draft-ietf-softwire-dslite-multicast-11.txt   draft-ietf-softwire-dslite-multicast-12.txt 
Softwire WG J. Qin Softwire WG J. Qin
Internet-Draft Cisco Internet-Draft Cisco
Intended status: Standards Track M. Boucadair Intended status: Standards Track M. Boucadair
Expires: August 29, 2016 C. Jacquenet Expires: December 10, 2016 C. Jacquenet
Orange Orange
Y. Lee Y. Lee
Comcast Comcast
Q. Wang Q. Wang
China Telecom China Telecom
February 26, 2016 June 8, 2016
Delivery of IPv4 Multicast Services to IPv4 Clients over an IPv6 Delivery of IPv4 Multicast Services to IPv4 Clients over an IPv6
Multicast Network Multicast Network
draft-ietf-softwire-dslite-multicast-11 draft-ietf-softwire-dslite-multicast-12
Abstract Abstract
This document specifies a solution for the delivery of IPv4 multicast This document specifies a solution for the delivery of IPv4 multicast
services to IPv4 clients over an IPv6 multicast network. The services to IPv4 clients over an IPv6 multicast network. The
solution relies upon a stateless IPv4-in-IPv6 encapsulation scheme solution relies upon a stateless IPv4-in-IPv6 encapsulation scheme
and uses the IPv6 multicast distribution tree to deliver IPv4 and uses the IPv6 multicast distribution tree to deliver IPv4
multicast traffic. The solution is particularly useful for the multicast traffic. The solution is particularly useful for the
delivery of multicast service offerings to DS-Lite serviced delivery of multicast service offerings to DS-Lite serviced
customers. customers.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 29, 2016. This Internet-Draft will expire on December 10, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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4.3. Multicast Data Forwarding . . . . . . . . . . . . . . . . 8 4.3. Multicast Data Forwarding . . . . . . . . . . . . . . . . 8
5. Address Mapping . . . . . . . . . . . . . . . . . . . . . . . 8 5. Address Mapping . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Prefix Assignment . . . . . . . . . . . . . . . . . . . . 8 5.1. Prefix Assignment . . . . . . . . . . . . . . . . . . . . 8
5.2. Address Translation Algorithm . . . . . . . . . . . . . . 9 5.2. Address Translation Algorithm . . . . . . . . . . . . . . 9
5.3. Textual Representation . . . . . . . . . . . . . . . . . 9 5.3. Textual Representation . . . . . . . . . . . . . . . . . 9
5.4. Examples . . . . . . . . . . . . . . . . . . . . . . . . 9 5.4. Examples . . . . . . . . . . . . . . . . . . . . . . . . 9
6. Multicast B4 (mB4) . . . . . . . . . . . . . . . . . . . . . 10 6. Multicast B4 (mB4) . . . . . . . . . . . . . . . . . . . . . 10
6.1. IGMP-MLD Interworking Function . . . . . . . . . . . . . 10 6.1. IGMP-MLD Interworking Function . . . . . . . . . . . . . 10
6.2. Multicast Data Forwarding . . . . . . . . . . . . . . . . 10 6.2. Multicast Data Forwarding . . . . . . . . . . . . . . . . 10
6.3. Fragmentation . . . . . . . . . . . . . . . . . . . . . . 11 6.3. Fragmentation . . . . . . . . . . . . . . . . . . . . . . 11
6.4. Host built-in mB4 Function . . . . . . . . . . . . . . . 11 6.4. Host Built-in mB4 Function . . . . . . . . . . . . . . . 11
6.5. Preserve the Scope . . . . . . . . . . . . . . . . . . . 11 6.5. Preserve the Scope . . . . . . . . . . . . . . . . . . . 11
7. Multicast AFTR (mAFTR) . . . . . . . . . . . . . . . . . . . 11 7. Multicast AFTR (mAFTR) . . . . . . . . . . . . . . . . . . . 11
7.1. Routing Considerations . . . . . . . . . . . . . . . . . 11 7.1. Routing Considerations . . . . . . . . . . . . . . . . . 11
7.2. Processing PIM Message . . . . . . . . . . . . . . . . . 12 7.2. Processing PIM Messages . . . . . . . . . . . . . . . . . 12
7.3. Switching from Shared Tree to Shortest Path Tree . . . . 13 7.3. Switching from Shared Tree to Shortest Path Tree . . . . 13
7.4. Multicast Data Forwarding . . . . . . . . . . . . . . . . 13 7.4. Multicast Data Forwarding . . . . . . . . . . . . . . . . 13
7.5. TTL/Scope . . . . . . . . . . . . . . . . . . . . . . . . 13 7.5. TTL/Scope . . . . . . . . . . . . . . . . . . . . . . . . 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8.1. Firewall Configuration . . . . . . . . . . . . . . . . . 14 8.1. Firewall Configuration . . . . . . . . . . . . . . . . . 14
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
11.1. Normative References . . . . . . . . . . . . . . . . . . 14 11.1. Normative References . . . . . . . . . . . . . . . . . . 14
11.2. Informative References . . . . . . . . . . . . . . . . . 15 11.2. Informative References . . . . . . . . . . . . . . . . . 15
Appendix A. Use Case: IPTV . . . . . . . . . . . . . . . . . . . 16 Appendix A. Use Case: IPTV . . . . . . . . . . . . . . . . . . . 16
Appendix B. Deployment Considerations . . . . . . . . . . . . . 17 Appendix B. Deployment Considerations . . . . . . . . . . . . . 17
B.1. Other operational Modes . . . . . . . . . . . . . . . . . 17 B.1. Other Operational Modes . . . . . . . . . . . . . . . . . 17
B.1.1. MLD Querier with mAFTR Embedded . . . . . . . . . . . 17 B.1.1. The MLD Querier is Co-Located with the mAFTR . . . . 17
B.1.2. mAFTR embedded in DR . . . . . . . . . . . . . . . . 17 B.1.2. The DR is Co-Located with the mAFTR . . . . . . . . . 17
B.2. Older Version of Group Membership management Protocols . 17 B.2. Older Versions of Group Membership Management Protocols . 17
B.3. Load-Balancing . . . . . . . . . . . . . . . . . . . . . 18 B.3. Load Balancing . . . . . . . . . . . . . . . . . . . . . 18
B.4. RP for IPv4-Embedded IPv6 Multicast Groups . . . . . . . 18 B.4. RP for IPv4-Embedded IPv6 Multicast Groups . . . . . . . 18
B.5. mAFTR Policy Configuration . . . . . . . . . . . . . . . 18 B.5. mAFTR Policy Configuration . . . . . . . . . . . . . . . 18
B.6. Static vs. Dynamic PIM Triggering . . . . . . . . . . . . 18 B.6. Static vs. Dynamic PIM Triggering . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
DS-Lite [RFC6333] is a technique that rationalizes the usage of the DS-Lite [RFC6333] is a technique that rationalizes the usage of the
remaining global IPv4 addresses during the transition period by remaining global IPv4 addresses during the transition period by
sharing a single IPv4 address with multiple users. A typical DS-Lite sharing a single IPv4 address with multiple users. A typical DS-Lite
scenario is the delivery of an IPv4 service to an IPv4 user over an scenario is the delivery of an IPv4 service to an IPv4 user over an
IPv6 network (denoted as a 4-6-4 scenario). [RFC6333] covers unicast IPv6 network (denoted as a 4-6-4 scenario). [RFC6333] covers unicast
services exclusively. services exclusively.
