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MPLS Working Group                                             G. Mirsky
Internet-Draft                                                 ZTE Corp.
Intended status: Standards Track                        October 12, 2018
Expires: April 15, 2019


     BFD for Multipoint Networks over Point-to-Multi-Point MPLS LSP
                     draft-mirsky-mpls-p2mp-bfd-04

Abstract

   This document describes procedures for using Bidirectional Forwarding
   Detection (BFD) for multipoint networks to detect data plane failures
   in Multiprotocol Label Switching (MPLS) point-to-multipoint (p2mp)
   Label Switched Paths (LSPs).  It also describes the applicability of
   out-band solutions to bootstrap a BFD session in this environment.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 15, 2019.

Copyright Notice

   Copyright (c) 2018 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   2
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
     2.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   3.  Multipoint BFD Encapsulation  . . . . . . . . . . . . . . . .   3
     3.1.  IP Encapsulation of Multipoint BFD  . . . . . . . . . . .   3
     3.2.  Non-IP Encapsulation of Multipoint BFD  . . . . . . . . .   4
   4.  Bootstrapping Multipoint BFD  . . . . . . . . . . . . . . . .   4
     4.1.  LSP Ping  . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.2.  Control Plane . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Source MEP ID IP Address Type . . . . . . . . . . . . . .   4
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   [I-D.ietf-bfd-multipoint] defines a method of using Bidirectional
   Detection (BFD) [RFC5880] to monitor and detect unicast failures
   between the sender (head) and one or more receivers (tails) in
   multipoint or multicast networks.  This document describes procedures
   for using such mode of BFD protocol to detect data plane failures in
   Multiprotocol Label Switching (MPLS) point-to-multipoint (p2mp) Label
   Switched Paths (LSPs).  The document also describes the applicability
   of out-band solutions to bootstrap a BFD session in this environment.

2.  Conventions used in this document

2.1.  Terminology

   MPLS: Multiprotocol Label Switching

   LSP: Label Switched Path

   BFD: Bidirectional Forwarding Detection

   p2mp: Point-to-Multipoint

   FEC: Forwarding Equivalence Class

   G-ACh: Generic Associated Channel

   ACH: Associated Channel Header




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   GAL: G-ACh Label

2.2.  Requirements Language

   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.

3.  Multipoint BFD Encapsulation

   [I-D.ietf-bfd-multipoint] defines how the tail of multipoint BFD
   session demultiplexes received BFD control packet when Your
   Discriminator is not set, i.e., equals zero.  Because
   [I-D.ietf-bfd-multipoint] uses BFD in Demand mode the head of BFD
   multipoint session transmits BFD control packets with Your
   Discriminator set to zero.  As a result, a tail cannot demultiplex
   BFD sessions using Your Discriminator, as defined in [RFC5880].
   [I-D.ietf-bfd-multipoint] requires that in order to demultiplex BFD
   sessions the tail uses the source IP address, My Discriminator and
   the identity of the multipoint tree which the Multipoint BFD Control
   packet was received from.  The identity of the multipoint tree MAY be
   provided by the p2mp MPLS LSP label in case of inclusive p-tree or
   upstream assigned label in case of aggregate p-tree.  The source IP
   address MAY be drawn from the IP header if BFD control packet
   transmitted by the head using IP/UDP encapsulation as described in
   Section 3.1.  Non-IP encapsulation case described in Section 3.2.

3.1.  IP Encapsulation of Multipoint BFD

   [I-D.ietf-bfd-multipoint] defines IP/UDP encapsulation for multipoint
   BFD over p2mp MPLS LSP:

      UDP destination port MUST be set to 3784;

      destination IP address MUST be from the 127/8 range for IPv4 and
      from the 0:0:0:0:0:FFFF:7F00/104 range for IPv6;

   This specification further clarifies that:

      if multiple alternative paths for the given p2mp LSP Forwarding
      Equivalence Class(FEC) exist, the MultipointHead SHOULD use
      Entropy Label [RFC6790] used for LSP Ping [RFC8029] to exercise
      that particular alternative path;






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      or the MultipointHead MAY use, as destination IP address, the IP
      address discovered by LSP Ping traceroute [RFC8029] to exercise
      that particular alternate path.

