draft-ietf-mboned-msdp-deploy-06.txt   rfc4611.txt 
INTERNET-DRAFT M. McBride Network Working Group M. McBride
J. Meylor Request for Comments: 4611 J. Meylor
D. Meyer BCP: 121 D. Meyer
Category Best Current Practice Category: Best Current Practice August 2006
Multicast Source Discovery Protocol (MSDP) Deployment Scenarios
<draft-ietf-mboned-msdp-deploy-06.txt>
Status of this Document
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
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The list of current Internet-Drafts can be accessed at Multicast Source Discovery Protocol (MSDP) Deployment Scenarios
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at Status of This Memo
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This document is a product of the MBONED Working Group. Comments This document specifies an Internet Best Current Practices for the
should be addressed to the authors, or the mailing list at Internet Community, and requests discussion and suggestions for
mboned@lists.uoregon.edu. improvements. Distribution of this memo is unlimited.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2006).
Abstract Abstract
This document describes best current practices for intra-domain and This document describes best current practices for intra-domain and
inter-domain deployment of the Multicast Source Discovery Protocol inter-domain deployment of the Multicast Source Discovery Protocol
(MSDP) in conjunction with Protocol Independent Multicast Sparse Mode (MSDP) in conjunction with Protocol Independent Multicast Sparse Mode
(PIM-SM). (PIM-SM).
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction ....................................................2
1.1. BCP, Experimental Protocols and Normative References. . . . 5 1.1. BCP, Experimental Protocols, and Normative References ......3
2. Inter-domain MSDP Peering Scenarios. . . . . . . . . . . . . . 6 2. Inter-domain MSDP Peering Scenarios .............................4
2.1. Peering between PIM Border Routers. . . . . . . . . . . . . 7 2.1. Peering between PIM Border Routers .........................4
2.2. Peering between Non-Border Routers. . . . . . . . . . . . . 8 2.2. Peering between Non-Border Routers .........................5
2.3. MSDP Peering without BGP. . . . . . . . . . . . . . . . . . 9 2.3. MSDP Peering without BGP ...................................7
2.4. MSDP Peering at a Multicast Exchange. . . . . . . . . . . . 10 2.4. MSDP Peering at a Multicast Exchange .......................7
3. Intra-domain MSDP Peering Scenarios. . . . . . . . . . . . . . 10 3. Intra-domain MSDP Peering Scenarios .............................7
3.1. Peering between MSDP and MBGP Configured Routers. . . . . . 10 3.1. Peering between MSDP- and MBGP-Configured Routers ..........8
3.2. MSDP Peer is not BGP Peer (or no BGP Peer). . . . . . . . . 11 3.2. MSDP Peer Is Not BGP Peer (or No BGP Peer) .................8
3.3. Hierarchical Mesh Groups. . . . . . . . . . . . . . . . . . 12 3.3. Hierarchical Mesh Groups ...................................9
3.4. MSDP and Route Reflectors . . . . . . . . . . . . . . . . . 13 3.4. MSDP and Route Reflectors .................................10
3.5. MSDP and Anycast RPs. . . . . . . . . . . . . . . . . . . . 14 3.5. MSDP and Anycast RPs ......................................11
4. Security Considerations. . . . . . . . . . . . . . . . . . . . 14 4. Security Considerations ........................................11
4.1. Filtering SA messages . . . . . . . . . . . . . . . . . . . 15 4.1. Filtering SA Messages .....................................11
4.2. SA message state limits . . . . . . . . . . . . . . . . . . 15 4.2. SA Message State Limits ...................................12
5. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 15 5. Acknowledgements ...............................................12
6. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 16 6. References .....................................................12
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 6.1. Normative References ......................................12
7.1. Normative References. . . . . . . . . . . . . . . . . . . . 17 6.2. Informative References ....................................13
7.2. Informative References. . . . . . . . . . . . . . . . . . . 18
8. Author's Addresses . . . . . . . . . . . . . . . . . . . . . . 18
9. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 18
10. Intellectual Property . . . . . . . . . . . . . . . . . . . . 19
11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
MSDP [RFC3618] is used primarily in two deployment scenarios: MSDP [RFC3618] is used primarily in two deployment scenarios:
o Between PIM Domains o Between PIM Domains
MSDP can be used between Protocol Independent Multicast Sparse MSDP can be used between Protocol Independent Multicast Sparse
Mode (PIM-SM) [PIM-SM] domains to convey information Mode (PIM-SM) [RFC4601] domains to convey information about active
about active sources available in other domains. MSDP peering sources available in other domains. MSDP peering used in such
used in such cases is generally one to one peering, and cases is generally one-to-one peering, and utilizes the
utilizes the deterministic peer-RPF (Reverse Path Forwarding) deterministic peer-RPF (Reverse Path Forwarding) rules described
rules described in the MSDP specification (i.e., does not use in the MSDP specification (i.e., it does not use mesh-groups).
mesh-groups). Peerings can be aggregated on a single MSDP Peerings can be aggregated on a single MSDP peer. Such a peer can
peer. Such a peer can typically have from one to hundreds of typically have from one to hundreds of peerings, which is similar
peerings, which is similar in scale to BGP peerings. in scale to BGP peerings.
o Within a PIM Domain o Within a PIM Domain
MSDP is often used between Anycast Rendezvous Points MSDP is often used between Anycast Rendezvous Points (Anycast-RPs)
(Anycast-RPs) [RFC3446] within a PIM domain to synchronize [RFC3446] within a PIM domain to synchronize information about the
information about the active sources being served by each active sources being served by each Anycast-RP peer (by virtue of
Anycast-RP peer (by virtue of IGP reachability). MSDP peering IGP reachability). MSDP peering used in this scenario is
used in this scenario is typically based on MSDP mesh groups, typically based on MSDP mesh groups, where anywhere from two to
where anywhere from two to tens of peers can comprise a given tens of peers can comprise a given mesh group, although more than
mesh group, although more than ten is not typical. One or more ten is not typical. One or more of these mesh-group peers may
of these mesh-group peers may then also have additional also have additional one-to-one peerings with MSDP peers outside
one-to-one peering with MSDP peers outside that PIM domain for that PIM domain for discovery of external sources. MSDP for
discovery of external sources. MSDP for anycast-RP without anycast-RP without external MSDP peering is a valid deployment
external MSDP peering is a valid deployment option and common. option and common.