This document specifies a generic solution for delivery of IPv4 This document specifies a generic solution for the delivery of IPv4
multicast services to IPv4 clients over an IPv6 multicast network. multicast services to IPv4 clients over an IPv6 multicast network.
The solution was developed with DS-Lite in mind (see more discussion The solution was developed with DS-Lite in mind (see more discussion
below). The solution is however not limited to DS-Lite; it can be below). The solution is however not limited to DS-Lite; it can be
applied in other deployment contexts such as [RFC7596][RFC7597]. applied in other deployment contexts such as [RFC7596][RFC7597].
If customers have to access IPv4 multicast-based services through DS- If customers have to access IPv4 multicast-based services through a
Lite environment, Address Family Transition Router (AFTR) devices DS-Lite environment, Address Family Transition Router (AFTR) devices
will have to process all the Internet Group Management Protocol will have to process all the Internet Group Management Protocol
(IGMP) Report messages [RFC2236] [RFC3376] that have been forwarded (IGMP) Report messages [RFC2236] [RFC3376] that have been forwarded
by the Customer Premises Equipment (CPE) into the IPv4-in-IPv6 by the Customer Premises Equipment (CPE) into the IPv4-in-IPv6
tunnels. From that standpoint, AFTR devices are likely to behave as tunnels. From that standpoint, AFTR devices are likely to behave as
a replication point for downstream multicast traffic. And the a replication point for downstream multicast traffic, and the
multicast packets will be replicated for each tunnel endpoint where multicast packets will be replicated for each tunnel endpoint that
IPv4 receivers are connected to. IPv4 receivers are connected to.
This kind of DS-Lite environment raises two major issues: This kind of DS-Lite environment raises two major issues:
1. The IPv6 network loses the benefits of the multicast traffic 1. The IPv6 network loses the benefits of the multicast traffic
forwarding efficiency because it is unable to deterministically forwarding efficiency because it is unable to deterministically
replicate the data as close to the receivers as possible. As a replicate the data as close to the receivers as possible. As a
consequence, the downstream bandwidth in the IPv6 network will be consequence, the downstream bandwidth in the IPv6 network will be
vastly consumed by sending multicast data over a unicast vastly consumed by sending multicast data over a unicast
infrastructure. infrastructure.
2. The AFTR is responsible for replicating multicast traffic and 2. The AFTR is responsible for replicating multicast traffic and
forwarding it into each tunnel endpoint connecting IPv4 receivers forwarding it into each tunnel endpoint connecting IPv4 receivers
that have explicitly asked for the corresponding contents. This that have explicitly asked for the corresponding contents. This
process may greatly consume AFTR's resources and overload the process may significantly consume the AFTR's resources and
AFTR. overload the AFTR.
This document specifies an extension to the DS-Lite model to deliver This document specifies an extension to the DS-Lite model to deliver
IPv4 multicast services to IPv4 clients over an IPv6 multicast- IPv4 multicast services to IPv4 clients over an IPv6 multicast-
enabled network. enabled network.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. Terminology 2. Terminology
This document makes use of the following terms: This document makes use of the following terms:
o IPv4-embedded IPv6 address: is an IPv6 address which embeds a 32- IPv4-embedded IPv6 address: an IPv6 address which embeds a 32-bit-
bit-encoded IPv4 address. An IPv4-embedded IPv6 address can be encoded IPv4 address. An IPv4-embedded IPv6 address can be
unicast or multicast. unicast or multicast.
o mPrefix64: is a dedicated multicast IPv6 prefix for constructing mPrefix64: a dedicated multicast IPv6 prefix for constructing
IPv4-embedded IPv6 multicast addresses. mPrefix64 can be of two IPv4-embedded IPv6 multicast addresses. mPrefix64 can be of two
types: ASM_mPrefix64 used in Any Source Multicast (ASM) mode or types: ASM_mPrefix64 used in Any Source Multicast (ASM) mode or
SSM_mPrefix64 used in Source Specific Multicast (SSM) mode SSM_mPrefix64 used in Source Specific Multicast (SSM) mode
[RFC4607]. [RFC4607].
o uPrefix64: is a dedicated IPv6 unicast prefix for constructing uPrefix64: a dedicated IPv6 unicast prefix for constructing
IPv4-embedded IPv6 unicast addresses [RFC6052]. IPv4-embedded IPv6 unicast addresses [RFC6052].
o Multicast AFTR (mAFTR): is a functional entity which supports Multicast AFTR (mAFTR): a functional entity which supports an
IPv4-IPv6 multicast interworking function (refer to Figure 3). It IPv4-IPv6 multicast interworking function (refer to Figure 3). It
receives and encapsulates the IPv4 multicast packets into IPv4-in- receives and encapsulates the IPv4 multicast packets into IPv4-in-
IPv6 packets and behaves as the corresponding IPv6 multicast IPv6 packets and behaves as the corresponding IPv6 multicast
source for the encapsulated IPv4-in-IPv6 packets. source for the encapsulated IPv4-in-IPv6 packets.
o Multicast B4 (mB4): is a functional entity which supports an IGMP- Multicast B4 (mB4): a functional entity which supports an IGMP-MLD
MLD interworking function (refer to Section 6.1) that relays interworking function (refer to Section 6.1) that relays
information conveyed in IGMP messages by forwarding the information conveyed in IGMP messages by forwarding the
corresponding Multicast Listener Discovery (MLD) messages towards corresponding Multicast Listener Discovery (MLD) messages towards
the MLD Querier in the IPv6 network. In addition, the mB4 the MLD Querier in the IPv6 network. In addition, the mB4
decapsulates IPv4-in-IPv6 multicast packets. decapsulates IPv4-in-IPv6 multicast packets.
o PIMv4: refers to Protocol Independent Multicast (PIM) when PIMv4: refers to Protocol Independent Multicast (PIM) when deployed
deployed in an IPv4 infrastructure (i.e., IPv4 transport in an IPv4 infrastructure (i.e., IPv4 transport capabilities are
capabilities are used to exchange PIM messages). used to exchange PIM messages).
o PIMv6: refers to PIM when deployed in an IPv6 infrastructure PIMv6: refers to PIM when deployed in an IPv6 infrastructure (i.e.,
(i.e., IPv6 transport capabilities are used to exchange PIM IPv6 transport capabilities are used to exchange PIM messages).
messages).
3. Scope 3. Scope
This document focuses only on subscription to an IPv4 multicast group This document focuses only on the subscription to an IPv4 multicast
and the delivery of IPv4-formatted content to IPv4 receivers over an group and the delivery of IPv4-formatted content to IPv4 receivers
IPv6-only network. In particular, only the following case is over an IPv6-only network. In particular, only the following case is
covered: covered:
An IPv4 receiver accesses IPv4 multicast contents over an IPv6- An IPv4 receiver accesses IPv4 multicast contents over an IPv6-
only multicast-enabled network. only multicast-enabled network.
This document does not cover the source/receiver heuristics, where as This document does not cover the source/receiver heuristics, where an
IPv4 receiver can also behave as an IPv4 multicast source. This IPv4 receiver can also behave as an IPv4 multicast source. This
document assumes that hosts behind the mB4 are IPv4 multicast document assumes that hosts behind the mB4 are IPv4 multicast
receivers only. receivers only.
4. Solution Overview 4. Solution Overview
In the original DS-Lite specification [RFC6333], an IPv4-in-IPv6 In the DS-Lite specification [RFC6333], an IPv4-in-IPv6 tunnel is
tunnel is used to carry bidirectional IPv4 unicast traffic between a used to carry bidirectional IPv4 unicast traffic between a B4 and an
B4 and an AFTR. The solution specified in this document provides an AFTR. The solution specified in this document provides an IPv4-in-
IPv4-in-IPv6 encapsulation scheme to deliver unidirectional IPv4 IPv6 encapsulation scheme to deliver unidirectional IPv4 multicast
multicast traffic from an mAFTR to an mB4. traffic from an mAFTR to an mB4.
