💾 Archived View for gemini.bortzmeyer.org › rfc-mirror › rfc6625.txt captured on 2021-11-30 at 20:18:30.
-=-=-=-=-=-=-
Internet Engineering Task Force (IETF) E. Rosen, Ed.
Request for Comments: 6625 Cisco Systems, Inc.
Updates: 6514 Y. Rekhter, Ed.
Category: Standards Track Juniper Networks, Inc.
ISSN: 2070-1721 W. Henderickx
Alcatel-Lucent
R. Qiu
Huawei
May 2012
Wildcards in Multicast VPN Auto-Discovery Routes
Abstract
In Multicast Virtual Private Networks (MVPNs), customer multicast
flows are carried in "tunnels" through a service provider's network.
The base specifications for MVPN define BGP multicast VPN "auto-
discovery routes" and specify how to use an auto-discovery route to
advertise the fact that an individual customer multicast flow is
being carried in a particular tunnel. However, those specifications
do not provide a way to specify, in a single such route, that
multiple customer flows are being carried in a single tunnel. Those
specifications also do not provide a way to advertise that a
particular tunnel is to be used by default to carry all customer
flows, except in the case where that tunnel is joined by all the
provider edge routers of the MVPN. This document eliminates these
restrictions by specifying the use of "wildcard" elements in the
customer flow identifiers. With wildcard elements, a single auto-
discovery route can refer to multiple customer flows or even to all
customer flows.
Status of This Memo
This is an Internet Standards Track document.
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
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6625.
Rosen, et al. Standards Track [Page 1]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
Copyright Notice
Copyright (c) 2012 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................3
1.1. Terminology ................................................3
1.2. Wildcards in S-PMSI A-D Routes .............................5
1.3. Use Cases ..................................................5
2. Encoding of Wildcards ...........................................7
3. Finding the Matching S-PMSI A-D Route ...........................8
3.1. Finding the Match for Data Transmission ....................8
3.2. Finding the Match for Data Reception .......................9
3.2.1. Finding the Match for (C-S,C-G) .....................9
3.2.2. Finding the Wildcard Match for (C-*,C-G) ............9
4. Procedures for S-PMSI A-D Routes with Wildcards ................10
4.1. Procedures for All Kinds of Wildcards .....................10
4.2. Procedures for (C-*,C-G) S-PMSI A-D Routes ................11
4.3. Procedures for (C-S,C-*) S-PMSI A-D Routes ................12
4.4. Procedures for (C-*,C-*) S-PMSI A-D Routes ................13
5. Security Considerations ........................................15
6. Acknowledgments ................................................15
7. Normative References ...........................................15
Rosen, et al. Standards Track [Page 2]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
1. Introduction
In Multicast Virtual Private Networks (MVPNs), customer multicast
flows are carried in tunnels through a service provider's network.
The base specifications for MVPN define BGP multicast VPN
"auto-discovery routes" and specify how to use an auto-discovery
route to advertise the fact that an individual customer multicast
flow is being carried in a particular tunnel. However, those
specifications do not provide a way to specify, in a single such
route, that multiple customer flows are being carried in a single
tunnel. Those specifications also do not provide a way to advertise
that a particular tunnel is to be used by default to carry all
customer flows, except in the case where that tunnel is joined by all
the provider edge routers of the MVPN. This document eliminates
these restrictions by specifying the use of "wildcard" elements in
the customer flow identifiers. With wildcard elements, a single
auto-discovery route can refer to multiple customer flows or even to
all customer flows.
1.1. Terminology
This document uses terminology from [MVPN] and, in particular, uses
the prefixes "C-" and "P-", as specified in Section 3.1 of [MVPN], to
distinguish addresses in the "customer address space" from addresses
in the "provider address space". The following terminology and
acronyms are particularly important in this document:
- MVPN
Multicast Virtual Private Network -- a VPN [L3VPN] in which
multicast service is offered.
- VRF
VPN Routing and Forwarding table [L3VPN].
- SP
Service Provider.
- P-tunnel
A tunnel through the network of one or more SPs.
- C-S
Multicast Source. A multicast source address, in the address
space of a customer network.
Rosen, et al. Standards Track [Page 3]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
- C-G
Multicast Group. A multicast group address (destination
address) in the address space of a customer network.