Current best practice for MSDP deployment utilizes PIM-SM and the Current best practice for MSDP deployment utilizes PIM-SM and the
Border Gateway Protocol with multi-protocol extensions (MBGP) Border Gateway Protocol with multi-protocol extensions (MBGP)
[RFC1771, RFC2858]. This document outlines how these protocols work [RFC4271, RFC2858]. This document outlines how these protocols work
together to provide an intra-domain and inter-domain Any Source together to provide an intra-domain and inter-domain Any Source
Multicast (ASM) service. Multicast (ASM) service.
The PIM-SM specification assumes that SM operates only in one PIM The PIM-SM specification assumes that SM operates only in one PIM
domain. MSDP is used to enable the use of multiple PIM domains by domain. MSDP is used to enable the use of multiple PIM domains by
distributing the required information about active multicast sources distributing the required information about active multicast sources
to other PIM domains. Due to breaking the Internet multicast to other PIM domains. Due to breaking the Internet multicast
infrastructure down to multiple PIM domains, MSDP also enables the infrastructure down to multiple PIM domains, MSDP also enables the
possibility to set policy on the visibility of the groups and possibility of setting policy on the visibility of the groups and
sources. sources.
Transit IP providers typically deploy MSDP to be part of the global Transit IP providers typically deploy MSDP to be part of the global
multicast infrastructure by connecting to their upstream and peer multicast infrastructure by connecting to their upstream and peer
multicast networks using MSDP. multicast networks using MSDP.
Edge multicast networks typically have two choices: to use their Edge multicast networks typically have two choices: to use their
Internet providers RP, or to have their own RP and connect it to Internet providers' RP, or to have their own RP and connect it to
their ISP using MSDP. By deploying their own RP and MSDP, one can their ISP using MSDP. By deploying their own RP and MSDP, they can
use internal multicast groups which are not visible to the provider's use internal multicast groups that are not visible to the provider's
RP. This helps with internal multicast being able to continue to work RP. This helps internal multicast be able to continue to work in the
in the event there is a problem with connectivity to the provider or event that there is a problem with connectivity to the provider or
the provider's RP/MSDP is experiencing difficulties. In the simplest that the provider's RP/MSDP is experiencing difficulties. In the
cases where no internal multicast groups are necessary, there is simplest cases, where no internal multicast groups are necessary,
often no need to deploy MSDP. there is often no need to deploy MSDP.
1.1. BCP, Experimental Protocols and Normative References 1.1. BCP, Experimental Protocols, and Normative References
This document describes the best current practice for a widely This document describes the best current practice for a widely
deployed Experimental protocol, MSDP. There is no plan to advance the deployed Experimental protocol, MSDP. There is no plan to advance
MSDP's status (for example, to Proposed Standard). The reasons for the MSDP's status (for example, to Proposed Standard). The reasons
this include: for this include:
o MSDP was originally envisioned as a temporary protocol to be o MSDP was originally envisioned as a temporary protocol to be
supplanted by whatever the IDMR working group produced as an supplanted by whatever the IDMR working group produced as an
inter-domain protocol. However, the IDMR WG (or subsequently, inter-domain protocol. However, the IDMR WG (or subsequently, the
the BGMP WG) never produced a protocol that could be deployed BGMP WG) never produced a protocol that could be deployed to
to replace MSDP. replace MSDP.
o One of the primary reasons given for MSDP to be classified as o One of the primary reasons given for MSDP to be classified as
Experimental was that the MSDP Working Group came up with Experimental was that the MSDP Working Group came up with
modifications to the protocol that the WG thought made it modifications to the protocol that the WG thought made it better
better but that implementors didn't see any reasons to but that implementors didn't see any reasons to deploy. Without
deploy. Without these modifications (e.g., UDP or GRE these modifications (e.g., UDP or GRE encapsulation), MSDP can
encapsulation), MSDP can have negative consequences to initial have negative consequences to initial packets in datagram streams.
packets in datagram streams.
o Scalability: Although we don't know what the hard limits might o Scalability: Although we don't know what the hard limits might be,
be, readvertising everything you know every 60 seconds clearly readvertising everything you know every 60 seconds clearly limits
limits the amount of state you can advertise. the amount of state you can advertise.
o MSDP reached near ubiquitous deployment as the de-facto o MSDP reached nearly ubiquitous deployment as the de facto standard
standard inter-domain multicast protocol in the IPv4 Internet. inter-domain multicast protocol in the IPv4 Internet.
o No consensus could be reached regarding the reworking of MSDP o No consensus could be reached regarding the reworking of MSDP to
to address the many concerns of various constituencies within address the many concerns of various constituencies within the
the IETF. As a result, a decision was taken to document what is IETF. As a result, a decision was taken to document what is
(ubiquitously) deployed and move that document to Experimental. (ubiquitously) deployed and to move that document to Experimental.
While advancement of MSDP to Proposed Standard was considered, While advancement of MSDP to Proposed Standard was considered, for
for the reasons mentioned above, it was immediately discarded. the reasons mentioned above, it was immediately discarded.
o The advent of protocols such as source specific multicast and o The advent of protocols such as source-specific multicast and bi-
bi-directional PIM, as well as embedded RP techniques for directional PIM, as well as embedded RP techniques for IPv6, have
IPv6, have further reduced consensus that a replacement further reduced consensus that a replacement protocol for MSDP for
protocol for MSDP for the IPv4 Internet is required. the IPv4 Internet is required.
The RFC Editor's policy regarding references is that they be split The RFC Editor's policy regarding references is that they be split
into two categories known as "normative" and "informative". Normative into two categories known as "normative" and "informative".
references specify those documents which must be read to understand Normative references specify those documents that must be read for
or implement the technology in an RFC (or whose technology must be one to understand or implement the technology in an RFC (or whose
present for the technology in the new RFC to work) [RFCED]. In order technology must be present for the technology in the new RFC to work)
to understand this document, one must also understand both the PIM [RFCED]. In order to understand this document, one must also
and MSDP documents. As a result, references to these documents are understand both the PIM and MSDP documents. As a result, references
normative. to these documents are normative.
