's operations and customer care functions must have visibility to
   what is happening in AD-2's network or to the service provided by AD-
   2, sufficient to verify their mutual goals and operations, e.g.  to
   know how the EU's are being served.  This can be done in two ways:

   o  Automated interfaces are built between AD-1 and AD-2 such that
      operations and customer care continue using their own systems.
      This requires coordination between the two AD's with appropriate
      provisioning of necessary resources.

   o  AD-1's operations and customer care personnel are provided access
      directly to AD-2's system.  In this scenario, additional
      provisioning in these systems will be needed to provide necessary
      access.  Additional provisioning must be agreed to by the two AD's
      to support this option.

4.3.2.  Interdomain Authentication Guidelines

   All interactions between pairs of AD's can be discovered and/or be
   associated with the account(s) utilized for delivered applications.
   Supporting guidelines are as follows:

   o  A unique identifier is recommended to designate each master

   o  AD-2 is expected to set up "accounts" (logical facility generally
      protected by credentials such as login passwords) for use by AD-1.
      Multiple accounts and multiple types or partitions of accounts can
      apply, e.g.  customer accounts, security accounts, etc.

   The reason to specifically mention the need for AD-1 to initiate
   interactions with AD-2 (and use some account for that), as opposed to
   the opposite direction is based on the recommended workflow initiated
   by customers (see Section 4.4): The customer contacts content source
   (part of AD-1), when AD-1 sees the need to propagate the issue, it
   will interact with AD-2 using the aforementioned guidelines.

4.3.3.  Log Management Guidelines

   Successful delivery (in terms of user experience) of applications or
   content via multicast between pairs of interconnecting AD's can be
   improved through the ability to exchange appropriate logs for various
   workflows - troubleshooting, accounting and billing, traffic and
   content transmission optimization, content and application
   development optimization and so on.

   The basic model as explained in before is that the content source and
   on its behalf AD-1 take over primary responsibility for customer
   experience and the AD-2's support this.  The application/content
   owner is the only participant who has and needs full insight into the
   application level and can map the customer application experience to
   the network traffic flows - which it then with the help of AD-2 or
   logs from AD-2 can analyze and interpret.

   The main difference between unicast delivery and multicast delivery
   is that the content source can infer a lot more about downstream
   network problems from a unicasted stream than from a multicasted
   stream: The multicasted stream is not per-EU except after the last
   replication, which is in most cases not in AD-1.  Logs from the
   application, including the receiver side at the EU, can provide
   insight, but can not help to fully isolate network problems because
   of the IP multicast per-application operational state built across
   AD-1 and AD-2 (aka: the (S,G) state and any other feature operational
   state such as DiffServ QoS).

   See Section 7 for more discussions about the privacy considerations
   of the model described here.

   Different type of logs are known to help support operations in AD-1
   when provided by AD-2.  This could be done as part of AD-1/AD-2
   contracts.  Note that except for implied multicast specific elements,
   the options listed here are not unique or novel for IP multicast, but
   they are more important for services novel to the operators than for
   operationally well established services (such as unicast).  Therefore
   we detail them as follows:

   o  Usage information logs at aggregate level.

   o  Usage failure instances at an aggregate level.

   o  Grouped or sequenced application access.  performance, behavior
      and failure at an aggregate level to support potential Application
      Provider-driven strategies.  Examples of aggregate levels include
      grouped video clips, web pages, and sets of software download.

   o  Security logs, aggregated or summarized according to agreement
      (with additional detail potentially provided during security
      events, by agreement).

   o  Access logs (EU), when needed for troubleshooting.

   o  Application logs (what is the application doing), when needed for
      shared troubleshooting.

   o  Syslogs (network management), when needed for shared

   The two AD's may supply additional security logs to each other as
   agreed to by contract(s).  Examples include the following:

   o  Information related to general security-relevant activity which
      may be of use from a protective or response perspective, such as
      types and counts of attacks detected, related source information,
      related target information, etc.

   o  Aggregated or summarized logs according to agreement (with
      additional detail potentially provided during security events, by

4.4.  Operations - Service Performance and Monitoring Guidelines

   Service Performance refers to monitoring metrics related to multicast
   delivery via probes.  The focus is on the service provided by AD-2 to
   AD-1 on behalf of all multicast application sources (metrics may be
   specified for SLA use or otherwise).  Associated guidelines are as

   o  Both AD's are expected to monitor, collect, and analyze service
      performance metrics for multicast applications.  AD-2 provides
      relevant performance information to AD-1; this enables AD-1 to
      create an end-to-end performance view on behalf of the multicast
      application source.

   o  Both AD's are expected to agree on the type of probes to be used
      to monitor multicast delivery performance.  For example, AD-2 may
      permit AD-1's probes to be utilized in the AD-2 multicast service
      footprint.  Alternately, AD-2 may deploy its own probes and relay
      performance information back to AD-1.

