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Versions: (draft-ietf-pwe3-p2mp-pw) 00 01 02 03

INTERNET-DRAFT                                         Sami Boutros(Ed.)
Intended Status: Standard Track                                   VMware

Updates: RFC7385                                     Siva Sivabalan(Ed.)
                                                           Cisco Systems


Expires: December 22, 2017                                 June 20, 2017


   Signaling Root-Initiated Point-to-Multipoint Pseudowire using LDP
                     draft-ietf-pals-p2mp-pw-03.txt


Abstract

   This document specifies a mechanism to signal Point-to-Multipoint
   (P2MP) Pseudowires (PW) tree using LDP. Such a mechanism is suitable
   for any Layer 2 VPN service requiring P2MP connectivity over an IP or
   MPLS enabled PSN. A P2MP PW established via the proposed mechanism is
   root initiated. This document updates RFC7385 by re-assigning
   reserved value 0xFF to be the wildcard transport tunnel type.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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Copyright and License Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the



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   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  . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  4
   2. Signaling P2MP PW . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1 PW ingress to egress incompatibility issues  . . . . . . . .  6
     2.2 P2MP PW FEC  . . . . . . . . . . . . . . . . . . . . . . . .  6
       2.2.1 P2MP PW Upstream FEC Element . . . . . . . . . . . . . .  6
       2.2.2 P2P PW Downstream FEC Element  . . . . . . . . . . . . . 10
     2.3 Typed Wildcard FEC Format for new FEC  . . . . . . . . . . . 10
     2.4 Group ID usage . . . . . . . . . . . . . . . . . . . . . . . 11
     2.5 Generic Label TLV  . . . . . . . . . . . . . . . . . . . . . 11
   3. LDP Capability Negotiation  . . . . . . . . . . . . . . . . . . 11
   4. P2MP PW Status  . . . . . . . . . . . . . . . . . . . . . . . . 13
   5 Security Considerations  . . . . . . . . . . . . . . . . . . . . 13
   6 Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . 13
   7  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 13
     7.1. FEC Type Name Space . . . . . . . . . . . . . . . . . . . . 13
     7.2. LDP TLV Type  . . . . . . . . . . . . . . . . . . . . . . . 14
     7.3. mLDP Opaque Value Element TLV Type  . . . . . . . . . . . . 14
     7.4. Selective Tree Interface Parameter sub-TLV Type . . . . . . 14
     7.5. WildCard PMSI tunnel type . . . . . . . . . . . . . . . . . 14
   8  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     8.1. Normative References  . . . . . . . . . . . . . . . . . . . 15
     8.2. Informative References  . . . . . . . . . . . . . . . . . . 16
   Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17










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1  Introduction

   A Point-to-Multipoint (P2MP) Pseudowire (PW) emulates the essential
   attributes of a unidirectional P2MP Telecommunications service such
   as P2MP ATM over PSN. A major difference between a Point-to-Point
   (P2P) PW outlined in [RFC3985] and a P2MP PW is that the former is
   intended for bidirectional service whereas the latter is intended for
   both unidirectional, and optionally bidirectional service.
   Requirements for P2MP PW are described in [RFC7338]. P2MP PW can be
   constructed as either Single Segment (P2MP SS-PW) or Multi Segment
   (P2MP MS-PW) Pseudowires as mentioned in [RFC7338]. P2MP MS-PW is
   outside the scope of this document. A reference model or a P2MP PW is
   depicted in Figure 1 below. A transport LSP associated with a P2MP
   SS-PW SHOULD be a P2MP MPLS LSP (i.e., P2MP TE tunnel established via
   RSVP-TE [RFC4875] or P2MP LSP established via mLDP [RFC6388])
   spanning from the Root-PE to the Leaf-PE(s) of the P2MP SS-PW tree.
   For example, in Figure 1, PW1 can be associated with a P2MP TE tunnel
   or P2MP LSP setup using mLDP originating from PE1 and terminating at
   PE2, PE3 and PE4.


