Internet Engineering Task Force (IETF) M. Abrahamsson
Request for Comments: 8815
BCP: 229 T. Chown
Category: Best Current Practice Jisc
ISSN: 2070-1721 L. Giuliano
Juniper Networks, Inc.
T.T.E.
T. Eckert
Futurewei Technologies Inc.
August 2020
Deprecating Any-Source Multicast (ASM) for Interdomain Multicast
Abstract
This document recommends deprecation of the use of Any-Source
Multicast (ASM) for interdomain multicast. It recommends the use of
Source-Specific Multicast (SSM) for interdomain multicast
applications and recommends that hosts and routers in these
deployments fully support SSM. The recommendations in this document
do not preclude the continued use of ASM within a single organization
or domain and are especially easy to adopt in existing deployments of
intradomain ASM and/or PIM Sparse Mode (PIM-SM).
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/rfc8815.
Copyright Notice
Copyright (c) 2020 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
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described in the Simplified BSD License.
Table of Contents
1. Introduction
2. Background
2.1. Multicast Service Models
2.2. ASM Routing Protocols
2.2.1. PIM Sparse Mode (PIM-SM)
2.2.2. Embedded-RP
2.2.3. Bidir-RP
2.3. SSM Routing Protocols
3. Discussion
3.1. Observations on ASM and SSM Deployments
3.2. Advantages of SSM for Interdomain Multicast
3.2.1. Reduced Network Operations Complexity
3.2.2. No Network-Wide IP Multicast Group-Address Management
3.2.3. Intrinsic Source-Control Security
4. Recommendations
4.1. Deprecating Use of ASM for Interdomain Multicast
4.2. Including Network Support for IGMPv3/MLDv2
4.3. Building Application Support for SSM
4.4. Developing Application Guidance: SSM, ASM, Service
Discovery
4.5. Preferring SSM Applications Intradomain
4.6. Documenting an ASM/SSM Protocol Mapping Mechanism
4.7. Not Filtering ASM Addressing between Domains
4.8. Not Precluding Intradomain ASM
4.9. Evolving PIM Deployments for SSM
5. Future Interdomain ASM Work
6. Security Considerations
7. IANA Considerations
8. References
8.1. Normative References
8.2. Informative References
Acknowledgments
Authors' Addresses
1. Introduction
IP Multicast has been deployed in various forms, within private
networks, the wider Internet, and federated networks such as national
or regional research networks. While a number of service models have
been published, and in many cases revised over time, there has been
no strong recommendation made by the IETF on the appropriateness of
those models to certain scenarios, even though vendors and
federations have often made such recommendations.
This document addresses this gap by making a BCP-level recommendation
to deprecate the use of Any-Source Multicast (ASM) for interdomain
multicast, leaving Source-Specific Multicast (SSM) as the recommended
interdomain mode of multicast. This document further recommends that
all hosts and routers that support interdomain multicast applications
fully support SSM.
This document does not make any statement on the use of ASM within a
single domain or organization and, therefore, does not preclude its
use. Indeed, there are application contexts for which ASM is
currently still widely considered well suited within a single domain.
The main issue in most cases with moving to SSM is application
support. Many applications are initially deployed for intradomain
use and are later deployed interdomain. Therefore, this document
recommends that applications support SSM, even when they are
initially intended for intradomain use. As explained below, SSM
applications are readily compatible with existing intradomain ASM
deployments,
deployments using PIM-SM, as SSM PIM-SSM is merely a subset of ASM. PIM-SM.
2. Background
2.1. Multicast Service Models
Any-Source Multicast (ASM) and Source-Specific Multicast (SSM) are
the two multicast service models in use today. In ASM, as originally
described in [RFC1112], receivers express interest in joining a
multicast group address, and routers use multicast routing protocols
to deliver traffic from the sender(s) to the receivers. If there are
multiple senders for a given group, traffic from all senders will be
delivered to the receivers. Since receivers specify only the group
address, the network -- and therefore the multicast routing protocols
-- are responsible for source discovery.
