Use of Multicast across Inter-domain Peering Points
RFC 8313 also known as BCP 213

Internet Engineering Task Force (IETF) P. Tarapore, Ed.
Request for Comments: 8313 R. Sayko
BCP: 213 AT&T
Category: Best Current Practice G. Shepherd
ISSN: 2070-1721 Cisco
 T. Eckert, Ed.
 Huawei
 R. Krishnan
 SupportVectors
 January 2018
 Use of Multicast across Inter-domain Peering Points
Abstract
 This document examines the use of Source-Specific Multicast (SSM)
 across inter-domain peering points for a specified set of deployment
 scenarios. The objectives are to (1) describe the setup process for
 multicast-based delivery across administrative domains for these
 scenarios and (2) document supporting functionality to enable this
 process.
Status of This Memo
 This memo documents an Internet Best Current Practice.
 This document is a product of the Internet Engineering Task Force
 (IETF). It represents the consensus of the IETF community. It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG). Further information on
 BCPs is available in Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 https://www.rfc-editor.org/info/rfc8313.
Tarapore, et al. Best Current Practice [Page 1]
RFC 8313 Multicast for Inter-domain Peering Points January 2018
Copyright Notice
 Copyright (c) 2018 IETF Trust and the persons identified as the
 document authors. All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (https://trustee.ietf.org/license-info) in effect on the date of
 publication of this document. Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document. Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
Table of Contents
 1. Introduction ....................................................4
 2. Overview of Inter-domain Multicast Application Transport ........6
 3. Inter-domain Peering Point Requirements for Multicast ...........7
 3.1. Native Multicast ...........................................8
 3.2. Peering Point Enabled with GRE Tunnel .....................10
 3.3. Peering Point Enabled with AMT - Both Domains
 Multicast Enabled .........................................12
 3.4. Peering Point Enabled with AMT - AD-2 Not
 Multicast Enabled .........................................14
 3.5. AD-2 Not Multicast Enabled - Multiple AMT Tunnels
 through AD-2 ..............................................16
 4. Functional Guidelines ..........................................18
 4.1. Network Interconnection Transport Guidelines ..............18
 4.1.1. Bandwidth Management ...............................19
 4.2. Routing Aspects and Related Guidelines ....................20
 4.2.1. Native Multicast Routing Aspects ...................21
 4.2.2. GRE Tunnel over Interconnecting Peering Point ......22
 4.2.3. Routing Aspects with AMT Tunnels ...................22
 4.2.4. Public Peering Routing Aspects .....................24
 4.3. Back-Office Functions - Provisioning and Logging
 Guidelines ................................................26
 4.3.1. Provisioning Guidelines ............................26
 4.3.2. Inter-domain Authentication Guidelines .............28
 4.3.3. Log-Management Guidelines ..........................28
 4.4. Operations - Service Performance and Monitoring
 Guidelines ................................................30
 4.5. Client Reliability Models / Service Assurance Guidelines ..32
 4.6. Application Accounting Guidelines .........................32
 5. Troubleshooting and Diagnostics ................................32
 6. Security Considerations ........................................33
 6.1. DoS Attacks (against State and Bandwidth) .................33
 6.2. Content Security ..........................................35
 6.3. Peering Encryption ........................................37
 6.4. Operational Aspects .......................................37
 7. Privacy Considerations .........................................39
 8. IANA Considerations ............................................40
 9. References .....................................................40
 9.1. Normative References ......................................40
 9.2. Informative References ....................................42
 Acknowledgments ...................................................43
 Authors' Addresses ................................................44
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
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 in terms of utilization of
 resources in any given administrative domain. End User (EU) 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 points.
 The objectives of this document are 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 cases (where "Use Case 3.1" corresponds to Section 3.1,
 "Use Case 3.2" corresponds to Section 3.2, etc.).
 o Catalog all required exchanges of information 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 EUs
 in one or more Administrative Domain 2 (AD-2) entities. AD-1 and
 AD-2 want to use IP multicast to allow support for large and
 growing EU populations, with a minimum amount of duplicated
 traffic to send across network links.
 * This document does not detail the case where EUs are
 originating content. To support that additional service, it is
 recommended that some method (outside the scope of this
 document) be used by which the content from EUs is transmitted
 to the application in AD-1 and AD-1 can 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 the EU to AD-1.
 * This document does not detail the case where AD-1 and AD-2 are
 not directly connected to each other and are instead connected
 via one or more other ADs (as opposed to a peering point) that
 serve as 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")
Tarapore, et al. Best Current Practice [Page 4]
RFC 8313 Multicast for Inter-domain Peering Points January 2018
 control, for example, would be different. Additional issues
 will likely exist as well in such scenarios. This topic is
 left for further study.
 o For the purposes 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, it is assumed that the peering point is 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
 (IXPs). See Section 4.2.4 for more details.
 o 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 Protocol-Independent Multicast - Sparse Mode
 (PIM-SM) and Protocol-Independent Multicast - Source-Specific
 Multicast (PIM-SSM) [RFC7761], the Internet Group Management
 Protocol (IGMP) [RFC3376], and Multicast Listener Discovery (MLD)
 [RFC3810].
 o As described in Section 2, the source IP address of the (so-called
 "(S,G)") multicast stream in the originating AD (AD-1) is known.