   Service Monitoring generally refers to a service (as a whole)
   provided on behalf of a particular multicast application source
   provider.  It thus involves complaints from End Users when service
   problems occur.  EUs direct their complaints to the source provider;
   in turn the source provider submits these complaints to AD-1.  The
   responsibility for service delivery lies with AD-1; as such AD-1 will
   need to determine where the service problem is occurring - its own
   network or in AD-2.  It is expected that each AD will have tools to
   monitor multicast service status in its own network.

   o  Both AD's will determine how best to deploy multicast service
      monitoring tools.  Typically, each AD will deploy its own set of
      monitoring tools; in which case, both AD's are expected to inform
      each other when multicast delivery problems are detected.

   o  AD-2 may experience some problems in its network.  For example,
      for the AMT Use Cases, one or more AMT Relays may be experiencing
      difficulties.  AD-2 may be able to fix the problem by rerouting
      the multicast streams via alternate AMT Relays.  If the fix is not
      successful and multicast service delivery degrades, then AD-2
      needs to report the issue to AD-1.

   o  When problem notification is received from a multicast application
      source, AD-1 determines whether the cause of the problem is within
      its own network or within the AD-2 domain.  If the cause is within
      the AD-2 domain, then AD-1 supplies all necessary information to
      AD-2.  Examples of supporting information include the following:

      o  Kind of problem(s).

      o  Starting point & duration of problem(s).

      o  Conditions in which problem(s) occur.

      o  IP address blocks of affected users.

      o  ISPs of affected users.

      o  Type of access e.g., mobile versus desktop.

      o  Network locations of affected EUs.

   o  Both AD's conduct some form of root cause analysis for multicast
      service delivery problems.  Examples of various factors for
      consideration include:

      o  Verification that the service configuration matches the product

      o  Correlation and consolidation of the various customer problems
         and resource troubles into a single root service problem.

      o  Prioritization of currently open service problems, giving
         consideration to problem impact, service level agreement, etc.

      o  Conduction of service tests, including one time tests or a
         series of tests over a period of time.

      o  Analysis of test results.

      o  Analysis of relevant network fault or performance data.

      o  Analysis of the problem information provided by the customer

   o  Once the cause of the problem has been determined and the problem
      has been fixed, both AD's need to work jointly to verify and
      validate the success of the fix.

4.5.  Client Reliability Models/Service Assurance Guidelines

   There are multiple options for instituting reliability architectures,
   most are at the application level.  Both AD's should work those out
   with their contract or agreement and with the multicast application
   source providers.

   Network reliability can also be enhanced by the two AD's by
   provisioning alternate delivery mechanisms via unicast means.

4.6.  Application Accounting Guidelines

   Application level accounting needs to be handled differently in the
   application than in IP unicast because the source side does not
   directly deliver packets to individual receivers.  Instead, this
   needs to be signalled back by the receiver to the source.

   For network transport diagnostics, AD-1 and AD-2 should have
   mechanisms in place to ensure proper accounting for the volume of
   bytes delivered through the peering point and separately the number
   of bytes delivered to EUs.

5.  Troubleshooting and Diagnostics

   Any service provider supporting multicast delivery of content should
   have the capability to collect diagnostics as part of multicast
   troubleshooting practices and resolve network issues accordingly.
   Issues may become apparent or identified either through network
   monitoring functions or by customer reported problems as described in
   section 4.4.

   It is recommended that multicast diagnostics will be performed
   leveraging established operational practices such as those documented
   in [MDH-04].  However, given that inter-domain multicast creates a
   significant interdependence of proper networking functionality
   between providers there does exist a need for providers to be able to
   signal (or otherwise alert) each other if there are any issues noted
   by either one.

