Seamless Integration of Ethernet VPN (EVPN) with Virtual Private LAN Service (VPLS) and Their Provider Backbone Bridge (PBB) Equivalents

Internet Engineering Task Force (IETF)                   A. Sajassi, Ed.
Request for Comments: 8560                                      S. Salam
Category: Standards Track                                          Cisco
ISSN: 2070-1721                                             N. Del Regno
                                                                 Verizon
                                                              J. Rabadan
                                                                   Nokia
                                                                May 2019


            Seamless Integration of Ethernet VPN (EVPN) with
                 Virtual Private LAN Service (VPLS) and
            Their Provider Backbone Bridge (PBB) Equivalents

Abstract

   This document specifies mechanisms for backward compatibility of
   Ethernet VPN (EVPN) and Provider Backbone Bridge Ethernet VPN
   (PBB-EVPN) solutions with Virtual Private LAN Service (VPLS) and
   Provider Backbone Bridge VPLS (PBB-VPLS) solutions.  It also provides
   mechanisms for the seamless integration of these two technologies in
   the same MPLS/IP network on a per-VPN-instance basis.  Implementation
   of this document enables service providers to introduce EVPN/PBB-EVPN
   Provider Edges (PEs) in their brownfield deployments of VPLS/PBB-VPLS
   networks.  This document specifies the control-plane and forwarding
   behavior needed for the auto-discovery of the following: 1) a VPN
   instance, 2) multicast and unicast operation, and 3) a Media Access
   Control (MAC) mobility operation.  This enables seamless integration
   between EVPN and VPLS PEs as well as between PBB-VPLS and PBB-EVPN
   PEs.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8560.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Specification of Requirements . . . . . . . . . . . . . .   4
     1.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   4
     1.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   6
   2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   6
   3.  VPLS Integration with EVPN  . . . . . . . . . . . . . . . . .   7
     3.1.  Capability Discovery  . . . . . . . . . . . . . . . . . .   7
     3.2.  Forwarding Setup and Unicast Operation  . . . . . . . . .   8
     3.3.  MAC Mobility  . . . . . . . . . . . . . . . . . . . . . .   9
     3.4.  Multicast Operation . . . . . . . . . . . . . . . . . . .  10
       3.4.1.  Ingress Replication . . . . . . . . . . . . . . . . .  10
       3.4.2.  P2MP Tunnel . . . . . . . . . . . . . . . . . . . . .  10
   4.  PBB-VPLS Integration with PBB-EVPN  . . . . . . . . . . . . .  10
     4.1.  Capability Discovery  . . . . . . . . . . . . . . . . . .  11
     4.2.  Forwarding Setup and Unicast Operation  . . . . . . . . .  11
     4.3.  MAC Mobility  . . . . . . . . . . . . . . . . . . . . . .  12
     4.4.  Multicast Operation . . . . . . . . . . . . . . . . . . .  12
       4.4.1.  Ingress Replication . . . . . . . . . . . . . . . . .  12
       4.4.2.  P2MP Tunnel: Inclusive Tree . . . . . . . . . . . . .  13
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Virtual Private LAN Service (VPLS) and Provider Backbone Bridging
   VPLS (PBB-VPLS) are widely deployed Layer 2 VPN (L2VPN) technologies.
   Many service providers who are looking at adopting Ethernet VPN
   (EVPN) and Provider Backbone Bridging EVPN (PBB-EVPN) want to
   preserve their investments in the VPLS and PBB-VPLS networks.  Hence,
   they require mechanisms by which EVPN and PBB-EVPN technologies can
   be introduced into their brownfield VPLS and PBB-VPLS networks
   without requiring any upgrades (software or hardware) to these
   networks.  This document specifies procedures for the seamless
   integration of the two technologies in the same MPLS/IP network.
   Throughout this document, we use the term "(PBB-)EVPN" to correspond
   to both EVPN and PBB-EVPN, and we use the term "(PBB-)VPLS" to
   correspond to both VPLS and PBB-VPLS.  This document specifies the
   control-plane and forwarding behavior needed for 1) auto-discovery of
   a VPN instance, 2) multicast and unicast operations, and 3) a MAC
   mobility operation.  This enables seamless integration between
   (PBB-)EVPN Provider Edge (PE) devices and (PBB-)VPLS PEs.

