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Versions: (draft-kumarzheng-bier-ping) 00 01 02

Network Work group                                              N. Kumar
Internet-Draft                                              C. Pignataro
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: January 22, 2018                                       N. Akiya
                                                     Big Switch Networks
                                                                L. Zheng
                                                                 M. Chen
                                                     Huawei Technologies
                                                               G. Mirsky
                                                                Ericsson
                                                           July 21, 2017


                          BIER Ping and Trace
                        draft-ietf-bier-ping-02

Abstract

   Bit Index Explicit Replication (BIER) is an architecture that
   provides optimal multicast forwarding through a "BIER domain" without
   requiring intermediate routers to maintain any multicast related per-
   flow state.  BIER also does not require any explicit tree-building
   protocol for its operation.  A multicast data packet enters a BIER
   domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the
   BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs).
   The BFIR router adds a BIER header to the packet.  The BIER header
   contains a bit-string in which each bit represents exactly one BFER
   to forward the packet to.  The set of BFERs to which the multicast
   packet needs to be forwarded is expressed by setting the bits that
   correspond to those routers in the BIER header.

   This document describes the mechanism and basic BIER OAM packet
   format that can be used to perform failure detection and isolation on
   BIER data plane.

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




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   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 January 22, 2018.

Copyright Notice

   Copyright (c) 2017 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Requirements notation . . . . . . . . . . . . . . . . . .   4
   3.  BIER OAM  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  BIER OAM message format . . . . . . . . . . . . . . . . .   4
     3.2.  Return Code . . . . . . . . . . . . . . . . . . . . . . .   7
     3.3.  BIER OAM TLV  . . . . . . . . . . . . . . . . . . . . . .   8
       3.3.1.  Original SI-BitString TLV . . . . . . . . . . . . . .   8
       3.3.2.  Target SI-BitString TLV . . . . . . . . . . . . . . .   9
       3.3.3.  Incoming SI-BitString TLV . . . . . . . . . . . . . .  10
       3.3.4.  Downstream Mapping TLV  . . . . . . . . . . . . . . .  11
       3.3.5.  Responder BFER TLV  . . . . . . . . . . . . . . . . .  14
       3.3.6.  Responder BFR TLV . . . . . . . . . . . . . . . . . .  15
       3.3.7.  Upstream Interface TLV  . . . . . . . . . . . . . . .  15
       3.3.8.  Reply-To TLV  . . . . . . . . . . . . . . . . . . . .  16
   4.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     4.1.  BIER OAM Processing . . . . . . . . . . . . . . . . . . .  17
     4.2.  Per BFER ECMP Discovery . . . . . . . . . . . . . . . . .  17
     4.3.  Sending BIER Echo Request . . . . . . . . . . . . . . . .  18
     4.4.  Receiving BIER Echo Request . . . . . . . . . . . . . . .  19
     4.5.  Sending Echo Reply  . . . . . . . . . . . . . . . . . . .  21
     4.6.  Receiving Echo Reply  . . . . . . . . . . . . . . . . . .  22
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  22
     5.1.  Message Types, Reply Modes, Return Codes  . . . . . . . .  22
     5.2.  TLVs  . . . . . . . . . . . . . . . . . . . . . . . . . .  22



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   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  23
   7.  Acknowledgement . . . . . . . . . . . . . . . . . . . . . . .  23
   8.  Contributing Authors  . . . . . . . . . . . . . . . . . . . .  23
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  23
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  23
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  24
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  25

1.  Introduction

   [I-D.ietf-bier-architecture] introduces and explains BIER
   architecture that provides optimal multicast forwarding through a
   "BIER domain" without requiring intermediate routers to maintain any
   multicast related per-flow state.  BIER also does not require any
   explicit tree-building protocol for its operation.  A multicast data
   packet enters a BIER domain at a "Bit-Forwarding Ingress Router"
   (BFIR), and leaves the BIER domain at one or more "Bit-Forwarding
   Egress Routers" (BFERs).  The BFIR router adds a BIER header to the
   packet.  The BIER header contains a bit-string in which each bit
   represents exactly one BFER to forward the packet to.  The set of
   BFERs to which the multicast packet needs to be forwarded is
   expressed by setting the bits that correspond to those routers in the
   BIER header.

   This document describes the mechanism and basic BIER OAM packet
   format that can be used to perform failure detection and isolation on
   BIER data plane without any dependency on other layers like IP layer.