In SSM, by contrast, receivers specify both group and source when
expressing interest in joining a multicast stream. Source discovery
in SSM is handled by some out-of-band mechanism in the application
layer, which drastically simplifies the network and how the multicast
routing protocols operate.
IANA has reserved specific ranges of IPv4 and IPv6 address space for
multicast addressing. Guidelines for IPv4 multicast address
assignments can be found in [RFC5771], while guidelines for IPv6
multicast address assignments can be found in [RFC2375] and
[RFC3307]. The IPv6 multicast address format is described in
[RFC4291].
2.2. ASM Routing Protocols
2.2.1. PIM Sparse Mode (PIM-SM)
The most commonly deployed ASM routing protocol is Protocol
Independent Multicast - Sparse Mode (PIM-SM), as detailed in
[RFC7761]. PIM-SM, as the name suggests, was designed to be used in
scenarios where the subnets with receivers are sparsely distributed
throughout the network. Because receivers do not indicate sender
addresses in ASM (but only group addresses), PIM-SM uses the concept
of a Rendezvous Point (RP) as a "meeting point" for sources and
receivers, and all routers in a PIM-SM domain are configured to use a
specific RP(s), either explicitly or through dynamic RP-discovery
protocols.
To enable PIM-SM to work between multiple domains, an interdomain,
inter-RP signaling protocol known as Multicast Source Discovery
Protocol (MSDP) [RFC3618] is used to allow an RP in one domain to
learn of the existence of a source in another domain. Deployment
scenarios for MSDP are given in [RFC4611]. MSDP floods information
about all active sources for all multicast streams to all RPs in all
the domains -- even if there is no receiver for a given application
in a domain. As a result of this key scalability and security issue,
along with other deployment challenges with the protocol, MSDP was
never extended to support IPv6 and remains an Experimental protocol.
At the time of writing, there is no IETF interdomain solution at the
level of Proposed Standard for IPv4 ASM multicast, because MSDP was
the de facto mechanism for the interdomain source discovery problem,
and it is Experimental. Other protocol options were investigated at
the same time but were never implemented or deployed and are now
historic (e.g., [RFC3913]).
2.2.2. Embedded-RP
Due to the availability of more bits in an IPv6 address than in IPv4,
an IPv6-specific mechanism was designed in support of interdomain
ASM, with PIM-SM leveraging those bits. Embedded-RP [RFC3956] allows
routers supporting the protocol to determine the RP for the group
without any prior configuration or discovery protocols, simply by
observing the unicast RP address that is embedded (included) in the
IPv6 multicast group address. Embedded-RP allows PIM-SM operation
across any IPv6 network in which there is an end-to-end path of
routers supporting this mechanism, including interdomain deployment.
2.2.3. Bidir-RP
Bidir-PIM [RFC5015] is another protocol to support ASM. There is no
standardized option to operate Bidir-PIM interdomain. It is deployed
intradomain for applications where many sources send traffic to the
same IP multicast groups because, unlike PIM-SM, it does not create
per-source state. Bidir-PIM is one of the important reasons for this
document to not deprecate intradomain ASM.
2.3. SSM Routing Protocols
SSM is detailed in [RFC4607]. It mandates the use of PIM-SSM for
routing of SSM. PIM-SSM is merely a subset of PIM-SM [RFC7761].
PIM-SSM expects the sender's source address(es) to be known in
advance by receivers through some out-of-band mechanism (typically in
the application layer); thus, the receiver's designated router can
send a PIM JOIN directly towards the source without needing to use an
RP.
IPv4 addresses in the 232/8 (232.0.0.0 to 232.255.255.255) range are
designated as Source-Specific Multicast (SSM) destination addresses
and are reserved for use by source-specific applications and
protocols. See [RFC4607]. For IPv6, the address prefix ff3x::/32 is reserved for
source-specific multicast use. See [RFC4607].