                            VPLS PE
                             +---+
                             |PE1|
                             +---+
                               /
        EVPN/VPLS PE  +---------------+   EVPN/VPLS PE
             +---+    |               |   +---+
             |PE4|----|    MPLS/IP    |---|PE5|
             +---+    |     Core      |   +---+
                      |               |
                      +---------------+
                        /        \
                     +---+     +---+
                     |PE2|     |PE3|
                     +---+     +---+
                   VPLS PE     VPLS PE

        Figure 1: Seamless Integration of (PBB-)EVPN and (PBB-)VPLS

   Section 2 provides the details of the requirements.  Section 3
   specifies procedures for the seamless integration of VPLS and EVPN
   networks.  Section 4 specifies procedures for the seamless
   integration of PBB-VPLS and PBB-EVPN networks.

   It should be noted that the scenarios for both PBB-VPLS integration
   with EVPN and VPLS integration with PBB-EVPN are not covered in this
   document because there haven't been any requirements from service
   providers for these scenarios; deployments that employ PBB-VPLS
   typically require PBB encapsulation for various reasons.  Hence, it
   is expected that for those deployments, the evolution path would move
   from PBB-VPLS towards PBB-EVPN.  Furthermore, the evolution path from
   VPLS is expected to move towards EVPN.

   The seamless integration solution described in this document has the
   following attributes:

   -  When ingress replication is used for multi-destination traffic
      delivery, the solution reduces the scope of MMRP (which is a soft-
      state protocol defined in Clause 10 of [IEEE.802.1Q]) to only that
      of existing VPLS PEs and uses the more robust BGP-based mechanism
      for multicast pruning among new EVPN PEs.

   -  It is completely backward compatible.

   -  New PEs can leverage the extensive multihoming mechanisms and
      provisioning simplifications of (PBB-)EVPN:

      (a)  Auto-sensing of Multihomed Networks (MHNs) / Multihomed
           Devices (MHDs)

      (b)  Auto-discovery of redundancy groups

      (c)  Auto-provisioning of Designated Forwarder election and VLAN
           carving

1.1.  Specification of Requirements

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

1.2.  Abbreviations

   B-MAC:      Backbone MAC, e.g., the PE's MAC address

   C-MAC:      Customer MAC, e.g., a host or CE's MAC address

   CE:         A Customer Edge device, e.g., a host, router, or switch

   ES:         Ethernet Segment -- refers to the set of Ethernet links
               that connects a customer site (device or network) to one
               or more PEs

   FEC:        Forwarding Equivalence Class
   FIB:        Forwarding Information Base -- an instantiation of a
               forwarding table on a MAC-VRF

   I-SID:      Service Instance Identifier

   LSP:        Label Switched Path

   MAC:        Media Access Control

   MAC-VRF:    A Virtual Routing and Forwarding table for Media Access
               Control (MAC) addresses on an EVPN PE

   MHD:        Multihomed Device

   MHN:        Multihomed Network

   MP2P:       Multipoint to Point -- an MP2P LSP typically refers to an
               LSP for unicast traffic as the result of a downstream-
               assigned label

   P2MP:       Point to Multipoint -- a P2MP LSP typically refers to an
               LSP for multicast traffic

   PBB:        Provider Backbone Bridge

   (PBB-)EVPN: Both PBB-EVPN and EVPN -- this document uses this
               abbreviation when a given description applies to both
               technologies

   (PBB-)VPLS: Both PBB-VPLS and VPLS -- this document uses this
               abbreviation when a given description applies to both
               technologies

   PE:         Provider Edge device

   PW:         Pseudowire

   RIB:        Routing Information Base -- an instantiation of a routing
               table on a MAC-VRF

   VSI:        Virtual Switch Instance

   VPLS:       Virtual Private LAN Service

   VPLS A-D:   Virtual Private LAN Service with BGP-based auto-discovery
               as in [RFC6074]

1.3.  Terminology

   All-Active redundancy mode:  When all PEs attached to an Ethernet
      segment are allowed to forward known unicast traffic to/from that
      Ethernet segment for a given VLAN, then the Ethernet segment is
      defined as operating in All-Active redundancy mode.

