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Versions: 00 01 02 draft-ietf-bier-mvpn

Internet Engineering Task Force                            E. Rosen, Ed.
Internet-Draft                                    Juniper Networks, Inc.
Intended status: Standards Track                            M. Sivakumar
Expires: June 7, 2015                                       IJ. Wijnands
                                                     Cisco Systems, Inc.
                                                               S. Aldrin
                                                     Huawei Technologies
                                                             A. Dolganow
                                                          Alcatel-Lucent
                                                           T. Przygienda
                                                                Ericsson
                                                        December 4, 2014


                        Multicast VPN Using BIER
                     draft-rosen-l3vpn-mvpn-bier-02

Abstract

   The Multicast Virtual Private Network (MVPN) specifications require
   the use of multicast tunnels ("P-tunnels") that traverse a Service
   Provider's backbone network.  The P-tunnels are used for carrying
   multicast traffic across the backbone.  A variety of P-tunnel types
   are supported.  Bit Index Explicit Replication (BIER) is a new
   architecture that provides optimal multicast forwarding through a
   "multicast domain", without requiring intermediate routers to
   maintain any per-flow state or to engage in an explicit tree-building
   protocol.  This document specifies the protocol and procedures that
   allow MVPN to use BIER as the method of carrying multicast traffic
   over an SP backbone network.

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 June 7, 2015.




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Copyright Notice

   Copyright (c) 2014 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Use of the PMSI Tunnel Attribute  . . . . . . . . . . . . . .   4
   3.  Explicit Tracking . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Data Plane  . . . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   [RFC6513] and [RFC6514] specify the protocols and procedures that a
   Service Provider (SP) can use to provide Multicast Virtual Private
   Network (MVPN) service to its customers.  Multicast tunnels are
   created through an SP's backbone network; these are known as
   "P-tunnels".  The P-tunnels are used for carrying multicast traffic
   across the backbone.  The MVPN specifications allow the use of
   several different kinds of P-tunnel technology.

   Bit Index Explicit Replication (BIER) ([BIER_ARCH]) is an
   architecture that provides optimal multicast forwarding through a
   "multicast domain", without requiring intermediate routers to
   maintain any per-flow state or to engage in an explicit tree-building
   protocol.  The purpose of the current document is to specify the
   protocols and procedures needed in order to provide MVPN service
   using BIER to transport the multicast traffic over the backbone.





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   Although BIER does not explicitly build and maintain multicast
   tunnels, one can think of BIER as using a number of implicitly
   created tunnels through a "BIER domain".  In particular, one can
   think of there as being one Point-to-Multipoint (P2MP) tunnel from
   each "Bit Forwarding Ingress Router" (BFIR) to all the "Bit
   Forwarding Egress Routers" (BFERs) in the BIER domain, where a BIER
   domain is generally co-extensive with an IGP network.  These
   "tunnels" are not specific to any particular VPN.  However, the MVPN
   architecture provides protocols and procedures that allow the traffic
   of multiple MVPNs to be aggregated on a single P-tunnel.  In this
   document, we specify how to use these multi-VPN aggregation
   procedures to enable BIER to transport traffic from multiple MVPNs.

   MVPN traffic must sometimes traverse more than one IGP domain,
   whereas BIER only carries multicast traffic within a single IGP
   domain.  However, the MVPN specifications allow P-tunnels to be
   "segmented", where the segmentation points may either be Autonomous
   System Border Routers (ASBRs), as described in [RFC6514], or Area
   Border Routers (ABRs), as described in [SEAMLESS_MCAST].  As long as
   the segmentation points are capable of acting as BFIRs and BFERs,
   BIER can be used to provide some or all of the segments of a
   P-tunnel.

   This revision of the document does not specify the procedures
   necessary to support MVPN customers that are using BIDIR-PIM.  Those
   procedures will be added in a future revision.

   This document uses the following terminology from [BIER_ARCH]:

   o  BFR: Bit-Forwarding Router.

   o  BFIR: Bit-Forwarding Ingress Router.

   o  BFER: Bit-Forwarding Egress Router.

   This document uses the following terminology from [RFC6513]:

   o  MVPN: Multicast Virtual Private Network -- a VPN [RFC4364] in
      which multicast service is offered.

   o  P-tunnel.  A multicast tunnel through the network of one or more
      SPs.  P-tunnels are used to transport MVPN multicast data

   o  C-S: A multicast source address, identifying a multicast source
      located at a VPN customer site.

   o  C-G: A multicast group address used by a VPN customer.




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   o  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).
      Sets of C-flows can be identified by the use of the "C-*" wildcard
      (see [RFC6625]), e.g., (C-*,C-G).

   o  I-PMSI A-D Route: Inclusive Provider Multicast Service Interface
      Auto-Discovery route.  Carried in BGP Update messages, these
      routes are used to advertise the "default" P-tunnel for a
      particular MVPN.

   o  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.

   o  PMSI Tunnel attribute (PTA).  This BGP attribute carried is used
      to identify a particular P-tunnel.  When C-flows of multiple VPNs
      is carried in a single P-tunnel, this attribute also carries the
      information needed to multiplex and demultiplex the C-flows.