2.  Conventions used in this document

2.1.  Terminology

   BFER - Bit Forwarding Egress Router

   BFIR - Bit Forwarding Ingress Router

   BIER - Bit Index Explicit Replication

   ECMP - Equal Cost Multi-Path

   OAM - Operation, Administration and Maintenance

   SI - Set Identifier








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2.2.  Requirements notation

   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].

3.  BIER OAM

   BIER OAM is defined in a way that it stays within BIER layer by
   following directly the BIER header without mandating the need for IP
   header.  [I-D.ietf-bier-mpls-encapsulation] defines a 4-bit field as
   "Proto" to identify the payload following BIER header.  When the
   payload is BIER OAM, the "Proto" field will be set to 5 as defined in
   [I-D.ietf-bier-mpls-encapsulation]

3.1.  BIER OAM message format

   The BIER OAM packet header format that follows BIER header is 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Ver  | Message Type  | Proto |             Reserved          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                  Message Type Dependent Data                  ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Ver

      Set to 1.

   Message Type

      This document defines the following Message Types:

                   Type      Value Field
                   --------  ---------------
                     1      BIER Echo Request
                     2      BIER Echo Reply

   Proto

      This field is used to define if there is any data packet
      immediately following the OAM payload which is used for passive




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      OAM functionality.  This field is set to 0 if there is no data
      packet following OAM payload.

   The Echo Request/Reply header format is 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Ver  | Echo Req/Rep  | Proto |             Reserved          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   QTF |   RTF |   Reply mode  |  Return Code  | Return Subcode|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Sender's Handle                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Sequence Number                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    TimeStamp Sent                             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  TimeStamp Sent                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  TimeStamp Received                           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                TimeStamp Received                             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                              TLVs                             ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Proto

      Set to 0 for Echo Request/Reply header.

   QTF

      Querier Timestamp Format.  When set to 2, the Timestamp Sent field
      is (in seconds and microseconds, according to the Initiator's
      clock) in NTP format [RFC5905].  When set to 3, the timestamp
      format is in IEEE 1588-2008 (1588v2) Precision Time Protocol
      format.  Any other value SHOULD be considered as sanity check
      failure

   RTF

      Responder Timestamp Format.  When set to 2, the Timestamp Received
      field is (in seconds and microseconds, according to the
      Initiator's clock) in NTP format [RFC5905].  When set to 3, the
      timestamp format is in IEEE 1588-2008 (1588v2) Precision Time



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      Protocol format.  Any other value SHOULD be considered as sanity
      check failure.

   Reply mode

      The Reply mode is set to one of the below:

                   Value      Meaning
                   --------  ---------------
                     1        Do not Reply
                     2        Reply via IPv4/IPv6 UDP packet.
                     3        Reply via BIER packet

   When Reply mode is set to 1, the receiver will not send any reply.
   This is used for unidirectional path validation.  The Reply mode by
   default would be set to 2 and the Responder BFR will encapsulate the
   Echo reply payload with IP header.  When the Initiator intend to
   validate the return BIER path, the Reply mode is set to 3 so that the
   Responder BFR will encapsulate the Echo Reply with BIER header.

   Return Code

      Set to zero if Type is "BIER Echo Request".  Set to one of the
      value defined in section 3.2, if Type is "BIER Echo Reply".

   Return subcode

      To Be updated.

   Sender's Handle, Sequence number and Timestamp

      The Sender's Handle is filled by the Initiator, and returned
      unchanged by responder BFR.  This is used for matching the replies
      to the request.

      The Sequence number is assigned by the Initiator and can be used
      to detect any missed replies.

      The Timestamp Sent is the time when the Echo Request is sent.  The
      TimeStamp Received in Echo Reply is the time (accordingly to
      responding BFR clock) that the corresponding Echo Request was
      received.  The format depends on the QTF/RTF value.

   TLVs

      Carries the TLVs as defined in Section 3.3.





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3.2.  Return Code

   Responder uses Return Code field to reply with validity check or
   other error message to Initiator.  It does not carry any meaning in
   Echo Request and MUST be set to zero.

   The Return Code can be one of the following:

           Value      Value Meaning
           --------  ---------------
            0      No return code
            1      Malformed Echo Request received
            2      One or more of the TLVs was not understood
            3      Replying BFR is the only BFER in header Bitstring
            4      Replying BFR is one of the BFER in header Bitstring
            5      Packet-Forward-Success
            6      Invalid Multipath Info Request
            8      No matching entry in forwarding table.
            9      Set-Identifier Mismatch

   "No return code" will be used by Initiator in the Echo Request.  This
   Value MUST NOT be used in Echo Reply.