An overview of the solution is provided in this section which is An overview of the solution is provided in this section which is
intended as an introduction to how it works, but is NOT normative. intended as an introduction to how it works, but is not normative.
For the normative specifications of the two new functional elements: For the normative specifications of the two new functional elements:
mB4 and mAFTR (Figure 1), refer to Section 6 and Section 7. mB4 and mAFTR (Figure 1), refer to Section 6 and Section 7.
------------ ------------
/ \ / \
| IPv4 network | | IPv4 network |
\ / \ /
------------ ------------
IPv4 multicast : | ^ PIMv4 Join IPv4 multicast : | ^ PIMv4 Join
v | : v | :
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| IPv4 | | IPv4 |
| receiver | | receiver |
+-----------+ +-----------+
Figure 1: Functional Architecture Figure 1: Functional Architecture
4.1. IPv4-Embedded IPv6 Prefixes 4.1. IPv4-Embedded IPv6 Prefixes
In order to map the addresses of IPv4 multicast traffic with IPv6 In order to map the addresses of IPv4 multicast traffic with IPv6
multicast addresses, an IPv6 multicast prefix (mPrefix64) and an IPv6 multicast addresses, an IPv6 multicast prefix (mPrefix64) and an IPv6
unicast prefix (uPrefix64) are provided to mAFTR and mB4 elements, unicast prefix (uPrefix64) are provided to the mAFTR and the mB4
both of which contribute to the computation and the maintenance of elements, both of which contribute to the computation and the
the IPv6 multicast distribution tree that extends the IPv4 multicast maintenance of the IPv6 multicast distribution tree that extends the
distribution tree into the IPv6 multicast network. IPv4 multicast distribution tree into the IPv6 multicast network.
The mAFTR and mB4 use mPrefix64 to convert an IPv4 multicast address The mAFTR and the mB4 use mPrefix64 to convert an IPv4 multicast
(G4) to an IPv4-embedded IPv6 multicast address (G6). The mAFTR and address (G4) into an IPv4-embedded IPv6 multicast address (G6). The
mB4 use uPrefix64 to convert an IPv4 multicast source address (S4) to mAFTR and the mB4 use uPrefix64 to convert an IPv4 multicast source
an IPv4-embedded IPv6 address (S6). The mAFTR and mB4 MUST use the address (S4) into an IPv4-embedded IPv6 address (S6). The mAFTR and
same mPrefix64 and uPrefix64, as well as run the same algorithm for the mB4 must use the same mPrefix64 and uPrefix64, and also run the
building IPv4-embedded IPv6 addresses. Refer to Section 5 for more same algorithm for building IPv4-embedded IPv6 addresses. Refer to
details about the address mapping. Section 5 for more details about the address mapping.
4.2. Multicast Distribution Tree Computation 4.2. Multicast Distribution Tree Computation
When an IPv4 receiver connected to the device that embeds the mB4 When an IPv4 receiver connected to the device that embeds the mB4
capability wants to subscribe to an IPv4 multicast group, it sends an capability wants to subscribe to an IPv4 multicast group, it sends an
IGMP Report message to the mB4. The mB4 creates the IPv6 multicast IGMP Report message to the mB4. The mB4 creates the IPv6 multicast
group (G6) address using mPrefix64 and the original IPv4 multicast group (G6) address using mPrefix64 and the original IPv4 multicast
group address. If the receiver sends a source-specific IGMPv3 Report group address. If the receiver sends a source-specific IGMPv3 Report
message, the mB4 will create the IPv6 source address (S6) using message, the mB4 will create the IPv6 source address (S6) using
uPrefix64 and the original IPv4 source address. uPrefix64 and the original IPv4 source address.
The mB4 uses the G6 (and both S6 and G6 in SSM) to create the The mB4 uses the G6 (and both S6 and G6 in SSM) to create the
corresponding MLD Report message. The mB4 sends the Report message corresponding MLD Report message. The mB4 sends the Report message
to the MLD Querier in the IPv6 network. The MLD Querier (typically to the MLD Querier in the IPv6 network. The MLD Querier (which
acts as the PIMv6 Designated Router) receives the MLD Report message usually acts as the PIMv6 Designated Router too) receives the MLD
and sends the PIMv6 Join to join the IPv6 multicast distribution Report message and sends the PIMv6 Join to join the IPv6 multicast
tree. The MLD Querier can send either PIMv6 Join (*,G6) in ASM or distribution tree. The MLD Querier can send either PIMv6 Join (*,G6)
PIMv6 Join (S6,G6) in SSM to the mAFTR. in ASM or PIMv6 Join (S6,G6) in SSM to the mAFTR.
The mAFTR acts as the DR to which the uPrefix64-derived S6 is The mAFTR acts as the DR to which the uPrefix64-derived S6 is
connected. The mAFTR will receive the source-specific PIMv6 Join connected. The mAFTR will receive the source-specific PIMv6 Join
message (S6,G6) from the IPv6 multicast network. If the mAFTR is the message (S6,G6) from the IPv6 multicast network. If the mAFTR is the
Rendezvous Point (RP) of G6, it will receive the any-source PIMv6 Rendezvous Point (RP) of G6, it will receive the any-source PIMv6
Join message (*,G6) from the IPv6 multicast network. If the mAFTR is Join message (*,G6) from the IPv6 multicast network. If the mAFTR is
not the RP of G6, it will send the PIM Register message to the RP of not the RP of G6, it will send the PIM Register message to the RP of
G6 located in the IPv6 multicast network. G6 located in the IPv6 multicast network.
When the mAFTR receives the PIMv6 Join message (*,G6), it will When the mAFTR receives the PIMv6 Join message (*,G6), it will
extract the IPv4 multicast group address (G4). If the mAFTR is the extract the IPv4 multicast group address (G4). If the mAFTR is the
RP of G4 in the IPv4 multicast network, it will create a (*,G4) entry RP of G4 in the IPv4 multicast network, it will create a (*,G4) entry
(if there is not yet an existing one) in its own IPv4 multicast (if such entry does not already exist) in its own IPv4 multicast
routing table. If the mAFTR is not the RP of G4, it will send the routing table. If the mAFTR is not the RP of G4, it will send the
corresponding PIMv4 Join message (*,G4) towards the RP of G4 in the corresponding PIMv4 Join message (*,G4) towards the RP of G4 in the
IPv4 multicast network. IPv4 multicast network.
When the mAFTR receives the PIMv6 Join message (S6,G6), it will When the mAFTR receives the PIMv6 Join message (S6,G6), it will
extract the IPv4 multicast group address (G4) and IPv4 source address extract the IPv4 multicast group address (G4) and IPv4 source address
(S4) and send the corresponding (S4,G4) PIMv4 Join message directly (S4) and send the corresponding (S4,G4) PIMv4 Join message directly
to the IPv4 source. to the IPv4 source.
A branch of the multicast distribution tree is constructed, A branch of the multicast distribution tree is thus constructed,
comprising both an IPv4 part (from the mAFTR upstream) and an IPv6 comprising both an IPv4 part (from the mAFTR upstream) and an IPv6
part (from mAFTR downstream to the mB4). part (from mAFTR downstream to the mB4).