The IETF has adopted the policy that BCPs must not have normative The IETF has adopted the policy that BCPs must not have normative
references to Experimental protocols. However, this document is a references to Experimental protocols. However, this document is a
special case in that the underlying Experimental document (MSDP) is special case in that the underlying Experimental document (MSDP) is
not planned to be advanced to Proposed Standard. not planned to be advanced to Proposed Standard.
The MBONED Working Group requests approval under the Variance The MBONED Working Group has requested approval under the Variance
Procedure as documented in RFC 2026 [RFC2026]. Procedure as documented in RFC 2026 [RFC2026]. The IESG followed the
Variance Procedure and, after an additional 4 week IETF Last Call,
Note to RFC-Editor: If IETF/IESG approves this, please change the evaluated the comments and status, and has approved this document.
above sentence into: The MBONED Working Group has requested approval
under the Variance Procedure as documented in RFC 2026 [RFC2026].
The IESG followed the Variance Procedure, and after an additional 4
week IETF Last Call evaluated the comments and status and has
approved this document.
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 [RFC 2119]. document are to be interpreted as described in RFC 2119 [RFC 2119].
2. Inter-domain MSDP Peering Scenarios 2. Inter-domain MSDP Peering Scenarios
The following sections describe the most common inter-domain MSDP The following sections describe the most common inter-domain MSDP
peering possibilities and their deployment options. peering possibilities and their deployment options.
2.1. Peering between PIM Border Routers 2.1. Peering between PIM Border Routers
In this case, the MSDP peers within the domain have their own RP In this case, the MSDP peers within the domain have their own RP
located within a bounded PIM domain. In addition, the domain will located within a bounded PIM domain. In addition, the domain will
typically have its own Autonomous System (AS) number and one or more typically have its own Autonomous System (AS) number and one or more
MBGP speakers. The domain may also have multiple MSDP speakers. Each MBGP speakers. The domain may also have multiple MSDP speakers.
border router has an MSDP and MBGP peering with its peer routers. Each border router has an MSDP and MBGP peering with its peer
These external MSDP peering deployments typically configure the MBGP routers. These external MSDP peering deployments typically configure
peering and MSDP peering using the same directly connected next hop the MBGP peering and MSDP peering using the same directly connected
peer IP address or other IP address from the same router. Typical next hop peer IP address or other IP address from the same router.
deployments of this type are providers who have a direct peering with Typical deployments of this type are providers who have a direct
other providers, providers peering at an exchange, or providers who peering with other providers, providers peering at an exchange, or
use their edge router to MSDP/MBGP peer with customers. providers who use their edge router to MSDP/MBGP peer with customers.
For a direct peering inter-domain environment to be successful, the For a direct peering inter-domain environment to be successful, the
first AS in the MBGP best path to the originating RP should be the first AS in the MBGP best path to the originating RP should be the
same as the AS of the MSDP peer. As an example, consider the same as the AS of the MSDP peer. As an example, consider the
following topology: following topology:
AS1----AS2----AS4 AS1----AS2----AS4
| / | /
| / | /
| / | /
AS3 AS3
In this case, AS4 receives a Source Active (SA) message, originated In this case, AS4 receives a Source Active (SA) message, originated
by AS1, from AS2. AS2 also has an MBGP peering with AS4. The MBGP by AS1, from AS2. AS2 also has an MBGP peering with AS4. The MBGP
first hop AS from AS4, in the best path to the originating RP, is first hop AS from AS4, in the best path to the originating RP, is
AS2. The AS of the sending MSDP peer is also AS2. In this case, the AS2. The AS of the sending MSDP peer is also AS2. In this case, the
peer-Reverse Path Forwarding check (peer-RPF check) passes and the SA peer-Reverse Path Forwarding check (peer-RPF check) passes, and the
message is forwarded. SA message is forwarded.
A peer-RPF failure would occur in this topology when the MBGP first A peer-RPF failure would occur in this topology when the MBGP first
hop AS, in the best path to the originating RP, is AS2 while the hop AS, in the best path to the originating RP, is AS2 and the origin
origin AS of the sending MSDP peer is AS3. This reliance upon BGP AS AS of the sending MSDP peer is AS3. This reliance upon BGP AS PATH
PATH information prevents endless looping of SA packets. information prevents endless looping of SA packets.
Router code, which has adopted the latest rules in the MSDP draft, Router code, which has adopted the latest rules in the MSDP document,
will relax the rules Between AS's a bit. In the following topology we will relax the rules between AS's a bit. In the following topology,
have an MSDP peering between AS1<->AS3 and AS3<->AS4: we have an MSDP peering between AS1<->AS3 and AS3<->AS4:
RP RP
AS1----AS2----AS3----AS4 AS1----AS2----AS3----AS4
If the first AS in best path to the RP does not equal the MSDP peer, If the first AS in best path to the RP does not equal the MSDP peer,
MSDP peer-RPF fails. So AS1 cannot MSDP peer with AS3 since AS2 is MSDP peer-RPF fails. So AS1 cannot MSDP peer with AS3, since AS2 is
the first AS in the MBGP best path to AS4 RP. With the latest MSDP the first AS in the MBGP best path to AS4 RP. With the latest MSDP
draft compliant code, AS 1 will choose the peer in the closest AS document compliant code, AS1 will choose the peer in the closest AS
along best AS path to the RP. AS1 will then accept SA's coming from along best AS path to the RP. AS1 will then accept SA's coming from
AS3. If there are multiple MSDP peers to routers within the same AS, AS3. If there are multiple MSDP peers to routers within the same AS,
the peer with the highest IP address is chosen as the RPF peer. the peer with the highest IP address is chosen as the RPF peer.