- C-multicast flow or C-flow
A customer multicast flow. Each C-flow is identified by the
ordered pair (source address, group address), where each address
is in the customer's address space. The identifier of a
particular C-flow is usually written as (C-S,C-G).
- RP
A "Rendezvous Point", as defined in [PIM].
- C-RP
A Rendezvous Point whose address is in the customer's address
space.
- Selective P-tunnel
A P-tunnel that is joined only by Provider Edge (PE) routers
that need to receive one or more of the C-flows that are
traveling through that P-tunnel.
- Inclusive P-tunnel
A P-tunnel that is joined by all PE routers that attach to sites
of a given MVPN.
- S-PMSI A-D route
Selective Provider Multicast Service Interface Auto-Discovery
route. Carried in BGP Update messages, these routes are used to
advertise the fact that particular C-flows are bound to (i.e.,
are traveling through) particular P-tunnels.
Familiarity with multicast concepts and terminology [PIM] is also
presupposed.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Rosen, et al. Standards Track [Page 4]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
1.2. Wildcards in S-PMSI A-D Routes
As specified in [MVPN] and [MVPN-BGP], an S-PMSI A-D route advertises
that a particular C-flow is bound to a particular selective P-tunnel.
The identifier of the specified C-flow, e.g., (C-S,C-G), is encoded
into the Network Layer Reachability Information (NLRI) of the S-PMSI
A-D route. The identifier of the specified P-tunnel is encoded into
an attribute (the "PMSI Tunnel Attribute") of the S-PMSI A-D route.
Each S-PMSI A-D route thus specifies a single C-flow. To bind
multiple C-flows to a single P-tunnel, it is necessary to advertise
one S-PMSI A-D route for each C-flow, specifying the same P-tunnel in
each such route.
This document defines OPTIONAL extensions to the procedures and
encodings specified in [MVPN] and [MVPN-BGP]. These extensions
enable a single S-PMSI A-D route to advertise that multiple
C-multicast flows are bound to a single P-tunnel.
The extensions specified in this document are based on the notion of
allowing the NLRI of an S-PMSI A-D route to contain a "wildcard". In
the NLRI encoding, a wildcard can replace the C-S, the C-G, or both.
We use the notation "C-*" to denote a wildcard. The extensions allow
the NLRI to encode three kinds of wildcards: (C-*,C-*), (C-S,C-*),
and (C-*,C-G).
By using wildcards, a PE may be able to reduce the number of S-PMSI
A-D routes it originates, thereby improving the scalability of the
control plane. There is, however, no impact on data plane
scalability, as the number of P-tunnels is not reduced.
Encoding and detailed procedures are specified in subsequent sections
of this document.
1.3. Use Cases
There are a number of situations in which it can be useful to use
wildcards in the NLRI of an S-PMSI A-D route.
- Using a selective P-tunnel as the default tunnel.
There are procedures in [MVPN] and [MVPN-BGP] that allow a PE to
advertise that it is going to use an inclusive P-tunnel as the
P-tunnel on which it will transmit all C-flows by "default".
However, those documents do not provide any way for a PE to
advertise that it is going to use a selective P-tunnel as the
P-tunnel on which it will transmit all C-flows by "default".
Using the extensions defined in this document, a PE can
Rosen, et al. Standards Track [Page 5]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
advertise that it is going to use a selective P-tunnel as its
default P-tunnel. It does so by advertising an S-PMSI A-D route
whose NLRI contains (C-*,C-*).
- Binding multiple C-flows traveling along a customer's Protocol
Independent Multicast - Sparse Mode (PIM-SM) shared tree to a
single P-tunnel.
A PE router may be connected to an MVPN site that contains a
customer RP (C-RP). The C-RP may be the root of one or more
shared trees. In multicast terminology, these are known as
(*,G) trees. By advertising a single S-PMSI A-D route whose
NLRI contains the (C-*,C-G) wildcard, the PE can bind all the
C-flows traveling along a customer's (*,G) tree to a single
P-tunnel. This use case applies only when C-G is a
non-bidirectional ASM (Any Source Multicast) group.