The mAFTR MUST advertise the route of uPrefix64 with an IPv6 Interior The mAFTR advertises the route of uPrefix64 with an IPv6 Interior
Gateway Protocol (IGP), so as to represent the IPv4-embedded IPv6 Gateway Protocol (IGP), so as to represent the IPv4-embedded IPv6
source in the IPv6 multicast network, and to pass the Reverse Path source in the IPv6 multicast network, and to run the Reverse Path
Forwarding (RPF) check on multicast devices. Forwarding (RPF) check procedure on incoming multicast traffic.
4.3. Multicast Data Forwarding 4.3. Multicast Data Forwarding
When the mAFTR receives an IPv4 multicast packet, it will encapsulate When the mAFTR receives an IPv4 multicast packet, it will encapsulate
the packet into an IPv6 multicast packet using the IPv4-embedded IPv6 the packet into an IPv6 multicast packet using the IPv4-embedded IPv6
multicast address as the destination address and an IPv4-embedded multicast address as the destination address and an IPv4-embedded
IPv6 unicast address as the source address. The encapsulated IPv6 IPv6 unicast address as the source address. The encapsulated IPv6
multicast packet will be forwarded down the IPv6 multicast multicast packet will be forwarded down the IPv6 multicast
distribution tree and the mB4 will eventually receive the packet. distribution tree and the mB4 will eventually receive the packet.
The IPv6 multicast network treats the IPv4-in-IPv6 encapsulated The IPv6 multicast network treats the IPv4-in-IPv6 encapsulated
multicast packets as native. The IPv6 multicast routers use the multicast packets as native IPv6 multicast packets. The IPv6
outer IPv6 header to make forwarding decisions. multicast routers use the outer IPv6 header to make their forwarding
decisions.
When the mB4 receive the IPv6 multicast packet (to G6) derived by When the mB4 receives the IPv6 multicast packet (to G6) derived by
mPrefix64, it MUST decapsulate it and forward the original IPv4 mPrefix64, it decapsulates it and forwards the original IPv4
multicast packet to the receivers subscribing to G4. multicast packet to the receivers subscribing to G4.
Note: At this point, only IPv4-in-IPv6 encapsulation is defined; Note: At this point, only IPv4-in-IPv6 encapsulation is defined;
however, other types of encapsulation could be defined in the future. however, other types of encapsulation could be defined in the future.
5. Address Mapping 5. Address Mapping
5.1. Prefix Assignment 5.1. Prefix Assignment
A dedicated IPv6 multicast prefix (mPrefix64) is provisioned to the A dedicated IPv6 multicast prefix (mPrefix64) is provisioned to the
mAFTR and the mB4. The mAFTR and the mB4 use the mPrefix64 to form mAFTR and the mB4. The mAFTR and the mB4 use the mPrefix64 to form
an IPv6 multicast group address from an IPv4 multicast group address. an IPv6 multicast group address from an IPv4 multicast group address.
The mPrefix64 can be of two types: ASM_mPrefix64 (a mPrefix64 used in The mPrefix64 can be of two types: ASM_mPrefix64 (a mPrefix64 used in
ASM mode) or SSM_mPrefix64 (a mPrefix64 used in SSM mode). The ASM mode) or SSM_mPrefix64 (a mPrefix64 used in SSM mode). The
mPrefix64 MUST be derived from the corresponding IPv6 multicast mPrefix64 MUST be derived from the corresponding IPv6 multicast
address space (e.g., the SSM_mPrefix64 MUST be in the range of address space (e.g., the SSM_mPrefix64 must be in the range of
multicast address space specified in [RFC4607]). multicast address space specified in [RFC4607]).
The IPv6 part of the multicast distribution tree can be seen as an The IPv6 part of the multicast distribution tree can be seen as an
extension of the IPv4 part of the multicast distribution tree. The extension of the IPv4 part of the multicast distribution tree. The
IPv4 multicast source address MUST be mapped to an IPv6 multicast IPv4 multicast source address MUST be mapped to an IPv6 multicast
source address. An IPv6 unicast prefix (uPrefix64) is provisioned to source address. An IPv6 unicast prefix (uPrefix64) is provisioned to
the mAFTR and the mB4. The mAFTR and the mB4 use the uPrefix64 to the mAFTR and the mB4. The mAFTR and the mB4 use the uPrefix64 to
form an IPv6 multicast source address from an IPv4 multicast source form an IPv6 multicast source address from an IPv4 multicast source
address. The uPrefix-formed IPv6 multicast source address will address. The uPrefix-formed IPv6 multicast source address will
represent the original IPv4 multicast source in the IPv6 multicast represent the original IPv4 multicast source in the IPv6 multicast
skipping to change at page 9, line 30 skipping to change at page 9, line 30
o If the multicast address has a pre-configured mPrefix64, extract o If the multicast address has a pre-configured mPrefix64, extract
the last 32 bits of the IPv6 multicast address. the last 32 bits of the IPv6 multicast address.
An IPv4 source is represented in the IPv6 realm with its An IPv4 source is represented in the IPv6 realm with its
IPv4-converted IPv6 address [RFC6052]. IPv4-converted IPv6 address [RFC6052].
5.3. Textual Representation 5.3. Textual Representation
The embedded IPv4 address in an IPv6 multicast address is included in The embedded IPv4 address in an IPv6 multicast address is included in
the last 32 bits; therefore dotted decimal notation can be used. the last 32 bits; therefore, dotted decimal notation can be used.
5.4. Examples 5.4. Examples
Group address mapping example: Group address mapping example:
+---------------------+--------------+----------------------------+ +---------------------+--------------+----------------------------+
| mPrefix64 | IPv4 address | IPv4-Embedded IPv6 address | | mPrefix64 | IPv4 address | IPv4-Embedded IPv6 address |
+---------------------+--------------+----------------------------+ +---------------------+--------------+----------------------------+
| ff0x::db8:0:0/96 | 233.252.0.1 | ff0x::db8::233.252.0.1 | | ff0x::db8:0:0/96 | 233.252.0.1 | ff0x::db8::233.252.0.1 |
+---------------------+--------------+----------------------------+ +---------------------+--------------+----------------------------+
skipping to change at page 10, line 18 skipping to change at page 10, line 18
6. Multicast B4 (mB4) 6. Multicast B4 (mB4)
6.1. IGMP-MLD Interworking Function 6.1. IGMP-MLD Interworking Function
The IGMP-MLD Interworking Function combines the IGMP/MLD Proxying The IGMP-MLD Interworking Function combines the IGMP/MLD Proxying
function and the address synthesizing operations. The IGMP/MLD function and the address synthesizing operations. The IGMP/MLD
Proxying function is specified in [RFC4605]. The address translation Proxying function is specified in [RFC4605]. The address translation
is stateless and MUST follow the address mapping specified in is stateless and MUST follow the address mapping specified in
Section 5. Section 5.
The mB4 with the IGMP-MLD Interworking Function embedded relays The mB4 performs the host portion of the MLD protocol on the upstream
between the IGMP domain and the MLD domain. The mB4 performs the interface. The composition of IPv6 membership in this context is
host portion of the MLD protocol on the upstream interface. The constructed through address synthesizing operations and MUST
composition of IPv6 membership in this context is constructed through synchronize with the membership database maintained in the IGMP
address synthesizing operations and MUST synchronize with the domain. MLD messages are forwarded natively towards the MLD Querier
membership database maintained in the IGMP domain. MLD messages will located upstream in the IPv6 network. The mB4 also performs the
be forwarded natively towards the MLD Querier located upstream in the router portion of the IGMP protocol on the downstream interface(s).