2.2. Peering between Non-Border Routers 2.2. Peering between Non-Border Routers
When MSDP peering between border routers, intra-domain MSDP For MSDP peering between border routers, intra-domain MSDP
scalability is restricted because it is necessary to also maintain scalability is restricted because it is necessary to also maintain
MBGP and MSDP peerings internally towards their border routers. MBGP and MSDP peerings internally towards their border routers.
Within the intra-domain, the border router becomes the announcer of Within the intra-domain, the border router becomes the announcer of
the next hop towards the originating RP. This requires that all the next hop towards the originating RP. This requires that all
intra-domain MSDP peerings must mirror the MBGP path back towards the intra-domain MSDP peerings mirror the MBGP path back towards the
border router. External MSDP (eMSDP) peerings rely upon AS path for border router. External MSDP (eMSDP) peerings rely upon AS path for
peer RPF checking, while internal MSDP (iMSDP) peerings rely upon the peer RPF checking, while internal MSDP (iMSDP) peerings rely upon the
announcer of the next hop. announcer of the next hop.
While the eMBGP peer is typically directly connected between border While the eMBGP peer is typically directly connected between border
routers, it is common for the eMSDP peer to be located deeper into routers, it is common for the eMSDP peer to be located deeper into
the transit providers AS. Providers, which desire more flexibility in the transit provider's AS. Providers, which desire more flexibility
MSDP peering placement, commonly choose a few dedicated routers in MSDP peering placement, commonly choose a few dedicated routers
within their core network for the inter-domain MSDP peerings to their within their core networks for the inter-domain MSDP peerings to
customers. These core MSDP routers will also typically be in the their customers. These core MSDP routers will also typically be in
providers intra-domain MSDP mesh group and configured for Anycast RP. the provider's intra-domain MSDP mesh group and be configured for
All multicast routers in the providers AS should statically point to Anycast RP. All multicast routers in the provider's AS should
the Anycast RP address. Static RP assignment is the most commonly statically point to the Anycast RP address. Static RP assignment is
used method for group to RP mapping due to its deterministic nature. the most commonly used method for group-to-RP mapping due to its
Auto-RP [AUTORP] and/or the Bootstrap Router (BSR) [BSR] dynamic RP deterministic nature. Auto-RP [RFC4601] and/or the Bootstrap Router
mapping mechanisms could be also used to disseminate RP information (BSR) [BSR] dynamic RP mapping mechanisms could also be used to
within the provider's network disseminate RP information within the provider's network
For an SA message to be accepted in this (multi-hop peering) For an SA message to be accepted in this (multi-hop peering)
environment, we rely upon the next (or closest, with latest MSDP environment, we rely upon the next (or closest, with latest MSDP
spec) AS in the best path towards originating RP for the RPF check. spec) AS in the best path towards the originating RP for the RPF
The MSDP peer address should be in the same AS as the AS of the check. The MSDP peer address should be in the same AS as the AS of
border router's MBGP peer. The MSDP peer address should be advertised the border router's MBGP peer. The MSDP peer address should be
via MBGP. advertised via MBGP.
For example, using the diagram below, if customer R1 router is MBGP For example, in the diagram below, if customer R1 router is MBGP
peering with R2 router and if R1 is MSDP peering with R3 router, then peering with the R2 router and if R1 is MSDP peering with the R3
R2 and R3 must be in the same AS (or appear, to AS1, to be from the router, then R2 and R3 must be in the same AS (or must appear, to
same AS in the event private AS numbers are deployed). The MSDP peer AS1, to be from the same AS in the event that private AS numbers are
with the highest IP address will be chosen as the MSDP RPF peer. R1 deployed). The MSDP peer with the highest IP address will be chosen
must also have the MSDP peer address of R3 in its MBGP table. as the MSDP RPF peer. R1 must also have the MSDP peer address of R3
in its MBGP table.
+--+ +--+ +--+ +--+ +--+ +--+
|R1|----|R2|----|R3| |R1|----|R2|----|R3|
+--+ +--+ +--+ +--+ +--+ +--+
AS1 AS2 AS2 AS1 AS2 AS2
From R3's perspective, AS1 (R1) is the MBGP next AS in the best path From R3's perspective, AS1 (R1) is the MBGP next AS in the best path
towards the originating RP. As long as AS1 is the next AS (or towards the originating RP. As long as AS1 is the next AS (or
closest) in the best path towards the originating RP, RPF will closest) in the best path towards the originating RP, RPF will
succeed on SAs arriving from R1. succeed on SAs arriving from R1.
In contrast, with the single hop scenario, with R2 (instead of R3) In contrast, with the single hop scenario, with R2 (instead of R3)
border MSDP peering with R1 border, R2's MBGP address becomes the border MSDP peering with R1 border, R2's MBGP address becomes the
announcer of the next hop for R3, towards the originating RP, and R3 announcer of the next hop for R3, towards the originating RP, and R3
must peer with that R2 address. And all AS2 intra-domain MSDP peers must peer with that R2 address. Moreover, all AS2 intra-domain MSDP
need to follow iMBGP (or other IGP) peerings towards R2 since iMSDP peers need to follow iMBGP (or other IGP) peerings towards R2 since
has a dependence upon peering with the address of the MBGP (or other iMSDP has a dependence upon peering with the address of the MBGP (or
IGP) announcer of the next hop. other IGP) announcer of the next hop.
2.3. MSDP Peering without BGP 2.3. MSDP Peering without BGP
In this case, an enterprise maintains its own RP and has an MSDP In this case, an enterprise maintains its own RP and has an MSDP
peering with their service provider, but does not BGP peer with them. peering with its service provider but does not BGP peer with them.
MSDP relies upon BGP path information to learn the MSDP topology for MSDP relies upon BGP path information to learn the MSDP topology for
the SA peer-RPF check. MSDP can be deployed without BGP, however, and the SA peer-RPF check. MSDP can be deployed without BGP, however,
as a result there are some special cases where the requirement to and as a result, there are some special cases where the requirement
perform an peer-RPF check on the BGP path information is suspended. to perform a peer-RPF check on the BGP path information is suspended.