- Binding multiple C-flows with the same C-group address to a
single P-tunnel, even if each such C-flow is traveling along a
customer's PIM source tree.
A PE router may be connected to an MVPN site containing several
multicast sources that are all sending to a common multicast
group, along a customer's PIM source trees. Alternatively, the
PE may be connected to several sites, each containing at least
one source sending to the common multicast group. By
advertising a single S-PMSI A-D route whose NLRI contains
(C-*,C-G), the PE can bind these C-flows to a single P-tunnel.
This use case applies only when the C-group is a
non-bidirectional ASM group.
- Binding multiple C-flows with the same C-group address to a
single P-tunnel, when those C-flows are traveling along a
customer's BIDIR-PIM shared tree.
This use case applies only when the C-group is a BIDIR-PIM
group.
- Binding multiple C-flows from a given C-source to a given
P-tunnel, irrespective of whether those C-flows all have the
same C-group address.
This can be useful when the C-group addresses are SSM (Single
Source Multicast) addresses. Suppose, for example, that a given
source transmits multiple "channels" of information, each with
Rosen, et al. Standards Track [Page 6]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
its own C-group address. It may be desirable to bind all these
channels to a single P-tunnel, without having to advertise an
S-PMSI A-D route for each one.
Of course, a specific C-flow, (C-S,C-G), can always be assigned
individually to a particular P-tunnel by advertising an S-PMSI A-D
route whose NLRI contains (C-S,C-G).
In Section 4, we will sometimes speak of an S-PMSI A-D route being
ignored. When we say the route is "ignored", we do not mean that its
normal BGP processing is not done, but that the route is not
considered when determining which P-tunnel to use when receiving
multicast data, and that the MPLS label values it conveys are not
used. We will use "ignore" in quotes to indicate this meaning.
This document provides procedures only for the case where the
P-tunnels are "unidirectional", i.e., point-to-multipoint. The use
of "bidirectional" (multipoint-to-multipoint) P-tunnels is outside
the scope of this document.
2. Encoding of Wildcards
Per [MVPN-BGP] Section 4.3, the MCAST-VPN NLRI in an S-PMSI A-D route
is encoded as follows:
+-----------------------------------+
| RD (8 octets) |
+-----------------------------------+
| Multicast Source Length (1 octet) |
+-----------------------------------+
| Multicast Source (variable) |
+-----------------------------------+
| Multicast Group Length (1 octet) |
+-----------------------------------+
| Multicast Group (variable) |
+-----------------------------------+
| Originating Router's IP Addr |
+-----------------------------------+
where the "source length" and "group length" fields always have a
non-zero value. This document specifies that a "zero-length" source
or group represents the corresponding wildcard. Specifically,
- A source wildcard is encoded as a zero-length source field.
That is, the "multicast source length" field contains the value
0x00, and the "multicast source" field is omitted.
Rosen, et al. Standards Track [Page 7]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
- A group wildcard is encoded as a zero-length group field. That
is, the "multicast group length" field contains the value 0x00,
and the "multicast group" field is omitted.
3. Finding the Matching S-PMSI A-D Route
This section gives the precise rules for determining the S-PMSI A-D
route that is "matched" by a given (C-S,C-G) or (C-*,C-G). The
procedures in Section 4 will make use of the matching rules defined
in this section.
All matching rules assume the context of a given VRF at a given PE.
The rules that a PE applies to find the S-PMSI A-D route that matches
a (C-S,C-G) C-flow that it needs to transmit are slightly different
than the rules it applies to find the S-PMSI A-D route that matches a
(C-S,C-G) C-flow that it needs to receive. These rules are specified
in Sections 3.1 and 3.2, respectively.
The S-PMSI A-D route that is matched by a given (C-S,C-G) may change
over time, as the result of S-PMSI A-D routes being withdrawn or as a
result of new S-PMSI A-D routes being originated and/or advertised.
In particular, if (C-S,C-G) matches an S-PMSI A-D route whose NLRI
contains (C-*,C-*), the origination or reception of an S-PMSI A-D
route whose NLRI contains (C-S,C-G) may cause (C-S,C-G) to match the
latter route instead. Note also that the S-PMSI A-D route that
matches a given (C-S,C-G) is independent of the order in which the
routes were originated or received.