 Under this condition, using PIM-SSM is beneficial, as it allows
 the receiver's upstream router to send a join message directly to
 the source without the need to invoke an intermediate Rendezvous
 Point (RP). The 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 that
 only SSM protocols be used; the setup of inter-domain peering for
 ASM (Any-Source Multicast) is out of scope for this document.
 o The rest of this document assumes that PIM-SSM and BGP are used
 across the peering point, plus Automatic Multicast Tunneling (AMT)
 [RFC7450] and/or Generic Routing Encapsulation (GRE), according to
 the scenario in question. The use of other protocols is beyond
 the scope of this document.
 o AMT is set up 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
Tarapore, et al. Best Current Practice [Page 5]
RFC 8313 Multicast for Inter-domain Peering Points January 2018
 this document. Note that using AMT 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 It is assumed that the collection of billing data is done at the
 application level and is not considered to be a networking issue.
 The settlements process for EU 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 connected by one of two
 possible tunnel types:
 * A GRE tunnel [RFC2784] allowing multicast tunneling across the
 peering point, or
 * AMT [RFC7450].
 o A service provider controls one or more application sources in
 AD-1 that 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) and that
 the packet streams will be carried by a suitable multicast
 transport protocol.
 o An EU controls a device connected to AD-2, which runs an
 application client compatible with the service provider's
 application source.
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
 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 AD-2 may be an independent network domain (e.g., a Tier 1
 network operator domain). Alternately, AD-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 enterprise networks; see Section 3.
 The use cases describing various architectural configurations for
 multicast distribution, along with associated requirements, are
 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 application
 transport.
3. Inter-domain Peering Point Requirements for Multicast
 The transport of applications using multicast requires that the
 inter-domain peering point be enabled to support such a process.
 This section presents five use cases for consideration.
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
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 = multicast (e.g., content) Application Source
 BR = Border Router
 I1 = AD-1 and AD-2 multicast interconnection (e.g., MP-BGP)
 I2 = AD-2 and EU multicast connection
 Figure 1: Content Distribution via End-to-End Native Multicast
 Advantages of this configuration:
 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 to 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 EUs
 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 so 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.
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
 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 the multicast
 traffic must support congestion control via any of the mechanisms
 described in Section 4.1 of [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. It is assumed that relevant information on multicast streams
 delivered to EUs in AD-2 is 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.
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
3.2. Peering Point Enabled with GRE Tunnel
 The peering point is not native multicast enabled in this use case.
 There is a GRE 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 = multicast (e.g., content) Application 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., MP-BGP)
 I2 = AD-2 and EU multicast connection
 Figure 2: Content Distribution via GRE Tunnel
 In this case, interconnection I1 between AD-1 and AD-2 in Figure 2 is
 multicast enabled via a GRE tunnel [RFC2784] between the two BRs and
 encapsulating the multicast protocols across it.
 Normally, this approach is chosen if the uBR physically connected to
 the peering link cannot or should not be enabled for IP multicast.
 This approach may also be beneficial if the BR and uBR are the same
 device but the peering link is a broadcast domain (IXP); see
 Section 4.2.4.
 The routing configuration is basically unchanged: instead of running
 BGP (SAFI-2) ("SAFI" stands for "Subsequent Address Family
 Identifier") across the native IP multicast link between AD-1 and
 AD-2, BGP (SAFI-2) is now run across the GRE tunnel.
Tarapore, et al. Best Current Practice [Page 10]
RFC 8313 Multicast for Inter-domain Peering Points January 2018
 Advantages of this configuration:
 o Highly efficient use of bandwidth in both domains, although not as
 efficient as the fully native multicast use case (Section 3.1).
 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 or paths between
 the AS/BR (AD-1) and the 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 (at least
 initially) be more acceptable. The 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 the uBR).
 o GRE is an existing technology and is relatively simple to
 implement.
 Disadvantages of this configuration:
 o Per Use Case 3.1, current router technology cannot count the
 number of EUs or the number of bytes transmitted.
 o The GRE tunnel requires manual configuration.
 o The GRE tunnel must be established prior to starting the stream.
 o The GRE tunnel is often left pinned up.
 Architectural guidelines for this configuration include the
 following:
 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 be such that it only
 advertises the routes to the application sources and not to the
 entire network. This practice will prevent unauthorized delivery
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
 of applications through the tunnel (for example, if the
 application (e.g., content) is not part of an agreed-upon
 inter-domain partnership).
3.3. Peering Point Enabled with AMT - Both Domains Multicast Enabled
 It is assumed that both administrative domains in this use case are
 native multicast enabled here; however, the peering point is not.
 The peering point is enabled with AMT. The basic configuration is
 depicted in Figure 3.