These cases are: These cases are:
o There is only a single MSDP peer connection o There is only a single MSDP peer connection.
o A default peer (default MSDP route) is configured
o The originating RP is directly connected o A default peer (default MSDP route) is configured.
o A mesh group is used o The originating RP is directly connected.
o An implementation is used which allows for an MSDP peer-RPF o A mesh group is used.
check using an IGP
These cases are when there is only a single MSDP peer connection, a o An implementation is used that allows for an MSDP peer-RPF check
default peer (default MSDP route) is configured, the originating RP using an IGP.
is directly connected, a mesh group is used, or an implementation is
used which allows for an MSDP peer-RPF check using an IGP.
An enterprise will typically configure a unicast default route from An enterprise will typically configure a unicast default route from
their border router to the provider's border router and then MSDP its border router to the provider's border router and then MSDP peer
peer with the provider's MSDP router. If internal MSDP peerings are with the provider's MSDP router. If internal MSDP peerings are also
also used within the enterprise, then an MSDP default peer will need used within the enterprise, then an MSDP default peer will need to be
to be configured on the border router pointing to the provider. In configured on the border router that points to the provider. In this
this way, all external multicast sources will be learned and internal way, all external multicast sources will be learned, and internal
sources can be advertised. If only a single MSDP peering was used (no sources can be advertised. If only a single MSDP peering was used
internal MSDP peerings) towards the provider, then this stub site (no internal MSDP peerings) towards the provider, then this stub site
will MSDP default peer towards the provider and skip the peer-RPF will MSDP default peer towards the provider and skip the peer-RPF
check. check.
2.4. MSDP Peering at a Multicast Exchange 2.4. MSDP Peering at a Multicast Exchange
Multicast exchanges allow multicast providers to peer at a common IP Multicast exchanges allow multicast providers to peer at a common IP
subnet (or by using point to point virtual LANs) and share MSDP SA subnet (or by using point-to-point virtual LANs) and share MSDP SA
updates. Each provider will MSDP and MBGP peer with each others updates. Each provider will MSDP and MBGP peer with each others
directly connected exchange IP address. Each exchange router will directly connected exchange IP address. Each exchange router will
send/receive SAs to/from their MSDP peers. They will then be able to send/receive SAs to/from their MSDP peers. They will then be able to
forward SAs throughout their domain to their customers and any direct forward SAs throughout their domain to their customers and any direct
provider peerings. provider peerings.
3. Intra-domain MSDP Peering Scenarios 3. Intra-domain MSDP Peering Scenarios
The following sections describe the different intra-domain MSDP The following sections describe the different intra-domain MSDP
peering possibilities and their deployment options. peering possibilities and their deployment options.
3.1. Peering between MSDP and MBGP Configured Routers 3.1. Peering between MSDP- and MBGP-Configured Routers
The next hop IP address of the iBGP peer is typically used for the The next hop IP address of the iBGP peer is typically used for the
MSDP peer-RPF check (IGP can also be used). This is different from MSDP peer-RPF check (IGP can also be used). This is different from
the inter-domain BGP/MSDP case, where AS path information is used for the inter-domain BGP/MSDP case, where AS path information is used for
the peer-RPF check. For this reason, it is necessary for the IP the peer-RPF check. For this reason, it is necessary for the IP
address of the MSDP peer connection be the same as the internal MBGP address of the MSDP peer connection to be the same as the internal
peer connection whether or not the MSDP/MBGP peers are directly MBGP peer connection whether or not the MSDP/MBGP peers are directly
connected. A successful deployment would be similar to the following: connected. A successful deployment would be similar to the
following:
+----+ +----+
| Rb | 3.3.3.3 | Rb | 3.3.3.3
/ +----+ / +----+
AS1 AS2 / | AS1 AS2 / |
+---+ +--+ / | +---+ +--+ / |
|RP1|---------|Ra| | |RP1|---------|Ra| |
+---+ +--+ | +---+ +--+ |
1.1.1.1 2.2.2.2 | 1.1.1.1 2.2.2.2 |
\ | \ |
\ | \ |
\ +-----+ \ +-----+
| RP2 | | RP2 |
+-----+ +-----+
Where RP2 MSDP and MBGP peers with Ra (using 2.2.2.2) and with Rb where RP2 MSDP and MBGP peers with Ra (using 2.2.2.2) and with Rb
(using 3.3.3.3). When the MSDP SA update arrives on RP2 from Ra, the (using 3.3.3.3). When the MSDP SA update arrives on RP2 from Ra, the
MSDP RPF check for 1.1.1.1 passes because RP2 receives the SA update MSDP RPF check for 1.1.1.1 passes because RP2 receives the SA update
from MSDP peer 2.2.2.2 which is also the correct MBGP next hop for from MSDP peer 2.2.2.2, which is also the correct MBGP next hop for
1.1.1.1. 1.1.1.1.
When RP2 receives the same SA update from MSDP peer 3.3.3.3, the MBGP When RP2 receives the same SA update from MSDP peer 3.3.3.3, the MBGP
lookup for 1.1.1.1 shows a next hop of 2.2.2.2 so RPF correctly lookup for 1.1.1.1 shows a next hop of 2.2.2.2, so RPF correctly
fails, preventing a loop. fails, preventing a loop.
This deployment could also fail on an update from Ra to RP2 if RP2 This deployment could also fail on an update from Ra to RP2 if RP2
was MBGP peering to an address other than 2.2.2.2 on Ra. Intra-domain was MBGP peering to an address other than 2.2.2.2 on Ra. Intra-
deployments must have MSDP and MBGP (or other IGP) peering addresses domain deployments must have MSDP and MBGP (or other IGP) peering
which match, unless a method to skip the peer-RPF check is deployed. addresses that match, unless a method to skip the peer-RPF check is
deployed.
3.2. MSDP Peer is not BGP Peer (or no BGP Peer) 3.2. MSDP Peer Is Not BGP Peer (or No BGP Peer)
This is a common MSDP intra-domain deployment in environments where This is a common MSDP intra-domain deployment in environments where
few routers are running MBGP or where the domain is not running MBGP. few routers are running MBGP or where the domain is not running MBGP.