3. Discussion
3.1. Observations on ASM and SSM Deployments
In enterprise and campus scenarios, ASM in the form of PIM-SM is
likely the most commonly deployed multicast protocol. The
configuration and management of an RP (including RP redundancy)
within a single domain is a well-understood operational practice.
However, if interworking with external PIM domains is needed in IPv4
multicast deployments, interdomain MSDP is required to exchange
information about sources between domain RPs. Deployment experience
has shown MSDP to be a complex and fragile protocol to manage and
troubleshoot. Some of these issues include complex Reverse Path
Forwarding (RPF) rules, state attack protection, and filtering of
undesired sources.
PIM-SM is a general-purpose protocol that can handle all use cases.
In particular, it was designed for cases such as videoconferencing
where multiple sources may come and go during a multicast session.
But for cases where a single, persistent source for a group is used,
and receivers can be configured to know of that source, PIM-SM has
unnecessary complexity. Therefore, SSM removes the need for many of
the most complex components of PIM-SM.
As explained above, MSDP was not extended to support IPv6. Instead,
the proposed interdomain ASM solution for PIM-SM with IPv6 is
Embedded-RP, which allows the RP address for a multicast group to be
embedded in the group address, making RP discovery automatic for all
routers on the path between a receiver and a sender. Embedded-RP can
support lightweight ad hoc deployments. However, it relies on a
single RP for an entire group that could only be made resilient
within one domain. While this approach solves the MSDP issues, it
does not solve the problem of unauthorized sources sending traffic to
ASM multicast groups; this security issue is one of biggest problems
of interdomain multicast.
As stated in RFC 4607, SSM is particularly well suited to either
dissemination-style applications with one or more senders whose
identities are known (by some out-of-band mechanism) before the
application starts running or applications that utilize some
signaling to indicate the source address of the multicast stream
(e.g., electronic programming guide in IPTV applications).
Therefore, SSM through PIM-SSM is very well suited to applications
such as classic linear-broadcast TV over IP.
SSM requires applications, host operating systems, and the designated
routers connected to receiving hosts to support Internet Group
Management Protocol, Version 3 (IGMPv3) [RFC3376] and Multicast
Listener Discovery, Version 2 (MLDv2) [RFC3810]. While support for
IGMPv3 and MLDv2 has been commonplace in routing platforms for a long
time, it has also now become widespread in common operating systems
for several years (Windows, Mac OS, Linux/Android) and is no longer
an impediment to SSM deployment.
3.2. Advantages of SSM for Interdomain Multicast
This section describes the three key benefits that SSM with PIM-SSM
has over ASM. These benefits also apply to intradomain deployment
but are even more important in interdomain deployments. See
[RFC4607] for more details.
3.2.1. Reduced Network Operations Complexity
A significant benefit of SSM is the reduced complexity that comes
through eliminating the network-based source discovery required in
ASM with PIM-SM. Specifically, SSM eliminates the need for RPs,
shared trees, Shortest Path Tree (SPT) switchovers, PIM registers,
MSDP, dynamic RP-discovery mechanisms (BSR/AutoRP), and data-driven
state creation. SSM simply utilizes a small subset of PIM-SM,
alongside the integration with IGMPv3/MLDv2, where the source address
signaled from the receiver is immediately used to create (S,G) state.
Eliminating network-based source discovery for interdomain multicast
means the vast majority of the complexity of multicast goes away.
This reduced complexity makes SSM radically simpler to manage,
troubleshoot, and operate, particularly for backbone network
operators. This is the main operator motivation for the
recommendation to deprecate the use of ASM in interdomain scenarios.
Note that this discussion does not apply to Bidir-PIM, and there is
(as mentioned above) no standardized interdomain solution for Bidir-
PIM. In Bidir-PIM, traffic is forwarded to the RP instead of
building state as in PIM-SM. This occurs even in the absence of
receivers. Therefore, Bidir-PIM trades state complexity with
unnecessary traffic (potentially a large amount).