 ------------------- -------------------
 / 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 = multicast (e.g., content) Application Source
 AR = AMT Relay
 AG = AMT Gateway
 uBR = unicast Border Router - not multicast enabled;
 also, either AR = uBR (AD-1) or 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:
 * Dynamic interconnection between the gateway-relay pair across
 the peering point.
 * Ability to serve clients and servers with differing policies.
Tarapore, et al. Best Current Practice [Page 12]
RFC 8313 Multicast for Inter-domain Peering Points January 2018
 Disadvantages of this configuration:
 o Per Use Case 3.1 (AD-2 is native multicast), current router
 technology cannot count the number of EUs or the number of bytes
 transmitted to all EUs.
 o Additional devices (AMT gateway and relay pairs) may be introduced
 into the path if these services are not incorporated into 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.
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
3.4. Peering Point Enabled with AMT - AD-2 Not Multicast Enabled
 In this AMT use case, AD-2 is not multicast enabled. Hence, the
 interconnection between AD-2 and the EU is also not multicast
 enabled. This use case is depicted in Figure 4.
 ------------------- -------------------
 / AD-1 \ / AD-2 \
 / (Multicast Enabled) \ / (Not Multicast \
 / \ / Enabled) \ N(large)
 | +----+ +---+ | | +---+ | # EUs
 | | | +--+ |uBR|-|--------|-|uBR| | +----+
 | | AS |-->|AR| +---+-| | +---+ ................>|EU/G|
 | | | +--+<........|........|........... |I2 +----+
 \ +----+ / N x AMT\ /
 \ / Tunnel \ /
 \ / \ /
 ------------------- -------------------
 AS = multicast (e.g., content) Application 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 EUs 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 EU.
 Advantages of this configuration:
 o Efficient use of bandwidth in AD-1 (the closer the AR is to the
 uBR, the more efficient).
 o Ability of AD-1 to introduce content delivery based on IP
 multicast, without any support by network devices in AD-2: only
 the application side in the EU device needs to perform AMT gateway
 library functionality to receive traffic from the AMT relay.
 o Allows AD-2 to "upgrade" to Use Case 3.5 (see Section 3.5) at a
 later time, without any change in AD-1 at that time.
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
 o AMT is an existing technology and is relatively simple to
 implement. Attractive properties of AMT include the following:
 * Dynamic interconnection between the AMT gateway-relay pair
 across the peering point.
 * Ability to serve clients and servers with differing policies.
 o Each AMT tunnel serves as a count for each EU 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. In addition,
 d. It is necessary that proper procedures be implemented such that
 the AMT gateway at the EU 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
 the use of anycast gateway addresses, anycast DNS names, or
 explicit configuration that maps (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's capabilities are expected to be sufficient for
 the purpose of collecting relevant information on the multicast
 streams delivered to EUs in AD-2.
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
3.5. AD-2 Not Multicast Enabled - Multiple AMT Tunnels through AD-2
 Figure 5 illustrates a variation of Use Case 3.4:
 ------------------- -------------------
 / AD-1 \ / AD-2 \
 / (Multicast Enabled) \ / (Not 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;
 also, either AR = uBR (AD-1) or uBR = AGAR1 (AD-2)
 AS = multicast (e.g., content) 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 gateway in AGAR1 in AD-2
 AGAR2 = AMT Gateway/Relay node at AD-2 network edge
 I2 = AMT tunnel connecting relay in AGAR1 to gateway 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 Gateways 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 EUs, 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. An
 AMT node comprises co-location of an AMT gateway and an AMT relay.
 No change is required by AD-1, as compared to Use Case 3.4. This
 can be done whenever AD-2 sees fit (e.g., too much traffic across
 the peering point).
 o One such node is on the AD-2 side of the peering point (AMT node
 AGAR1 in Figure 5).
Tarapore, et al. Best Current Practice [Page 16]
RFC 8313 Multicast for Inter-domain Peering Points January 2018
 o A single AMT tunnel established across the peering point linking
 the AMT relay in AD-1 to the AMT gateway in AMT node AGAR1
 in AD-2.
 o AMT tunnels linking AMT node AGAR1 at the peering point in AD-2 to
 other AMT nodes located at the edges of AD-2: e.g., AMT tunnel I2
 linking the AMT relay in AGAR1 to the AMT gateway in AMT
 node AGAR2 (Figure 5).
 o AMT tunnels linking an EU device (via a gateway client embedded in
 the device) and an AMT relay in an appropriate AMT node at the
 edge of AD-2: e.g., I3 linking the EU gateway in the device to the
 AMT relay in AMT node AGAR2.
 o In the simplest option (not shown), AD-2 only deploys a single
 AGAR1 node and lets the 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 a need to support more AMT
 tunnels to the EU/G, then additional AGAR2 nodes can be deployed
 by AD-2.
 The advantage of 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. In addition,
 d. It is necessary that proper procedures be implemented such that
 the various AMT gateways (at the EU 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 the use of anycast
 gateway addresses, anycast DNS names, or explicit configuration
 that maps (S,G) to a relay address. On the EU/G, this mapping
 information may come from the application.
 e. The AMT tunnel's capabilities are expected to be sufficient for
 the purpose of collecting relevant information on the multicast
 streams delivered to EUs in AD-2.