IPv6 network. The mB4 also performs the router portion of the IGMP Refer to [RFC4605] for more details.
protocol on the downstream interface(s). Refer to [RFC4605] for more
details
+----------+ IGMP +-------+ MLD +---------+ +----------+ IGMP +-------+ MLD +---------+
| IPv4 |---------| mB4 |---------| MLD | | IPv4 |---------| mB4 |---------| MLD |
| Receiver | | | | Querier | | Receiver | | | | Querier |
+----------+ +-------+ +---------+ +----------+ +-------+ +---------+
Figure 2: IGMP-MLD Interworking Figure 2: IGMP-MLD Interworking
If SSM is deployed, the mB4 MUST construct the IPv6 source address If SSM is deployed, the mB4 MUST construct the IPv6 source address
(or retrieve the IPv4 source address) using the uPrefix64. The mB4 (or retrieve the IPv4 source address) using the uPrefix64. The mB4
may create a membership database which associates the IPv4-IPv6 may create a membership database which associates the IPv4-IPv6
multicast groups with the interfaces (e.g., WLAN and Wired Ethernet) multicast groups with the interfaces (e.g., WLAN and Wired Ethernet)
facing IPv4 multicast receivers. facing IPv4 multicast receivers.
6.2. Multicast Data Forwarding 6.2. Multicast Data Forwarding
When the mB4 receives an IPv6 multicast packet, it MUST check the When the mB4 receives an IPv6 multicast packet, it MUST check the
group address and the source address. If the IPv6 multicast group group address and the source address. If the IPv6 multicast group
prefix is mPrefix64 and the IPv6 source prefix is uPrefix64, the mB4 prefix is mPrefix64 and the IPv6 source prefix is uPrefix64, the mB4
MUST decapsulate the IPv6 header and forward the IPv4 multicast MUST decapsulate the IPv6 header and forward the IPv4 multicast
packet through each relevant interface. Otherwise, the mB4 MUST drop packet through each relevant interface. Otherwise, the mB4 MUST
the packet silently. silently drop the packet.
As an illustration, if a packet is received from source As an illustration, if a packet is received from source
2001:db8::192.0.2.33 and to be forwarded to group 2001:db8::192.0.2.33 and needs to be forwarded to group
ff3x:1000::233.252.0.1, the mB4 will decapsulate it into an IPv4 ff3x:1000::233.252.0.1, the mB4 decapsulates it into an IPv4
multicast packet using 192.0.2.33 as the IPv4 multicast source multicast packet using 192.0.2.33 as the IPv4 multicast source
address and using 233.252.0.1 as the IPv4 destination address. address and using 233.252.0.1 as the IPv4 destination address.
6.3. Fragmentation 6.3. Fragmentation
Encapsulating IPv4 multicast packets into IPv6 multicast packets that Encapsulating IPv4 multicast packets into IPv6 multicast packets that
will be forwarded by the mAFTR to the mB4 along the IPv6 multicast will be forwarded by the mAFTR to the mB4 along the IPv6 multicast
distribution tree reduces the effective MTU size by the size of an distribution tree reduces the effective MTU size by the size of an
IPv6 header. In this specification, the data flow is unidirectional IPv6 header. In this specification, the data flow is unidirectional
from mAFTR to mB4, the mAFTR MUST fragment the oversized IPv6 packet from the mAFTR to the mB4. The mAFTR MUST fragment the oversized
after the encapsulation into two IPv6 packets. The mB4 MUST IPv6 packet after the encapsulation into two IPv6 packets. The mB4
reassemble the IPv6 packets, decapsulate the IPv6 packet, and forward MUST reassemble the IPv6 packets, decapsulate the IPv6 packet, and
the IPv4 packet to the hosts subscribing the multicast group. forward the IPv4 packet to the hosts that have subscribed to the
Further considerations about fragmentation issues are documented in corresponding multicast group. Further considerations about
[RFC6333]. fragmentation issues are documented in [RFC6333].
6.4. Host built-in mB4 Function 6.4. Host Built-in mB4 Function
If the mB4 function is implemented in the host which is directly If the mB4 function is implemented in the host which is directly
connected to an IPv6-only network, the host MUST implement connected to an IPv6-only network, the host MUST implement
Section 6.1, Section 6.2, and Section 6.3. The host MAY optimize the Section 6.1, Section 6.2, and Section 6.3. The host MAY optimize the
implementation to provide an Application Programming Interface (API) implementation to provide an Application Programming Interface (API)
or kernel module to skip the IGMP-MLD Interworking Function. The or kernel module to skip the IGMP-MLD Interworking Function.
optimization is out of scope of the specification. Optimization considerations are out of scope of this specification.
6.5. Preserve the Scope 6.5. Preserve the Scope
When several mPrefix64s are available, if each enclosed IPv4-embedded When several mPrefix64s are available, if each enclosed IPv4-embedded
IPv6 multicast prefix has a distinct scope, mB4 MUST select the IPv6 multicast prefix has a distinct scope, the mB4 MUST select the
appropriate IPv4-embedded IPv6 multicast prefix having a scope appropriate IPv4-embedded IPv6 multicast prefix whose scope matches
matching the IPv4 multicast address used to synthesize an the IPv4 multicast address used to synthesize an IPv4-embedded IPv6
IPv4-embedded IPv6 multicast address. multicast address.
The mB4 MAY be configured to not preserve the scope when enforcing The mB4 MAY be configured to not preserve the scope when enforcing
the address translation algorithm. the address translation algorithm.
7. Multicast AFTR (mAFTR) 7. Multicast AFTR (mAFTR)
7.1. Routing Considerations 7.1. Routing Considerations
The mAFTR is responsible for interconnecting the IPv4 multicast The mAFTR is responsible for interconnecting the IPv4 multicast
distribution tree with the corresponding IPv6 multicast distribution distribution tree with the corresponding IPv6 multicast distribution
tree. The mAFTR MUST use the uPrefix64 to build the IPv6 source tree. The mAFTR MUST use the uPrefix64 to build the IPv6 source
addresses of the multicast group address derived from mPrefix64. In addresses of the multicast group address derived from mPrefix64. In
other words, the mAFTR MUST be the multicast source derived from other words, the mAFTR MUST be the multicast source whose address is
uPrefix64. derived from uPrefix64.
The mAFTR MUST advertise the route of uPrefix64 to the IPv6 IGP. The mAFTR MUST advertise the route towards uPrefix64 with the IPv6
This is needed for the IPv6 multicast routers to have routing IGP. This is needed by the IPv6 multicast routers so that they
information to discover the source. acquire the routing information to discover the source.
7.2. Processing PIM Message 7.2. Processing PIM Messages
The mAFTR MUST interwork PIM Join/Prune messages for (*, G6) and (S6, The mAFTR MUST interwork PIM Join/Prune messages for (*, G6) and (S6,
G6) on their corresponding (*, G4) and (S4, G4). The following text G6) on their corresponding (*, G4) and (S4, G4). The following text
specifies the expected behavior of mAFTR for PIM Join message. specifies the expected behavior of the mAFTR for PIM Join messages.