The problem here is that the MSDP peer address needs to be the same The problem here is that the MSDP peer address needs to be the same
as the MBGP peer address. To get around this requirement, the intra- as the MBGP peer address. To get around this requirement, the intra-
domain MSDP RPF rules have been relaxed in the following topologies: domain MSDP RPF rules have been relaxed in the following topologies:
o By configuring the MSDP peer as a mesh group peer o By configuring the MSDP peer as a mesh group peer.
o By having the MSDP peer be the only MSDP peer o By having the MSDP peer be the only MSDP peer.
o By configuring a default MSDP peer.
o By configuring a default MSDP peer
o By peering with the originating RP. o By peering with the originating RP.
o By relying upon an IGP for MSDP peer-RPF o By relying upon an IGP for MSDP peer-RPF.
The common choice around the intra-domain BGP peering requirement, The common choice around the intra-domain BGP peering requirement,
when more than one MSDP peer is configured, is to deploy MSDP mesh when more than one MSDP peer is configured, is to deploy MSDP mesh
groups. When a MSDP mesh group is deployed, there is no RPF check on groups. When an MSDP mesh group is deployed, there is no RPF check
arriving SA messages when received from a mesh group peer. on arriving SA messages when they are received from a mesh group
Subsequently, SA messages are always accepted from mesh group peers. peer. Subsequently, SA messages are always accepted from mesh group
MSDP mesh groups were developed to reduce the amount of SA traffic in peers. MSDP mesh groups were developed to reduce the amount of SA
the network since SAs, which arrive from a mesh group peer, are not traffic in the network since SAs, which arrive from a mesh group
flooded to peers within that same mesh group. Mesh groups must be peer, are not flooded to peers within that same mesh group. Mesh
fully meshed. groups must be fully meshed.
If recent (but not currently widely deployed) router code is running If recent (but not currently widely deployed) router code is running
which is fully complaint with the latest MSDP draft, another option, that is fully compliant with the latest MSDP document, another
to work around not having BGP to MSDP RPF peer, is to RPF using an option, to work around not having BGP to MSDP RPF peer, is to RPF
IGP like OSPF, IS-IS, RIP, etc. This new capability will allow for using an IGP like OSPF, IS-IS, RIP, etc. This new capability will
enterprise customers, who are not running BGP and who don't want to allow for enterprise customers, who are not running BGP and who don't
run mesh groups, to use their existing IGP to satisfy the MSDP peer- want to run mesh groups, to use their existing IGP to satisfy the
RPF rules. MSDP peer-RPF rules.
3.3. Hierarchical Mesh Groups 3.3. Hierarchical Mesh Groups
Hierarchal Mesh Groups are occasionally deployed in intra-domain Hierarchical mesh groups are occasionally deployed in intra-domain
environments where there are a large number of MSDP peers. Allowing environments where there are a large number of MSDP peers. Allowing
multiple mesh groups to forward to one another can reduce the number multiple mesh groups to forward to one another can reduce the number
of MSDP peerings per router (due to the full mesh requirement) and of MSDP peerings per router (due to the full mesh requirement) and
hence reduce router load. A good hierarchical mesh group hence reduce router load. A good hierarchical mesh group
implementation (one which prevents looping) contains a core mesh implementation (one that prevents looping) contains a core mesh group
group in the backbone and these core routers serve as mesh group in the backbone, and these core routers serve as mesh group
aggregation routers: aggregation routers:
[R2]{A,2} [R2]{A,2}
/ \ / \
/ \ / \
/ \ / \
/ \ / \
/ \ / \
/ \ / \
/ \ / \
{A,1}[R1]-------------[R3]{A,3} {A,1}[R1]-------------[R3]{A,3}
In this example, R1, R2, R3 are in MSDP mesh group A (the core mesh In this example, R1, R2, and R3 are in MSDP mesh group A (the core
group) and each serves as MSDP aggregation routers for their leaf (or mesh group), and each serves as MSDP aggregation routers for their
second tier) mesh groups 1, 2, and 3. Since SA messages received from leaf (or second tier) mesh groups 1, 2, and 3. Since SA messages
a mesh group peer are not forwarded to peers within that same mesh received from a mesh group peer are not forwarded to peers within
group, SA messages will not loop. Do not create topologies which that same mesh group, SA messages will not loop. Do not create
connect mesh-groups in a loop. In the above example for instance, topologies that connect mesh groups in a loop. In the above example,
second tier mesh-groups 1, 2, and 3 must not directly exchange SA for instance, second-tier mesh groups 1, 2, and 3 must not directly
messages with each other or an endless SA loop will occur. exchange SA messages with each other or an endless SA loop will
occur.
Redundancy, between mesh groups, will also cause a loop and is Redundancy between mesh groups will also cause a loop and is
subsequently not available with Hierarchical mesh groups. For subsequently not available with hierarchical mesh groups. For
instance, assume R3 had two routers connecting its leaf mesh group 3 instance, assume that R3 had two routers connecting its leaf mesh
with the core mesh group A. A loop would be created between mesh group 3 with the core mesh group A. A loop would be created between
group 3 and mesh group A because each mesh group must be fully meshed mesh group 3 and mesh group A because each mesh group must be fully
between peers. meshed between peers.
3.4. MSDP and Route Reflectors 3.4. MSDP and Route Reflectors
BGP requires all iBGP speakers, that are not route-reflector clients BGP requires all iBGP speakers that are not route-reflector clients
or confederation members, be fully meshed to prevent loops. In the or confederation members be fully meshed to prevent loops. In the
route reflector environment, MSDP requires that the route reflector route reflector environment, MSDP requires that the route reflector
clients peer with the route reflector since the router reflector (RR) clients peer with the route reflector since the router reflector (RR)
is the BGP announcer of the next hop towards the originating RP. The is the BGP announcer of the next hop towards the originating RP. The
RR is not the BGP next hop, but is the announcer of the BGP next hop. RR is not the BGP next hop, but is the announcer of the BGP next hop.