   Bridge table:  An instantiation of a broadcast domain on a MAC-VRF
      (VPN Routing and Forwarding).

   Broadcast domain:  In a bridged network, the broadcast domain
      corresponds to a Virtual LAN (VLAN), where a VLAN is typically
      represented by a single VLAN ID (VID) but can be represented by
      several VIDs where Shared VLAN Learning (SVL) is used, per
      [IEEE.802.1Q].

   Ethernet Tag:  An Ethernet Tag identifies a particular broadcast
      domain, e.g., a VLAN.  An EVPN instance consists of one or more
      broadcast domains.

   Single-Active redundancy mode:  When only a single PE, among all the
      PEs attached to an Ethernet segment, is allowed to forward traffic
      to/from that Ethernet segment for a given VLAN, then the Ethernet
      segment is defined as operating in Single-Active redundancy mode.

2.  Requirements

   The following are the key requirements for backward compatibility
   between (PBB-)EVPN and (PBB-)VPLS:

   1.  The solution must allow for staged migration towards (PBB-)EVPN
       on a site-by-site basis per VPN instance, e.g., new EVPN sites to
       be provisioned on (PBB-)EVPN Provider Edge devices (PEs).

   2.  The solution must not require any changes to existing VPLS or
       PBB-VPLS PEs, not even a software upgrade.

   3.  The solution must allow for the coexistence of PE devices running
       (PBB-)EVPN and (PBB-)VPLS for the same VPN instance and single-
       homed segments.

   4.  The solution must support single-active redundancy of multihomed
       networks and multihomed devices for (PBB-)EVPN PEs.

   5.  In cases of single-active redundancy, the participant VPN
       instances may span across both (PBB-)EVPN PEs and (PBB-)VPLS PEs
       as long as the MHD or MHN is connected to (PBB-)EVPN PEs.

   6.  Support of the All-Active redundancy mode across both (PBB-)EVPN
       PEs and (PBB-)VPLS PEs is outside the scope of this document.
       All-Active redundancy is not applicable to VPLS and PBB-VPLS.
       Therefore, when EVPN (or PBB-EVPN) PEs need to operate seamlessly
       with VPLS (or PBB-VPLS) PEs, they MUST use a redundancy mode that
       is applicable to VPLS (or PBB-VPLS).  This redundancy mode is
       Single-Active.

   These requirements collectively allow for the seamless insertion of
   (PBB-)EVPN technology into brownfield (PBB-)VPLS deployments.

3.  VPLS Integration with EVPN

   In order to support seamless integration with VPLS PEs, this document
   requires that VPLS PEs support VPLS A-D per [RFC6074], and it
   requires EVPN PEs to support both BGP EVPN routes per [RFC7432] and
   VPLS A-D per [RFC6074].  All the logic for seamless integration shall
   reside on the EVPN PEs.  If a VPLS instance is set up without the use
   of VPLS A-D, it is still possible (but cumbersome) for EVPN PEs to
   integrate that VPLS instance by manually configuring pseudowires
   (PWs) to all the VPLS PEs in that instance (i.e., the integration is
   no longer seamless).

3.1.  Capability Discovery

   The EVPN PEs MUST advertise both the BGP VPLS auto-discovery (A-D)
   route as well as the BGP EVPN Inclusive Multicast Ethernet Tag (IMET)
   route for a given VPN instance.  The VPLS PEs only advertise the BGP
   VPLS A-D route, per the procedures specified in [RFC4761], [RFC4762]
   and [RFC6074].  The operator may decide to use the same Route Target
   (RT) to identify a VPN on both EVPN and VPLS networks.  In this case,
   when a VPLS PE receives the EVPN IMET route, it MUST ignore it on the
   basis that it belongs to an unknown Subsequent Address Family
   Identifier (SAFI).  However, the operator may choose to use two RTs
   -- one to identify the VPN on the VPLS network and another for the
   EVPN network -- and employ RT Constrain mechanisms [RFC4684] in order
   to prevent BGP EVPN routes from reaching the VPLS PEs.