   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 RFC 2119 [RFC2119].

2.  Use of the PMSI Tunnel Attribute

   As defined in [RFC6514], the PMSI Tunnel attribute is used to
   identify the particular P-tunnel to which one or more multicast flows
   are being assigned.

   The PMSI Tunnel attribute (PTA)contains the following fields:

   o  "Tunnel Type".  IANA is requested to assign a new tunnel type
      codepoint for "BIER".  This codepoint will be used to indicate
      that the PMSI is instantiated by BIER.

   o  "Tunnel Identifier".  When the "tunnel type" field is "BIER", this
      field contains two subfields:

      1.  The first subfield is a single octet, containing the sub-
          domain-id of the sub-domain to which the BFIR will assign the
          packets that it transmits on the PMSI identified by the NLRI
          of the BGP I-PMSI or S-PMSI A-D route that contains this PTA.
          (How that sub-domain is chosen is outside the scope of this
          document.)




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      2.  The second subfield is the BFR-Prefix (see [BIER_ARCH]) of the
          originator of the route that is carrying this PTA.  This will
          either be a /32 IPv4 address or a /128 IPv6 address.  Whether
          the address is IPv4 or IPv6 can be inferred from the total
          length of the PMSI Tunnel attribute.

   o  "MPLS label".  This field contains an upstream-assigned MPLS
      label.  It is assigned by the router that originates the BGP route
      to which the PTA is attached.  Constraints on the way in which the
      originating router selects this label are discussed below.

   o  "Leaf Info Required Bit".  The setting of this bit depends upon
      the type of route and the NLRI of the route that carries the PTA.

      *  In an I-PMSI A-D route or a (C-*,C-*) S-PMSI A-D route, the bit
         SHOULD be clear.

      *  In other S-PMSI A-D routes, the bit SHOULD be set.

   Note that if a PTA specifying "BIER" is attached to an I-PMSI or
   S-PMSI A-D route, the route MUST NOT be distributed beyond the
   boundaries of a BIER domain.  That is, any routers that receive the
   route must be in the same BIER domain as the originator of the route.
   If the originator is in more than one BIER domain, the route must be
   distributed only within the BIER domain in which the BFR-Prefix in
   the PTA uniquely identifies the originator.  As with all MVPN routes,
   distribution of these routes is controlled by the provisioning of
   Route Targets.

   Suppose an ingress PE originates two x-PMSI A-D routes, where we use
   the term "x-PMSI" to mean "I-PMSI or S-PMSI".  Suppose both routes
   carry a PTA, and the PTA of each route specifies"BIER".

   o  If the two routes do not carry the same set of Route Targets
      (RTs), then their respective PTAs MUST contain different MPLS
      label values.

   o  If the ingress PE is supporting MVPN extranet ([EXTRANET])
      functionality, and if the two routes originate from different
      VRFs, then the respective PTAs of the two routes MUST contain
      different MPLS label values.

   o  If the ingress PE is supporting the "Extranet Separation" feature
      of MVPN extranet (see Section 7.3 of [EXTRANET], section ), and if
      one of the routes carries the "Extranet Separation" extended
      community and the other does not, then the respective PTAs of the
      two routes MUST contain different MPLS label values.




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   When segmented P-tunnels are being used, an ABR or ASBR may receive,
   from a BIER domain, an x-PMSI A-D route whose PTA specifies "BIER".
   This means that BIER is being used for one segment of a segmented
   P-tunnel.  The ABR/ASBR may in turn need to originate an x-PMSI A-D
   route whose PTA identifies the next segment of the P-tunnel.  The
   next segment may also be "BIER".  Suppose an ASBR receives x-PMSI A-D
   routes R1 and R2, and as a result originates x-PMSI A-D routes R3 and
   R4 respectively, where the PTAs of each of the four routes specify a
   BIER..  Then the PTAs of R3 and R4 MUST NOT specify the same MPLS
   label, UNLESS both of the following conditions hold:

   o  R1 and R2 have the same "originating router" in their respective
      NLRIs.

   o  R1 and R2 specify the same MPLS label in their respective PTAs.

3.  Explicit Tracking

   [Editor's note: The procedures of this section are still under
   discussion, and significant changes may be expected in the next
   revision.]

   When using BIER to transport an MVPN data packet through a BIER
   domain, an ingress PE functions as a BFIR (see [BIER_ARCH]).  The
   BFIR must determine the set of BFERs to which the packet needs to be
   delivered.  This is done by using the explicit tracking mechanism
   specified in [RFC6513] and [RFC6514].

   To determine the set of BFERs to which a given MVPN data packet needs
   to be delivered, the BFIR originating an S-PMSI A-D route sets the
   LIR bit in the route's PTA.  Per [RFC6514], the BFERs will respond
   with Leaf A-D routes.  By matching the received Leaf A-D routes to
   the originated S-PMSI A-D routes, the originator of the S-PMSI A-D
   route determines the set of BFERs that need to receive the multicast
   data flow (or flows) that is (are) identified in the NLRI of the of
   the S-PMSI A-D route.