                 |<--------------P2MP PW---------------->|
          Native |                                       |  Native
         Service |     |<--PSN1->|      |<--PSN2->|      |  Service
          (AC)   V     V         V      V         V      V   (AC)
            |    +-----+         +------+         +------+    |
            |    |     |         |   P1 |=========|T-PE2 |AC3 |    +---+
            |    |     |         |   .......PW1.........>|-------->|CE3|
            |    |T-PE1|=========|   .  |=========|      |    |    +---+
            |    |  .......PW1........  |         +------+    |
            |    |  .  |=========|   .  |         +------+    |
            |    |  .  |         |   .  |=========|T-PE3 |AC4 |    +---+
    +---+   |AC1 |  .  |         |   .......PW1.........>|-------->|CE4|
    |CE1|------->|...  |         |      |=========|      |    |    +---+
    +---+   |    |  .  |         +------+         +------+    |
            |    |  .  |         +------+         +------+    |
            |    |  .  |=========|   P2 |=========|T-PE4 |AC5 |    +---+
            |    |  .......PW1..............PW1.........>|-------->|CE5|
            |    |     |=========|      |=========|      |    |    +---+
            |    +-----+         +------+         +------+    |

                                 Figure 1: P2MP PW

   Mechanisms for establishing P2P SS-PW using LDP are described in
   [RFC4447bis]. This document specify a method of signaling P2MP PW
   using LDP. In particular, this document defines new FEC, TLVs,
   parameters, and status codes to facilitate LDP to signal and maintain
   P2MP PWs.



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   As outlined in [RFC7338], even though the traffic flow from a Root-PE
   (R-PE) to Leaf-PE(s) (L-PEs) is P2MP in nature, it may be desirable
   for any L-PE to send unidirectional P2P traffic destined only to the
   R-PE. The proposed mechanism takes such option into consideration.

   The P2MP PW requires an MPLS LSP to carry the PW traffic, and the
   MPLS packets carrying the PW upstream label will be encapsulated
   according to the methods described in [RFC5332].


1.1  Terminology

   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].

   FEC: Forwarding Equivalence Class

   LDP: Label Distribution Protocol

   mLDP: Label Distribution Protocol for P2MP/MP2MP LSP

   LSP: Label Switching Path

   MS-PW: Multi-Segment Pseudowire

   P2P: Point to Point

   P2MP: Point to Multipoint

   PE: Provider Edge

   PSN: Packet Switched Network

   PW: Pseudowire

   SS-PW: Single-Segment Pseudowire

   S-PE: Switching Provider Edge of MS-PW

   TE: Traffic Engineering

   R-PE: Root-PE - ingress PE, PE initiating P2MP PW setup.

   L-PE: Leaf-PE - egress PE.

2. Signaling P2MP PW




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   In order to advertise labels as well as exchange PW related LDP
   messages, PEs must establish LDP sessions among themselves. A PE
   discovers other PEs that are to be connected via P2MP PWs either via
   manual configuration or autodiscovery [RFC6074].

   R-PE and each L-PE MUST be configured with the same FEC as defined in
   the following section.

   P2MP PW requires that there is an active P2MP PSN LSP set up between
   R-PE and L-PE(s). Note that the procedure to set up the P2MP PSN LSP
   is different depending on the signaling protocol used (RSVP-TE or
   mLDP).

   In case of mLDP, a Leaf-PE can decide to join the P2MP LSP at any
   time. In the case of RSVP-TE, the P2MP LSP is set up by the R-PE,
   generally at the initial service provisioning time. It should be
   noted that local policy can override any decision to join, add or
   prune existing or new L-PE(s) from the tree. In any case, the PW
   setup can ignore these differences, and simply assume that the P2MP
   PSN LSP is available when needed.

   P2MP PW signaling is initiated by the R-PE which sends a separate
   P2MP-PW LDP label mapping message to each of the the L-PE(s)
   belonging to that P2MP PW. This label mapping message will contain
   the following:
         1. A FEC TLV containing P2MP PW Upstream FEC element that
            includes Transport LSP sub TLV.
         2. An Interface Parameters TLV, as described in [RFC4447bis].
         3. A PW Grouping TLV, as described in [RFC4447bis].
         4. A label TLV for the upstream-assigned label used by R-PE
            for the traffic going from R-PE to L-PE(s).