+---------+ +---------+
---------| mAFTR |--------- ---------| mAFTR |---------
PIMv6 |uPrefix64| PIMv4 PIMv6 |uPrefix64| PIMv4
|mPreifx64| |mPreifx64|
+---------+ +---------+
Figure 3: PIMv6-PIMv4 Interworking Function Figure 3: PIMv6-PIMv4 Interworking Function
The mAFTR contains two separate Tree Information Base (TIB): IPv4 The mAFTR contains two separate Tree Information Bases (TIBs): the
Tree Information Base (TIB4) and IPv6 Tree Information Base (TIB6), IPv4 Tree Information Base (TIB4) and the IPv6 Tree Information Base
which are bridged by one IPv4-in-IPv6 virtual interface. It should (TIB6), which are bridged by one IPv4-in-IPv6 virtual interface. It
be noted that the implementations may vary (e.g., using one should be noted that TIB implementations may vary (e.g., some may
integrated TIB without any virtual interface), while they should rely upon a single integrated TIB without any virtual interface), but
follow the specification herein for the consistency of overall they should follow this specification for the sake of global and
functionality. functional consistency.
When a mAFTR receives a PIMv6 Join message (*,G6) with an IPv6 When a mAFTR receives a PIMv6 Join message (*,G6) with an IPv6
multicast group address (G6) that is derived from the mPrefix64, it multicast group address (G6) that is derived from the mPrefix64, it
MUST check its IPv6 Tree Information Base (TIB6). If there is an MUST check its IPv6 Tree Information Base (TIB6). If there is an
entry for this G6, it MUST check whether the interface through which entry for this G6 address, it MUST check whether the interface
the PIMv6 Join message has been received is on the outgoing interface through which the PIMv6 Join message has been received is in the
list. If not, the mAFTR MUST add the interface to the outgoing outgoing interface (oif) list. If not, the mAFTR MUST add the
interface list. If there is no entry in the TIB6, the mAFTR MUST interface to the oif list. If there is no entry in the TIB6, the
create a new entry (*,G6) for the multicast group. While, whether or mAFTR MUST create a new entry (*,G6) for the multicast group.
not to set the IPv4-in-IPv6 virtual interface as the incoming Whether or not the IPv4-in-IPv6 virtual interface is set as the
interface of the newly created entry is up to the implementation but incoming interface of the newly created entry is up to the
should comply with the mAFTR's behavior of multicast data forwarding, implementation but it should comply with the mAFTR's multicast data
see Section 7.4. forwarding behavior, see Section 7.4.
The mAFTR MUST extract the IPv4 multicast group address (G4) from the The mAFTR MUST extract the IPv4 multicast group address (G4) from the
IPv4-embedded IPv6 multicast address (G6) contained in the PIMv6 Join IPv4-embedded IPv6 multicast address (G6) contained in the PIMv6 Join
message. The mAFTR MUST check its IPv4 Tree Information Base (TIB4). message. The mAFTR MUST check its IPv4 Tree Information Base (TIB4).
If there is an entry for G4, it MUST check whether the IPv4-in-IPv6 If there is an entry for G4, it MUST check whether the IPv4-in-IPv6
virtual interface is on the outgoing interface list. If not, the virtual interface is in the outgoing interface list. If not, the
mAFTR MUST add the interface to the outgoing interface list. If mAFTR MUST add the interface to the oif list. If there is no entry
there is no entry for G4, the mAFTR MUST create a new (*,G4) entry in for G4, the mAFTR MUST create a new (*,G4) entry in its TIB4 and
its TIB4 and initiate the procedure for building the shared tree in initiate the procedure for building the shared tree in the IPv4
the IPv4 multicast network without any additional requirement. multicast network without any additional requirement.
If mAFTR receives a source-specific Join message, the (S6, G6) will If the mAFTR receives a source-specific Join message, the (S6, G6) is
be processed rather than (*,G6). The procedures of processing processed rather than (*,G6). The procedures of processing (S6,G6)
(S6,G6) and (*,G6) are almost the same. Differences have been and (*,G6) are almost the same. Differences have been detailed in
detailed in [RFC4601]. [RFC7761].
7.3. Switching from Shared Tree to Shortest Path Tree 7.3. Switching from Shared Tree to Shortest Path Tree
When the mAFTR receives the first IPv4 multicast packet, it may When the mAFTR receives the first IPv4 multicast packet, it may
extract the multicast source address (S4) from the packet and send an extract the multicast source address (S4) from the packet and send an
Explicit PIMv4 (S4,G4) Join message directly to S4. The mAFTR will Explicit PIMv4 (S4,G4) Join message directly to S4. The mAFTR
switch from the shared Rendezvous Point Tree (RPT) to the Shortest switches from the shared Rendezvous Point Tree (RPT) to the Shortest
Path Tree (SPT) for G4. Path Tree (SPT) for G4.
For IPv6 multicast routers to switch to the SPT, there is no new For IPv6 multicast routers to switch to the SPT, there is no new
requirement. IPv6 multicast routers may send an Explicit PIMv6 Join requirement. IPv6 multicast routers may send an Explicit PIMv6 Join
to mAFTR once the first (S6,G6) multicast packet arrives from to the mAFTR once the first (S6,G6) multicast packet arrives from
upstream multicast routers. upstream multicast routers.
7.4. Multicast Data Forwarding 7.4. Multicast Data Forwarding
When the mAFTR receives an IPv4 multicast packet, it will look up the When the mAFTR receives an IPv4 multicast packet, it checks its TIB4
TIB4 to find a matching entry and then forward the packet to the to find a matching entry and then forwards the packet to the
interface(s) on the outgoing interface list. If the IPv4-in-IPv6 interface(s) listed in the outgoing interface list. If the IPv4-in-
virtual interface also belongs to this list, the packet will be IPv6 virtual interface also belongs to this list, the packet is
encapsulated with the mPrefix64-derived and uPrefix64-derived encapsulated with the mPrefix64-derived and uPrefix64-derived
IPv4-embedded IPv6 addresses to form an IPv6 multicast packet. Then IPv4-embedded IPv6 addresses to form an IPv6 multicast packet. Then
another lookup is executed to find a matching entry in the TIB6, another lookup is made by the mAFTR to find a matching entry in the
while whether or not to perform RPF check for the second lookup is up TIB6. Whether the RPF check for the second lookup is performed or
to the implementation and is out of the scope of this document. The not is up to the implementation and is out of the scope of this
IPv6 multicast packet is forwarded along the IPv6 multicast document. The IPv6 multicast packet is then forwarded along the IPv6
distribution tree, based upon the outgoing interface list of the multicast distribution tree, based upon the outgoing interface list
matching entry in the TIB6. of the matching entry in the TIB6.
As an illustration, if a packet is received from source 192.0.2.33 As an illustration, if a packet is received from source 192.0.2.33
and to be forwarded to group 233.252.0.1, the mAFTR encapsulates it and needs to be forwarded to group 233.252.0.1, the mAFTR
into an IPv6 multicast packet using ff3x:1000::233.252.0.1 as the encapsulates it into an IPv6 multicast packet using
IPv6 destination address and using 2001:db8::192.0.2.33 as the IPv6 ff3x:1000::233.252.0.1 as the IPv6 destination address and using
multicast source address. 2001:db8::192.0.2.33 as the IPv6 multicast source address.
7.5. TTL/Scope 7.5. TTL/Scope
The Scope field of IPv4-in-IPv6 multicast addresses should be valued The Scope field of IPv4-in-IPv6 multicast addresses should be valued
accordingly (e.g, to "E", Global scope;) in the deployment accordingly (e.g, to "E", Global scope;) in the deployment
environment. This specification does not discuss the scope value environment. This specification does not discuss the scope value
that should be used. that should be used.