The announcer of the next hop is the address typically used for MSDP The announcer of the next hop is the address typically used for MSDP
peer-RPF checks. For example, consider the following case: peer-RPF checks. For example, consider the following case:
Ra--------RR Ra--------RR
/|\ /|\
/ | \ / | \
A B C A B C
Ra is forwarding MSDP SAs to the route reflector RR. Routers A, B, Ra is forwarding MSDP SAs to the route reflector RR. Routers A, B,
and C also MSDP peer with RR. When RR forwards the SA to A, B, and C, and C also MSDP peer with RR. When RR forwards the SA to A, B, and
these RR clients will accept the SA because RR is the announcer of C, these RR clients will accept the SA because RR is the announcer of
the next hop to the originating RP address. the next hop to the originating RP address.
An SA will peer-RPF fail, if Ra MSDP peers directly with Routers A, An SA will peer-RPF fail if Ra MSDP peers directly with Routers A, B,
B, or C, because the announcer of the next hop is RR, but the SA or C because the announcer of the next hop is RR but the SA update
update came from Ra. Proper deployment is to have RR clients MSDP came from Ra. Proper deployment is to have RR clients MSDP peer with
peer with the RR. MSDP mesh groups may be used to work around this the RR. MSDP mesh groups may be used to work around this
requirement. External MSDP peerings will also prevent this requirement. External MSDP peerings will also prevent this
requirement since the next AS is compared between MBGP and MSDP requirement since the next AS is compared between MBGP and MSDP
peerings, rather than the IP address of the announcer of the next peerings, rather than the IP address of the announcer of the next
hop. hop.
Some recent MSDP implementations conform to the latest MSDP draft Some recent MSDP implementations conform to the latest MSDP document,
which relaxes the requirement of peering with the Advertiser of the which relaxes the requirement of peering with the Advertiser of the
Next Hop (the Route Reflector). This new rule allows for peering with next hop (the Route Reflector). This new rule allows for peering
the Next-Hop, in addition to the Advertiser of the next hop. In the with the next hop, in addition to the Advertiser of the next hop. In
example above, for instance, if Ra is the Next-Hop (perhaps due to the example above, for instance, if Ra is the next hop (perhaps due
using BGP's Next hop self attribute) and if routers A,B,C are peering to using BGP's next hop self attribute), and if routers A, B, and C
with Ra, the SA's received from Ra will now succeed. are peering with Ra, the SA's received from Ra will now succeed.
3.5. MSDP and Anycast RPs 3.5. MSDP and Anycast RPs
A network, with multiple RPs, can achieve RP load sharing and A network with multiple RPs can achieve RP load sharing and
redundancy by using the Anycast RP mechanism in conjunction with MSDP redundancy by using the Anycast RP mechanism in conjunction with MSDP
mesh groups [RFC3446]. This mechanism is a common deployment mesh groups [RFC3446]. This mechanism is a common deployment
technique used within a domain by service providers and enterprises technique used within a domain by service providers and enterprises
which deploy several RPs within their domain. These RPs will each that deploy several RPs within their domains. These RPs will each
have the same IP address configured on a Loopback interface (making have the same IP address configured on a Loopback interface (making
this the Anycast address). These RPs will MSDP peer with each other this the Anycast address). These RPs will MSDP peer with each other
using a separate loopback interface and are part of the same fully using a separate loopback interface and are part of the same fully
meshed MSDP mesh group. This loopback interface, used for MSDP meshed MSDP mesh group. This loopback interface, used for MSDP
peering, will typically also be used for the MBGP peering. All peering, will typically also be used for the MBGP peering. All
routers within the provider's domain will learn of the Anycast RP routers within the provider's domain will learn of the Anycast RP
address either through Auto-RP, BSR, or a static RP assignment. Each address through Auto-RP, BSR, or a static RP assignment. Each
designated router in the domain will send source registers and group designated router in the domain will send source registers and group
joins to the Anycast RP address. Unicast routing will direct those joins to the Anycast RP address. Unicast routing will direct those
registers and joins to the nearest Anycast RP. If a particular registers and joins to the nearest Anycast RP. If a particular
Anycast RP router fails, unicast routing will direct subsequent Anycast RP router fails, unicast routing will direct subsequent
registers and joins to the nearest Anycast RP. That RP will then registers and joins to the nearest Anycast RP. That RP will then
forward an MSDP update to all peers within the Anycast MSDP mesh forward an MSDP update to all peers within the Anycast MSDP mesh
group. Each RP will then forward (or receive) the SAs to (from) group. Each RP will then forward (or receive) the SAs to (from)
external customers and providers. external customers and providers.
4. Security Considerations 4. Security Considerations
An MSDP service should be secured by explicitly controlling the state An MSDP service should be secured by explicitly controlling the state
which is created by, and passed within, the MSDP service. As with that is created by, and passed within, the MSDP service. As with
unicast routing state, MSDP state should be controlled locally, at unicast routing state, MSDP state should be controlled locally, at
the edge origination points. Selective filtering at the multicast the edge origination points. Selective filtering at the multicast
service edge helps ensure that only intended sources result in SA service edge helps ensure that only intended sources result in SA
message creation, and this control helps to reduce the likelihood of message creation, and this control helps to reduce the likelihood of
state-aggregation related problems in the core. There are a variety state-aggregation related problems in the core. There are a variety
of points where local policy should be applied to the MSDP service. of points where local policy should be applied to the MSDP service.
4.1. Filtering SA messages 4.1. Filtering SA Messages
The process of originating SA messages should be filtered to ensure The process of originating SA messages should be filtered to ensure
only intended local sources are resulting in SA message origination. that only intended local sources are resulting in SA message
In addition, MSDP speakers should filter on which SA messages get origination. In addition, MSDP speakers should filter which SA
received and forwarded. messages get received and forwarded.
Typically there is a fair amount of (S,G) state in a PIM-SM domain Typically, there is a fair amount of (S,G) state in a PIM-SM domain
that is local to the domain. However, without proper filtering, sa- that is local to the domain. However, without proper filtering, SA
messages containing these local (S,G) announcements may be advertised messages containing these local (S,G) announcements may be advertised
to the global MSDP infrastructure. Examples of this includes domain to the global MSDP infrastructure. Examples of this include domain-
local applications that use global IP multicast addresses and sources local applications that use global IP multicast addresses and sources
that use RFC 1918 addresses [RFC1918]. To improve on the scalability that use RFC 1918 addresses [RFC1918]. To improve on the scalability
of MSDP and to avoid global visibility of domain local (S,G) of MSDP and to avoid global visibility of domain local (S,G)
information, an external SA filter list is recommended to help information, an external SA filter list is recommended to help
prevent unnecessary creation, forwarding, and caching of well-known prevent unnecessary creation, forwarding, and caching of well-known
domain local sources. domain local sources.