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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 the two
 administrative domains will need to agree on to support multicast
 delivery.
 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 ADs 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 such protocols include External BGP (EBGP)
 [RFC4760] peering via MP-BGP (Multiprotocol BGP) SAFI-2 [RFC4760].
 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.
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4.1.1. Bandwidth Management
 Like IP unicast traffic, IP multicast traffic carried across
 non-controlled networks must comply with congestion control
 principles as described in [BCP41] and as explained in detail for UDP
 IP multicast in [BCP145].
 Non-controlled networks (such as the Internet) are networks where
 there is no policy for managing bandwidth other than best effort with
 a fair share of bandwidth under congestion. As a simplified rule of
 thumb, complying with congestion control principles means reducing
 bandwidth under congestion in a way that is fair to competing
 (typically TCP) flows ("rate adaptive").
 In many instances, multicast content delivery evolves from
 intra-domain deployments where it is handled as a controlled network
 service and does not comply with 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
 inter-domain 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 (subject to congestion), this will not work: under
 congestion, some amount of that traffic will be dropped, often
 rendering the remaining packets as undecodable garbage clogging up
 the network in AD-2; because this traffic 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 frustrated by the
 extremely bad quality of both their IP multicast traffic and other
 (e.g., TCP) traffic. Note that this is not an IP multicast
 technology issue but is solely a transport-layer / application-layer
 issue: the problem would just as likely happen if AD-1 were to send
 non-rate-adaptive unicast traffic -- for example, legacy IPTV
 video-on-demand traffic, which is typically also non-congestion
 aware. Note that because rate adaptation in IP unicast video is
 commonplace today due to the availability of ABR (Adaptive Bitrate)
 video, it is very unlikely that this will happen in reality with IP
 unicast.
 While the rules for traffic management apply whether 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
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 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 the EU/G, on the other hand,
 scale with the number of EUs. In the vicinity of the AMT relay, they
 can introduce a very large amount of replicated traffic, and it is
 not always feasible to provision enough bandwidth for all possible
 EUs 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 that IP multicast
 rate adaptation be used, even inside controlled networks, when using
 AMT tunnels directly to the 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 ABR streaming over TCP. Therefore, migration
 from a non-rate-adaptive bitrate to a rate-adaptive bitrate in IP
 multicast will also change the dynamic (S,G) join behavior in the
 network, resulting in potentially higher performance requirements for
 IP multicast protocols (IGMP/PIM), especially on the last hops where
 dynamic changes occur (including AMT gateways/relays): in non-rate-
 adaptive IP multicast, only "channel change" causes state change, but
 in rate-adaptive multicast, congestion also causes state change.
 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 tunneled IP multicast traffic must be
 rate adaptive in order to not violate BCP 41 across those
 transit ADs.
4.2. Routing Aspects and Related Guidelines
 The main objective for multicast delivery routing is to ensure that
 the EU 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 route distance of the network(s).
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 This routing objective applies to both native multicast and AMT; the
 actual methodology of the solution will be different for each.
 Regardless, the routing solution is expected to:
 o Be scalable,
 o Avoid or minimize new protocol development or modifications, and
 o Be robust enough to achieve high reliability and to 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., BRs). 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 (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 ADs need to
 do the following:
 * Advertise the source ID(s) over the peering points.
 * Exchange such relevant peering point information as capacity
 and utilization.
 * Implement compatible multicast protocols to ensure proper
 multicast delivery across the peering points.
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4.2.2. GRE Tunnel over Interconnecting Peering Point
 If the interconnecting peering point is not multicast enabled and
 both ADs are multicast enabled, then a simple solution is to
 provision a GRE tunnel between the two ADs; see Use Case 3.2
 (Section 3.2). The termination points of the tunnel will usually be
 a network engineering decision but generally will be between the BRs
 or even between the AD-2 BR 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 are still required.
 The two ADs need to follow the same process as the process described
 in Section 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 two-layered problem
 in that there are two criteria that should be simultaneously met:
 o Find the closest AMT relay to the EU that also has multicast
 connectivity to the content source, and
 o Minimize the AMT unicast tunnel distance.
 There are essentially two components in the AMT specification:
 AMT relays: These serve the purpose of tunneling UDP multicast
 traffic to the receivers (i.e., endpoints). 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 gateways. In
 addition, the AMT relay may collect various usage and activity
 statistics. This results in moving the replication point closer
 to the EU 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
 endpoint within the unicast-only network.
 AMT gateway: The gateway will reside on an endpoint; 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 endpoint to conduct itself as a true multicast endpoint. The
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 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 ADs. 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 of this arrangement is that the tunnel is
 established on an as-needed basis and need not be a provisioned
 element. The two ADs can coordinate and advertise special AMT relay
 anycast addresses with, and to, 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 AMT situations that are more
 complicated, as AD-2 is not multicast enabled in these two cases.
 For these cases, the EU device needs to be able to set up 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 and
 is left for further study.