Nevertheless, when several mPrefix64s are available, if each enclosed Nevertheless, when several mPrefix64s are available, if each enclosed
IPv4-embedded IPv6 multicast prefix has a distinct scope, mAFTR MUST IPv4-embedded IPv6 multicast prefix has a distinct scope, the mAFTR
select the appropriate IPv4-embedded IPv6 multicast prefix having a MUST select the appropriate IPv4-embedded IPv6 multicast prefix whose
scope matching the IPv4 multicast address used to synthesize an scope matches the IPv4 multicast address used to synthesize an
IPv4-embedded IPv6 multicast address. IPv4-embedded IPv6 multicast address.
mAFTR MAY be configured to not preserve the scope when enforcing the An mAFTR MAY be configured to not preserve the scope when enforcing
address translation algorithm. the address translation algorithm.
8. Security Considerations 8. Security Considerations
A part for multicast scoping considerations (see Section 6.5 and Besides multicast scoping considerations (see Section 6.5 and
Section 7.5), this document does not introduce any new security Section 7.5), this document does not introduce any new security
concern in addition to what is discussed in Section 5 of [RFC6052], concern in addition to what is discussed in Section 5 of [RFC6052],
Section 10 of [RFC3810] and Section 6 of [RFC4601]. Section 10 of [RFC3810] and Section 6 of [RFC7761].
mB4 SHOULD be provided with appropriate configuration to enable An mB4 SHOULD be provided with appropriate configuration information
preserving the scope of a multicast message when mapping an IPv4 to preserve the scope of a multicast message when mapping an IPv4
multicast address into an IPv4-embedded IPv6 multicast address and multicast address into an IPv4-embedded IPv6 multicast address and
vice versa. vice versa.
8.1. Firewall Configuration 8.1. Firewall Configuration
The CPE that embeds the mB4 function SHOULD be configured to accept The CPE that embeds the mB4 function SHOULD be configured to accept
incoming MLD messages and traffic forwarded to multicast groups incoming MLD messages and traffic forwarded to multicast groups
subscribed by receivers located in the customer premises. subscribed by receivers located in the customer premises.
9. Acknowledgements 9. Acknowledgements
The authors would like to thank Dan Wing for his guidance in the The authors would like to thank Dan Wing for his guidance in the
early discussions which initiated this work. We also thank Peng Sun, early discussions which initiated this work. We also thank Peng Sun,
Jie Hu, Qiong Sun, Lizhong Jin, Alain Durand, Dean Cheng, Behcet Jie Hu, Qiong Sun, Lizhong Jin, Alain Durand, Dean Cheng, Behcet
Sarikaya, Tina Tsou, Rajiv Asati, Xiaohong Deng, and S. Venaas for Sarikaya, Tina Tsou, Rajiv Asati, Xiaohong Deng, and Stig Venaas for
their valuable comments. their valuable comments.
Many thanks to Ian Farrer for the review.
10. IANA Considerations 10. IANA Considerations
This document includes no request to IANA. This document includes no request to IANA.
11. References 11. References
11.1. Normative References 11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
skipping to change at page 15, line 15 skipping to change at page 15, line 15
[RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
Thyagarajan, "Internet Group Management Protocol, Version Thyagarajan, "Internet Group Management Protocol, Version
3", RFC 3376, DOI 10.17487/RFC3376, October 2002, 3", RFC 3376, DOI 10.17487/RFC3376, October 2002,
<http://www.rfc-editor.org/info/rfc3376>. <http://www.rfc-editor.org/info/rfc3376>.
[RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
Discovery Version 2 (MLDv2) for IPv6", RFC 3810, Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
DOI 10.17487/RFC3810, June 2004, DOI 10.17487/RFC3810, June 2004,
<http://www.rfc-editor.org/info/rfc3810>. <http://www.rfc-editor.org/info/rfc3810>.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601,
DOI 10.17487/RFC4601, August 2006,
<http://www.rfc-editor.org/info/rfc4601>.
[RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick,
"Internet Group Management Protocol (IGMP) / Multicast "Internet Group Management Protocol (IGMP) / Multicast
Listener Discovery (MLD)-Based Multicast Forwarding Listener Discovery (MLD)-Based Multicast Forwarding
("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605,
August 2006, <http://www.rfc-editor.org/info/rfc4605>. August 2006, <http://www.rfc-editor.org/info/rfc4605>.
[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for
IP", RFC 4607, DOI 10.17487/RFC4607, August 2006, IP", RFC 4607, DOI 10.17487/RFC4607, August 2006,
<http://www.rfc-editor.org/info/rfc4607>. <http://www.rfc-editor.org/info/rfc4607>.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
DOI 10.17487/RFC6052, October 2010, DOI 10.17487/RFC6052, October 2010,
<http://www.rfc-editor.org/info/rfc6052>. <http://www.rfc-editor.org/info/rfc6052>.
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4 Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011, Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011,
<http://www.rfc-editor.org/info/rfc6333>. <http://www.rfc-editor.org/info/rfc6333>.
[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, <http://www.rfc-editor.org/info/rfc7761>.
11.2. Informative References 11.2. Informative References
[I-D.ietf-softwire-multicast-prefix-option] [I-D.ietf-softwire-multicast-prefix-option]
Boucadair, M., Qin, J., Tsou, T., and X. Deng, "DHCPv6 Boucadair, M., Qin, J., Tsou, T., and X. Deng, "DHCPv6
Option for IPv4-Embedded Multicast and Unicast IPv6 Option for IPv4-Embedded Multicast and Unicast IPv6
Prefixes", draft-ietf-softwire-multicast-prefix-option-09 Prefixes", draft-ietf-softwire-multicast-prefix-option-10
(work in progress), August 2015. (work in progress), February 2016.
[RFC2236] Fenner, W., "Internet Group Management Protocol, Version [RFC2236] Fenner, W., "Internet Group Management Protocol, Version
2", RFC 2236, DOI 10.17487/RFC2236, November 1997, 2", RFC 2236, DOI 10.17487/RFC2236, November 1997,
<http://www.rfc-editor.org/info/rfc2236>. <http://www.rfc-editor.org/info/rfc2236>.
[RFC6676] Venaas, S., Parekh, R., Van de Velde, G., Chown, T., and [RFC6676] Venaas, S., Parekh, R., Van de Velde, G., Chown, T., and
M. Eubanks, "Multicast Addresses for Documentation", M. Eubanks, "Multicast Addresses for Documentation",
RFC 6676, DOI 10.17487/RFC6676, August 2012, RFC 6676, DOI 10.17487/RFC6676, August 2012,
<http://www.rfc-editor.org/info/rfc6676>. <http://www.rfc-editor.org/info/rfc6676>.
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o Content Providers, who usually own the contents that is multicast o Content Providers, who usually own the contents that is multicast
to receivers. Content providers may contractually define an to receivers. Content providers may contractually define an
agreement with network providers to deliver contents to receivers. agreement with network providers to deliver contents to receivers.
o Network Providers, who provide network connectivity services o Network Providers, who provide network connectivity services
(e.g., network providers are responsible for carrying multicast (e.g., network providers are responsible for carrying multicast
flows from head-ends to receivers). flows from head-ends to receivers).
Note that some contract agreements prevent a network provider from Note that some contract agreements prevent a network provider from
altering the content as sent by the content provider for various altering the content as sent by the content provider for various
reasons. Under the contract, multicast streams should be delivered reasons. Depending on these contract agreements, multicast streams
unaltered to the requesting users. should be delivered unaltered to the requesting users.