   "Malformed Echo Request received" will be used by any BFR if the
   received Echo Request packet is not properly formatted.

   When any TLV included in the Echo Request is not understood by
   receiver, the Return code will be set to "One or more of the TLVs was
   not understood" carrying the respective TLVs.

   When the received header BitString in Echo Request packet contains
   only its own Bit-ID, "Replying BFR is the only BFER in header
   BitString" is set in the reply.  This implies that the receiver is
   BFER and the packet is not forwarded to any more neighbors.

   When the received header BitString in Echo Request packet contains
   its own Bit-ID in addition to other Bit-IDs, "Replying BFR is one of
   the BFER in header BitString" is set in the reply.  This implies that
   the responder is a BFER and the packet is further forwarded to one or
   more neighbors.

   Any transit BFR will send the Echo Reply with "Packet-Forward-
   Success", if the TLV in received Echo Request are understood and
   forwarding table have forwarding entries for the BitString.  This is
   used by transit BFR during traceroute mode.

   When Echo Request is received with multipath info for more than one
   BFER, the return-code is set to "Invalid Multipath Info Request".



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   If the receiving BFER does not have any state entry in Overlay
   Multicast table.  For example, if there is no Opaque value in mLDP
   table or S,G entry in respective PIM table, the return-code is set to
   "No matching entry in forwarding table".

   If the BitString cannot be matched in local forwarding table, the BFR
   will use "No matching entry in forwarding table" in the reply.

   If the BIER-MPLS label in received Echo Request is not the one
   assigned for SI in Original SI-BitString TLV, "Set-Identifier
   Mismatch" is set inorder to report the mismatch.

3.3.  BIER OAM TLV

   This section defines various TLVs that can be used in BIER OAM
   packet.  The TLVs (Type-Length-Value tuples) have the following
   format:


      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               Type            |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     ~                              Value                            ~
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   TLV Types are defined below; Length is the length of the Value field
   in octets.  The Value field depends on the TLV Type.

3.3.1.  Original SI-BitString TLV

   The Original SI-BitString TLV carries the set of BFER and carries the
   same BitString that Initiator includes in BIER header.This TLV has
   the following format:













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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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Type = 1              |       Length = variable       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Set ID     | Sub-domain ID |BS Len|  Reserved              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                BitString  (first 32 bits)                     ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                BitString  (last 32 bits)                      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Set ID field is set to the Set Identifier to which the BitString
   belongs to.  This value is derived as defined in section 3 of
   [I-D.ietf-bier-architecture]

   Sub-domain ID is set to the Sub domain value to which BFER in
   BitString belongs to.

   BS Len is set based on the length of BitString as defined in section
   3 of [I-D.ietf-bier-mpls-encapsulation]

   The BitString field carries the set of BFR-IDs that Initiator will
   include in the BIER header.  This TLV MUST be included by Initiator
   in Echo Request packet

3.3.2.  Target SI-BitString TLV

   The Target SI-BitString TLV carries the set of BFER from which the
   Initiator expects the reply from.This TLV has the following format:


















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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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Type = 2              |       Length = variable       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Set ID     | Sub-domain ID |BS Len|  Reserved              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                BitString  (first 32 bits)                     ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                BitString  (last 32 bits)                      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Set ID field is set to the Set Identifier to which the BitString
   belongs to.  This value is derived as defined in section 3 of
   [I-D.ietf-bier-architecture]

   Sub-domain ID is set to the Sub domain value to which BFER in
   BitString belongs to.

   BS Len is set based on the length of BitString as defined in section
   3 of [I-D.ietf-bier-mpls-encapsulation]

   The BitString field carries the set of BFR-IDs of BFER(s) that
   Initiator expects the response from.  The BitString in this TLV may
   be different from the BitString in BIER header and allows to control
   the BFER responding to the Echo Request.  This TLV MUST be included
   by Initiator in BIER OAM packet if the Downstream Mapping TLV
   (section 3.3.4) is included.

3.3.3.  Incoming SI-BitString TLV

   The Incoming SI-BitString TLV will be included by Responder BFR in
   Reply message and copies the BitString from BIER header of incoming
   Echo Request message.  This TLV has the following format:














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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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Type = 3              |       Length = variable       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Set ID     | Sub-domain ID |BS Len|  Reserved              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                BitString  (first 32 bits)                     ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                BitString  (last 32 bits)                      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Set ID field is set to the Set Identifier to which the BitString
   belongs to.  This value is derived as defined in section 3 of
   [I-D.ietf-bier-architecture]

   Sub-domain ID is set to the Sub domain value to which BFER in
   BitString belongs to.

