Internet DRAFT - draft-raggarwa-l3vpn-bgp-mvpn-extranet
draft-raggarwa-l3vpn-bgp-mvpn-extranet
Network Working Group R. Aggarwal
Internet Draft Juniper Networks
Intended status: Standards Track
Expires: February 2013 Y. Rekhter
Juniper Networks
T. Morin
France Telecom
W. Henderickx
Alcatel-Lucent
P. Muley
Alcatel-Lucent
R. Qiu
Huawei
August 1 2012
Extranet in BGP Multicast VPN (MVPN)
draft-raggarwa-l3vpn-bgp-mvpn-extranet-08.txt
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Abstract
This document describes clarifications and extensions to the
procedures in [BGP-MVPN] for supporting extranets. The procedures
specified in this document assume that BGP is used for transmission
of MVPN customers' multicast routing information within the service
provider(s) infrastructure.
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Table of Contents
1 Specification of requirements ......................... 3
2 Introduction .......................................... 4
3 Extranet Service Model ................................ 4
4 Routing Exchange in Support of Extranets .............. 5
4.1 Exchange of Unicast Routes ............................ 5
4.2 Exchange of Source Active and S-PMSI auto-discovery routes 6
4.3 Exchange of I-PMSI auto-discovery routes .............. 6
5 Originating C-multicast routes ........................ 7
6 Multicast Extranet over Selective P-tunnels ........... 7
6.1 Non-aggregated S-PMSIs ................................ 7
6.2 Aggregated S-PMSIs .................................... 7
7 Multicast Extranet over Inclusive P-tunnels ........... 8
7.1 Option 1 .............................................. 8
7.2 Option 2 .............................................. 8
7.3 Option 3 .............................................. 9
7.4 Option 4 .............................................. 10
8 Multiple Extranet VRFs on the same PE ................. 11
9 IANA Considerations ................................... 11
10 Security Considerations ............................... 11
11 Acknowledgements ...................................... 11
12 References ............................................ 12
12.1 Normative References .................................. 12
12.2 Informative References ................................ 12
13 Authors' Addresses .................................... 12
1. Specification of requirements
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].
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2. Introduction
The extranet functionality that allows a MVPN site to receive/send
multicast traffic from/to sites of other MVPNs is a requirement of
RFC4834 [RFC4834] (section 5.1.6).
This document describes clarifications and extensions to the
procedures in [BGP-MVPN] for supporting extranets. The procedures
described in this document assume that BGP is used for transmission
of MVPN customers' multicast routing information within the service
provider(s) infrastructure [BGP-MVPN].
3. Extranet Service Model
In the context of MVPN the term "extranet" refers to the ability for
multicast sources in one MVPN to send multicast traffic to multicast
receivers in other MVPN(s), and likewise, the ability for multicast
receivers in one MVPN to receive multicast traffic from multicast
sources in other MVPN(s). Such multicast sources are referred to as
"extranet sources". The multicast groups to which the extranet
sources generate traffic are referred to as "extranet groups". The
receivers that receive multicast traffic from extranet sources are
referred to as "extranet receivers".
If a given VRF has (multicast) receivers behind attached CEs that can
receive multicast traffic sourced in the configured set of extranet
MVPNs, then the (unicast) addresses of these sources MUST be
unambiguous both among these extranet MVPNs, as well as between any
of these extranet MVPNs and the MVPN of the VRF.
Moreover, if a given VRF has (multicast) receivers behind attached
CEs that can receive multicast traffic sourced in the configured set
of extranet MVPNs, then the group addresses within the ASM range that
these receivers can join MUST be unambiguous both among these
extranet MVPNs, as well as between any of these extranet MVPNs and
the MVPN of the VRF.
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4. Routing Exchange in Support of Extranets
If a given VRF has (multicast) receivers behind attached CEs that can
receive multicast traffic sourced in the configured set of extranet
MVPNs, then this VRF MUST be able to import the "necessary" unicast
and BGP MVPN auto-discovery routes advertised by other PEs for the
MVPNs that contain the extranet sources.
The "necessary" routes are the routes required by the VRF to receive
multicast traffic for the extranet sources and groups from other
MVPNs. This includes unicast VPN-IP routes to the extranet sources,
as well as BGP MVPN Source Active auto-discovery routes for the
extranet sources and groups. It also includes Intra-AS, Inter-AS and
S-PMSI auto-discovery routes that carry P-Tunnel attributes for the
P-Tunnels used by the other MVPNs for sending multicast traffic for
multicast sources and groups.