Many current IPTV contents are likely to remain IPv4-formatted and Many current IPTV contents are likely to remain IPv4-formatted and
out of control of the network providers. Additionally, there are out of control of the network providers. Additionally, there are
numerous legacy receivers (e.g., IPv4-only Set Top Boxes (STB)) that numerous legacy receivers (e.g., IPv4-only Set Top Boxes (STB)) that
can't be upgraded or be easily replaced to support IPv6. As a can't be upgraded or be easily replaced to support IPv6. As a
consequence, IPv4 service continuity MUST be guaranteed during the consequence, IPv4 service continuity must be guaranteed during the
transition period, including the delivery of multicast services such transition period, including the delivery of multicast services such
as Live TV Broadcasting to users. as Live TV Broadcasting to users.
Appendix B. Deployment Considerations Appendix B. Deployment Considerations
B.1. Other operational Modes B.1. Other Operational Modes
B.1.1. MLD Querier with mAFTR Embedded B.1.1. The MLD Querier is Co-Located with the mAFTR
mAFTR can embed the MLD Querier function (as well as the PIMv6 DR) The mAFTR can embed the MLD Querier function (as well as the PIMv6
for optimization. When mB4 sends MLD Report message to this mAFTR, DR) for optimization purposes. When the mB4 sends a MLD Report
the mAFTR should process the MLD Report message that contain message to this mAFTR, the mAFTR should process the MLD Report
IPv4-embedded IPv6 multicast group subscription information then send message that contains the IPv4-embedded IPv6 multicast group address
the corresponding PIMv4 Join message. (Figure 4) and then send the corresponding PIMv4 Join message. (Figure 4)
+---------+ +---------+
---------| mAFTR |--------- ---------| mAFTR |---------
MLD |uPrefix64| PIMv4 MLD |uPrefix64| PIMv4
|mPreifx64| |mPreifx64|
+---------+ +---------+
Figure 4: MLD-PIMv4 Interworking Function Figure 4: MLD-PIMv4 Interworking Function
Discussions about the location of the mAFTR capability and related Discussions about the location of the mAFTR capability and related
ASM or SSM multicast design considerations are out of the scope of ASM or SSM multicast design considerations are out of the scope of
this document. this document.
B.1.2. mAFTR embedded in DR B.1.2. The DR is Co-Located with the mAFTR
If mAFTR is the DR of the original IPv4 source, it may simply use the If the mAFTR is co-located with the DR connected to the original IPv4
uPrefix64 and mPrefix64 to build the IPv4-embedded IPv6 multicast source, it may simply use the uPrefix64 and mPrefix64 prefixes to
traffic, the sending of PIMv4 Join message is not necessary. build the IPv4-embedded IPv6 multicast packets, and the sending of
PIMv4 Join messages becomes unnecessary.
B.2. Older Version of Group Membership management Protocols B.2. Older Versions of Group Membership Management Protocols
Given the multiple versions of group membership management protocols, Given the multiple versions of group membership management protocols,
mismatch issues may be raised in the mB4 Function (refer to mismatch issues may arise at the mB4 (refer to Section 6.1).
Section 6.1).
If IGMPv2 operates on the IPv4 receivers while MLDv2 operates on the If IGMPv2 operates on the IPv4 receivers while MLDv2 operates on the
MLD Querier, or if IGMPv3 operates on the IPv4 receivers while MLDv1 MLD Querier, or if IGMPv3 operates on the IPv4 receivers while MLDv1
operates on the MLD Querier, the issue mentioned above will be operates on the MLD Querier, the issue mentioned above will be
encountered. To solve this problem, the mB4 SHOULD perform the encountered. To solve this problem, the mB4 should perform the
router portion of IGMP which is of the same as the corresponding MLD router portion of IGMP which is similar to the corresponding MLD
version (IGMPv2 as of MLDv1, or IGMPv3 as of MLDv2) operating in the version (IGMPv2 as of MLDv1, or IGMPv3 as of MLDv2) operating in the
IPv6 domain, then the protocol interaction approach specified in IPv6 domain. Then, the protocol interaction approach specified in
Section 7 of [RFC3376] can be used to exchange signaling messages Section 7 of [RFC3376] can be applied to exchange signaling messages
with the IPv4 receivers on which the different version of IGMP is with the IPv4 receivers on which the different version of IGMP is
operating. operating.
B.3. Load-Balancing B.3. Load Balancing
For robustness and load distribution purposes, several nodes in the For robustness and load distribution purposes, several nodes in the
network can embed the mAFTR function. In such case, the same IPv6 network can embed the mAFTR function. In such case, the same IPv6
prefixes (i.e., mPrefix64 and uPrefix64) and algorithm to build IPv4- prefixes (i.e., mPrefix64 and uPrefix64) and algorithm to build IPv4-
embedded IPv6 addresses MUST be configured on those nodes. embedded IPv6 addresses must be configured on those nodes.
B.4. RP for IPv4-Embedded IPv6 Multicast Groups B.4. RP for IPv4-Embedded IPv6 Multicast Groups
For the sake of simplicity, it is RECOMMENDED to configure mAFTR as For the sake of simplicity, it is recommended to configure the mAFTR
the RP for the IPv4-embedded IPv6 multicast groups it manages. No as the RP for the IPv4-embedded IPv6 multicast groups it manages. No
registration procedure is required under this configuration. registration procedure is required under this configuration.
B.5. mAFTR Policy Configuration B.5. mAFTR Policy Configuration
mAFTR may be configured with a list of IPv4 multicast groups and The mAFTR may be configured with a list of IPv4 multicast groups and
sources. Only multicast flows bound to the configured addresses sources. Only multicast flows bound to the configured addresses
should be handled by the mAFTR. Otherwise, packets are silently should be handled by the mAFTR. Otherwise, packets are silently
drooped. dropped.
B.6. Static vs. Dynamic PIM Triggering B.6. Static vs. Dynamic PIM Triggering
To optimize the usage of network resources in current deployments, To optimize the usage of network resources in current deployments,
all multicast streams are conveyed in the core network while only all multicast streams are conveyed in the core network while only the
popular ones are continuously conveyed in the aggregation/access most popular ones are forwarded in the aggregation/access networks
network (static mode). Non-popular streams are conveyed in the (static mode). Less popular streams are forwarded in the access
access network upon request (dynamic mode). Depending on the network upon request (dynamic mode). Depending on the location of
location of the mAFTR in the network, two modes can be envisaged: the mAFTR in the network, two modes can be envisaged: static and
static and dynamic. dynamic.
o Static Mode: the mAFTR is configured to instantiate permanent (S6, Static Mode: the mAFTR is configured to instantiate permanent (S6,
G6) and (*, G6) entries in its TIB6 using a pre-configured (S4, G6) and (*, G6) entries in its TIB6 using a pre-configured (S4,
G4) list. G4) list.
o Dynamic Mode: the instantiation and deletion of (S6, g6) or (*, Dynamic Mode: the instantiation or withdrawal of (S6, G6) or (*, G6)
G6) is triggered by the receipt of PIMv6 messages. entries is triggered by the receipt of PIMv6 messages.
Authors' Addresses Authors' Addresses
Jacni Qin Jacni Qin
Cisco Cisco
Shanghai Shanghai
China China
Email: jacni@jacni.com Email: jacni@jacni.com
Mohamed Boucadair Mohamed Boucadair
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Yiu L. Lee Yiu L. Lee
Comcast Comcast
U.S.A. U.S.A.
Email: yiu_lee@cable.comcast.com Email: yiu_lee@cable.comcast.com
URI: http://www.comcast.com URI: http://www.comcast.com
Qian Wang Qian Wang
China Telecom China Telecom
No.118, Xizhimennei
Beijing 100035
China China
Phone: +86 10 5855 2177 Phone: +86 10 58502462
Email: wangqian@ctbri.com.cn Email: wangqian@chinatelecom.cn
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