   BS Len is set based on the length of BitString as defined in section
   3 of [I-D.ietf-bier-mpls-encapsulation]

   The BitString field copies the BitString from BIER header of the
   incoming Echo Request.  A Responder BFR SHOULD include this TLV in
   Echo Reply if the Echo Request is received with I flag set in
   Downstream Mapping TLV.

   An Initiator MUST NOT include this TLV in Echo Request.

3.3.4.  Downstream Mapping TLV

   This TLV has the following format:
















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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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Type = 4              |       Length = variable       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               MTU             | Address Type  |     Flags     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               Downstream Address (4 or 16 octets)             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Downstream Interface Address (4 or 16 octets)         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        Sub-tlv Length         |                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
     .                                                               .
     .                      List of Sub-TLVs                         .
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   MTU

      Set to MTU value of outgoing interface.

   Address Type

      The Address Type indicates the address type and length of IP
      address for downstream interface.  The Address type is set to one
      of the below:

                   Type     Addr. Type       DA Length    DIA Length
              -------  ---------------   ----------   ----------
                  1       IPv4 Numbered        4              4
                  2       IPv4 Unnumbered      4              4
                  3       IPv6 Numbered        16            16
                  4       IPv6 Unnumbered      16             4

                  DA Length - Downstream Address field Length
                  DIA Length - Downstream Interface Address field Length

   Flags

      The Flags field has the following format:

                                           0 1 2 3 4 5 6 7
                          +-+-+-+-+-+-+-+-+
                          |     Rsvd    |I|
                          +-+-+-+-+-+-+-+-+




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   When I flag is set, the Responding BFR SHOULD include the Incoming
   SI-BitString TLV in Echo Reply message.

   Downstream Address and Downstream Interface Address

      If the Address Type is 1, the Downstream Address MUST be set to
      IPV4 BFR-Prefix of downstream BFR and Downstream Interface Address
      is set to downstream interface address.

      If the Address Type is 2, the Downstream Address MUST be set to
      IPV4 BFR-Prefix of downstream BFR and Downstream Interface Address
      is set to the index assigned by upstream BFR to the interface.

      If the Address Type is 3, the Downstream Address MUST be set to
      IPV6 BFR-Prefix of downstream BFR and Downstream Interface Address
      is set to downstream interface address.

      If the Address Type is 4, the Downstream Address MUST be set to
      IPv6 BFR-Prefix of downstream BFR and Downstream Interface Address
      is set to index assigned by upstream BFR to the interface.

3.3.4.1.  Downstream Detailed Mapping Sub-TLVs

   This section defines the optional Sub-TLVs that can be included in
   Downstream Mapping TLV.

                   Sub-TLV Type     Value
                   ---------------  --------------
                       1         Multipath Entropy Data
                       2         Egress BitString

3.3.4.1.1.  Multipath Entropy Data


        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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |M|  Reserved     |                                             |
      +-+-+-+-+-+-+-+-+-+                                             |
      |                                                               |
      |                  (Multipath Information)                      |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   M Flag





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      This flag is set to 0 if all packets will be forwarded out through
      interface defined in Downstream Mapping TLV.  When set to 1,
      Multipath Information will be defined with Bit masked Entropy
      data.

   Multipath Information

      Entropy Data encoded as defined in section x3.

3.3.4.1.2.  Egress BitString

   This Sub-TLV MAY be included by Responder BFR with the rewritten
   BitString in outgoing interface as defined in section 6.1 of
   [I-D.ietf-bier-architecture]


      0                   1                   2                   3
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Set ID     | Sub-domain ID |BS Len|  Reserved              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                BitString  (first 32 bits)                     ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                BitString  (last 32 bits)                      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


3.3.5.  Responder BFER TLV

   The Responder BFER TLV will be included by the BFER replying to the
   request.  This is used to identify the originator of BIER Echo Reply.
   This TLV have the following format:


      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Type = 5              |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Reserved              |           BFR-ID              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   BFR-ID

      The BFR-ID field carries the BFR-ID of replying BFER.  This TLV
      MAY be included by Responding BFER in BIER Echo Reply packet.



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3.3.6.  Responder BFR TLV

   The Responder BFR TLV will be included by the transit BFR replying to
   the request.  This is used to identify the replying BFR without BFR-
   ID.  This TLV have the following format:


      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     TLV Type = 6              |       Length = variable       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Reserved              |          Address Type         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     ~                       BFR-Prefix (4 or 16 bytes)              ~
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Length

      The Length field varies depending on the Address Type.