 An illustrative example of a relay selection based on DNS queries as
 part of an anycast IP address process is described here for Use
 Cases 3.4 and 3.5 (Sections 3.4 and 3.5). Using an anycast
 IP address for AMT relays allows 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 (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.
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 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 a particular relay, e.g., the relay that is closest to
 the EU. Details are outside the scope of 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 The AMT gateway provides the (S,G) information to the AMT relay
 (embedded in AMT protocol messages).
 o The AMT relay receives the (S,G) information and uses it to join
 the appropriate multicast stream, if it has not already subscribed
 to that stream.
 o The 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
 Figure 6 shows an example of a broadcast peering point.
 AD-1a AD-1b
 BR BR
 | |
 --+-+---------------+-+-- broadcast peering point LAN
 | |
 BR BR
 AD-2a AD-2b
 Figure 6: Broadcast Peering Point
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 A broadcast peering point is an L2 subnet connecting three 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 that 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 contact this content from the same content source.
 In this case, AD-2a and AD-2b can no longer control which upstream
 domain -- AD-1a or AD-1b -- will forward this (S,G) into the LAN.
 The AD-2a BR requests the (S,G) from the AD-1a BR, and the AD-2b BR
 requests the same (S,G) from the AD-1b BR. To avoid duplicate
 packets, an (S,G) can be forwarded by only one router onto the LAN;
 PIM-SM / PIM-SSM detects requests for duplicate transmissions and
 resolves them via the so-called "assert" protocol operation, which
 results in only one BR forwarding the traffic. Assume that this is
 the AD-1a BR. AD-2b will then receive unexpected multicast traffic
 from a provider with whom it does not have a mutual agreement for
 that traffic. Quality issues in EUs behind AD-2b caused by AD-1a
 will cause a lot of issues related to responsibility and
 troubleshooting.
 In light of these technical issues, we describe, via 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 a GRE tunnel between the upstream BR
 (e.g., AD-1a) and downstream BR (e.g., AD-2a) is specifically
 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 followed to prohibit such a 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 the upstream BR is the only possible next hop
 reachable across this LAN. Also, routing policies can be
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 configured to avoid falling back to using SAFI-1 (unicast) routes
 for IP multicast if unicast BGP peering is not limited in the
 same way.
 3. The LAN has multiple upstream ADs, 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 (the problematic case mentioned in the
 example in Figure 6 above), but the upstream domains also provide
 mutual operational insight to help with 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 ADs.
 o Functionality associated with logging, reporting, ordering,
 provisioning, maintenance, service assurance, settlement, etc.
4.3.1. Provisioning Guidelines
 Resources for basic connectivity between ADs' providers need to be
 provisioned as follows:
 o Sufficient capacity must be provisioned to support multicast-based
 delivery across ADs.
 o Sufficient capacity must be provisioned for connectivity between
 all supporting back offices of the ADs as appropriate. This
 includes activating proper security treatment for these
 back-office connections (gateways, firewalls, etc.) as
 appropriate.
 Provisioning aspects related to multicast-based inter-domain delivery
 are as follows.
 The ability to receive a requested application via multicast is
 triggered via receipt of the necessary metadata. Hence, this
 metadata must be provided to the EU regarding the 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
 purpose.
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 It is assumed that native multicast functionality is available across
 many ISP backbones, peering points, and access networks. If,
 however, native multicast is not an option (Use Cases 3.4 and 3.5),
 then:
 o The EU must have a multicast client to use AMT multicast obtained
 from either (1) the application source (per agreement with AD-1)
 or (2) AD-1 or AD-2 (if delegated by the application source).
 o If provided by AD-1 or 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 that 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 and group
 addresses for streams it is allowed to join.
 o DNS across each AD must be provisioned to enable a client gateway
 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 as
 follows.
 It is assumed that each AD provider will provision operations and
 customer care access to their own systems.
 AD-1's operations and customer care functions must be able to see
 enough of what is happening in AD-2's network or in the service
 provided by AD-2 to verify their mutual goals and operations, e.g.,
 to know how the EUs 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 ADs, with appropriate
 provisioning of necessary resources.
 o AD-1's operations and customer care personnel are provided direct
 access to AD-2's systems. In this scenario, additional
 provisioning in these systems will be needed to provide necessary
 access. The two ADs must agree on additional provisioning to
 support this option.
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4.3.2. Inter-domain Authentication Guidelines
 All interactions between pairs of ADs can be discovered and/or
 associated with the account(s) utilized for delivered applications.
 Supporting guidelines are as follows:
 o A unique identifier is recommended to designate each master
 account.
 o AD-2 is expected to set up "accounts" (a 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.
 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, is based on the recommended workflow initiated by
 customers (see Section 4.4): the customer contacts the content
 source, which is part of AD-1. Consequently, if AD-1 sees the need
 to escalate the issue to AD-2, 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 ADs can be
 improved through the ability to exchange appropriate logs for various
 workflows -- troubleshooting, accounting and billing, optimization of
 traffic and content transmission, optimization of content and
 application development, and so on.