   Service providers may also wish to allow limited read-only
   administrative access to their routers to their AD peers for
   troubleshooting.  Of specific interest are access to active
   troubleshooting tools especially [Traceroute] and

   Another option is to include this functionality into the IP multicast
   receiver application on the EU device and allow for these diagnostics
   to be remotely used by support operations.  Note though that AMT does
   not allow to pass traceroute or mtrace requests, therefore
   troubleshooting in the presence of AMT does not work as well end-to-
   end as it can with native (or even GRE encapsulated) IP multicast,
   especially wrt. to traceroute and mtrace.  Instead, troubleshooting
   directly on the actual network devices is then more likely necessary.

   The specifics of the notification and alerts are beyond the scope of
   this document, but general guidelines are similar to those described
   in section 4.4 (Service Performance and Monitoring).  Some general
   communications issues are stated as follows.

   o  Appropriate communications channels will be established between
      the customer service and operations groups from both AD's to
      facilitate information sharing related to diagnostic

   o  A default resolution period may be considered to resolve open
      issues.  Alternately, mutually acceptable resolution periods could
      be established depending on the severity of the identified

6.  Security Considerations

6.1.  DoS attacks (against state and bandwidth)

   Reliable operations of IP multicast requires some basic protection
   against DoS (Denial of Service) attacks.

   SSM IP multicast is self protecting against attacks from illicit
   sources.  Their traffic will not be forwarded beyond the first hop
   router because that would require (S,G) memership reports from
   receiver.  Traffic from sources will only be forwarded from the valid
   source because RPF ("Reverse Path Forwarding") is part of the
   protocols.  One can say that [BCP38] style protection against spoofed
   source traffic is therefore built into PIM-SM/PIM-SSM.

   Receivers can attack SSM IP multicast by originating such (S,G)
   membership reports.  This can result in a DoS attack against state
   through the creation of a large number of (S,G) states that create
   high control plane load or even inhibit later creation of valid
   (S,G).  In conjunction with collaborating illicit sources it can also
   result in illicit sources traffic being forwarded.

   Today, these type of attacks are usually mitigated by explicitly
   defining the set of permissible (S,G) on e.g.: the last hop routers
   in replicating IP multicast to EUs; For example via (S,G) Access
   Control Lists applied to IGMP/MLD membership state creation.  Each AD
   is expected to prohibit (S,G) state creation for invalid sources
   inside their own AD.

   In the peering case, AD-2 is without further information not aware of
   the set of valid (S,G) from AD-1, so this set needs to be
   communicated via operational procedures from AD-1 to AD-2 to provide
   protection against this type of DoS attacks.  Future work could
   signal this information in an automated way: BGP extensions, DNS
   Resource Records or backend automation between AD-1 and AD-2.
   Backend automation is the short term most viable solution because it
   does not require router software extensions like the other two.
   Observation of traffic flowing via (S,G) state could also be used to
   automate recognition of invalid (S,G) state created by receivers in
   the absence of explicit information from AD-1.

   The second DoS attack through (S,G) membership reports is when
   receivers create too much valid (S,G) state to attack bandwidth
   available to other EU.  Consider the uplink into a last-hop-router
   connecting to 100 EU.  If one EU joins to more multicast content than
   what fits into this link, then this would impact also the quality of
   the same content for the other 99 EU.  If traffic is not rate
   adaptive, the effects are even worse.

   The mitigation is the same as what is often employed for unicast:
   Policing of per-EU total amont of traffic.  Unlike unicast though,
   this can not be done anywhere along the path (e.g.: on an arbitrary
   bottleneck link), but it has to happen at the point of last
   replication to the different EU.  Simple solutions such as limiting
   the maximum number of joined (S,G) per EU are readily available,
   solutions that consider bandwidth consumed exist as vendor specific
   feature in routers.  Note that this is primarily a non-peering issue
   in AD-2, it only becomes a peering issue if the peering-link itself
   is not big enough to carry all possible content from AD-1 or in case
   3.4 where the AMT relay in AD-1 is that last replication point.

   Limiting the amount of (S,G) state per EU is also a good first
   measure to prohibit too much undesired "empty" state to be built
   (state not carrying traffic), but it would not suffice in case of
   DDoS attack - viruses that impact a large number of EU devices.