3.2.  Non-IP Encapsulation of Multipoint BFD

   Non-IP encapsulation for multipoint BFD over p2mp MPLS LSP MUST use
   Generic Associated Channel (G-ACh) Label (GAL) [RFC5586] at the
   bottom of the label stack followed by Associated Channel Header
   (ACH).  Channel Type field in ACH MUST be set to BFD CV [RFC6428].
   To provide the identity of the MultipointHead for the particular
   multipoint BFD session this document defines new Source MEP ID IP
   Address type (TBA1) in Section 6.1.  If the Length value is 4, then
   the Value field contains an IPv4 address.  If the Length value is 16,
   then the Value field contains an IPv6 address.  Any other value of
   the Length field MUST be considered as an error, and the BFD control
   packet MUST be discarded.

4.  Bootstrapping Multipoint BFD

4.1.  LSP Ping

   MaultipointHead MAY use LSP Ping [RFC8029] using in Target FEC TLV,
   as appropriate, sub-TLVs defined in Section 3.1 [RFC6425].

4.2.  Control Plane

   BGP-BFD Attribute [I-D.ietf-bess-mvpn-fast-failover] MAY be used to
   bootstrap multipoint BFD session on a tail.

5.  Security Considerations

   This document does not introduce new security aspects but inherits
   all security considerations from [RFC5880], [RFC5884], [RFC7726],
   [I-D.ietf-bfd-multipoint], [RFC8029], and [RFC6425].

6.  IANA Considerations

6.1.  Source MEP ID IP Address Type

   IANA is required to allocate value (TBD) for the Source MEP ID IP
   Address type from the "CC/CV MEP-ID TLV" registry which is under the
   "Pseudowire Associated Channel Types" registry.








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                  +-------+-------------+---------------+
                  | Value | Description | Reference     |
                  +-------+-------------+---------------+
                  | TBA1  |  IP Address | This document |
                  +-------+-------------+---------------+

                Table 1: Source MEP ID IP Address TLV Type

7.  Acknowledgements

   TBD

8.  Normative References

   [I-D.ietf-bess-mvpn-fast-failover]
              Morin, T., Kebler, R., and G. Mirsky, "Multicast VPN fast
              upstream failover", draft-ietf-bess-mvpn-fast-failover-03
              (work in progress), May 2018.

   [I-D.ietf-bfd-multipoint]
              Katz, D., Ward, D., Networks, J., and G. Mirsky, "BFD for
              Multipoint Networks", draft-ietf-bfd-multipoint-18 (work
              in progress), June 2018.

   [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>.

   [RFC5586]  Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
              "MPLS Generic Associated Channel", RFC 5586,
              DOI 10.17487/RFC5586, June 2009,
              <https://www.rfc-editor.org/info/rfc5586>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC5884]  Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
              "Bidirectional Forwarding Detection (BFD) for MPLS Label
              Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
              June 2010, <https://www.rfc-editor.org/info/rfc5884>.

   [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,
              <https://www.rfc-editor.org/info/rfc6425>.



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   [RFC6428]  Allan, D., Ed., Swallow, G., Ed., and J. Drake, Ed.,
              "Proactive Connectivity Verification, Continuity Check,
              and Remote Defect Indication for the MPLS Transport
              Profile", RFC 6428, DOI 10.17487/RFC6428, November 2011,
              <https://www.rfc-editor.org/info/rfc6428>.

   [RFC6790]  Kompella, K., Drake, J., Amante, S., Henderickx, W., and
              L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
              RFC 6790, DOI 10.17487/RFC6790, November 2012,
              <https://www.rfc-editor.org/info/rfc6790>.

   [RFC7726]  Govindan, V., Rajaraman, K., Mirsky, G., Akiya, N., and S.
              Aldrin, "Clarifying Procedures for Establishing BFD
              Sessions for MPLS Label Switched Paths (LSPs)", RFC 7726,
              DOI 10.17487/RFC7726, January 2016,
              <https://www.rfc-editor.org/info/rfc7726>.

   [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,
              <https://www.rfc-editor.org/info/rfc8029>.

   [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>.

Author's Address

   Greg Mirsky
   ZTE Corp.

   Email: gregimirsky@gmail.com


















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