   When an EVPN PE receives both a VPLS A-D route as well as an EVPN
   IMET route from a given remote PE for the same VPN instance, it MUST
   give preference to the EVPN route for the purpose of discovery.  This
   ensures that, at the end of the route exchanges, all EVPN-capable PEs
   discover other EVPN-capable PEs in addition to the VPLS-only PEs for
   that VPN instance.  Furthermore, all the VPLS-only PEs will discover
   the EVPN PEs as if they were standard VPLS PEs.  In other words, when
   the discovery phase is complete, the EVPN PEs will have discovered
   all the PEs in the VPN instance along with their associated
   capability (EVPN or VPLS-only), whereas the VPLS PEs will have
   discovered all the PEs in the VPN instance as if they were all VPLS-
   only PEs.

3.2.  Forwarding Setup and Unicast Operation

   The procedures for the forwarding state setup and unicast operation
   on the VPLS PE are per [RFC8077], [RFC4761], and [RFC4762].

   The procedures for forwarding state setup and unicast operation on
   the EVPN PE are as follows:

   -  The EVPN PE MUST establish a PW to each remote PE from which it
      has received only a VPLS A-D route for the corresponding VPN
      instance and MUST set up the label stack corresponding to the PW
      FEC.  For seamless integration between EVPN and VPLS PEs, the PW
      that is set up between a pair of VPLS and EVPN PEs is between the
      VSI of the VPLS PE and the MAC-VRF of the EVPN PE.

   -  The EVPN PE MUST set up the label stack corresponding to the MP2P
      VPN unicast FEC to any remote PE that has advertised an EVPN IMET
      route.

   -  If an EVPN PE receives a VPLS A-D route from a given PE, it sets
      up a PW to that PE.  If it then receives an EVPN IMET route from
      the same PE, the EVPN PE MUST bring that PW operationally down.

   -  If an EVPN PE receives an EVPN IMET route followed by a VPLS A-D
      route from the same PE, then the EVPN PE will set up the PW but
      MUST keep it operationally down.

   -  In case VPLS A-D is not used in some VPLS PEs, the EVPN PEs need
      to be provisioned manually with PWs to those remote VPLS PEs for
      each VPN instance.  In that case, if an EVPN PE receives an EVPN
      IMET route from a PE to which a PW exists, the EVPN PE MUST bring
      the PW operationally down.

   When the EVPN PE receives traffic over the VPLS PWs, it learns the
   associated C-MAC addresses in the data plane.  The C-MAC addresses
   learned over these PWs MUST be injected into the bridge table of the
   associated MAC-VRF on that EVPN PE.  The learned C-MAC addresses MAY
   also be injected into the RIB/FIB tables of the associated MAC-VRF on
   that EVPN PE.  For seamless integration between EVPN and VPLS PEs,
   because these PWs belong to the same split-horizon group (see
   [RFC4761] and [RFC4762]) as the MP2P EVPN service tunnels, the C-MAC
   addresses learned and associated with the PWs MUST NOT be advertised
   in the control plane to any remote EVPN PEs.  This is because every
   EVPN PE can send and receive traffic directly to/from every VPLS PE
   belonging to the same VPN instance; thus, every EVPN PE can learn the
   C-MAC addresses over the corresponding PWs directly.

   The C-MAC addresses learned over local Attachment Circuits (ACs) by
   an EVPN PE are learned in the data plane.  For EVPN PEs, these C-MAC
   addresses MUST be injected into the corresponding MAC-VRF and
   advertised in the control plane using BGP EVPN routes.  Furthermore,
   the C-MAC addresses learned in the control plane via the BGP EVPN
   routes sent by remote EVPN PEs are injected into the corresponding
   MAC-VRF table.

   In case of a link failure in a single-active Ethernet segment, the
   EVPN PEs MUST perform both of the following tasks:

   1.  send a BGP mass withdraw to the EVPN peers

   2.  follow existing VPLS MAC Flush procedures with the VPLS peers

3.3.  MAC Mobility

   In EVPN, host addresses (C-MAC addresses) can move around among EVPN
   PEs or even between EVPN and VPLS PEs.