6.2.  Content Security

   Content confidentiality, DRM (Digital Restrictions Management),
   authentication and authorization are optional based on the content
   delivered.  For content that is "FTA" (Free To Air), the following
   considerations can be ignored and content can be sent unencrypted and
   without EU authentication and authorization.  Note though that the
   mechanisms described here may also be desireable by the application
   source to better track users even if the content itself would not
   require it.

   For interdomain content, there are at least two models for content
   confidentiality, DRM and end-user authentication and authorization:

   In the classical (IP)TV model, responsibility is per-domain and
   content is and can be passed on unencrypted.  AD-1 delivers content
   to AD-2, AD-2 can further process the content including features like
   ad-insertion and AD-2 is the sole point of contact regarding the
   contact for its EUs.  In this document, we do not consider this case
   because it typically involves higher than network layer service
   aspects operated by AD-2 and this document focusses on the network
   layer AD-1/AD-2 peering case, but not the application layer peering
   case.  Nevertheless, this model can be derived through additional
   work from what is describe here.

   The other case is the one in which content confidentiality, DRM, end-
   user authentication and authorization are end-to-end:
   responsibilities of the multicast application source provider and
   receiver application.  This is the model assumed here.  It is also
   the model used in Internet OTT video delivery.  We discuss the
   threads incurred in this model due to the use of IP multicast in AD-
   1/AD-2 and across the peering.

   End-to-end encryption enables end-to-end EU authentication and
   authorization: The EU may be able to IGMP/MLD join and receive the
   content, but it can only decrypt it when it receives the decryption
   key from the content source in AD-1.  The key is the authorization.
   Keeping that key to itself and prohibiting playout of the decrypted
   content to non-copy-protected interfaces are typical DRM features in
   that receiver application or EU device operating system.

   End-to-end ecnryption is continuously attacked.  Keys may be subject
   to brute force attack so that content can be decrypted potentially
   later, or keys are extracted from the EU application/device and
   shared with other unauthenticated receivers.  One important class of
   content is where the value is in live consumption, such as sports or
   other event (concert) streaming.  Extraction of keying material from
   compromised authenticated EU and sharing with unauthenticated EU is
   not sufficient.  It is also necessary for those unauthenticated EUs
   to get a streaming copy of the content itself.  In unicast streaming,
   they can not get such a copy from the content source (because they
   can not authenticate) and because of asymmetric bandwidths, it is
   often impossible to get the content from compromised EUs to large
   number of unauthenticated EUs.  EUs behind classical 16 Mbps down, 1
   Mbps up ADSL links are the best example.  With increasing broadband
   access speeds unicast peer-to-peer copying of content becomes easier,
   but it likely will always be easily detectable by the ADs because of
   its traffic patterns and volume.

   When IP multicast is being used without additionals security, AD-2 is
   not aware which EU is authenticated for which content.  Any
   unauthenticated EU in AD-2 could therefore get a copy of the
   encrypted content without suspicion by AD-2 or AD-1 and either live-
   deode it in the presence of compromised authenticated EU and key
   sharing, or later decrypt it in the presence of federated brute force
   key cracking.

   To mitigate this issue, the last replication point that is creating
   (S,G) copies to EUs would need to permit those copies only after
   authentication of EUs.  This would establish the same authenticated
   EU only copy deliver thast is used in unicast.

   Schemes for per EU IP multicast authentication/authorization (and in
   result non-delivery/copying of per-content IP multicast traffic) have
   been built in the past and are deployed in service providers for
   intradomain IPTV services, but no standard exist for this.  For
   example, there is no standardized radius attribute for authenticating
   the IGMP/MLD filter set, but implementations of this exist.  The
   authors are specifically also not aware of schemes where the same
   authentication credentials used to get the encryption key from the
   content source could also be used to authenticate and authorize the
   network layer IP multicast replication for the content.  Such schemes
   are technically not difficult to build and would avoid creating and
   maintaining a separate network forwarding authentication/
   authorization scheme decoupled from the end-to-end authentication/
   authorization system of the application.

   If delivery of such high value content in conjunction with the
   peering described here is desired, the short term recommendations are
   for sources to clearly isolate the source and group addresses used
   for different content bundles, communicate those (S,G) patterns from
   AD-1 to the AD-2 and let AD-2 leverage existing per-EU
   authentication/ authorization mechanisms in network devices to
   establish filters for (S,G) sets to each EU.