   The R-PE imposes the upstream-assigned PW label on the outbound
   packets sent over the P2MP-PW, and using this label an L-PE
   identifies the inbound packets arriving over the P2MP PW.

   Additionally, the R-PE MAY send label mapping message(s) to one or
   more L-PE(s) to signal unidirectional P2P PW(s). The L-PE(s) can use
   such PW(s) to send traffic to the R-PE. This optional label mapping
   message will contain the following:

         1. P2P PW Downstream FEC element.
         2. A label TLV for the down-stream assigned label used by the
            corresponding L-PE to send traffic to the R-PE.

   The LDP liberal label retention mode MUST be used, and per
   requirements specified in [RFC5036], the Label Request message MUST
   also be supported.



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   The upstream-assigned label is allocated according to the rules in
   [RFC5331].

   When an L-PE receives a PW Label Mapping Message, it MUST verify the
   associated P2MP PSN LSP is in place. If the associated P2MP PSN LSP
   is not in place, and its type is LDP P2MP LSP, the L-PE MUST attempt
   to join the P2MP LSP associated with the P2MP PW. If the associated
   P2MP PSN LSP is not in place, and its type is RSVP-TE P2MP LSP, the
   L-PE SHOULD wait till the P2MP transport LSP is signaled.  If an L-PE
   fails to join the P2MP PSN LSP, that L-PE MUST not enable the PW, and
   MUST notify the user. In this case, a PW status message with status
   code of 0x00000008 (Local PSN-facing PW (ingress) Receive Fault) MUST
   also be sent to the R-PE.

2.1 PW ingress to egress incompatibility issues

   If an R-PE signals a PW with a pw type, CW mode, or interface
   parameters that a particular L-PE cannot accept, then the L-PE MUST
   not enable the PW, and notify the user. In this case, a PW status
   message with status code of 0x00000001 (Pseudowire Not Forwarding)
   MUST also be sent to the R-PE.

   Note that this procedure does not apply if the L-PE had not been
   provisioned with this particular P2MP PW. In this case according to
   the LDP liberal label retention rules, no action is taken.


2.2 P2MP PW FEC

   [RFC4447bis] specifies two types of LDP FEC elements called "PWid FEC
   Element" and "Generalized PWid FEC Element" used to signal P2P PWs.
   This document defines two new types of FEC elements called "P2MP PW
   Upstream FEC Element" and "P2P PW Downstream FEC Element". These FEC
   elements are associated with a mandatory upstream assigned label and
   an optional downstream assigned label respectively.

2.2.1 P2MP PW Upstream FEC Element

   A new FEC type for the P2MP PW Upstream FEC Element is encoded as
   follows:











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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |P2MP PW Up=0x82|C|           PW Type           | PW Info Length|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    AGI Type   |     Length    |         AGI Value             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                       AGI Value (contd.)                      ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    AII Type   |     Length    |         SAII Value            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                       SAII Value (contd.)                     ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |PMSI Tunnel typ|     Length    |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
      +                                                               +
      ~                   Transport LSP ID                            ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                       Optional Parameters                     |
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                   Figure 2: P2MP PW Upstream FEC Element

   * P2MP PW Up:

   8 bits representation for the P2MP PW Upstream FEC type.

   * PW Type:

   15 bits representation of PW type as specified in [RFC4447].

   * C bit:

   A value of 1 or 0 indicates whether control word is present or absent
   for the P2MP PW.

   * PW Info Length:

   Sum of the lengths of AGI, SAII, PMSI Tunnel info, and Optional
   Parameters field in octets. If this value is 0, then it references
   all PWs using the specified grouping ID. In this case, there are
   neither other FEC element fields (AGI, SAII, etc.) present, nor any



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   interface parameters TLVs. Alternatively, typed wildcard FEC
   described in section 3.3, can be used to achieve the same or to have
   better filtering.

   * AGI:

   Attachment Group Identifier can be used to uniquely identify VPN or
   VPLS instance associated with the P2MP PW. This has the same format
   as the Generalized PWid FEC element [RFC4447bis].