   When a C-MAC address moves from an EVPN PE to a VPLS PE, as soon as
   Broadcast, Unknown Unicast, and Multicast (BUM) traffic is initiated
   from that MAC address, it is flooded to all other PEs (both VPLS and
   EVPN PEs), and the receiving PEs update their MAC tables (VSI or
   MAC-VRF).  The EVPN PEs do not advertise the C-MAC addresses learned
   over the PW to each other because every EVPN PE learns them directly
   over its associated PW to that VPLS PE.  If only known unicast
   traffic is initiated from the moved C-MAC address toward a known
   C-MAC, the result can be the black-holing of traffic destined to the
   C-MAC that has moved until there is BUM traffic that has been
   originated with the moved C-MAC address as the source MAC address
   (e.g., as a result of the MAC age-out timer expiring).  Such
   black-holing happens for traffic destined to the moved C-MAC from
   both EVPN and VPLS PEs and is typical for VPLS PEs.

   When a C-MAC address moves from a VPLS PE to an EVPN PE, then as soon
   as any traffic is initiated from that C-MAC address, the C-MAC is
   learned and advertised in the BGP to other EVPN PEs, and the MAC
   mobility procedure is performed among EVPN PEs.  For BUM traffic,
   both EVPN and VPLS PEs learn the new location of the moved C-MAC
   address; however, if there is only known unicast traffic, then only
   EVPN PEs learn the new location of the C-MAC that has moved and not
   VPLS PEs.  This can result in the black-holing of traffic sent from
   VPLS PEs destined to the C-MAC that has moved until there is BUM
   traffic originated with the moved C-MAC address as the source MAC
   address (e.g., as a result of the MAC age-out timer expiring).  Such
   black-holing happens for traffic destined to the moved C-MAC for only
   VPLS PEs but not for EVPN PEs and is typical for VPLS PEs.

3.4.  Multicast Operation

3.4.1.  Ingress Replication

   The procedures for multicast operation on the VPLS PE using ingress
   replication are per [RFC4761], [RFC4762], and [RFC7080].

   The procedures for multicast operation on the EVPN PE for ingress
   replication are as follows:

   -  The EVPN PE builds a replication sub-list to all the remote EVPN
      PEs per EVPN instance as the result of the exchange of the EVPN
      IMET routes per [RFC7432].  This will be referred to as sub-list
      A.  It comprises MP2P service tunnels (for ingress replication)
      used for delivering EVPN BUM traffic [RFC7432].

   -  The EVPN PE builds a replication sub-list per VPLS instance to all
      the remote VPLS PEs.  This will be referred to as sub-list B.  It
      comprises PWs from the EVPN PE in question to all the remote VPLS
      PEs in the same VPLS instance.

   The replication list, maintained per VPN instance, on a given EVPN PE
   will be the union of sub-list A and sub-list B.  The EVPN PE MUST
   enable split horizon over all the entries in the replication list
   across both PWs and MP2P service tunnels.

3.4.2.  P2MP Tunnel

   The procedures for multicast operation on the EVPN PEs using P2MP
   tunnels are outside of the scope of this document.

4.  PBB-VPLS Integration with PBB-EVPN

   In order to support seamless integration between PBB-VPLS and
   PBB-EVPN PEs, this document requires that PBB-VPLS PEs support VPLS
   A-D per [RFC6074] and PBB-EVPN PEs support both BGP EVPN routes per
   [RFC7432] and VPLS A-D per [RFC6074].  All the logic for this
   seamless integration shall reside on the PBB-EVPN PEs.

4.1.  Capability Discovery

   The procedures for capability discovery are per Section 3.1.

4.2.  Forwarding Setup and Unicast Operation

   The procedures for forwarding state setup and unicast operation on
   the PBB-VPLS PE are per [RFC8077] and [RFC7080].

   The procedures for forwarding state setup and unicast operation on
   the PBB-EVPN PE are as follows:

   -  The PBB-EVPN PE MUST establish a PW to each remote PBB-VPLS PE
      from which it has received only a VPLS A-D route for the
      corresponding VPN instance and MUST set up the label stack
      corresponding to the PW FEC.  For seamless integration between
      PBB-EVPN and PBB-VPLS PEs, the PW that is set up between a pair of
      PBB-VPLS and PBB-EVPN PEs is between the B-components of PBB-EVPN
      PE and PBB-VPLS PE per Section 4 of [RFC7041].

   -  The PBB-EVPN PE MUST set up the label stack corresponding to the
      MP2P VPN unicast FEC to any remote PBB-EVPN PE that has advertised
      an EVPN IMET route.