   Address Type

      Set to 1 for IPv4 or 2 for IPv6.

   BFR-Prefix

      Carries the local BFR-Prefix of the replying BFR.  This TLV MAY be
      included by Responding BFR in BIER Echo Reply packet.

3.3.7.  Upstream Interface TLV

   The Upstream Interface TLV will be included by the replying BFR in
   Echo Reply.  This is used to identify the incoming interface and the
   BIER-MPLS label in the incoming Echo Request.  This TLV have the
   following format:













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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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     TLV Type = 7              |       Length = variable       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Reserved              |          Address Type         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     ~                 Upstream Address (4 or 16 bytes)              ~
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Length

      The Length field varies depending on the Address Type.

   Address Type

      Set to 1 for IPv4 numbered, 2 for IPv4 Unnumbered 3 for IPv6
      numbered or 4 for IPv6 Unnumbered.

   Upstream Address

      As defined in Section 3.3.4

3.3.8.  Reply-To TLV

   The Reply-To TLV MAY be included by the Initiator BFR in Echo
   Request.  This is used by transit BFR or BFER when the reply mode is
   2.  The IP address will be used to generate Echo Reply.  This TLV
   have the following format:


      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     TLV Type = 8              |       Length = variable       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Reserved              |          Address Type         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     ~                    Reply-To Address (4 or 16 bytes)           ~
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Length

      The Length field varies depending on the Address Type.



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   Address Type

      Set to 1 for IPv4 or 2 for IPv6.

   Reply-To Address

      Set to any locally configured address to which the Echo reply
      should be sent to.

4.  Procedures

   This section describes aspects of Ping and traceroute operations.
   While this document explains the behavior when Reply mode is "Reply
   via BIER packet", the future version will be updated with details
   about the format when the reply mode is "Reply via IP/UDP packet".

4.1.  BIER OAM Processing

   A BIER OAM packet MUST be sent to BIER control plane for OAM
   processing if one of the following conditions is true:

   o  The receiving BFR is a BFER.

   o  TTL of BIER-MPLS Label expired.

   o  Presence of Router Alert label in the label stack.

4.2.  Per BFER ECMP Discovery

   As defined in [I-D.ietf-bier-architecture], BIER follows unicast
   forwarding path and allows load balancing over ECMP paths between
   BFIR and BFER.  BIER OAM MUST support ECMP path discovery between a
   BFIR and a given BFER and MUST support path validation and failure
   detection of any particular ECMP path between BFIR and BFER.

   [I-D.ietf-bier-mpls-encapsulation] proposes the BIER header with
   Entropy field that can be leveraged to exercise all ECMP paths.
   Initiator/BFIR will use traceroute message to query each hop about
   the Entropy information for each downstream paths.  To avoid
   complexity, it is suggested that the ECMP query is performed per BFER
   by carrying required information in BIER OAM message.

   Initiator MUST include Multipath Entropy Data Sub-TLV in Downstream
   Mapping TLV.  It MUST also include the BFER in BitString TLV to which
   the Multipath query is performed.

   Any transit BFR will reply back with Bit-masked Entropy for each
   downstream path as defined in [RFC8029]



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4.3.  Sending BIER Echo Request

   Initiator MUST set the Message Type as 1 and Return Code as 0.  The
   Proto field in OAM packet MUST be set to 0.  The choice of Sender's
   Handle and Sequence number is a local matter to Initiator and SHOULD
   increment the Sequence number by 1 for every subsequent Echo Request.
   The QTF field is set to Initiator's local timestamp format and
   TimeStamp Sent field is set to the time that the Echo Request is
   sent.

   Initiator MUST include Original SI-BitString TLV.  Initiator MUST NOT
   include more than one Original SI-BitString TLV.  Initiator infers
   the Set Identifier value and Sub-domain ID value from the respective
   BitString that will be included in BIER header of the packet and
   includes the values in "SI" and Sub-Domain ID fields respectively.

   In Ping mode, Initiator MAY include Target SI-BitString TLV to
   control the responding BFER(s) by listing all the BFERs from which
   the Initiator expects a response.  In trace route mode, Initiator MAY
   include Target SI-Bitstring TLV to control the path trace towards any
   specific BFER or set of BFERs.  Initiator on receiving a reply with
   Return code as "Replying BFR is the only BFER in header Bitstring" or
   "Replying router is one of the BFER in header Bitstring", SHOULD
   unset the respective BFR-id from Target SI-BitString for any
   subsequent Echo Request.