3.2.2. No Network-Wide IP Multicast Group-Address Management
In ASM, IP multicast group addresses need to be assigned to
applications and instances thereof, so that two simultaneously active
application instances will not share the same group address and
receive IP multicast traffic from each other.
In SSM, no such IP multicast group management is necessary. Instead,
the IP multicast group address simply needs to be assigned locally on
a source like a unicast transport protocol port number: the only
coordination required is to ensure that different applications
running on the same host don't send to the same group address. This
does not require any network-operator involvement.
3.2.3. Intrinsic Source-Control Security
SSM is implicitly secure against off-path unauthorized/undesired
sources. Receivers only receive packets from the sources they
explicitly specify in their IGMPv3/MLDv2 membership messages, as
opposed to ASM, where any host can send traffic to a group address
and have it transmitted to all receivers. With PIM-SSM, traffic from
sources not requested by any receiver will be discarded by the First-
Hop Router (FHR) of that source, minimizing source attacks against
shared network bandwidth and receivers.
This benefit is particularly important in interdomain deployments,
because there are no standardized solutions for ASM control of
sources and the most common intradomain operational practices on the
sender's FHR, such as Access Control Lists (ACLs), are not feasible
for interdomain deployments.
This topic is expanded upon in [RFC4609].
4. Recommendations
This section provides recommendations for a variety of stakeholders
in SSM deployment, including vendors, operators, and application
developers. It also suggests further work that could be undertaken
within the IETF.
4.1. Deprecating Use of ASM for Interdomain Multicast
This document recommends that the use of ASM be deprecated for
interdomain multicast; thus, implicitly, it recommends that hosts and
routers that support such interdomain applications fully support SSM
and its associated protocols. best current practices for deploying
interdomain multicast using SSM are documented in [RFC8313].
The recommendation applies to the use of ASM between domains where
either MSDP (IPv4) or Embedded-RP (IPv6) is used.
An interdomain use of ASM multicast in the context of this document
is one where PIM-SM with RPs/MSDP/Embedded-RP is run on routers
operated by two or more separate administrative entities.
The focus of this document is deprecation of interdomain ASM
multicast, and while encouraging the use of SSM within domains, it
leaves operators free to choose to use ASM within their own domains.
A more inclusive interpretation of this recommendation is that it
also extends to deprecating use of ASM in the case where PIM is
operated in a single operator domain, but where user hosts or non-PIM
network edge devices are under different operator control. A typical
example of this case is a service provider offering IPTV (single
operator domain for PIM) to subscribers operating an IGMP proxy home
gateway and IGMPv3/MLDv2 hosts (computer, tablets, set-top boxes).
4.2. Including Network Support for IGMPv3/MLDv2
This document recommends that all hosts, router platforms, and
security appliances used for deploying multicast support the
components of IGMPv3 [RFC3376] and MLDv2 [RFC3810] necessary to
support SSM (i.e., explicitly sending source-specific reports).
"IPv6 Node Requirements" [RFC8504] states that MLDv2 must be
supported in all implementations. Such support is already widespread
in common host and router platforms.
Further guidance on IGMPv3 and MLDv2 is given in [RFC4604].
Multicast snooping is often used to limit the flooding of multicast
traffic in a Layer 2 network. With snooping, an L2 switch will
monitor IGMP/MLD messages and only forward multicast traffic out on
host ports that have interested receivers connected. Such snooping
capability should therefore support IGMPv3 and MLDv2. There is
further discussion in [RFC4541].
4.3. Building Application Support for SSM
The recommendation to use SSM for interdomain multicast means that
applications should properly trigger the sending of IGMPv3/MLDv2
source-specific report messages. It should be noted, however, that
there is a wide range of applications today that only support ASM.