   * SAII:

   Source Attachment Individual Identifier is used to identify the root
   of the P2MP PW. The root is represented using AII type 2 format
   specified in [RFC5003].  Note that the SAII can be omitted by simply
   setting the length and type to zero.

   P2MP PW is identified by the Source Attachment Identifier (SAI). If
   the AGI is non-null, the SAI is the combination of the SAII and the
   AGI, if the AGI is null, the SAI is the SAII.

   * PMSI Tunnel Type and Transport LSP ID:

   A P2MP PW MUST be associated with a transport LSP which can be
   established using RSVP-TE or mLDP.

   * PMSI Tunnel Type:

   The PMSI tunnel type is defined in [RFC6514].

   When the type is set to mLDP P2MP LSP, the Tunnel Identifier is a
   P2MP FEC Element as defined in [RFC6388]. A new mLDP Opaque Value
   Element type for L2VPN-MCAST application as specified in the IANA
   considerations MUST be used.

   * Transport LSP ID: This is the Tunnel Identifier which is defined in
   [RFC6514].

   An R-PE sends Label Mapping Message as soon as the transport LSP ID
   associated with the P2MP PW is known (e.g., via configuration)
   regardless of the operational state of that transport LSP. Similarly,
   an R-PE does not withdraw the labels when the corresponding transport
   LSP goes down. Furthermore, an L-PE retains the P2MP PW labels
   regardless of the operational status of the transport LSP.

   Note that a given transport LSP can be associated with more than one
   P2MP PWs in which case P2MP PWs will be sharing the same R-PE and L-
   PE(s). An R-PE may also have many P2MP PWs with disjoint L-PE sets.



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   In the case of LDP P2MP LSP, when an L-PE receives the Label Mapping
   Message, it can initiate the process of joining the P2MP LSP tree
   associated with the P2MP PW.

   In the case of RSVP-TE P2MP LSP, only the R-PE initiates the
   signaling of P2MP LSP.

   * Optional Parameters:

   The Optional Parameter field can contain some TLVs that are not part
   of the FEC, but are necessary for the operation of the PW. This
   proposed mechanism uses two such TLVs: Interface Parameters TLV, and
   Group ID TLV.

   The Interface Parameters TLV and Group ID TLV specified in
   [RFC4447bis] can also be used in conjunction with P2MP PW FEC in a
   label message. For Group ID TLV, the sender and receiver of these
   TLVs should follow the same rules and procedures specified in
   [RFC4447bis]. For Interface Parameters TLV, the procedure differs
   from the one specified in [RFC4447bis] due to specifics of P2MP
   connectivity. When the interface parameters are signaled by a R-PE,
   each L-PE must check if its configured value(s) is less than or equal
   to the threshold value provided by the R-PE (e.g. MTU size
   (Ethernet), max number of concatenated ATM cells, etc)). For other
   interface parameters like CEP/TDM Payload bytes (TDM), the value MUST
   exactly match the values signaled by the R-PE.

   Multicast traffic stream associated with a P2MP PW can be selective
   or inclusive. To support the former, this document defines a new
   optional Selective Tree Interface Parameter sub-TLV, as described in
   the IANA considerations and according to the format described in
   [RFC4447bis]. The value of the sub-TLV contains the source and the
   group for a given multicast tree as shown in Figure 3. Also, if a
   P2MP PW is associated with multiple selective trees, the
   corresponding label mapping message will carry more than one instance
   of this Sub-TLV. Furthermore, in the absence of this sub-TLV, the
   P2MP PW is associated with all multicast traffic stream originating
   from the root.

                      +----------------------------------------- +
                      |            Sub-TLV Type (1 Octet)        |
                      +----------------------------------------- +
                      |              Length (1 Octet)            |
                      +----------------------------------------- +
                      | Multicast Source Length (1 Octet)        |
                      +----------------------------------------- +
                      | Multicast Source (variable length)       |
                      +----------------------------------------- +



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                      | Multicast Group Length (1 Octet)         |
                      +----------------------------------------- +
                      | Multicast Group (variable length)        |
                      +----------------------------------------- +


              Figure 3: Selective Tree Interface Parameter Sub-TLV Value

   Note that since the LDP label mapping message is only sent by the R-
   PE to all the L-PEs, it is not possible to negotiate any interface
   parameters.