   When the Reply mode is set to 2, Initiator MUST include Reply-To TLV
   (section 3.3.8) in the Echo Request.  Initiator MUST also listen to
   the UDP port defined in this TLV and process any segment received
   with destination port as value defined in the TLV and sent to control
   plane for BIER OAM payload processing.

   Initiator MAY include Downstream Mapping TLV (section 3.3.4) in the
   Echo Request to query additional information from transit BFRs and
   BFERs.  In case of ECMP discovery, Initiator MUST include the
   Multipath Entropy Data Sub-TLV and SHOULD set the Target SI-BitString
   TLV carrying a specific BFER id.

   Initiator MUST encapsulate the OAM packet with BIER header and MUST
   set the Proto as 5 and further encapsulates with BIER-MPLS label.  In
   ping mode, the BIER-MPLS Label TTL MUST be set to 255.  In traceroute
   mode, the BIER-MPLS Label TTL is set successively starting from 1 and
   MUST stop sending the Echo Request if it receives a reply with Return
   code as "Replying router is the only BFER in BIER header Bitstring"
   from all BFER listed in Target SI-BitString TLV.






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4.4.  Receiving BIER Echo Request

   Sending a BIER OAM Echo Request to control plane for payload
   processing is triggered as mentioned in section 4.1.

   Any BFR on receiving Echo Request MUST send Echo Reply with Return
   Code set to "Malformed Echo Request received", if the packet fails
   sanity check.  If the packet sanity check is fine, it SHOULD
   initiates the below set of variables:

   Reply-Flag

      This flag is initially set to 1.

   Interface-I

      The incoming interface on which the Echo Request was received.
      This may be used to validate the DDMAP info and to populate the
      Upstream Interface TLV.

   BIER-Label-L

      The BIER-MPLS Label received as the top label on received Echo
      Request.  This may be used to validate if the packet is traversing
      the desired Set Identifier and sub-domain path.

   Header-H

      The BIER header from the received Echo Request.  This may be used
      to validate the DDMAP info and to populate the Incoming SI-
      BitString TLV.  In addition, it can be used to perform Entropy
      calculation considering different field in header and reply via
      Multipath Entropy Data Sub-TLV.

   BFR MUST initialize Best-return-code variable to null value.

   BFR will populate Interface-I with interface over which the Echo
   Request is received, top label in the MPLS stack of the received Echo
   Request to BIER-Label-L, and the BIER header to BIER-Header.  If the
   received Echo Request carries Target SI-BitString TLV, a BFR SHOULD
   run boolean NAD operation between BitString in Header-H and BitString
   in Target SI-BitString TLV.  If the resulting BitString is all-zero,
   reset Return-Flag=0 and go to section 4.5.  Else:

   o  If the BIER-Label-L does not correspond to the local label
      assigned for {sub-domain, BitStringLen, SI} in Original SI-
      BitString TLV, Set the Best-return-code to "Set-Identifier
      Mismatch" and Go to section 4.5.



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      *  /* This detects any BIER-Label to {sub-domain, BitStringLen,
         SI} synchronization problem in the upstream BFR causing any
         unintended packet leak between sub-domains */

   o  Set the Best-return-code to "One or more of the TLVs was not
      understood", if any of the TLVs in Echo Request message is not
      understood.  Go to section 4.5.

   o  If the BitString in Header-H does not match the BitString in
      Egress BitString Sub-TLV of DDMAP TLV, set the Best-return-code to
      ERR-TBD.  When there are more than one DDMAP TLV in the received
      Request packet, the Downstream Address and Downstream Interface
      Address should be matched with Interface-I to identify the right
      DDMAP TLV and then perform the BitString match.

      *  /* This detects any deviation between in BIER control plane and
         BIER forwarding plane in the previous hop that may result in
         loop or packet duplication.  */

   o  Set the Best-return-code to "Invalid Multipath Info Request", when
      the DDMAP TLV carries Multipath Entropy Data Sub-TLV and if the
      Target SI-BitString TLV in the received Echo Request carries more
      than 1 BFER id.  Go to section 4.5.  Else, list the ECMP
      downstream neighbors to reach BFR-id in Target SI-BitString TLV,
      calculate the Entropy considering the BitString in Header-H and
      Multipath Entropy Data Sub-TLV from received Echo Request.  Store
      the Data for each Downstream interface in temporary variable.  Set
      the Best-return-code to 5 (Packet-Forward-Success) and goto
      Section 4.5