4.2. SA message state limits 4.2. SA Message State Limits
Proper filtering on SA message origination, receipt, and forwarding Proper filtering on SA message origination, receipt, and forwarding
will significantly reduce the likelihood of unintended and unexpected will significantly reduce the likelihood of unintended and unexpected
spikes in MSDP state However, a sa-cache state limit SHOULD be spikes in MSDP state. However, an SA-cache state limit SHOULD be
configured as a final safeguard to state spikes. When an MSDP peering configured as a final safeguard to state spikes. When an MSDP
has reached a stable state (i.e., when the peering has been peering has reached a stable state (i.e., when the peering has been
established and the initial SA state has been transferred), it may established and the initial SA state has been transferred), it may
also be desirable to configure a rate limiter for the creation of new also be desirable to configure a rate limiter for the creation of new
SA state entries. SA state entries.
5. IANA Considerations 5. Acknowledgements
This document creates no new requirements on IANA namespaces
[RFC2434].
6. Acknowledgments
The authors would like to thank Pekka Savola, John Zwiebel, Swapna The authors would like to thank Pekka Savola, John Zwiebel, Swapna
Yelamanchi, Greg Shepherd, and Jay Ford for their feedback on earlier Yelamanchi, Greg Shepherd, and Jay Ford for their feedback on earlier
versions of this document. versions of this document.
7. References 6. References
7.1. Normative References
[PIM-SM] Fenner, B., et. al, "Protocol Independent Multicast -
Sparse Mode (PIM-SM): Protocol Specification
(Revised)", draft-ietf-pim-sm-v2-new-09.txt. Work
in progress.
[RFC1771] Rekhter, Y., and T. Li, "A Border Gateway
Protocol 4 (BGP-4)", RFC 1771, March 1995.
[RFC1918] Y. Rekhter, R. Moskowitz, D. Karrenberg, G. de
Groot, E. Lear, "Address Allocation for Private
Internets", RFC 1918, Feburary, 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels" RFC 2119/BCP 14,
March 1997.
[RFC2365] Meyer, D. "Administratively Scoped IP Multicast", 6.1. Normative References
RFC 2365, July, 1998.
[RFC2434] Narten, T., and H. Alvestrand, "Guidelines for [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
Writing an IANA Considerations Section in "Protocol Independent Multicast - Sparse Mode (PIM-SM):
RFCs", RFC 2434/BCP 0026, October, 1998. Protocol Specification (Revised)", RFC 4601, August 2006.
[RFC2858] Bates T., Y. Rekhter, R. Chandra, D. Katz, [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
"Multiprotocol Extensions for BGP-4", RFC 2858, Protocol 4 (BGP-4)", RFC 4271, January 2006.
June 2000.
[RFC3330] IANA, "Special-User IPv4 Addresses", RFC 3330, [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
September 2002. and E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, February 1996.
[RFC3446] Kim, D., et. al., "Anycast Rendezvous Point (RP) [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Mechanism using Protocol Independent Multicast Requirement Levels", BCP 14, RFC 2119, March 1997.
(PIM) and Multicast Source Discovery Protocol
(MSDP)", RFC 3446, January, 2003.
[RFC3618] Meyer, D. and W. Fenner (Editors), "The Multicast [RFC2858] Bates, T., Rekhter, Y., Chandra, R., and D. Katz,
Source Discovery Protocol (MSDP)", RFC 3618, "Multiprotocol Extensions for BGP-4", RFC 2858, June 2000.
October, 2003.
7.2. Informative References [RFC3446] Kim, D., Meyer, D., Kilmer, H., and D. Farinacci, "Anycast
Rendevous Point (RP) mechanism using Protocol Independent
Multicast (PIM) and Multicast Source Discovery Protocol
(MSDP)", RFC 3446, January 2003.
[AUTORP] Fenner, W., et. al., " Protocol Independent [RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery
Multicast - Sparse Mode (PIM-SM): Protocol Protocol (MSDP)", RFC 3618, October 2003.
Specification (Revised)", draft-ietf-pim-sm-v2-new-08.txt,
April, 2004. Work in progress.
[BSR] Fenner, W., et. al., "Bootstrap Router (BSR) 6.2. Informative References
Mechanism for PIM Sparse Mode", draft-ietf-pim-sm-bsr-03.txt,
February, 2003. Work in progress.
[IANA] http://www.iana.org [BSR] Fenner, W., et. al., "Bootstrap Router (BSR) Mechanism for
PIM Sparse Mode", Work in Progress, February 2003.
[RFCED] http://www.rfc-editor.org/policy.html#policy.refs [RFCED] http://www.rfc-editor.org/policy.html
8. Author's Addresses Authors' Addresses
Mike McBride Mike McBride
Cisco Systems Cisco Systems
Email: mcbride@cisco.com
EMail: mcbride@cisco.com
John Meylor John Meylor
Cisco Systems Cisco Systems
Email: jmeylor@cisco.com
EMail: jmeylor@cisco.com
David Meyer David Meyer
Email: dmm@1-4-5.net
9. Full Copyright Statement EMail: dmm@1-4-5.net
Copyright (C) The Internet Society (2004). This document is subject Full Copyright Statement
to the rights, licenses and restrictions contained in BCP 78 and
except as set forth therein, the authors retain all their rights.
This document and translations of it may be copied and furnished to Copyright (C) The Internet Society (2006).
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
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The limited permissions granted above are perpetual and will not be This document is subject to the rights, licenses and restrictions
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retain all their rights.
This document and the information contained herein is provided on an This document and the information contained herein are provided on an
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11. Acknowledgement Acknowledgement
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
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