Internet DRAFT - draft-zzhang-l3vpn-mvpn-bidir-ingress-replication
draft-zzhang-l3vpn-mvpn-bidir-ingress-replication
Network Working Group Zhang
Internet-Draft Rekhter
Updates: 6514 (if approved) Juniper Networks
Intended status: Standards Track Dolganow
Expires: April 24, 2014 Alcatel-Lucent
October 21, 2013
Simulating "Partial Mesh of MP2MP P-Tunnels" with Ingress Replication
draft-zzhang-l3vpn-mvpn-bidir-ingress-replication-01.txt
Abstract
RFC 6513 described a method to support bidirectional C-flow using
"Partial Mesh of MP2MP P-Tunnels". This document describes how
partial mesh of MP2MP P-Tunnels can be simulated with Ingress
Replication, instead of a real MP2MP tunnel. This enables a Service
Provider to use Ingress Replication to offer transparent BIDIR-PIM
service to its VPN customers.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on April 24, 2014.
Copyright Notice
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document authors. All rights reserved.
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include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Control State . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Forwarding State . . . . . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
7. Normative References . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
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1. Introduction
Section 11.2 of RFC 6513, "Partitioned Sets of PEs", describes two
methods of carrying bidirectional C-flow traffic over a provider core
without using the core as RPL or requiring Designated Forwarder
election.
With these two methods, all PEs of a particular VPN are separated
into partitions, with each partition being all the PEs that elect the
same PE as the Upstream PE wrt the C-RPA. A PE must discard
bidirectional C-flow traffic from PEs that are not in the same
partition as the PE itself.
In particular, Section 11.2.3 of RFC 6513, "Partial Mesh of MP2MP
P-Tunnels", guarantees the above discard behavior without using an
extra PE Distinguisher label by having all PEs in the same partition
join a single MP2MP tunnel dedicated to that partition and use it to
transmit traffic. All traffic arriving on the tunnel will be from
PEs in the same partition, so it will be always accepted.
RFC 6514 specifies BGP encodings and procedures used to implement
MVPN as specified in RFC 6513, while the details related to MP2MP
tunnels are specified in [draft-ietf-l3vpn-mvpn-bidir-05].
[draft-ietf-l3vpn-mvpn-bidir-05] assumes that an MP2MP P-tunnel is
realized either via PIM-Bidir, or via MP2MP mLDP. Each of them would
require signaling and state not just on PEs, but on the P routers as
well. This document describes how the MP2MP tunnel can be simulated
with a mesh of P2MP tunnels, each of which is instantiated by Ingress
Replication. This does not require each PE on the MP2MP tunnel to
send an S-PMSI A-D route for the P2MP tunnel that the PE is the root
for, nor does it require each PE to send a Leaf A-D route to the root
of each P2MP tunnel in the mesh.
With the use of Ingress Replication,this scheme has both the
advantages and the disadvantages of Ingress Replication in general.
1.1. Terminology
This document uses terminology from [RFC6513], [RFC6514], and
[draft-ietf-l3vpn-mvpn-bidir-05]. In particular, the following new
term is defined:
o C-G-BIDIR: A C-G where G is a Bidir-PIM group.
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2. Requirements Language
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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3. Operation
In following sections, the originator of an S-PMSI A-D route or Leaf
A-D route is determined from the "originating router's IP address"
field of the corresponding route.
3.1. Control State
If a PE, say PEx, is connected to a site of a given VPN, and PEx's
next hop interface to some C-RPA is a VRF interface, then PEx MUST
advertises a (C-*,C-BIDIR) S-PMSI A-D route, regardless of whether it
has any local Bidir-PIM join states corresponding to the C-RPA
learned from its CEs. It MAY also advertise one or more (C-*,C-G-
BIDIR) S-PMSI A-D route, just like how any other S-PMSI A-D routes
are triggered. Here the C-G-BIDIR refers to a C-G where G is a
Bidir-PIM group, and the corresponding C-RPA is in the site that the
PEx connects to. For example, the (C-*,C-G-BIDIR) S-PMSI A-D routes
could be triggered when the (C-*, C-G-BIDIR) traffic rate goes above
a threshold, and fan-out could also be taken into account. Note that
this requires measuring the traffic in both directions, due to the
nature of Bidir-PIM.
The S-PMSI A-D routes include a PMSI Tunnel Attribute (PTA) with
tunnel type set to Ingress Replication, with Leaf Information
Required flag set, with a downstream allocated MPLS label that other
PEs in the same partition MUST use when sending relevant C-bidir
flows to this PE, and with the Tunnel Identifier field in the PTA set
to a routable address of the originator. The label may be shared
with other P-tunnels, subject to the anti-ambiguity rules for
extranet. For example, the (C-*,C-BIDIR) and (C-*,C-G-BIDIR) S-PMSI
A-D routes originated by a given PE can optionally share a label.