3.1. Finding the Match for Data Transmission
Consider a given PE; call it PE1. At any given time, for a given VRF
at PE1, there is a (possibly empty) set of S-PMSI A-D routes that PE1
has originated and advertised, but not withdrawn. We will refer to
these routes as "currently originated" by PE1. Suppose that PE1
needs to transmit a particular C-flow (C-S,C-G) to one or more other
PEs. We use the following algorithm to find the S-PMSI A-D route
that the C-flow "matches":
- If there is an S-PMSI A-D route currently originated by PE1,
whose NLRI contains (C-S,C-G), the (C-S,C-G) C-flow matches that
route.
- Otherwise, if there is an S-PMSI A-D route currently originated
by PE1, whose NLRI contains (C-S,C-*), AND if C-G is an SSM
group address, the (C-S,C-G) C-flow matches that route.
Rosen, et al. Standards Track [Page 8]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
- Otherwise, if there is an S-PMSI A-D route currently originated
by PE1, whose NLRI contains (C-*,C-G), AND if C-G is an ASM
group address, the (C-S,C-G) C-flow matches that route.
- Otherwise, if there is an S-PMSI A-D route currently originated
by PE1, whose NLRI contains (C-*,C-*), the (C-S,C-G) C-flow
matches that route.
3.2. Finding the Match for Data Reception
We refer to an S-PMSI A-D route as being "installed" (in a given VRF)
if it has been selected by the BGP decision process as the preferred
route for its NLRI.
An S-PMSI A-D route is considered to be "originated by a given PE" if
that PE's IP address is contained in the "Originating Router's IP
Address" field in the MCAST-VPN NLRI of the route.
3.2.1. Finding the Match for (C-S,C-G)
Suppose that a PE router (call it PE1) needs to receive (C-S,C-G),
and that PE1 has chosen another PE router (call it PE2) as the
"upstream PE" [MVPN] for that flow.
- If there is an installed S-PMSI A-D route originated by PE2,
whose NLRI contains (C-S,C-G), then (C-S,C-G) matches that
route.
- Otherwise, if there is an installed S-PMSI A-D route originated
by PE2, whose NLRI contains (C-S,C-*), AND if C-G is an SSM
multicast group address, then (C-S,C-G) matches that route.
- Otherwise, if there is an installed S-PMSI A-D route originated
by PE2, whose NLRI contains (C-*,C-G), AND if C-G is an ASM
multicast group address, then (C-S,C-G) matches that route.
- Otherwise, if there is an installed S-PMSI A-D route originated
by PE2, whose NLRI contains (C-*,C-*), then (C-S,C-G) matches
that route.
3.2.2. Finding the Wildcard Match for (C-*,C-G)
Suppose that a PE router (call it PE1) needs to receive (C-*,C-G)
traffic. Note that even if (C-*,C-G) matches a non-wildcard S-PMSI
A-D route (as detailed in Section 12.3 of [MVPN-BGP]), it may also
match one or more wildcard S-PMSI A-D routes, as specified below.
Rosen, et al. Standards Track [Page 9]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
If on PE1 there is an installed S-PMSI A-D route originated by PE2,
whose NLRI contains (C-*,C-G), then (C-*,C-G) matches this route if
one of the following conditions holds:
- PE1 determines that PE2 is the "upstream" PE [MVPN] for the C-RP
of C-G, or
- PE1 has installed one or more Source Active A-D routes for C-G
originated by PE2, and for at least one of these routes, PE1
does not have a corresponding (C-S,C-G) state, or
- C-G is a BIDIR-PIM group, or
- Source Active A-D routes are not being used.
If (C-*,C-G) does not match a (C-*,C-G) S-PMSI A-D route from PE2,
but PE1 has an installed (C-*,C-*) S-PMSI A-D route from PE2, then
(C-*,C-G) matches the (C-*,C-*) route if one of the following
conditions holds:
- PE1 determines that PE2 is the "upstream" PE [MVPN] for the C-RP
of C-G, or
- PE1 has installed one or more Source Active A-D routes for C-G
originated by PE2, and for at least one of these routes, PE1
does not have a corresponding (C-S,C-G) state, or
- C-G is a BIDIR-PIM group, or
- Source Active A-D routes are not being used.