   -  If a PBB-EVPN PE receives a VPLS A-D route from a given PE, it
      sets up a PW to that PE.  If it then receives an EVPN IMET route
      from the same PE, the PBB-EVPN PE MUST bring that PW operationally
      down.

   -  If a PBB-EVPN PE receives an EVPN IMET route followed by a VPLS
      A-D route from the same PE, then the PBB-EVPN PE will set up the
      PW but MUST keep it operationally down.

   -  In case VPLS A-D is not used in some PBB-VPLS PEs, the PBB-EVPN
      PEs need to be provisioned manually with PWs to those remote
      PBB-VPLS PEs for each VPN instance.  In that case, if a PBB-EVPN
      PE receives an EVPN IMET route from a PE to which a PW exists, the
      PBB-EVPN PE MUST bring the PW operationally down.

   -  When the PBB-EVPN PE receives traffic over the PBB-VPLS PWs, it
      learns the associated B-MAC addresses in the data plane.  The
      B-MAC addresses learned over these PWs MUST be injected into the
      bridge table of the associated MAC-VRF on that PBB-EVPN PE.  The
      learned B-MAC addresses MAY also be injected into the RIB/FIB
      tables of the associated MAC-VRF on that BPP-EVPN PE.  For
      seamless integration between PBB-EVPN and PBB-VPLS PEs, since
      these PWs belong to the same split-horizon group as the MP2P EVPN
      service tunnels, the B-MAC addresses learned and associated with
      the PWs MUST NOT be advertised in the control plane to any remote
      PBB-EVPN PEs.  This is because every PBB-EVPN PE can send and
      receive traffic directly to/from every PBB-VPLS PE belonging to
      the same VPN instance.

   -  The C-MAC addresses learned over local Attachment Circuits (ACs)
      by a PBB-EVPN PE are learned in the data plane.  For PBB-EVPN PEs,
      these C-MAC addresses are learned in the I-component of PBB-EVPN
      PEs and are not advertised in the control plane, per [RFC7623].

   -  The B-MAC addresses learned in the control plane via the BGP EVPN
      routes sent by remote PBB-EVPN PEs are injected into the
      corresponding MAC-VRF table.

   In case of a link failure in a single-active Ethernet segment, the
   PBB-EVPN PEs MUST perform both of the following tasks:

   1.  send a BGP B-MAC withdraw message to the PBB-EVPN peers *or* MAC
       advertisement with the MAC Mobility extended community

   2.  follow existing VPLS MAC Flush procedures with the PBB-VPLS peers

4.3.  MAC Mobility

   In PBB-EVPN, a given B-MAC address can be learned either over the BGP
   control plane from a remote PBB-EVPN PE or in the data plane over a
   PW from a remote PBB-VPLS PE.  There is no mobility associated with
   B-MAC addresses in this context.  Hence, when the same B-MAC address
   shows up behind both a remote PBB-VPLS PE as well as a PBB-EVPN PE,
   the local PE can deduce that it is an anomaly and SHOULD notify the
   operator.

4.4.  Multicast Operation

4.4.1.  Ingress Replication

   The procedures for multicast operation on the PBB-VPLS PE using
   ingress replication are per [RFC7041] and [RFC7080].

   The procedures for multicast operation on the PBB-EVPN PE for ingress
   replication are as follows:

   -  The PBB-EVPN PE builds a replication sub-list per I-SID to all the
      remote PBB-EVPN PEs in a given VPN instance as a result of the
      exchange of the EVPN IMET routes, as described in [RFC7623].  This
      will be referred to as sub-list A.  It comprises MP2P service
      tunnels used for delivering PBB-EVPN BUM traffic.

   -  The PBB-EVPN PE builds a replication sub-list per VPN instance to
      all the remote PBB-VPLS PEs.  This will be referred to as sub-list
      B.  It comprises PWs from the PBB-EVPN PE in question to all the
      remote PBB-VPLS PEs in the same VPN instance.

   -  The PBB-EVPN PE may further prune sub-list B on a per-I-SID basis
      by running MMRP (see Clause 10 of [IEEE.802.1Q]) over the PBB-VPLS
      network.  This will be referred to as sub-list C.  This list
      comprises a pruned set of the PWs in sub-list B.