2.2.2 P2P PW Downstream FEC Element

   The optional P2P PW Downstream FEC Element is encoded as follows:


       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |P2P PWDown=0x83|C|           PW Type           | PW Info Length|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    AGI Type   |     Length    |         AGI Value             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                       AGI Value (contd.)                      ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    AII Type   |     Length    |         SAII Value            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                       SAII Value (contd.)                     ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 4: P2P PW Downstream FEC Element

   The definition of the fields in the P2P PW Downstream FEC Element is
   the same as those of P2MP PW Upstream FEC Element shown in Figure 2.

2.3 Typed Wildcard FEC Format for new FEC

   [RFC5918] defines the general notion of a "Typed Wildcard" FEC
   Element, and requires FEC designer to specify a typed wildcard FEC
   element for newly defined FEC element types. This document defines
   two new FEC elements, "P2MP PW Upstream" and "P2P PW Downstream" FEC
   element, and hence requires us to define their Typed Wildcard format.

   [RFC6667] defines Typed Wildcard FEC element format for other PW FEC
   Element types (PWid and Gen. PWid FEC Element) in section 2 as



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   follows:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Typed Wcard=0x5|Type=PW FEC    |   Len = 3     |R|   PW type   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    . . .      | PMSI Tun Type |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            Figure 5: Typed Wildcard Format for P2MP PW FEC Elements

   [RFC6667] specifies that "Type" field can be either "PWid" (0x80) or
   "Generalized PWid" (0x81) FEC element type. This document reuses the
   existing typed wildcard format as specified in [RFC6667] and
   illustrated in Figure 5 and extends the definition of "Type" field to
   also include "P2MP PW Upstream" and "P2P PW Downstream" FEC element
   types. This document adds an additional field "PMSI Tun Type". This
   document reserves PMSI tunnel Type 0xFF to mean "wildcard" transport
   tunnel type. The PMSI tunnel Type field only applies to Typed
   wildcard P2MP PW Upstream FEC and MUST be set to "wildcard" for "P2P
   PW Downstream FEC" typed wildcard element.

2.4 Group ID usage

   The Grouping TLV as defined in [RFC4447bis] contains a group ID
   capable of indicating an arbitrary group membership of a P2MP-PW.
   This group ID can be used in LDP "wild card" status, and withdraw
   label messages, as described in [RFC4447bis].

2.5 Generic Label TLV

   As in the case of P2P PW signaling, P2MP PW labels are carried within
   Generic Label TLV contained in LDP Label Mapping Message. A Generic
   Label TLV is formatted and processed as per the rules and procedures
   specified in [RFC4447bis]. For a given P2MP PW, a single upstream-
   assigned label is allocated by the R-PE, and is advertised to all L-
   PEs using the Generic Label TLV in label mapping message containing
   the P2MP PW Upstream FEC element.

   The R-PE can also allocate a unique label for each L-PE from which it
   intends to receive P2P traffic. Such a label is advertised to the L-
   PE using Generic Label TLV and P2P PW Downstream FEC in label mapping
   message.


3. LDP Capability Negotiation

   The capability of supporting P2MP PW MUST be advertised to all LDP



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   peers. This is achieved by using the methods in [RFC5561] to
   advertise the LDP "P2MP PW Capability" TLV. If an LDP peer supports
   the dynamic capability advertisement, this can be done by sending a
   new Capability message with the S bit set for the P2MP PW capability
   TLV. If the peer does not supports dynamic capability advertisement,
   then the P2MP PW Capability TLV MUST be included in the LDP
   Initialization message during the session establishment. An LSR
   having P2MP PW capability MUST recognize both P2MP PW Upstream FEC
   Element and P2P PW Downstream FEC Element in LDP label messages.