4.1. Exchange of Unicast Routes
Case 1: PIM-SM in SSM mode. To fit the SSM model, if a given (C-S, C-
G) is in the extranet, then C-S should be in the extranet as well (or
to be more precise, the VPN-IP route to C-S has to be advertised in
the extranet).
Case 2: PIM-SM in ASM mode. To fit the ASM model, if a given C-G is
in the extranet, then the C-RP for that C-G and all the C-Ss sending
to that C-G should be in the extranet as well (or to be more precise,
all the VPN-IP routes to C-RP and these C-Ss have to advertised in
the extranet). Note that for a given C-G that is part of the extranet
formed by several MVPNs, C-Ss for that C-G may be present in any of
these MVPNs.
For both ASM and SSM modes, the VRFs connected to the sites that have
extranet receivers for a given extranet source MUST be able to import
a VPN-IP route to that source. In addition, for the ASM mode the VRFs
connected to the sites that have extranet receivers for a given
extranet group MUST be able to import a VPN-IP route to the C-RP of
that extranet group.
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4.2. Exchange of Source Active and S-PMSI auto-discovery routes
When all the VPN-IP routes originated by the same VRF carry the same
set of RTs, then as long as the Source Active auto-discovery routes
and S-PMSI auto-discovery routes use the default setting for their
RTs (as specified in [BGP-MVPN]), setting up the appropriate RTs for
the VPN-IP routes, would also result in the appropriate import of
Source Active auto-discovery routes and S-PMSI auto-discovery routes.
When different VPN-IP routes originated by the same VRF carry
different RTs, then the following rules result in the appropriate
import of Source Active auto-discovery routes and S-PMSI auto-
discovery routes:
+ By default a Source Active auto-discovery route for a given (C-S,
C-G) MUST carry the same RT(s) as the VPN-IP route for C-S.
+ By default an S-PMSI auto-discovery route for a given (C-S, C-G)
or (C-S, C-*) MUST carry the same RT(s) as the VPN-IP route for
C-S.
+ By default an S-PMSI auto-discovery route for a given (C-*, C-G)
MUST carry the same RT(s) as the VPN-IP route(s) for the
multicast sources that are in the sites connected to that VRF and
that originate (multicast) traffic for that C-G.
4.3. Exchange of I-PMSI auto-discovery routes
A VRF connected to the site(s) that have extranet receivers for a
given extranet source MUST be able to import the I-PMSI auto-
discovery route originated by the VRF connected to the source. Note
that as long as the I-PMSI auto-discovery routes use the default
setting for their RTs (as specified in [BGP-MVPN]), setting up the
appropriate RTs for the VPN-IP routes, would also result in the
appropriate import of I-PMSI auto-discovery routes.
If a given VRF connected to a given extranet source uses P2MP RSVP-TE
as an inclusive P-tunnel to carry (multicast) traffic from that
source, then the RT(s) carried by the I-PMSI auto-discovery routes
originated by the VRFs connected to the sites that have the extranet
receivers for that source, and the import RT(s) of the VRF connected
to the (extranet) source MUST be such that these routes will be
imported into that VRF.
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5. Originating C-multicast routes
Procedures specified in section "Constructing the rest of the C-
multicast route" of [BGP-MVPN] are modified as follows. If the local
and the upstream PEs are in different ASes, then the local PE has to
find in its VRF not just an Inter-AS I-PMSI A-D route whose Source AS
field carries the autonomous system number of the upstream PE (as
specified in section 11.1.3 of [BGP-MVPN]), but an Inter-AS I-PMSI A-
D route whose Source AS field carries the autonomous system number of
the upstream PE, and whose RTs form a non-empty intersection with the
RTs carried in the VPN-IP route imported into that VRF for the
address carried in the Multicast Source field of MCAST-VPN NLRI.
6. Multicast Extranet over Selective P-tunnels
In the following we consider only the S-PMSI auto-discovery routes
used for the extranets.
6.1. Non-aggregated S-PMSIs
When each S-PMSI auto-discovery routes originated from a VRF on a
given PE advertises a distinct P-tunnel in the PMSI Tunnel attribute,
the procedures in [BGP-MVPN], along with the routing exchange
clarifications described above, are sufficient to support the
scenario when the multicast extranet traffic is carried over
selective P-tunnels (P-tunnels advertised by the S-PMSI auto-
discovery routes).
An implementation MUST support multicast extranets with non-
aggregated S-PMSIs.