In many cases, this is due to application developers being unaware of
the operational concerns of networks and the implications of using
ASM versus SSM. This document serves to provide clear direction for
application developers who might currently only consider using ASM to
instead support SSM, which only requires relatively minor changes for
many applications, particularly those with single sources.
It is often thought that ASM is required for multicast applications
where there are multiple sources. However, RFC 4607 also describes
how SSM can be used instead of PIM-SM for multi-party applications:
| SSM can be used to build multi-source applications where all
| participants' identities are not known in advance, but the multi-
| source "rendezvous" functionality does not occur in the network
| layer in this case. Just like in an application that uses unicast
| as the underlying transport, this functionality can be implemented
| by the application or by an application-layer library.
Some useful considerations for multicast applications can be found in
[RFC3170].
4.4. Developing Application Guidance: SSM, ASM, Service Discovery
Applications with many-to-many communication patterns can create more
(S,G) state than is feasible for networks to manage, whether the
source discovery is done by ASM with PIM-SM or at the application
level and SSM/PIM-SM. SSM/PIM-SSM. These applications are not best supported by
either SSM/PIM-SSM or ASM/PIM-SM.
Instead, these applications are better served by routing protocols
that do not create (S,G), such as Bidir-PIM. Unfortunately, many
applications today use ASM solely for service discovery. One example
is where clients send IP multicast packets to elicit unicast replies
from server(s). Deploying any form of IP multicast solely in support
of such service discovery is, in general, not recommended. Dedicated
service discovery via DNS-based Service Discovery (DNS-SD) [RFC6763]
should be used for this instead.
This document describes best practices to explain when to use SSM in
applications -- e.g., when ASM without (S,G) state in the network is
better, or when dedicated service-discovery mechanisms should be
used. However, specifying how applications can support these
practices is outside the scope of this document. Further work on
this subject may be expected within the IETF.
4.5. Preferring SSM Applications Intradomain
If feasible, it is recommended for applications to use SSM even if
they are initially only meant to be used in intradomain environments
supporting ASM. Because PIM-SSM is a subset of PIM-SM, existing
intradomain PIM-SM networks are automatically compatible with SSM
applications. Thus, SSM applications can operate alongside existing
ASM applications. SSM's benefits of simplified address management
and significantly reduced operational complexity apply equally to
intradomain use.
However, for some applications, it may be prohibitively difficult to
add support for source discovery, so intradomain ASM may still be
appropriate.
4.6. Documenting an ASM/SSM Protocol Mapping Mechanism
In the case of existing ASM applications that cannot readily be
ported to SSM, it may be possible to use some form of protocol
mapping -- i.e., to have a mechanism to translate a (*,G) join or
leave to a (S,G) join or leave for a specific source S. The general
challenge in performing such mapping is determining where the
configured source address, S, comes from.
There are existing vendor-specific mechanisms deployed that achieve
this function, but none are documented in IETF documents. This may
be a useful area for the IETF to work on as an interim transition
mechanism. However, these mechanisms would introduce additional
administrative burdens, along with the need for some form of address
management, neither of which are required in SSM. Hence, this should
not be considered a long-term solution.
4.7. Not Filtering ASM Addressing between Domains
A key benefit of SSM is that the receiver specifies the source-group
tuple when signaling interest in a multicast stream. Hence, the
group address need not be globally unique, so there is no need for
multicast address allocation as long the reserved SSM range is used.
Despite the deprecation of interdomain ASM, it is recommended that
operators not filter ASM group ranges at domain boundaries, as some
form of ASM-SSM mappings may continue to be used for some time.
4.8. Not Precluding Intradomain ASM
The use of ASM within a single multicast domain such as a campus or
enterprise is still relatively common today. There are even global
enterprise networks that have successfully been using PIM-SM for many
years. The operators of such networks most often use Anycast-RP
[RFC4610] or MSDP (with IPv4) for RP resilience, at the expense of
the extra operational complexity. These existing practices are
unaffected by this document.