If some other PE, PEy, receives and imports into one of its VRFs any
(C-*, C-BIDIR) S-PMSI A-D route whose PTA specifies an IR P-tunnel,
and the VRF has any local Bidir-PIM join state that PEy has received
from its CEs, and if PEy chooses PEx as its Upstream PE wrt the C-RPA
for those states, PEy MUST advertise a Leaf A-D route in response.
Or, if PEy has received and imported into one of its VRFs a (C-*,C-
BIDIR) S-PMSI A-D route from PEx before, then upon receiving in the
VRF any local Bidir-PIM join state from its CEs with PEx being the
Upstream PE for those states' C-RPA, PEy MUST advertise a Leaf A-D
route.
The encoding of the Leaf A-D route is as specified in RFC 6514,
except that the Route Targets are set to the same value as in the
corresponding S-PMSI A-D route so that the Leaf A-D route will be
imported by all VRFs that import the corresponding S-PMSI A-D route.
This is irrespective of whether from a receiving PE, PEz's
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perspective PEx (originator of the S-PMSI A-D route) is the Upstream
PE or not. The label in the PTA of the Leaf A-D route originated by
PEy MUST be allocated specifically for PEx, so that when traffic
arrives with that label, the traffic can associated with the
partition (represented by the PEx). The label may be shared with
other P-tunnels, subject to the anti-ambiguity rules for extranet.
For example, the (C-*,C-BIDIR) and (C-*,C-G-BIDIR) S-PMSI A-D routes
originated by a given PE can optionally share a label.
Note that RFC 6514 requires a PE/ASBR take no action with regard to a
Leaf A-D route unless that Leaf A-D route carries an IP Address
Specific RT identifying the PE/ASBR. This document removes that
requirement when the route key of a Leaf A-D route identifies a
(C-*,C-BIDIR) or a (C-*,C-G-BIDIR) S-PMSI.
To speed up convergence (so that PEy starts receiving traffic from
its new Upstream PE immediately instead of waiting until the new Leaf
A-D route corresponding to the new Upstream PE is received by sending
PEs), PEy MAY advertise a Leaf A-D route even if does not choose PEx
as its Upstream PE wrt the C-RPA. With that, it will receive traffic
from all PEs, but some will arrive with the label corresponding to
its choice of Upstream PE while some will arrive with a different
label, and the traffic in the latter case will be discarded.
Similar to the (C-*,C-BIDIR) case, if PEy receives and imports into
one of its VRFs any (C-*,C-G-BIDIR) S-PMSI A-D route whose PTA
specifies an IR P-tunnel, and PEy chooses PEx as its Upstream PE wrt
the C-RPA, and it has corresponding local (C-*,C-G-BIDIR) join state
that it has received from its CEs in the VRF, PEy MUST advertise a
Leaf A-D route in response. Or, if PEy has received and imported
into one of its VRFs a (C-*,C-G-BIDIR) S-PMSI A-D route before, then
upon receiving its local (C-*,C-G-BIDIR) join state from its CEs in
the VRF, it MUST advertise a Leaf A-D route.
The encoding of the Leaf A-D route is as specified in RFC 6514,
except that the Route Targets are set to the same as in the
corresponding S-PMSI A-D route so that the Leaf A-D route will be
imported by all VRFs that import the corresponding S-PMSI A-D route.
This is irrespective of whether from the receiving PE, PEz's
perspective PEx (originator of the S-PMSI A-D route) is the Upstream
PE or not. The label in the PTA of the Leaf A-D route originated by
PEy MUST be allocated specifically for PEx, so that when traffic
arrives with that label, the traffic can associated with the
partition (represented by the PEx). The label may be shared with
other P-tunnels, subject to the anti-ambiguity rules for extranet.
For example, the (C-*,C-BIDIR) and (C-*,C-G-BIDIR) S-PMSI A-D routes
originated by a given PE can optionally share a label.
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Whenever the (C-*,C-BIDIR) or (C-*,C-G-BIDIR) S-PMSI A-D route is
withdrawn, or if PEy no longer chooses the originator PEx as its
Upstream PE wrt C-RPA and PEy only advertises Leaf A-D routes in
response to its Upstream PE's S-PMSI A-D route, or if relevant local
join state is pruned, PEy MUST withdraw the corresponding Leaf A-D
route.