   The replication list maintained per I-SID on a given PBB-EVPN PE will
   be the union of sub-list A and sub-list B if MMRP is not used and the
   union of sub-list A and sub-list C if MMRP is used.  Note that the PE
   MUST enable split horizon over all the entries in the replication
   list, across both pseudowires and MP2P service tunnels.

4.4.2.  P2MP Tunnel: Inclusive Tree

   The procedures for multicast operation on the PBB-EVPN PEs using P2MP
   tunnels are outside of the scope of this document.

5.  Security Considerations

   All the security considerations in [RFC4761], [RFC4762], [RFC7080],
   [RFC7432], and [RFC7623] apply directly to this document because it
   leverages the control-plane and data-plane procedures described in
   those RFCs.

   This document does not introduce any new security considerations
   beyond those of the above RFCs because the advertisements and
   processing of MAC addresses in BGP follow [RFC7432], and the
   processing of MAC addresses learned over PWs follows [RFC4761],
   [RFC4762], and [RFC7080].

6.  IANA Considerations

   This document has no IANA actions.

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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4761]  Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private
              LAN Service (VPLS) Using BGP for Auto-Discovery and
              Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007,
              <https://www.rfc-editor.org/info/rfc4761>.

   [RFC4762]  Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private
              LAN Service (VPLS) Using Label Distribution Protocol (LDP)
              Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007,
              <https://www.rfc-editor.org/info/rfc4762>.

   [RFC6074]  Rosen, E., Davie, B., Radoaca, V., and W. Luo,
              "Provisioning, Auto-Discovery, and Signaling in Layer 2
              Virtual Private Networks (L2VPNs)", RFC 6074,
              DOI 10.17487/RFC6074, January 2011,
              <https://www.rfc-editor.org/info/rfc6074>.

   [RFC7041]  Balus, F., Ed., Sajassi, A., Ed., and N. Bitar, Ed.,
              "Extensions to the Virtual Private LAN Service (VPLS)
              Provider Edge (PE) Model for Provider Backbone Bridging",
              RFC 7041, DOI 10.17487/RFC7041, November 2013,
              <https://www.rfc-editor.org/info/rfc7041>.

   [RFC7432]  Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
              Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
              Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
              2015, <https://www.rfc-editor.org/info/rfc7432>.

   [RFC7623]  Sajassi, A., Ed., Salam, S., Bitar, N., Isaac, A., and
              W. Henderickx, "Provider Backbone Bridging Combined with
              Ethernet VPN (PBB-EVPN)", RFC 7623, DOI 10.17487/RFC7623,
              September 2015, <https://www.rfc-editor.org/info/rfc7623>.

   [RFC8077]  Martini, L., Ed. and G. Heron, Ed., "Pseudowire Setup and
              Maintenance Using the Label Distribution Protocol (LDP)",
              STD 84, RFC 8077, DOI 10.17487/RFC8077, February 2017,
              <https://www.rfc-editor.org/info/rfc8077>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

7.2.  Informative References

   [IEEE.802.1Q]
              IEEE, "IEEE Standard for Local and Metropolitan Area
              Network -- Bridges and Bridged Networks", IEEE
              Standard 802.1Q, DOI 10.1109/IEEESTD.2018.8403927, July
              2018.

   [RFC4684]  Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk,
              R., Patel, K., and J. Guichard, "Constrained Route
              Distribution for Border Gateway Protocol/MultiProtocol
              Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual
              Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684,
              November 2006, <https://www.rfc-editor.org/info/rfc4684>.

   [RFC7080]  Sajassi, A., Salam, S., Bitar, N., and F. Balus, "Virtual
              Private LAN Service (VPLS) Interoperability with Provider
              Backbone Bridges", RFC 7080, DOI 10.17487/RFC7080,
              December 2013, <https://www.rfc-editor.org/info/rfc7080>.

Authors' Addresses

   Ali Sajassi (editor)
   Cisco

   Email: sajassi@cisco.com


   Samer Salam
   Cisco

   Email: ssalam@cisco.com


   Nick Del Regno
   Verizon

   Email: nick.delregno@verizon.com


   Jorge Rabadan
   Nokia

   Email: jorge.rabadan@nokia.com