In the past decade, some Bidir-PIM deployments have scaled
interdomain ASM deployments beyond the capabilities of PIM-SM. This,
too, is unaffected by this document; instead, it is encouraged where
necessary due to application requirements (see Section 4.4).
This document also does not preclude continued use of ASM with
multiple PIM-SM domains inside organizations, such as with IPv4 MSDP
or IPv6 Embedded-RP. This includes organizations that are
federations and have appropriate, nonstandardized mechanisms to deal
with the interdomain ASM issues explained in Section 3.2.
4.9. Evolving PIM Deployments for SSM
Existing PIM-SM deployments can usually be used to run SSM
applications with few-to-no changes. In some widely available router
implementations of PIM-SM, PIM-SSM is simply enabled by default in
the designated SSM address spaces whenever PIM-SM is enabled. In
other implementations, simple configuration options exist to enable
it. This allows migration of ASM applications to SSM/PIM-SSM solely
through application-side development to handle source-signaling via
IGMPv3/MLDv2 and using SSM addresses. No network actions are
required for this transition; unchanged ASM applications can continue
to coexist without issues.
When running PIM-SM, IGMPv3/MLDv2 (S,G) membership reports may also
result in the desired PIM-SSM (S,G) operations and bypass any RP
procedures. This is not standardized but depends on implementation
and may require additional configuration in available products. In
general, it is recommended to always use SSM address space for SSM
applications. For example, the interaction of IGMPv3/MLDv2 (S,G)
membership reports and Bidir-PIM is undefined and may not result in
forwarding of any traffic.
Note that these migration recommendations do not include
considerations on when or how to evolve those intradomain
applications best served by ASM/Bidir-PIM from PIM-SM to Bidir-PIM.
This may also be important but is outside the scope of this document.
5. Future Interdomain ASM Work
Future work may attempt to overcome current limitations of ASM
solutions, such as interdomain deployment solutions for Bidir-PIM or
source-access-control mechanisms for IPv6 PIM-SM with embedded-RP.
Such work could modify or amend the recommendations of this document
(like any future IETF Standards Track / BCP work).
Nevertheless, it is very unlikely that any ASM solution, even with
such future work, can ever provide the same intrinsic security and
network- and address-management simplicity as SSM (see Section 3.2).
Accordingly, this document recommends that future work for general-
purpose interdomain IP multicast focus on SSM items listed in
Section 4.
6. Security Considerations
This document adds no new security considerations. It instead
removes security issues incurred by interdomain ASM with PIM-SM/MSDP,
such as infrastructure control-plane attacks and application and
bandwidth/congestion attacks from unauthorized sources sending to ASM
multicast groups. RFC 4609 describes the additional security
benefits of using SSM instead of ASM.
7. IANA Considerations
This document has no IANA actions.
8. References
8.1. Normative References
[RFC1112] Deering, S., "Host extensions for IP multicasting", STD 5,
RFC 1112, DOI 10.17487/RFC1112, August 1989,
<https://www.rfc-editor.org/info/rfc1112>.
[RFC3307] Haberman, B., "Allocation Guidelines for IPv6 Multicast
Addresses", RFC 3307, DOI 10.17487/RFC3307, August 2002,
<https://www.rfc-editor.org/info/rfc3307>.
[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>.
[RFC3956] Savola, P. and B. Haberman, "Embedding the Rendezvous
Point (RP) Address in an IPv6 Multicast Address",
RFC 3956, DOI 10.17487/RFC3956, November 2004,
<https://www.rfc-editor.org/info/rfc3956>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for
IP", RFC 4607, DOI 10.17487/RFC4607, August 2006,
<https://www.rfc-editor.org/info/rfc4607>.
[RFC5771] Cotton, M., Vegoda, L., and D. Meyer, "IANA Guidelines for
IPv4 Multicast Address Assignments", BCP 51, RFC 5771,
DOI 10.17487/RFC5771, March 2010,
<https://www.rfc-editor.org/info/rfc5771>.