   In line with requirements listed in [RFC5561], the following TLV is
   defined to indicate the P2MP PW capability:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |U|F| P2MP PW Capability TLV    |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |S| Reserved    |    Reserved   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 7: LDP P2MP PW Capability TLV

   * U-bit:

     SHOULD be 1 (ignore if not understood).

   * F-bit:

     SHOULD be 0 (don't forward if not understood).

   * P2MP PW Capability TLV Code Point:

     The TLV type, which identifies a specific capability. The P2MP PW
   capability code point is requested in the IANA allocation section
   below.

   * S-bit:

     The State Bit indicates whether the sender is advertising or
   withdrawing the P2MP PW capability. The State bit is used as
   follows:
         1 - The TLV is advertising the capability specified by the
             TLV Code Point.

         0 - The TLV is withdrawing the capability specified by the
             TLV Code Point.




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   * Length:

     MUST be set to 2 (octet).


4. P2MP PW Status

   In order to support the proposed mechanism, an LSR MUST be capable of
   handling PW status. As such, PW status negotiation procedure
   described in [RFC4447bis] is not applicable to P2MP PW. An LSR MUST
   NOT claim to be  P2MP PW capable by sending a LDP P2MP PW Capability
   TLV  if it is not also capable of handling PW status.

   Once an L-PE successfully processes a Label Mapping Message for a
   P2MP PW, it MUST send appropriate PW status according to the
   procedure specified [RFC4447bis] to report the PW status. If no PW
   status notification is required, then no PW status notification is
   sent (for example if the P2MP PW is established and operational with
   a status code of Success (0x00000000), a PW status message is not
   necessary). A PW status message sent from an L-PE to R-PE MUST
   contain the P2P PW Downstream FEC to identify the PW.

   An R-PE also sends PW status to L-PE(s) to reflect its view of a P2MP
   PW state. Such PW status message contains P2MP PW Upstream FEC to
   identify the PW.

   Connectivity status of the underlying P2MP LSP that P2MP PW is
   associated with, can be verified using LSP Ping and Traceroute
   procedures described in [RFC6425].

5 Security Considerations

   The security measures described in [RFC4447bis] are adequate for the
   proposed mechanism.

6 Acknowledgment

   Authors would like thank Andre Pelletier and Parag Jain for their
   valuable suggestions.

7  IANA Considerations

7.1. FEC Type Name Space

   This document uses two new FEC element types, number 0x82 and 0x83
   are suggested for assignment from the registry "FEC Type Name Space"
   for the Label Distribution Protocol (LDP RFC5036):




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      Value    Hex    Name                               Reference
      -------  -----  -----------------------------      ---------
       130     0x82   P2MP PW Upstream FEC Element       RFCxxxx
       131     0x83   P2P PW Downstream FEC Element      RFCxxxx

7.2. LDP TLV Type

   This document uses a new LDP TLV types, IANA already maintains a
   registry of name "TLV TYPE NAME SPACE" defined by RFC5036. The
   following values are suggested for assignment:

         TLV type  Description:

         0x0703   P2MP PW Capability TLV

7.3. mLDP Opaque Value Element TLV Type

   This document requires allocation of a new mLDP Opaque Value Element
   Type from "LDP MP Opaque Value Element basic type" name space defined
   in [RFC6388].

   The following value is suggested for assignment:

         TLV type  Description
         0x3       L2VPN-MCAST application TLV

7.4. Selective Tree Interface Parameter sub-TLV Type

   This document requires allocation of a sub-TLV from the registry
   "Pseudowire Interface Parameters Sub-TLV Type" defined in [RFC4446].


   The following value is suggested for assignment:

         TLV type  Description
         0x1b      Selective Tree Interface Parameter.

7.5. WildCard PMSI tunnel type

   This document requests that IANA modify the following entry in the
   "P-Multicast Service Interface Tunnel (PMSI Tunnel) Tunnel Types"
   registry  within the "Border Gateway Protocol (BGP) Parameters"
   namespace previously assigned by RFC7385 as "reserved".

     Value     Meaning                                Reference
     0xFF      wildcard transport tunnel type         [This document]





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8  References

8.1. Normative References

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

   [RFC4447bis] "Pseudowire Setup and Maintenance using the Label
   Distribution Protocol", Martini, L., et al., draft-ietf-pals-
   rfc4447bis-05.txt, July 2016.