 Specifically, AD-1 take over primary responsibility for customer
 experience on behalf of the content source, with support from AD-2 as
 needed. 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, with the help of AD-2 or logs from AD-2, it can then 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 unicast stream than from a multicast stream:
 the multicast 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 cannot help to fully isolate network problems because of
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 the IP multicast per-application operational state built across AD-1
 and AD-2 (aka the (S,G) state and any other operational-state
 features, such as Diffserv QoS).
 See Section 7 for more discussion regarding the privacy
 considerations of the model described here.
 Different types 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). We
 therefore detail them as follows:
 o Usage information logs at an 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 software-
 download sets.
 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
 troubleshooting.
 The two ADs may supply additional security logs to each other, as
 agreed upon in contract(s). Examples include the following:
 o Information related to general security-relevant activity, which
 may be of use from a protection or response perspective: 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
 agreement).
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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 follows:
 o Both ADs 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 ADs are expected to agree on the types 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 EUs when service problems
 occur. EUs direct their complaints to the source provider; the
 source provider in turn 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 -- in
 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 ADs 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 ADs 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 (Sections 3.3, 3.4, and 3.5), 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.
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 o When a 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 AD-2. If the cause is
 within AD-2, then AD-1 supplies all necessary information to AD-2.
 Examples of supporting information include the following:
 * Kind(s) of problem(s).
 * Starting point and duration of problem(s).
 * Conditions in which one or more problems occur.
 * IP address blocks of affected users.
 * ISPs of affected users.
 * Type of access, e.g., mobile versus desktop.
 * Network locations of affected EUs.
 o Both ADs conduct some form of root-cause analysis for multicast
 service delivery problems. Examples of various factors for
 consideration include:
 * Verification that the service configuration matches the product
 features.
 * Correlation and consolidation of the various customer problems
 and resource troubles into a single root-service problem.
 * Prioritization of currently open service problems, giving
 consideration to problem impacts, SLAs, etc.
 * Conducting service tests, including tests performed once or a
 series of tests over a period of time.
 * Analysis of test results.
 * Analysis of relevant network fault or performance data.
 * 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 ADs need to work jointly to verify and
 validate the success of the fix.
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4.5. Client Reliability Models / Service Assurance Guidelines
 There are multiple options for instituting reliability architectures.
 Most are at the application level. Both ADs should work these
 options out per their contract or agreement and also with the
 multicast application source providers.
 Network reliability can also be enhanced by the two ADs if they
 provision 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 signaled 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
 be able to collect diagnostics as part of multicast troubleshooting
 practices and resolve network issues accordingly. Issues may become
 apparent or identifiable through either (1) network monitoring
 functions or (2) problems reported by customers, as described in
 Section 4.4.
 It is recommended that multicast diagnostics be performed, leveraging
 established operational practices such as those documented in
 [MDH-05]. However, given that inter-domain multicast creates a
 significant interdependence of proper networking functionality
 between providers, there exists a need for providers to be able to
 signal (or otherwise alert) each other if there are any issues noted
 by either one.
 For troubleshooting purposes, service providers may also wish to
 allow limited read-only administrative access to their routers to
 their AD peers. Access to active troubleshooting tools -- especially
 [Traceroute] and the tools discussed in [Mtrace-v2] -- is of specific
 interest.
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 Another option is to include this functionality in the IP multicast
 receiver application on the EU device and allow these diagnostics to
 be remotely used by support operations. Note, though, that AMT
 does not allow the passing of 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 with regard to traceroute and mtrace. Instead,
 troubleshooting directly on the actual network devices is then more
 likely necessary.
 The specifics of notifications and alerts are beyond the scope of
 this document, but general guidelines are similar to those described
 in Section 4.4. Some general communications issues are as follows.
 o Appropriate communications channels will be established between
 the customer service and operations groups from both ADs to
 facilitate information-sharing related to diagnostic
 troubleshooting.
 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
 trouble.
6. Security Considerations
6.1. DoS Attacks (against State and Bandwidth)
 Reliable IP multicast operations require some basic protection
 against DoS (Denial of Service) attacks.
 SSM IP multicast is self-protecting against attacks from illicit
 sources; such traffic will not be forwarded beyond the first-hop
 router, because that would require (S,G) membership reports from the
 receiver. Only valid traffic from sources will be forwarded, because
 RPF ("Reverse Path Forwarding") is part of the protocols. One can
 say that protection against spoofed source traffic performed in the
 style of [BCP38] 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 the later creation of a valid
 (S,G). In conjunction with collaborating illicit sources, it can
 also result in the forwarding of traffic from illicit sources.
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 Today, these types of attacks are usually mitigated by explicitly
 defining the set of permissible (S,G) on, for example, the last-hop
 routers in replicating IP multicast to EUs (e.g., via (S,G) access
 control lists applied to IGMP/MLD membership state creation). Each
 AD (say, "ADi") is expected to know what sources located in ADi are
 permitted to send and what their valid (S,G)s are. ADi can therefore
 also filter invalid (S,G)s for any "S" located inside ADi, but not
 sources located in another AD.