6.2. Aggregated S-PMSIs
When multiple S-PMSI auto-discovery routes originated from a VRF on a
given PE advertise the same P-tunnel in the PMSI Tunnel attribute,
and each such route also advertises a distinct (upstream assigned)
label in the attribute, then the procedures in [BGP-MVPN], along with
the routing exchange clarifications described above, are sufficient.
When multiple S-PMSI auto-discovery routes originated from a VRF on a
given PE advertise the same P-tunnel in the PMSI Tunnel attribute,
and the PMSI Tunnel attribute of each of these routes does not carry
a distinct (upstream assigned) label per route, then in addition to
the procedures in [BGP-MVPN] and the routing exchange clarifications
described above, the following is required.
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When the local PE receives from some other PE (C-S, C-G) traffic on a
P-tunnel that the other PE advertised in an S-PMSI auto-discovery
route that has been imported into a VRF on the local PE, the local PE
performs procedures specified in section 12.3 of [BGP-MVPN] only if:
(1) the VRF does contain an S-PMSI auto-discovery route for (C-S, C-
G), and (2) the (C-S, C-G) traffic is received on the P-tunnel
advertised in the PMSI Tunnel attribute of that route, and (3) RTs of
that route form a non-empty intersection with the RTs carried in the
VPN-IP route for C-S imported into that VRF. Otherwise, if at least
one of the above conditions is false, the local PE MUST discard (and
not forward) this traffic.
An implementation SHOULD support multicast extranets with aggregated
S-PMSI.
7. Multicast Extranet over Inclusive P-tunnels
There are (at least) four possible ways to support extranet multicast
over inclusive P-tunnels.
7.1. Option 1
This option assumes that the set of the extranet sources within a
given VRF is the same as the set of the multicast sources within that
VRF.
Procedures in [BGP-MVPN], along with the routing exchange
clarifications described above, are sufficient to support this
option.
An implementation MUST support this option.
7.2. Option 2
Each VRF that has set of extranet sources being part of that VRF uses
not one, but two inclusive P-tunnels for sending multicast traffic.
The first one is used for sending multicast traffic from the non-
extranet sources; the second is used for sending multicast traffic
from the extranet sources.
Each of these P-tunnels is advertised by its own I-PMSI auto-
discovery route. Therefore, these two routes MUST NOT use the same
RD. The distribution scope of the second route SHOULD include all the
VRFs that are within the scope of the first route, plus all the other
VRFs that have the extranet receivers for the extranet sources of the
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VRF that originates the route. Thus the P-tunnel advertised by the
second route spans all the VRFs spanned by the P-tunnel advertised by
the first route, plus all the VRFs that have the extranet receivers
for the extranet sources of the VRF that originates the route.
The set of RTs carried by the first I-PMSI auto-discovery route
follows the rules specified in [BGP-MVPN]. The set of RTs carried by
the second I-PMSI auto-discovery route MUST form a non-empty
intersection with the RTs carried by the VPN-IP routes for the
extranet multicast sources in the VRF that originates the route.
To carry (C-S, C-G) multicast traffic the PE by default should use
the P-tunnel that the PE advertises in the I-PMSI auto-discovery
route that has the same set of RTs as the VPN-IP route to C-S
advertised by the PE.
When the local PE receives from other PEs (multicast) traffic
corresponding to the (multicast) state advertised in the C-multicast
route originated from given VRF on the local PE, the PE MUST discard
(and not forward) this traffic if it was received on a P-tunnel that
is advertised by an I-PMSI auto-discovery route that has been
imported into the VRF, and whose RTs form an empty intersection with
the RTs carried in the VPN-IP route imported into that VRF for the
address carried in the Multicast Source field of MCAST-VPN NLRI.
Note that this check is in addition to the checks specified in
section 9.1 of [MVPN-ARCH].
An implementation SHOULD support this option.
7.3. Option 3
Each VRF has just one inclusive P-tunnel that is used to send data
originated by the sites connected to that VRF. In this case if the
set of extranet multicast sources are part of that VRF, then all
other VRFs that are part of the extranet must be able to receive data
on that P-tunnel (all these VRFs must be able import the I-PMSI auto-
discovery route that advertises this P-tunnel).
In addition to the rules specified in [BGP-MVPN], the set of RTs
carried by the I-PMSI auto-discovery route that advertises this P-
tunnel MUST form a non-empty intersection with the RTs carried by the
VPN-IP routes for the extranet multicast sources in that VRF.
Moreover, with this option the set of RTs of the I-PMSI auto-
discovery routes originated by the VRFs that contain extranet
multicast sources MUST be the same as in the absence of the extranet.