4. Procedures for S-PMSI A-D Routes with Wildcards
4.1. Procedures for All Kinds of Wildcards
This document defines procedures for the following uses of the
wildcard in the NLRI of an S-PMSI A-D route:
- (C-*,C-G): Source wildcard, group specified.
- (C-S,C-*): Source specified, group wildcard.
- (C-*,C-*): Source wildcard, group wildcard.
All other wildcard functionality is outside the scope of this
document.
Rosen, et al. Standards Track [Page 10]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
The ability to originate S-PMSI A-D routes with a particular kind of
wildcard is OPTIONAL. However, if a PE has the ability to originate
S-PMSI A-D routes with a particular kind of wildcard, it MUST have
the ability to interpret and correctly process S-PMSI A-D routes with
that kind of wildcard, and it SHOULD have the ability to interpret
and correctly process all three kinds of wildcards.
For a given MVPN, A PE MUST NOT originate S-PMSI A-D routes with a
particular kind of wildcard unless it is known a priori that all PEs
attached to that MVPN have the ability to interpret and correctly
process that kind of wildcard.
The criteria for originating and withdrawing S-PMSI A-D routes with
wildcards are local to the originating PE.
As specified in [MVPN-BGP], an S-PMSI A-D route is carried in the
NLRI field of an MP_REACH_NLRI attribute (see [BGP-MP]). Every
S-PMSI A-D route has a particular address family (IPv4 or IPv6), as
specified in the Address Family Identifier (AFI) field of the
MP_REACH_NLRI attribute. A wildcard in a particular S-PMSI A-D route
always refers only to multicast flows of that same address family.
The procedures specified in this document apply only when the PMSI
Tunnel Attribute of an S-PMSI A-D route specifies a "unidirectional"
P-tunnel. The use of "bidirectional" P-tunnels (e.g., Multipoint-to-
Multipoint Label Switched Paths, BIDIR-PIM trees) is outside the
scope of this document.
In the following sections, an S-PMSI A-D route whose NLRI contains
(C-*,C-G), (C-S,C-*), or (C-*,C-*) will be referred to as a
"(C-*,C-G) route", a "(C-S,C-*) route", or a "(C-*,C-*)" route,
respectively.
4.2. Procedures for (C-*,C-G) S-PMSI A-D Routes
This document specifies the use of (C-*,C-G) S-PMSI A-D routes only
in the case where C-G is an ASM group address. Use of (C-*,C-G)
S-PMSI A-D routes where C-G is an SSM group address is outside the
scope of this document. If a PE receives a (C-*,C-G) S-PMSI A-D
route, and the PE can determine that C-G is an SSM group address, the
PE SHOULD "ignore" this S-PMSI A-D route.
By default, the set of Route Targets carried by a (C-*,C-G) S-PMSI
A-D route originated by a given VRF is the same as the set of Route
Targets carried in the (unicast) VPN-IP routes that originated from
that VRF. An implementation MUST allow the set of Route Targets
Rosen, et al. Standards Track [Page 11]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
carried by the (C-*,C-G) S-PMSI A-D route to be specified by
configuration. In the absence of a configured set of Route Targets,
the route MUST carry the default set of Route Targets.
If a PE needs to transmit packets of a (C-S,C-G) C-flow, and if
(C-S,C-G) matches a (C-*,C-G) S-PMSI A-D route according to the rules
of Section 3.1, then the PE MUST use the P-tunnel advertised in this
route for transmitting that C-flow. (Note that it is impossible for
a given (C-S,C-G) to match both a (C-*,C-G) wildcard and a (C-S,C-*)
wildcard.)
If PIM is being used as the PE-PE control protocol, then if the PE
has (C-*,C-G) and/or (C-S,C-G) state that matches (according to the
procedures of Section 3.2) an S-PMSI A-D route, the PE MUST join the
P-tunnel specified in the PMSI Tunnel Attribute of that route.
If BGP is being used as the PE-PE control protocol, then
- If a given PE has currently originated a C-multicast Shared Tree
Join for (C-*,C-G), and if (C-*,C-G) matches a (C-*,C-G) S-PMSI
A-D route, then the PE applies the procedures of Section 12.3
("Receiving S-PMSI A-D Routes by PEs") of [MVPN-BGP] to that
S-PMSI A-D route.
