Simulating "Partial Mesh of MP2MP P-Tunnels" with Ingress Replication
draft-ietf-bess-mvpn-bidir-ingress-replication-02

Network Working Group                                           Z. Zhang
Internet-Draft                                                Y. Rekhter
Updates: 6514 (if approved)                             Juniper Networks
Intended status: Standards Track                             A. Dolganow
Expires: February 4, 2016                                 Alcatel-Lucent
                                                          August 3, 2015

 Simulating "Partial Mesh of MP2MP P-Tunnels" with Ingress Replication
         draft-ietf-bess-mvpn-bidir-ingress-replication-02.txt

Abstract

   RFC 6513 described a method to support bidirectional C-flow using
   "Partial Mesh of MP2MP P-Tunnels".  This document specifiess 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.  These specifications update RFC 6514.

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 February 4, 2016.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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
   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.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     7.2.  Informative 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 [RFC7582].

   RFC 7582 assumes that an MP2MP P-tunnel is realized either via Bidir-
   PIM, 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
   [I-D.ietf-bess-ir].  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
   [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, 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 (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.  The label may be shared
   with other P-tunnels, subject to the anti-ambiguity rules for
   extranet [I-D.ietf-bess-mvpn-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.

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   This is irrespective of whether the originator of the S-PMSI A-D
   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).  The label may be shared with other
   P-tunnels, subject to the anti-ambiguity rules for extranet
   [I-D.ietf-bess-mvpn-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 the originator of the S-PMSI A-D
   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).  The label may be shared with other
   P-tunnels, subject to the anti-ambiguity rules for extranet
   [I-D.ietf-bess-mvpn-extranet].  For example, the (C-*,C-*-BIDIR) and

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   (C-*,C-G-BIDIR) S-PMSI A-D routes originated by a given PE can
   optionally share a label.

   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
   [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 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

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   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 [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

   [I-D.ietf-bess-ir]
              Rosen, E., Subramanian, K., and J. Zhang, "Ingress
              Replication Tunnels in Multicast VPN",
              draft-ietf-bess-ir-01 (work in progress), May 2015.

   [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
   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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