6.3.  Peering Encryption

   Encryption at peering points for multicast delivery may be used per
   agreement between AD-1/AD-2.

   In the case of a private peering link, IP multicast does not have
   attack vectors on a peering link different from those of IP unicast,
   but the content owner may have defined high bars against
   unauthenticated copying of even the end-to-end encrypted content, and
   in this case AD-1/AD-2 can agree on additional transport encryption
   across that peering link.  In the case of a broadcast peering
   connection (e.g.: IXP), transport encryption is also the easiest way
   to prohibit unauthenticated copies by other ADs on the same peering

   If peering is across a tunnel going across intermittent transit ADs
   (not discused in detail in this document), then encryption of that
   tunnel traffic is recommended.  It not only prohibits possible
   "leakage" of content, but also to protects the the information what
   content is being consumed in AD-2 (aggregated privacy protection).

   See the following subsection for reasons why the peering point may
   also need to be encrypted for operational reasons.

6.4.  Operational Aspects

   Section 4.3.3 discusses exchange of log information, this section
   discussed exchange of (S,G) information and Section 7 discusses
   exhange of program information.  All these operational pieces of data
   should by default be exchanged via authenticated and encrypted peer-
   to-peer communication protocols between AD-1 and AD-2 so that only
   the intended recipient in the peers AD have access to it.  Even
   exposure of the least sensitive information to third parties opens up
   attack vectors.  Putting for example valid (S,G) information into DNS
   (as opposed to passing it via secured channels from AD-1 to AD-2) to
   allow easier filtering of invalid (S,G) would also allow attackers to
   easier identify valid (S,G) and change their attack vector.

   From the perspective of the ADs, security is most critical for the
   log information as it provides operational insight into the
   originating AD, but it also contains sensitive user data:

   Sensitive user data exported from AD-2 to AD-1 as part of logs could
   be as much as the equivalent of 5-tuple unicast traffic flow
   accounting (but not more, e.g.: no application level information).
   As mentioned in Section 7, in unicast, AD-1 could capture these
   traffic statistics itself because this is all about AD-1 originated
   traffic flows to EU receivers in AD-2, and operationally passing it
   from AD-2 to AD-1 may be necessary when IP multicast is used because
   of the replication happening in AD-2.

   Nevertheless, passing such traffic statistics inside AD-1 from a
   capturing router to a backend system is likely less subject to third
   party attacks then passing it interdomain from AD-2 to AD-1, so more
   diligence needs to be applied to secure it.

   If any protocols used for the operational information exchange are
   not easily secured at transport layer or higher (because of the use
   of legacy products or protocols in the network), then AD-1 and AD-2
   can also consider to ensure that all operational data exchange goes
   across the same peering point as the traffic and use network layer
   encryption of the peering point as discussed in before to protect it.

   End-to-end authentication and authorization of EU may involve some
   kind of token authentication and is done at the application layer
   independently of the two AD's.  If there are problems related to
   failure of token authentication when end-users are supported by AD-2,
   then some means of validating proper working of the token
   authentication process (e.g., back-end servers querying the multicast
   application source provider's token authentication server are
   communicating properly) should be considered.  Implementation details
   are beyond the scope of this document.

   Security Breach Mitigation Plan - In the event of a security breach,
   the two AD's are expected to have a mitigation plan for shutting down
   the peering point and directing multicast traffic over alternative
   peering points.  It is also expected that appropriate information
   will be shared for the purpose of securing the identified breach.

7.  Privacy Considerations

   The described flow of information about content and the end-user
   described in this document aims to maintain privacy:

   AD-1 is operating on behalf (or owns) the content source and is
   therefore part of the content-consumption relationship with the end-
   user.  The privacy considerations between the EU and AD-1 are
   therefore in general (exception see below) the same as if no IP
   multicast was used, especially because for any privacy conscious
   content, end-to-end encryption can and should be used.

   Interdomain multicast transport service related information is
   provided by the AD-2 operators to AD-1.  AD-2 is not required to gain
   additional insight into the user behavior through this process that
   it would not already have without the service collaboration with AD-1
   - unless AD-1 and AD-2 agree on it and get approval from the EU.