      *  /* This instructs to calculate the Entropy Data for each
         downstream interface to reach the BFER in Target SI-BitString
         TLV by considering the incoming BitString and Entropy Data.*/

   o  Set the Best-return-code to "Replying router is the only BFER in
      BIER header Bitstring", and go to section 4.5 if the responder is
      BFER and there is no more bits in BIER header Bitstring left for
      forwarding.

   o  Set the Best-return-code to "Replying router is one of the BFER in
      BIER header Bitstring", and include Downstream Mapping TLV, if the
      responder is BFER and there are more bits in BitString left for
      forwarding.  In addition, include the Multipath information as
      defined in Section 4.2 if the received Echo Request carries
      Multipath Entropy Data Sub-TLV.  Go to section 4.5.

   o  Set the Best-return-code to "No matching entry in forwarding
      table", if the forwarding lookup defined in section 6.5 of



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      [I-D.ietf-bier-architecture] does not match any entry for the
      received BitString in BIER header.

      *  /* This detects any missing BFR-id in the BIER forwarding
         table.  It could be noted that it is difficult to detect such
         missing BFR-id while sending the Request with more than one
         BFR-id in BitString and so may need to just include the BFER id
         that is not responding to detect such failure.*/

   o  Set the Best-return-code to "Packet-Forward-Success", and include
      Downstream Mapping TLV.  Go to section 4.5

4.5.  Sending Echo Reply

   If Return-Flag=0; BFR MUST release the variables and MUST not send
   any response to the Initiator.  If Return-Flag=1, proceed as below:

   The Responder BFR SHOULD include the BitString from Header-H to
   Incoming SI-BitString TLV and include the Set ID, Sub-domain ID and
   BS Len corresponding to BIER-Label-L.  Responder BFR SHOULD include
   the Upstream Interface TLV and populate the address from Interface-I.

   When the Best-return-code is "Replying BFR is one of the BFER in
   header Bitstring", it MUST include Responder BFER TLV.

      If the received Echo Request had DDMAP with Multipath Entropy Data
      Sub-TLV, Responder BFR MUST include DDMAP as defined in
      Section 3.3.4 for each outgoing interface over which the packet
      will be replicated and include the respective Multipath Entropy
      Data Sub-TLV.  For each outgoing interface, respective Egress
      BitString MUST be included in DDMAP TLV.

      If the received Echo Request had DDMAP without Multipath Entropy
      Data Sub-TLV, Responder BFR MUST include DDMAP as defined in
      Section 3.3.4 for each outgoing interface over which the packet
      will be replicated.  For each outgoing interface, respective
      Egress BitString MUST be included in DDMAP TLV.

   When the Best-return-code is "Replying BFR is the only BFER in header
   Bitstring", it MUST include Responder BFER TLV.

   Responder MUST set the Message Type as 2 and Return Code as Best-
   return-code.  The Proto field MUST be set to 0.

   The Echo Reply can be sent either as BIER-encapsulated or IP/UDP
   encapsulated depending on the Reply mode in received Echo Request.
   When the Reply mode in received Echo Request is set to 3, Responder
   appends BIER header listing the BitString with BFIR ID (from Header-



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   H), set the Proto to 5 and set the BFIR as 0.  When the Reply mode in
   received Echo Request is set to 2, Responder encapsulates with IP/UDP
   header.  The UDP destination port MUST be set to TBD1 and source port
   MAY be set to TBD1 or other random local value.  The source IP is any
   local address of the responder and destiantion IP is derived from
   Reply-To TLV.

4.6.  Receiving Echo Reply

   Initiator on receiving Echo Reply will use the Sender's Handle to
   match with Echo Request sent.  If no match is found, Initiator MUST
   ignore the Echo Reply.

   If receiving Echo Reply have Downstream Mapping, Initiator SHOULD
   copy the same to subsequent Echo Request(s).

   If one of the Echo Reply is received with Return Code as "Replying
   BFR is one of the BFER in header Bitstring", it SHOULD reset the BFR-
   id of the responder from Target SI-BisString TLV in subsequent Echo
   Request.

      /* This helps avoiding any BFR that is both BFER and also transit
      BFR to continuously responding with Echo Reply.*/

5.  IANA Considerations

   This document request UDP port TBD1 to be allocated by IANA for BIER
   Echo.

   This document request the IANA for creation and management of below
   registries:

5.1.  Message Types, Reply Modes, Return Codes

   This document request to assign the Message Types and Reply mode
   mentioned in section 3.1, , Return code mentioned in Section 3.2.