 In the peering case, without further information, AD-2 is 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 attack. 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, in the short term, the most viable solution: unlike
 BGP extensions or DNS resource records, backend automation does not
 require router software extensions. Observation of traffic flowing
 via (S,G) state could also be used to automate the recognition of
 invalid (S,G) state created by receivers in the absence of explicit
 information from AD-1.
 The second type of DoS attack through (S,G) membership reports exists
 when the attacking receiver creates too much valid (S,G) state and
 the traffic carried by these (S,G)s congests bandwidth on links
 shared with other EUs. Consider the uplink to a last-hop router
 connecting to 100 EUs. If one EU joins to more multicast content
 than what fits into this link, then this would also impact the
 quality of the same content for the other 99 EUs. If traffic is not
 rate adaptive, the effects are even worse.
 The mitigation technique is the same as what is often employed for
 unicast: policing of the per-EU total amount of traffic. Unlike
 unicast, though, this cannot be done anywhere along the path (e.g.,
 on an arbitrary bottleneck link); 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)s per EU are readily
 available; solutions that take consumed bandwidth into account are
 available as vendor-specific features 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, as in Use Case 3.4, when 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 from being built
 (state not carrying traffic), but it would not suffice in the case of
 DDoS attacks, e.g., viruses that impact a large number of EU devices.
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6.2. Content Security
 Content confidentiality, DRM (Digital Rights 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 desirable for the
 application source to better track users even if the content itself
 would not require it.
 For inter-domain content, there are at least two models for content
 confidentiality, including (1) DRM authentication and authorization
 and (2) EU authentication and authorization:
 o 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 service aspects
 operated by AD-2 that are higher than the network layer; this
 document focuses 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 beyond what is described
 here.
 o The other model is the one in which content confidentiality, DRM,
 EU authentication, and EU 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 "Over the Top" (OTT) video delivery.
 Below, we discuss the threats incurred in this model due to the
 use of IP multicast in AD-1 or AD-2 and across the peering point.
 End-to-end encryption enables end-to-end EU authentication and
 authorization: the EU may be able to join (via IGMP/MLD) 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 encryption is continuously attacked. Keys may be subject
 to brute-force attacks so that content can potentially be decrypted
 later, or keys are extracted from the EU application/device and
 shared with other unauthenticated receivers. One important class of
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 content is where the value is in live consumption, such as sports or
 other event (e.g., concert) streaming. Extraction of keying material
 from compromised authenticated EUs and sharing with unauthenticated
 EUs are not sufficient. It is also necessary for those
 unauthenticated EUs to get a streaming copy of the content itself.
 In unicast streaming, they cannot get such a copy from the content
 source (because they cannot authenticate), and, because of asymmetric
 bandwidths, it is often impossible to get the content from
 compromised EUs to a 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 additional security, AD-2 is
 not aware of which EU is authenticated for which content. Any
 unauthenticated EU in AD-2 could therefore get a copy of the
 encrypted content without triggering suspicion on the part of AD-2 or
 AD-1 and then either (1) live-decode it, in the presence of the
 compromised authenticated EU and key-sharing or (2) decrypt it later,
 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 the EUs. This would establish the same
 authenticated "EU only" copy that is used in unicast.
 Schemes for per-EU IP multicast authentication/authorization (and, as
 a result, non-delivery or copying of per-content IP multicast
 traffic) have been built in the past and are deployed in service
 providers for intra-domain IPTV services, but no standards exist for
 this. For example, there is no standardized RADIUS attribute for
 authenticating the IGMP/MLD filter set, but such implementations
 exist. The authors of this document 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
 traffic-forwarding authentication/authorization scheme decoupled from
 the end-to-end authentication/authorization system of the
 application.
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 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 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 and 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 strict constraints against
 unauthenticated copying of even the end-to-end encrypted content; in
 this case, AD-1 and 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 again the easiest way
 to prohibit unauthenticated copies by other ADs on the same peering
 point.
 If peering is across a tunnel that spans intermittent transit ADs
 (not discussed in detail in this document), then encryption of that
 tunnel traffic is recommended. It not only prohibits possible
 "leakage" of content but also protects the information regarding what
 content is being consumed in AD-2 (aggregated privacy protection).
 See Section 6.4 for reasons why the peering point may also need to be
 encrypted for operational reasons.
6.4. Operational Aspects
 Section 4.3.3 discusses the exchange of log information, and
 Section 7 discusses the exchange 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 recipients in the
 peers' AD have access to it. Even exposure of the least sensitive
 information to third parties opens up attack vectors. Putting valid
 (S,G) information, for example, into DNS (as opposed to passing it
 via secured channels from AD-1 to AD-2) to allow easier filtering of
 invalid (S,G) information would also allow attackers to more easily
 identify valid (S,G) information and change their attack vector.
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
 From the perspective of the ADs, security is most critical for log
 information, as it provides operational insight into the originating
 AD but 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 traffic flows
 (originated by AD-1) 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 taking place 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 than passing it "inter-domain" from AD-2 to AD-1,
 so more diligence needs to be applied to secure it.