   For example, if it is deemed beneficial for EU to directly get
   support from AD-2 then it would in general be necessary for AD-2 to
   be aware of the mapping between content and network (S,G) state so
   that AD-2 knows which (S,G) to troubleshoot when the EU complains
   about problems with a specific content.  The degree to which this
   dissemination is done by AD-1 explicitly to meet privacy expectations
   of EUs is typically easy to assess by AD-1.  Two simple examples:

   For a sports content bundle, every EU will happily click on the "i
   approve that the content program information is shared with your
   service provider" button, to ensure best service reliability because
   service conscious AD-2 would likely also try to ensure that high
   value content, such as the (S,G) for SuperBowl like content would be
   the first to receive care in case of network issues.

   If the content in question was one where the EU expected more
   privacy, the EU should prefer a content bundle that included this
   content in a large variety of other content, have all content end-to-
   end encrypted and the programming information not be shared with AD-2
   to maximize privacy.  Nevertheless, the privacy of the EU against
   AD-2 observing traffic would still be lower than in the equivalent
   setup using unicast, because in unicast, AD-2 could not correlate
   which EUs are watching the same content and use that to deduce the
   content.  Note that even the setup in Section 3.4 where AD-2 is not
   involved in IP multicast at all does not provide privacy against this
   level of analysis by AD-2 because there is no transport layer
   encryption in AMT and therefore AD-2 can correlate by onpath traffic
   analysis who is consuming the same content from an AMT relay from
   both the (S,G) join messages in AMT and the identical content
   segments (that where replicated at the AMT relay).

   In summary: Because only content to be consumed by multiple EUs is
   carried via IP multicast here, and all that content can be end-to-end
   encrypted, the only IP multicast specific privacy consideration is
   for AD-2 to know or reconstruct what content an EU is consuming.  For
   content for which this is undesirable, some form of protections as
   explained above are possible, but ideally, the model of Section 3.4
   could be used in conjunction with future work adding e.g.: dTLS
   [RFC6347] encryption between AMT relay and EU.

   Note that IP multicast by nature would permit the EU privacy against
   the countent source operator because unlike unicast, the content
   source does not natively know which EU is consuming which content: In
   all cases where AD-2 provides replication, only AD-2 does know this
   directly.  This document does not attempt to describe a model that
   does maintain such level of privacy against the content source but
   only against exposure to intermediate parties, in this case AD-2.

8.  IANA Considerations

   No considerations identified in this document.

9.  Acknowledgments

   The authors would like to thank the following individuals for their
   suggestions, comments, and corrections:

   Mikael Abrahamsson

   Hitoshi Asaeda

   Dale Carder

   Tim Chown

   Leonard Giuliano

   Jake Holland

   Joel Jaeggli

   Albert Manfredi

   Stig Venaas

   Henrik Levkowetz

10.  Change log [RFC Editor: Please remove]

   Please see discussion on mailing list for changes before -111. -11.

   -11: version in IESG review.

   -12: XML'ified version of -11, committed solely to make rfcdiff
   easier.  XML versions hosted on https://www.github.com/toerless/


   o  IESG feedback.  Complete details in:

   o  Ben Campbell: Location information about EU (End User) is Network
      Locatio information

   o  Ben Campbell: Added explanation of assumption to introduction that
      traffic is sourced from AD-1 to (one or many) AD-2, mentioned that
      sourcing from EU is out of scope.

   o  Introduction: moved up bullet points about exchanges and transit
      to clean up flow of assumptions.

   o  Ben Campbell: Added picture for the GRE case, visualized tunnels
      in all pictures.

   o  Ben Campbell: See 13-discus.txt on github for more details of
      changes for this review.

   o  Alissia Cooper: Added more explanation for Log Management,
      explained privacy context.

   o  Alissia Cooper: removed pre pre-RFC5378 disclaimer.

   o  Alissia Cooper: removed mentioning of potential mutual
      compensation between domains if the other violates SLA.

   o  Mirja Kuehlewind: created section 4.1.1 to discuss congestion
      control more detailled, adding reference to BCP145, removed stub
      CC paragraphs from section 3.1 (principle applies to every section
      3.x, and did not want to duplicate text between 3.x and 4.x).

   o  Mirja Kuehlewind: removed section 8 (conclusion).  Text was not
      very good, not important to hae conclusion, maybe bring back with
      better text if strong interest.