The route import policy for both intra-AS and inter-AS I-PMSI auto-
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discovery routes on the VRFs that have receivers for the (multicast)
traffic originated by these sources MUST be such that these VRF MUST
be able to import these routes.
A VRF that is receiving traffic on an inclusive P-tunnel from the
extranet sources connected to another VRF may also receive on that P-
tunnel the non-extranet traffic from that VRF. Such traffic will be
dropped by the receiving VRF anyway if it doesn't have (C-S, C-G) or
(C-*, C-G) forwarding state for this non-extranet traffic. However,
the receiving VRF may have forwarding state for such traffic if the
address space for the non-extranet sources connected to the sending
VRF overlaps with the address space of the sources in the receiving
VRF's MVPN. To take care of this case the receiving VRF MUST be able
to drop the non-extranet traffic if it arrives on the unexpected P-
Tunnel. The following describes how the unexpected P-Tunnel is
determined.
When the local PE receives from other PEs (multicast) traffic
corresponding to the (multicast) state advertised in the C-multicast
route originated from given VRF on the local PE, the PE MUST discard
(and not forward) this traffic if it was received on a P-tunnel that
is advertised by an I-PMSI auto-discovery route that has been
imported into the VRF, and whose RTs form an empty intersection with
the RTs carried in the VPN-IP route imported into that VRF for the
address carried in the Multicast Source field of MCAST-VPN NLRI.
Note that this check is in addition to the checks specified in
section 9.1 of [MVPN-ARCH].
An implementation SHOULD support this option.
7.4. Option 4
Each VRF that has set of extranet multicast sources being part of
that VRF is a root of as many inclusive P-tunnels as the number of
MVPNs in the extranet. A given (C-S, C-G) multicast traffic has to be
sent over each of these P-tunnels. From the point of view of the
number of P-tunnels, and the amount of replication required this is
the least desirable option, and is included here just for the sake of
completeness.
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8. Multiple Extranet VRFs on the same PE
When multiple VRFs that contain extranet receivers for a given
extranet source are present on the same PE, this PE becomes a single
leaf of the P-tunnel used for sending (multicast) traffic from that
source to these extranet receivers. Specific procedures for
replicating this traffic on that PE to these multiple VRFs are a
purely local to the PE matter, and thus are out of the scope of this
document.
For a given extranet the site(s) that contain the extranet source(s)
and the site(s) that contain the extranet receiver(s) may be
connected to the same PE. In this scenario the procedures by which
(multicast) traffic from these sources is delivered to these
receivers is purely local matter to the PE matter, and thus are
outside the scope of this document.
An implementation MUST support multiple extranet VRFs on a PE.
9. IANA Considerations
This document does not impose any new IANA considerations.
10. Security Considerations
A VRF must be able to drop non-extranet traffic, if it receives such
traffic from another PE. The procedures for dropping such traffic are
described in this document.
11. Acknowledgements
The authors would like to thank Eric Rosen for his comments.
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12. References
12.1. Normative References
[RFC2119] "Key words for use in RFCs to Indicate Requirement
Levels.", Bradner, March 1997
[MVPN-ARCH] E. Rosen, R. Aggarwal [Editors], "Multicast in MPLS/BGP
IP VPNs", draft-ietf-l3vpn-2547bis-mcast, work in progress
[BGP-MVPN], R. Aggarwal, E. Rosen, T. Morin, Y. Rekhter, "BGP
Encodings for Multicast in MPLS/BGP IP VPNs", draft-ietf-
l3vpn-2547bis-mcast-bgp, work in progress
12.2. Informative References
[RFC4834] T. Morin, Ed., "Requirements for Multicast in L3 Provider-
Provisioned VPNs", RFC 4834, April 2007
13. Authors' Addresses
Rahul Aggarwal
Email: raggarwa_1@yahoo.com
Yakov Rekhter
Juniper Networks
1194 North Mathilda Ave.
Sunnyvale, CA 94089
Email: yakov@juniper.net
Thomas Morin
France Telecom - Orange Labs
2, avenue Pierre-Marzin
22307 Lannion Cedex
France
Email: thomas.morin@orange-ftgroup.com
Wim Henderickx
Alcatel-Lucent
e-mail: wim.henderickx@alcatel-lucent.be
Praveen Muley
Alcatel-Lucent
e-mail: Praveen.Muley@alcatel-lucent.com
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Ray (Lei) Qiu
2330 Central Expressway
Santa Clara, CA 95050
USA
e-mail: rayq@huawei.com
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