   [RFC5036]  Andersson, L., Minei, I., and B. Thomas, "LDP
   Specification", RFC 5036, October 2007.

   [RFC5003] C. Metz, L. Martini, F. Balus, J. Sugimoto, "Attachment
   Individual Identifier (AII) Types for Aggregation", RFC5003,
   September 2007.

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

   [RFC5332] T. Eckert, E. Rosen, Ed.,R. Aggarwal, Y. Rekhter, "MPLS
   Multicast Encapsulations", RFC 5332, August 2008.

   [RFC6388] I. Minei, K. Kompella, I. Wijnands, B. Thomas, "Label
   Distribution Protocol Extensions for Point-to-Multipoint and
   Multipoint-to-Multipoint Label Switched Paths", RFC 6388, November
   2011.

   [RFC4875] R. Aggarwal, Ed., D. Papadimitriou, Ed., S. Yasukawa, Ed.,
   "Extensions to Resource Reservation Protocol - Traffic Engineering
   (RSVP-TE) for Point-to-Multipoint TE Label Switched Paths (LSPs).",
   RFC 4875, May 2007.

   [RFC6514] R. Aggarwal, E. Rosen, T. Morin, Y. Rekhter, "BGP Encodings
   and Procedures for Multicast in MPLS/BGP IP VPNs", RFC6514, February
   2012.

   [RFC5561] B.Thomas, K.Raza, S.Aggarwal, R.Agarwal, JL. Le Roux, "LDP
   Capabilities", RFC 5561, July 2009.

   [RFC5918] R. Asati, I. Minei, and B. Thomas, "LDP Typed Wildcard
   Forwarding Equivalence Class", RFC 5918, August 2010.

   [RFC6667] K. Raza, S. Boutros, and C. Pignataro, "LDP Typed Wildcard
   FEC for PWid and Generalized PWid FEC Elements", RFC 6667, July 2012.





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8.2. Informative References

   [RFC3985] Stewart Bryant, et al., "PWE3 Architecture", RFC3985

   [RFC6074] E. Rosen,W. Luo,B. Davie,V. Radoaca "Provisioning, Auto-
   Discovery, and Signaling in Layer 2 Virtual Private Networks
   (L2VPNs)", RFC6074, January 2011.

   [RFC7338]   F. Jounay, et. al, "Requirements for Point to Multipoint
   Pseudowire", RFC7338, September 2014.

   [RFC6425] A. Farrel, S. Yasukawa, "Detecting Data Plane Failures in
   Point-to-Multipoint Multiprotocol Label Switching (MPLS)- Extensions
   to LSP Ping", RFC6425, November 2011.


Contributors


      The following co-authors have also contributed to this document:

      Luca Martini
      Cisco Systems, Inc.
      Email: lmartini@cisco.com

      Maciek Konstantynowicz
      Cisco Systems, Inc.
      e-mail: maciek@cisco.com

      Gianni Del Vecchio
      Swisscom
      Email: Gianni.DelVecchio@swisscom.com

      Thomas D. Nadeau
      Brocade
      Email: tnadeau@lucidvision.com

      Frederic Jounay
      Orange CH
      Email: Frederic.Jounay@salt.ch

      Philippe Niger
      Orange CH
      Email: philippe.niger@orange.com

      Yuji Kamite
      NTT Communications Corporation
      Email: y.kamite@ntt.com



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      Lizhong Jin
      Email: lizho.jin@gmail.com

      Martin Vigoureux
      Nokia
      Email: martin.vigoureux@nokia.com

      Laurent Ciavaglia
      Nokia
      Email: laurent.ciavaglia@nokia.com


      Simon Delord
      Telstra
      E-mail: simon.delord@gmail.com

      Kamran Raza
      Cisco Systems
      Email: skraza@cisco.com

Authors' Addresses


      Sami Boutros
      VMware Inc.
      Email: sboutros@vmware.com

      Siva Sivabalan
      Cisco Systems, Inc.
      Email: msiva@cisco.com





















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