   This requires that each BFIR originate an S-PMSI A-D route for each
   C-flow for which it serves as BFIR.  The BFIR MAY include, in each
   such route, a PTA as described in Section 2.  However, if the BFIR
   has originated an I-PMSI A-D route or a wildcard S-PMSI A-D route
   that "matches" (according to the rules of [RFC6625]) a particular
   C-flow, then it may do explicit tracking for that C-flow by
   originating an S-PMSI A-D route for that C-flow, but including a PTA
   that specifies "no tunnel type".






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4.  Data Plane

   The MVPN application plays the role of the "multicast flow layer" as
   described in [BIER_ARCH].

   To transmit an MVPN data packet, an ingress PE follows the rules of
   [RFC6625] to find the S-PMSI A-D route or I-PMSI A-D route that is a
   "match for transmission" for that packet.  (In applying the rules of
   [RFC6625], any S-PMSI A-D route with a PTA specifying "no tunnel
   information" is ignored.)  If the matching route has a PTA specifying
   a "BIER", the (upstream-assigned) MPLS label from that PTA is pushed
   on the packet's label stack.  Then the packet is forwarded according
   to the procedures of [BIER_ARCH] and [BIER_ENCAPS].  (See especially
   Section 4, "Imposing and Processing the BIER Encapsulation", of
   [BIER_ENCAPS].)

   When a BFER receives an MVPN multicast data packet that has been
   BIER-encapsulated, the BIER layer passes the following information to
   the multicast flow layer:

   o  The BFR-prefix corresponding to the sub-domain-id and BFIR-id in
      the BIER header.

   o  The "payload", which is an MPLS packet whose top label is an
      upstream-assigned label.  The BFR-prefix provides the "context" in
      which the upstream-assigned label is interpreted.

      Note that per [RFC5331], the context for an upstream-assigned
      label is the IP address of the label assigner, which in this case
      is the BFR-prefix of the BFIR.

5.  Acknowledgments

   The authors wish to thank Jeffrey Zhang for his ideas and
   contributions to this work.

6.  IANA Considerations

   IANA is requested to assign a value for "BIER" from the "P-Multicast
   Service Interface Tunnel (PMSI Tunnel) Tunnel Types" registry.  The
   reference should be this document.

7.  Security Considerations

   The security considerations of [BIER_ARCH], [BIER_ENCAPS], [RFC6513]
   and [RFC6514] are applicable.





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8.  References

8.1.  Normative References

   [BIER_ARCH]
              Wijnands, IJ., "Multicast using Bit Index Explicit
              Replication Architecture", internet-draft draft-wijnands-
              bier-architecture-02, December 2014.

   [BIER_ENCAPS]
              Wijnands, IJ., "Multicast using Bit Index Explicit
              Replication Architecture", internet-draft draft-wijnands-
              mpls-bier-encapsulation-02, December 2014.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, February 2006.

   [RFC5331]  Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream
              Label Assignment and Context-Specific Label Space", RFC
              5331, August 2008.

   [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.

   [RFC6625]  Rosen, E., Rekhter, Y., Hendrickx, W., and R. Qiu,
              "Wildcards in Multicast VPN Auto-Discovery Routes", RFC
              6625, May 2012.

8.2.  Informative References

   [EXTRANET]
              Rekhter, Y. and E. Rosen, "Extranet Multicast in BGP/IP
              MPLS VPNs", internet-draft draft-ietf-l3vpn-mvpn-extranet-
              05, July 2014.

   [SEAMLESS_MCAST]
              Rekhter, Y., Aggarwal, R., Morin, T., Grosclaude, I.,
              Leymann, N., and S. Saad, "Inter-Area P2MP Segmented
              LSPs", internet-draft draft-ietf-mpls-seamless-mcast-14,
              June 2014.




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Authors' Addresses

   Eric C. Rosen (editor)
   Juniper Networks, Inc.
   10 Technology Park Drive
   Westford, Massachusetts  01886
   US

   Email: erosen@juniper.net


   Mahesh Sivakumar
   Cisco Systems, Inc.
   510 McCarthy Blvd
   Milpitas, California  95035
   US

   Email: masivaku@cisco.com


   IJsbrand Wijnands
   Cisco Systems, Inc.
   De Kleetlaan 6a
   Diegem  1831
   BE

   Email: ice@cisco.com


   Sam K Aldrin
   Huawei Technologies
   2330 Central Express Way
   Santa Clara, California
   US

   Email: aldrin.ietf@gmail.com


   Andrew Dolganow
   Alcatel-Lucent
   600 March Rd.
   Ottawa, Ontario  K2K 2E6
   CA

   Email: andrew.dolganow@alcatel-lucent.com






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   Tony Przygienda
   Ericsson
   300 Holger Way
   San Jose, California  95134
   US

   Email: antoni.przygienda@ericsson.com












































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