5.2.  TLVs

   The TLVs and Sub-TLVs defined in this document is not limited to Echo
   Request or Reply message types and is applicable for other message
   types.  The TLVs and Sub-TLVs requested by this document for IANA
   consideration are the following:








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             Type        Sub-Type            Value Field
             -------      --------            -----------
             1                               Original SI-BitString
             2                               Target SI-BitString
             3                               Incoming SI-BitString
             4                               Downstream Mapping
             4              1                Multipath Entropy Data
             4              2                Egress BitString
             5                               Responder BFER
             6                               Responder BFR
             7                               Upstream Interface

6.  Security Considerations

   The security consideration for BIER Ping is similar to ICMP or LSP
   Ping.  AS like ICMP or LSP ping, BFR may be exposed to Denial-of-
   service attacks and it is RECOMMENDED to regulate the BIER Ping
   packet flow to control plane.  A rate limiter SHOULD be applied to
   avoid any attack.

   As like ICMP or LSP Ping, a traceroute can be used to obtain network
   information.  It is RECOMMENDED that the implementation check the
   integrity of BFIR of the Echo messages against any local secured list
   before processing the message further

7.  Acknowledgement

   The authors would like to thank Antoni Przygienda, Eric Rosen, Faisal
   Iqbal and Jeffrey (Zhaohui) Zhang for thier review and comments.

8.  Contributing Authors

   TBD

9.  References

9.1.  Normative References

   [I-D.ietf-bier-architecture]
              Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
              S. Aldrin, "Multicast using Bit Index Explicit
              Replication", draft-ietf-bier-architecture-07 (work in
              progress), June 2017.








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   [I-D.ietf-bier-mpls-encapsulation]
              Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J.,
              Aldrin, S., and I. Meilik, "Encapsulation for Bit Index
              Explicit Replication in MPLS and non-MPLS Networks",
              draft-ietf-bier-mpls-encapsulation-07 (work in progress),
              June 2017.

   [I-D.ietf-bier-ospf-bier-extensions]
              Psenak, P., Kumar, N., Wijnands, I., Dolganow, A.,
              Przygienda, T., Zhang, Z., and S. Aldrin, "OSPF Extensions
              for BIER", draft-ietf-bier-ospf-bier-extensions-07 (work
              in progress), July 2017.

   [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>.

   [RFC5905]  Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
              "Network Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
              <http://www.rfc-editor.org/info/rfc5905>.

   [RFC8029]  Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
              Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
              Switched (MPLS) Data-Plane Failures", RFC 8029,
              DOI 10.17487/RFC8029, March 2017,
              <http://www.rfc-editor.org/info/rfc8029>.

9.2.  Informative References

   [RFC0792]  Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, DOI 10.17487/RFC0792, September 1981,
              <http://www.rfc-editor.org/info/rfc792>.

   [RFC6291]  Andersson, L., van Helvoort, H., Bonica, R., Romascanu,
              D., and S. Mansfield, "Guidelines for the Use of the "OAM"
              Acronym in the IETF", BCP 161, RFC 6291,
              DOI 10.17487/RFC6291, June 2011,
              <http://www.rfc-editor.org/info/rfc6291>.

   [RFC6424]  Bahadur, N., Kompella, K., and G. Swallow, "Mechanism for
              Performing Label Switched Path Ping (LSP Ping) over MPLS
              Tunnels", RFC 6424, DOI 10.17487/RFC6424, November 2011,
              <http://www.rfc-editor.org/info/rfc6424>.






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   [RFC6425]  Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A.,
              Yasukawa, S., and T. Nadeau, "Detecting Data-Plane
              Failures in Point-to-Multipoint MPLS - Extensions to LSP
              Ping", RFC 6425, DOI 10.17487/RFC6425, November 2011,
              <http://www.rfc-editor.org/info/rfc6425>.

Authors' Addresses

   Nagendra Kumar
   Cisco Systems, Inc.
   7200 Kit Creek Road
   Research Triangle Park, NC  27709
   US

   Email: naikumar@cisco.com


   Carlos Pignataro
   Cisco Systems, Inc.
   7200 Kit Creek Road
   Research Triangle Park, NC  27709-4987
   US

   Email: cpignata@cisco.com


   Nobo Akiya
   Big Switch Networks
   Japan

   Email: nobo.akiya.dev@gmail.com


   Lianshu Zheng
   Huawei Technologies
   China

   Email: vero.zheng@huawei.com


   Mach Chen
   Huawei Technologies

   Email: mach.chen@huawei.com







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   Greg Mirsky
   Ericsson

   Email: gregory.mirsky@ericsson.com















































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