- Otherwise (the given PE does not have a currently originated
C-multicast Shared Tree Join for (C-*,C-G)), if there are one or
more values of C-S for which the PE has a currently originated
Source Tree Join C-multicast route for (C-S,C-G), the PE MUST
join the tunnels advertised by the S-PMSI A-D routes that match
(according to Section 3.2) each such (C-S,C-G).
- Otherwise, the PE "ignores" the route.
4.3. Procedures for (C-S,C-*) S-PMSI A-D Routes
This document covers the use of (C-S,C-*) S-PMSI A-D routes for only
the C-multicast flows where C-G is an SSM group address. Use of
(C-S,C-*) S-PMSI A-D routes for other C-multicast flows is outside
the scope of this document. Specifically, if a PE receives a
(C-S,C-*) S-PMSI A-D route, and the PE can determine that C-G is not
an SSM group address, the PE SHOULD "ignore" this S-PMSI A-D route.
By default, the set of Route Targets carried by a (C-S,C-*) S-PMSI
A-D route originated by a given VRF is an intersection between the
set of Route Targets carried in the Intra-AS I-PMSI A-D route that
originated from that VRF, and the set of Route Targets carried by the
unicast VPN-IP route to C-S originated from that VRF. An
implementation MUST allow the set of Route Targets carried by the
Rosen, et al. Standards Track [Page 12]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
(C-S,C-*) S-PMSI A-D route to be specified by configuration. In the
absence of a configured set of Route Targets, the route MUST carry
the default set of Route Targets.
If a PE needs to transmit packets of a (C-S,C-G) C-flow, and if
(C-S,C-G) matches a (C-S,C-*) S-PMSI A-D route according to the rules
of Section 3.1, then the PE MUST use the P-tunnel advertised in this
route for transmitting that C-flow. (Note that it is impossible for
a given (C-S,C-G) to match both a (C-*,C-G) wildcard and a (C-S,C-*)
wildcard.)
If PIM is being used as the PE-PE control protocol for distributing
C-multicast routing, and if a given PE needs to receive a (C-S,C-G)
flow, and if (C-S,C-G) matches the (C-S,C-*) S-PMSI A-D route
(according to the procedures of Section 3.2), then the PE MUST join
the P-tunnel specified in the PMSI Tunnel Attribute of that route.
If BGP is being used as the PE-PE control protocol for distributing
C-multicast routing, and if there is some (C-S,C-G) such that (a) the
PE has a currently originated (C-S,C-G) Source Tree Join C-multicast
route, AND (b) the given (C-S,C-G) matches (according to the
procedures of Section 3.2) a (C-S,C-*) S-PMSI A-D route, then PE1
applies the procedures of Section 12.3 ("Receiving S-PMSI A-D Routes
by PEs") of [MVPN-BGP] to the matching S-PMSI A-D route.
4.4. Procedures for (C-*,C-*) S-PMSI A-D Routes
(C-*,C-*) S-PMSI A-D routes are used when, for a given MVPN, a PE has
a policy not to use an I-PMSI for carrying multicast data traffic
originated in the MVPN's site(s) connected to that PE. When the
(C-*,C-*) wildcard is used together with BGP C-multicast routing,
this results in the "S-PMSI only" model, where no I-PMSIs are used at
all for the given MVPN.
A (C-*,C-*) S-PMSI A-D route is originated for a given MVPN by a
given PE only if that PE has been provisioned with the policy to
do so.
When so provisioned, the PE MAY originate the (C-*,C-*) S-PMSI A-D
route as soon as it is enabled to support the given MVPN.
Alternatively, the PE MAY delay originating the route until one of
the following conditions holds:
- The PE-PE protocol for distributing C-multicast routing is PIM,
and for the given MVPN, the PE has some (C-S,C-G) or (C-*,C-G)
state for which the upstream interface is one of the VRF
interfaces for the given MVPN.
Rosen, et al. Standards Track [Page 13]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
- The PE-PE protocol for distributing C-multicast routing is BGP,
and the given PE has received and installed either of the
following:
* a Source Tree Join C-multicast route, with the C-S contained
in the route's NLRI being reachable via one of the given
MVPN's VRF interfaces, or
* a Shared Tree Join C-multicast route, with the C-RP carried in
that route being reachable via one of the given MVPN's VRF
interfaces.