[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>.
[RFC8313] Tarapore, P., Ed., Sayko, R., Shepherd, G., Eckert, T.,
Ed., and R. Krishnan, "Use of Multicast across Inter-
domain Peering Points", BCP 213, RFC 8313,
DOI 10.17487/RFC8313, January 2018,
<https://www.rfc-editor.org/info/rfc8313>.
8.2. Informative References
[RFC2375] Hinden, R. and S. Deering, "IPv6 Multicast Address
Assignments", RFC 2375, DOI 10.17487/RFC2375, July 1998,
<https://www.rfc-editor.org/info/rfc2375>.
[RFC3170] Quinn, B. and K. Almeroth, "IP Multicast Applications:
Challenges and Solutions", RFC 3170, DOI 10.17487/RFC3170,
September 2001, <https://www.rfc-editor.org/info/rfc3170>.
[RFC3618] Fenner, B., Ed. and D. Meyer, Ed., "Multicast Source
Discovery Protocol (MSDP)", RFC 3618,
DOI 10.17487/RFC3618, October 2003,
<https://www.rfc-editor.org/info/rfc3618>.
[RFC3913] Thaler, D., "Border Gateway Multicast Protocol (BGMP):
Protocol Specification", RFC 3913, DOI 10.17487/RFC3913,
September 2004, <https://www.rfc-editor.org/info/rfc3913>.
[RFC4541] Christensen, M., Kimball, K., and F. Solensky,
"Considerations for Internet Group Management Protocol
(IGMP) and Multicast Listener Discovery (MLD) Snooping
Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006,
<https://www.rfc-editor.org/info/rfc4541>.
[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>.
[RFC4610] Farinacci, D. and Y. Cai, "Anycast-RP Using Protocol
Independent Multicast (PIM)", RFC 4610,
DOI 10.17487/RFC4610, August 2006,
<https://www.rfc-editor.org/info/rfc4610>.
[RFC4611] McBride, M., Meylor, J., and D. Meyer, "Multicast Source
Discovery Protocol (MSDP) Deployment Scenarios", BCP 121,
RFC 4611, DOI 10.17487/RFC4611, August 2006,
<https://www.rfc-editor.org/info/rfc4611>.
[RFC5015] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano,
"Bidirectional Protocol Independent Multicast (BIDIR-
PIM)", RFC 5015, DOI 10.17487/RFC5015, October 2007,
<https://www.rfc-editor.org/info/rfc5015>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<https://www.rfc-editor.org/info/rfc6763>.
[RFC8504] Chown, T., Loughney, J., and T. Winters, "IPv6 Node
Requirements", BCP 220, RFC 8504, DOI 10.17487/RFC8504,
January 2019, <https://www.rfc-editor.org/info/rfc8504>.
Acknowledgments
The authors would like to thank members of the IETF MBONE Deployment
Working Group for discussions on the content of this document, with
specific thanks to the following people for their contributions to
the document: Hitoshi Asaeda, Dale Carder, Jake Holland, Albert
Manfredi, Mike McBride, Per Nihlen, Greg Shepherd, James Stevens,
Stig Venaas, Nils Warnke, and Sandy Zhang.
Authors' Addresses
Mikael Abrahamsson
Stockholm
Sweden
Email: swmike@swm.pp.se
Tim Chown
Jisc
Harwell Oxford
Lumen House, Library Avenue
Didcot
OX11 0SG
United Kingdom
Email: tim.chown@jisc.ac.uk
Lenny Giuliano
Juniper Networks, Inc.
2251 Corporate Park Drive
Herndon, Virginia 20171
United States of America
Email: lenny@juniper.net
Toerless Eckert
Futurewei Technologies Inc.
2330 Central Expy
Santa Clara, California 95050
United States of America
Email: tte+ietf@cs.fau.de tte@cs.fau.de