3.2. Forwarding State
The following specification regarding forwarding state matches the
"When an S-PMSI is a 'Match for Transmission'" and "When an S-PMSI is
a 'Match for Reception'" rules for "Flat Partitioning" method in
[draft-ietf-l3vpn-mvpn-bidir-05], except that the rules about
(C-*,C-*) are not applicable, because this document requires that
(C-*,C-BIDIR) S-PMSI A-D routes are always originated for a VPN that
supports C-Bidir flows.
For the (C-*,C-G-BIDIR) S-PMSI A-D route that a PEy receives and
imports into one of its VRFs from its Upstream PE wrt the C-RPA, or
if PEy itself advertises the S-PMSI A-D route in the VRF, PEy
maintains a (C-*,C-G-BIDR) forwarding state in the VRF, with the
Ingress Replication provider tunnel leaves being the originators of
the S-PMSI A-D route and all relevant Leaf-A-D routes. The relevant
Leaf A-D routes are the routes whose Route Key field contains the
same information as the MCAST-VPN NLRI of the (C-*, C-G-BIDIR) S-PMSI
A-D route advertised by the Upstream PE.
For the (C-*,C-BIDIR) S-PMSI A-D route that a PEy receives and
imports into one of its VRFs from its Upstream PE wrt a C-RPA, or if
PEy itself advertises the S-PMSI A-D route in the VRF, it maintains
appropriate forwarding states in the VRF for the ranges of
bidirectional groups for which the C-RPA is responsible. The
provider tunnel leaves are the originators of the S-PMSI A-D route
and all relevant Leaf-A-D routes. The relevant Leaf A-D routes are
the routes whose Route Key field contains the same information as the
MCAST-VPN NLRI of the (C-*, C-BIDIR) S-PMSI A-D route advertised by
the Upstream PE. This is for the so-called "Sender Only Branches"
where a router only has data to send upstream towards C-RPA but no
explicit join state for a particular bidirectional group. Note that
the traffic must be sent to all PEs (not just the Upstream PE) in the
partition, because they may have specific (C-*,C-G-BIDIR) join states
that this PEy is not aware of, while there is no corresponding
(C-*,C-G-BIDIR) S-PMSI A-D and Leaf A-D routes.
For a (C-*,C-G-BIDIR) join state that a PEy has received from its CEs
in a VRF, if there is no corresponding (C-*,C-G-BIDIR) S-PMSI A-D
route from its Upstream PE in the VRF, PEy maintains a corresponding
forwarding state in the VRF, with the provider tunnel leaves being
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the originators of the (C-*,C-BIDIR) S-PMSI A-D route and all
relevant Leaf-A-D routes (same as the above Sender Only Branch case).
The relevant Leaf A-D routes are the routes whose Route Key field
contains the same information as the MCAST-VPN NLRI of the (C-*,
C-BIDIR) S-PMSI A-D route originated by the Upstream PE. If there is
no (C-*,C-BIDIR) S-PMSI A-D route from its Upstream PE either, then
the provider tunnel has an empty set of leaves and PEy does not
forward relevant traffic across the provider network.
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4. Security Considerations
This document raises no new security issues. Security considerations
for the base protocol are covered in [RFC6514].
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5. IANA Considerations
This document has no IANA considerations.
This section should be removed by the RFC Editor prior to final
publication.
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6. Acknowledgements
We would like to thank Eric Rosen for his comments, and suggestions
of some texts used in the document.
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7. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6513] Rosen, E. and R. Aggarwal, "Multicast in MPLS/BGP IP
VPNs", RFC 6513, February 2012.
[RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
Encodings and Procedures for Multicast in MPLS/BGP IP
VPNs", RFC 6514, February 2012.
[RFC5015] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano,
"Bidirectional Protocol Independent Multicast (BIDIR-
PIM)", RFC 5015, October 2007.
[I-D.ietf-l3vpn-mvpn-bidir]
Rosen, E., Wijnands, I., Cai, Y., and A. Boers, "MVPN:
Using Bidirectional P-Tunnels",
draft-ietf-l3vpn-mvpn-bidir-06 (work in progress),
October 2013.
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Authors' Addresses
Jeffrey Zhang
Juniper Networks
10 Technology Park Dr.
Westford, MA 01886
US
Email: zzhang@juniper.net
Yakov Rekhter
Juniper Networks
1194 North Mathilda Ave.
Sunnyvale, CA 94089
US
Email: yakov@juniper.net
Andrew Dolganow
Alcatel-Lucent
600 March Rd.
Ottawa, ON K2K 2E6
CANADA
Email: andrew.dolganow@alcatel-lucent.com
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