   o  Introduced section about broadcast peering points because there
      where too many places already where references to that case
      existed (4.2.4).

   o  Introduced section about privact considerations because of comment
      by Ben Campbell and Alissa Cooper.

   o  Rewrote security considerations and structured it into key
      aspects: DoS attacks, content protection, peering point encryption
      and operational aspects.

   o  Kathleen Moriarty: Added operational aspects to security section
      (also for Alissia), e.g.: covering securing the exchange of
      operational data between ADs.

   o  Spencer Dawkins: Various editorial fixes.  Removed BCP38 text from
      section 3, superceeded be explanation of PIM-SM RPF check to
      provide equvialent security to BCP38 in security section 7.1).

   o  Eric Roscorla: (fixed from other reviews already).

   o  Adam Roach: Fixed up text about MDH-04, added reference to

   -13: Fix for Mirja's review on must for congestion control.

11.  References

11.1.  Normative References

   [RFC2784]  Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
              Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
              DOI 10.17487/RFC2784, March 2000,

   [RFC3376]  Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
              Thyagarajan, "Internet Group Management Protocol, Version
              3", RFC 3376, DOI 10.17487/RFC3376, October 2002,

   [RFC3810]  Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
              Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
              DOI 10.17487/RFC3810, June 2004,

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760,
              DOI 10.17487/RFC4760, January 2007,

   [RFC4604]  Holbrook, H., Cain, B., and B. Haberman, "Using Internet
              Group Management Protocol Version 3 (IGMPv3) and Multicast
              Listener Discovery Protocol Version 2 (MLDv2) for Source-
              Specific Multicast", RFC 4604, DOI 10.17487/RFC4604,
              August 2006, <https://www.rfc-editor.org/info/rfc4604>.

   [RFC4609]  Savola, P., Lehtonen, R., and D. Meyer, "Protocol
              Independent Multicast - Sparse Mode (PIM-SM) Multicast
              Routing Security Issues and Enhancements", RFC 4609,
              DOI 10.17487/RFC4609, October 2006,

   [RFC7450]  Bumgardner, G., "Automatic Multicast Tunneling", RFC 7450,
              DOI 10.17487/RFC7450, February 2015,

   [RFC7761]  Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
              Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
              Multicast - Sparse Mode (PIM-SM): Protocol Specification
              (Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
              2016, <https://www.rfc-editor.org/info/rfc7761>.

   [BCP38]    Ferguson, P. and D. Senie, "Network Ingress Filtering:
              Defeating Denial of Service Attacks which employ IP Source
              Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
              May 2000, <https://www.rfc-editor.org/info/rfc2827>.

   [BCP41]    Floyd, S., "Congestion Control Principles", BCP 41,
              RFC 2914, DOI 10.17487/RFC2914, September 2000,

   [BCP145]   Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
              Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
              March 2017, <https://www.rfc-editor.org/info/rfc8085>.

11.2.  Informative References

   [RFC4786]  Abley, J. and K. Lindqvist, "Operation of Anycast
              Services", BCP 126, RFC 4786, DOI 10.17487/RFC4786,
              December 2006, <https://www.rfc-editor.org/info/rfc4786>.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
              January 2012, <https://www.rfc-editor.org/info/rfc6347>.

              "CDN Interconnection Use Cases and Requirements in a
              Multi-Party Federation Environment", ATIS Standard
              A-0200010, December 2012.

   [MDH-04]   Thaler, D. and others, "Multicast Debugging Handbook",
              IETF I-D draft-ietf-mboned-mdh-04.txt, May 2000.

              , <http://traceroute.org/#source%20code>.

              Asaeda, H., Meyer, K., and W. Lee, "Mtrace Version 2:
              Traceroute Facility for IP Multicast", draft-ietf-mboned-
              mtrace-v2-20 (work in progress), October 2017.

Authors' Addresses

   Percy S. Tarapore (editor)

   Phone: 1-732-420-4172
   Email: tarapore@att.com

   Robert Sayko

   Phone: 1-732-420-3292
   Email: rs1983@att.com

   Greg Shepherd

   Email: shep@cisco.com

   Toerless Eckert (editor)
   Futurewei Technologies Inc.

   Email: tte+ietf@cs.fau.de

   Ram Krishnan

   Email: ramkri123@gmail.com