 If any protocols used for the operational exchange of information are
 not easily secured at the 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 ensuring that all operational data exchanges
 go across the same peering point as the traffic and use network-layer
 encryption of the peering point (as discussed previously) to
 protect it.
 End-to-end authentication and authorization of EUs may involve some
 kind of token authentication and are done at the application layer,
 independently of the two ADs. If there are problems related to the
 failure of token authentication when EUs are supported by AD-2, then
 some means of validating proper operation of the token authentication
 process (e.g., validating that backend 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.
 In the event of a security breach, the two ADs 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.
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7. Privacy Considerations
 The described flow of information about content and EUs as described
 in this document aims to maintain privacy:
 AD-1 is operating on behalf of (or owns) the content source and is
 therefore part of the content-consumption relationship with the EU.
 The privacy considerations between the EU and AD-1 are therefore
 generally the same (with one exception; see below) as they would be
 if no IP multicast was used, especially because end-to-end encryption
 can and should be used for any privacy-conscious content.
 Information related to inter-domain multicast transport service is
 provided to AD-1 by the AD-2 operators. AD-2 is not required to gain
 additional insight into the user's behavior through this process
 other than what it would already have without 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 the EU to get support
 directly from AD-2, then it would generally 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 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 are
 as follows:
 o 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 the Super Bowl,
 would be the first to receive care in the case of network issues.
 o If the content in question was content for which 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 not share programming information 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; therefore, AD-2 can
 correlate by on-path traffic analysis who is consuming the same
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
 content from an AMT relay from both the (S,G) join messages in AMT
 and the identical content segments (that were replicated at the
 AMT relay).
 In summary, because only content to be consumed by multiple EUs is
 carried via IP multicast here and all of that content can be
 end-to-end encrypted, the only privacy consideration specific to IP
 multicast 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
 described in Section 3.4 could be used in conjunction with future
 work, e.g., adding Datagram Transport Layer Security (DTLS)
 encryption [RFC6347] between the AMT relay and the EU.
 Note that IP multicast by nature would permit the EU's privacy
 against the content 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
 knows this directly. This document does not attempt to describe a
 model that maintains such a level of privacy against the content
 source; rather, we describe a model that only protects against
 exposure to intermediate parties -- in this case, AD-2.
8. IANA Considerations
 This document does not require any IANA actions.
9. References
9.1. 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,
 <https://www.rfc-editor.org/info/rfc2784>.
 [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,
 <https://www.rfc-editor.org/info/rfc3376>.
 [RFC3810] Vida, R., Ed., and L. Costa, Ed., "Multicast Listener
 Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
 DOI 10.17487/RFC3810, June 2004,
 <https://www.rfc-editor.org/info/rfc3810>.
Tarapore, et al. Best Current Practice [Page 40]
RFC 8313 Multicast for Inter-domain Peering Points January 2018
 [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
 "Multiprotocol Extensions for BGP-4", RFC 4760,
 DOI 10.17487/RFC4760, January 2007,
 <https://www.rfc-editor.org/info/rfc4760>.
 [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,
 <https://www.rfc-editor.org/info/rfc4609>.
 [RFC7450] Bumgardner, G., "Automatic Multicast Tunneling", RFC 7450,
 DOI 10.17487/RFC7450, February 2015,
 <https://www.rfc-editor.org/info/rfc7450>.
 [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, May 2000,
 <https://www.rfc-editor.org/info/rfc2827>.
 [BCP41] Floyd, S., "Congestion Control Principles", BCP 41,
 RFC 2914, September 2000,
 <https://www.rfc-editor.org/info/rfc2914>.
 [BCP145] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
 Guidelines", BCP 145, RFC 8085, March 2017,
 <https://www.rfc-editor.org/info/rfc8085>.
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
9.2. 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>.
 [INF_ATIS_10]
 "CDN Interconnection Use Cases and Requirements in a
 Multi-Party Federation Environment", ATIS Standard
 A-0200010, December 2012.
 [MDH-05] Thaler, D. and B. Aboba, "Multicast Debugging Handbook",
 Work in Progress, draft-ietf-mboned-mdh-05, November 2000.
 [Traceroute]
 "traceroute.org", <http://traceroute.org/#source%20code>.
 [Mtrace-v2]
 Asaeda, H., Meyer, K., and W. Lee, Ed., "Mtrace Version 2:
 Traceroute Facility for IP Multicast", Work in Progress,
 draft-ietf-mboned-mtrace-v2-22, December 2017.
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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
 Henrik Levkowetz
 Albert Manfredi
 Stig Venaas
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RFC 8313 Multicast for Inter-domain Peering Points January 2018
Authors' Addresses
 Percy S. Tarapore (editor)
 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
 Email: shep@cisco.com
 Toerless Eckert (editor)
 Huawei USA - Futurewei Technologies Inc.
 Email: tte+ietf@cs.fau.de, toerless.eckert@huawei.com
 Ram Krishnan
 SupportVectors
 Email: ramkri123@gmail.com
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