Internet DRAFT - draft-ietf-bess-mvpn-bidir-ingress-replication
draft-ietf-bess-mvpn-bidir-ingress-replication
Network Working Group Z. Zhang
Internet-Draft Y. Rekhter
Intended status: Standards Track Juniper Networks
Expires: April 18, 2016 A. Dolganow
Alcatel-Lucent
October 16, 2015
Simulating "Partial Mesh of MP2MP P-Tunnels" with Ingress Replication
draft-ietf-bess-mvpn-bidir-ingress-replication-04.txt
Abstract
RFC 6513 (Multicast in MPLS/BGP IP VPNs) describes a method to
support bidirectional customer multicast flows using a partial mesh
of Multipoint-to-Multipoint (MP2MP) tunnels. This document specifies
how a partial mesh of MP2MP tunnels can be simulated using Ingress
Replication. This solution enables a Service Provider to use Ingress
Replication to offer transparent bidirectional multicast 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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 18, 2016.
Copyright Notice
Copyright (c) 2015 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
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to this document. Code Components extracted from this document must
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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 . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. Normative References . . . . . . . . . . . . . . . . . . . 11
7.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
Section 11.2 of RFC 6513, "Partitioned Sets of PEs", describes two
methods of carrying BIDIR-PIM [RFC5015] C-flow traffic over a
provider core without using the core as the Rendezvous Point Link
(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 with respect to 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 [RFC7582].
RFC 7582 assumes that an MP2MP P-tunnel is realized either via Bidir-
PIM [RFC5015], or via MP2MP mLDP [RFC6388]. 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 (IR) [RFC6513, RFC6514]. Different from the procedures
in RFC 6514 that are used to set up the mesh of Ingress Replication
tunnels, the procedures in this document do 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 [RFC5015], [RFC6513], [RFC6514],
and [RFC7582].
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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, if selective distribution trees are needed
for those C-G-BIDIR groups, 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 (this may require measuring the
traffic in both directions, due to the nature of Bidir-PIM), and fan-
out could also be taken into account.
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. This specification does not
prevent sharing of labels between P-tunnels, such as a label being
shared by a (C-*,C-*- BIDIR) and a (C-*,C-G-BIDIR) S-PMSI A-D route
originated by a given PE (note that other specs put constraints on
how that can be done, e.g. [I-D.ietf-bess-mvpn-extranet]).
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 with respect
to 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 the originator of the S-PMSI A-D
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route is the Upstream PE or not from a receiving PE's perspective.
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). This specification does not prevent
sharing of labels between P-tunnels, such as a label being shared by
a (C-*,C-*- BIDIR) and a (C-*,C-G-BIDIR) Leaf A-D route originated by
a given PE (note that other specs put constraints on how that can be
done, e.g. [I-D.ietf-bess-mvpn-extranet]).
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 with respect to 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 with
respect to 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 the similar to the (C-*,C-*-
BIDIR) case. Also similarly, PEy MAY advertise a Leaf A-D route even
if it does not choose PEx as its Upstream PE with respect to the
C-RPA.
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 with respect to 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.
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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
[RFC7582], 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 with respect to 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 with respect to 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
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 RFC6513 and 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. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/
BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513,
February 2012, <http://www.rfc-editor.org/info/rfc6513>.
[RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
Encodings and Procedures for Multicast in MPLS/BGP IP
VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012,
<http://www.rfc-editor.org/info/rfc6514>.
[RFC7582] Rosen, E., Wijnands, IJ., Cai, Y., and A. Boers,
"Multicast Virtual Private Network (MVPN): Using
Bidirectional P-Tunnels", RFC 7582, DOI 10.17487/RFC7582,
July 2015, <http://www.rfc-editor.org/info/rfc7582>.
7.2. Informative References
[RFC5015] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano,
"Bidirectional Protocol Independent Multicast (BIDIR-
PIM)", RFC 5015, DOI 10.17487/RFC5015, October 2007,
<http://www.rfc-editor.org/info/rfc5015>.
[RFC6388] Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B.
Thomas, "Label Distribution Protocol Extensions for Point-
to-Multipoint and Multipoint-to-Multipoint Label Switched
Paths", RFC 6388, DOI 10.17487/RFC6388, November 2011,
<http://www.rfc-editor.org/info/rfc6388>.
[I-D.ietf-bess-mvpn-extranet]
Rekhter, Y., Rosen, E., Aggarwal, R., Cai, Y., and T.
Morin, "Extranet Multicast in BGP/IP MPLS VPNs",
draft-ietf-bess-mvpn-extranet-02 (work in progress),
May 2015.
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Authors' Addresses
Zhaohui Zhang
Juniper Networks
10 Technology Park Dr.
Westford, MA 01886
US
Email: zzhang@juniper.net
Yakov Rekhter
Juniper Networks
Andrew Dolganow
Alcatel-Lucent
600 March Rd.
Ottawa, ON K2K 2E6
CANADA
Email: andrew.dolganow@alcatel-lucent.com
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