By default, the set of Route Targets carried by a (C-*,C-*) S-PMSI
A-D route originated from a given VRF is the same as the set of Route
Targets carried in the VPN-IP unicast routes originated from that
VRF. An implementation MUST allow the set of Route Targets carried
by the (C-*,C-*) S-PMSI A-D route to be specified by configuration.
In the absence of a configured set of Route Targets, the route MUST
carry the default set of Route Targets, as specified above.
If a PE needs to transmit packets of a (C-S,C-G) C-flow, and if
(C-S,C-G) matches a (C-*,C-*) S-PMSI A-D route according to the rules
of Section 3.1, then the PE MUST use the P-tunnel advertised in this
route for transmitting that C-flow. (Note that it is impossible for
a given (C-S,C-G) to match both a (C-*,C-*) wildcard and any other
wildcard.)
If PIM is being used as the PE-PE control protocol for distributing
C-multicast routing, and if a given PE, say PE1, needs to receive a
(C-S,C-G) flow, and if (C-S,C-G) matches the (C-*,C-*) S-PMSI A-D
route (according to the procedures of Section 3.2), then PE1 MUST
join the P-tunnel specified in the PMSI Tunnel Attribute of that
route.
If BGP is being used as the PE-PE control protocol for distributing
C-multicast routing, then if (and only if) one of the following
conditions holds, the PE applies the procedures of Section 12.3
("Receiving S-PMSI A-D Routes by PEs") of [MVPN-BGP] to the matching
S-PMSI A-D route. The conditions are as follows:
- The PE has a currently originated C-multicast Source Tree Join
route for (C-S,C-G) that matches (according to the procedures of
Section 3.2) the (C-*,C-*) S-PMSI A-D route, or
- The PE has a currently originated a C-multicast Shared Tree Join
route for (C-*,C-G) that matches (according to the procedures of
Section 3.2) the (C-*,C-*) S-PMSI A-D route.
Rosen, et al. Standards Track [Page 14]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
5. Security Considerations
There are no additional security considerations beyond those of
[MVPN] and [MVPN-BGP].
6. Acknowledgments
The authors wish to thank Arjen Boers, Dongling Duan, Apoorva Karan,
Thomas Morin, Keyur Patel, Karthik Subramanian, and Kurt Windisch for
many helpful discussions.
7. Normative References
[BGP-MP] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
January 2007.
[L3VPN] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006.
[MVPN] Rosen, E., Ed., and R. Aggarwal, Ed., "Multicast in
MPLS/BGP IP VPNs", RFC 6513, February 2012.
[MVPN-BGP] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
Encodings and Procedures for Multicast in MPLS/BGP IP
VPNs", RFC 6514, February 2012.
[PIM] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2006.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Rosen, et al. Standards Track [Page 15]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
Authors' Addresses
Rahul Aggarwal
Arktan
EMail: raggarwa_1@yahoo.com
Yiqun Cai
Microsoft
1065 La Avenida
Mountain View, CA 94043
EMail: yiqunc@microsoft.com
Wim Henderickx
Alcatel-Lucent
EMail: wim.henderickx@alcatel-lucent.be
Praveen Muley
Alcatel-Lucent
EMail: Praveen.Muley@alcatel-lucent.com
Ray (Lei) Qiu
2330 Central Expressway
Santa Clara, CA 95050
USA
EMail: rayq@huawei.com
Yakov Rekhter (editor)
Juniper Networks
1194 North Mathilda Ave.
Sunnyvale, CA 94089
EMail: yakov@juniper.net
Rosen, et al. Standards Track [Page 16]
RFC 6625 Wildcards in MVPN A-D Routes May 2012
Eric C. Rosen (editor)
Cisco Systems, Inc.
1414 Massachusetts Avenue
Boxborough, MA 01719
EMail: erosen@cisco.com
IJsbrand Wijnands
Cisco Systems, Inc.
De kleetlaan 6a Diegem 1831
Belgium
EMail: ice@cisco.com
Rosen, et al. Standards Track [Page 17]