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Versions: (draft-zhang-trill-p2mp-bfd) 00 01 02 03 04 05 06 07 08 09

TRILL                                                           M. Zhang
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                           S. Pallagatti
Updates: 7175, 7177
                                                             V. Govindan
                                                           Cisco Systems
Expires: August 11, 2018                                February 7, 2018


                TRILL Support of Point to Multipoint BFD
                      draft-ietf-trill-p2mp-bfd-09

Abstract

   Point to multipoint (P2MP) BFD is designed to verify multipoint
   connectivity.  This document specifies the support of P2MP BFD in
   TRILL.  Similar to TRILL point-to-point BFD, BFD Control packets in
   TRILL P2MP BFD are transmitted using RBridge Channel messages. This
   document updates RFC 7175 and RFC 7177.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

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
   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



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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Acronyms and Terminology . . . . . . . . . . . . . . . . . . .  2
     2.1.  Acronyms . . . . . . . . . . . . . . . . . . . . . . . . .  3
     2.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Bootstrapping  . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.  A New RBridge Channel Message for P2MP BFD . . . . . . . . . .  3
   5.  Discriminators and Packet Demultiplexing . . . . . . . . . . .  4
   6.  Tracking Active Tails  . . . . . . . . . . . . . . . . . . . .  4
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  4
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  5
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  5
   10.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  5
     10.1.  Normative References  . . . . . . . . . . . . . . . . . .  5
     10.2.  Informative References  . . . . . . . . . . . . . . . . .  6
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  7



1.  Introduction

   TRILL supports multicast forwarding.  Applications based on TRILL
   multicast may need quick detection of multicast failures using P2MP
   BFD [I-D.ietf-bfd-multipoint].  This document specifies TRILL support
   of P2MP BFD.

   To use P2MP BFD, the head end needs to periodically transmit BFD
   Control packets to all tails using TRILL multicast.  A new RBridge
   Channel message is allocated for this purpose.

   In order to execute the global protection of distribution used for
   multicast forwarding [I-D.ietf-trill-resilient-trees], the head needs
   to track the active status of tails
   [I-D.ietf-bfd-multipoint-active-tail].  If the tail loses
   connectivity as detected by not receiving the new RBridge Channel
   message from the head, the tail should notify the head of the lack of
   multipoint connectivity with unicast BFD Control packets.  These
   unicast BFD Control packets are transmitted using the existing
   RBridge Channel message assigned to BFD Control [RFC7175].

   This document updates [RFC7177] as specified in Section 3 and updates
   [RFC7175] as specified in Section 4 and Section 5.

2.  Acronyms and Terminology




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2.1.  Acronyms

   Data Label: VLAN or Fine Grained Label [RFC7172].

   BFD: Bidirectional Forwarding Detection

   P2MP: Point to Multi-Point

   TRILL: Transparent Interconnection of Lots of Links or Tunneled
   Routing in the Link Layer

2.2.  Terminology

   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.

   Familiarity with [RFC6325], [RFC7175], and [RFC7178] is assumed in
   this document.

3.  Bootstrapping

   The TRILL adjacency mechanism bootstraps the establishment of one-hop
   TRILL BFD sessions [RFC7177]. Multi-hop sessions are expected to be
   configured by the network manager. A slight wording update to the
   second sentence in Section 6 of [RFC7177] is required.

   It currently read:

      If an RBridge supports BFD [RFC7175], it will have learned whether
      the other RBridge has BFD enabled by whether or not a BFD-Enabled
      TLV [RFC6213] was included in its Hellos.

   Now it should read:

      If an RBridge supports BFD [RFC7175] [this document], it will have
      learned whether the other RBridge has BFD enabled by whether or
      not a BFD-Enabled TLV [RFC6213] was included in its Hellos.

4.  A New RBridge Channel Message for P2MP BFD

   RBridge Channel message protocol 0x002 is defined for TRILL point-to-
   point BFD Control packets in [RFC7175].  That RFC provides that if
   the M bit of the TRILL Header of the RBridge channel packet
   containing a BFD Control packet is non-zero, the packet is generally
   dropped.  In P2MP BFD, the head is required to probe tails using



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   multicast.  This means the M bit will be set to 1.  For this reason,
   a new RBridge Channel message, whose protocol code point is TBD, is
   specified in this document.  An RBridge that supports P2MP BFD MUST
   support the new RBridge Channel message for P2MP BFD. The capability
   to support the RBridge Channel message for P2MP BFD, and therefore
   support performing P2MP BFD, is announced within the "RBridge Channel
   Protocols Sub-TLV" in LSPs [RFC7176].

   As specified in [RFC7178], when the tail receives TRILL Data packets
   sent as BFD RBridge channel messages, it will absorb the packets
   itself rather than deliver these packets to its attached end-
   stations.

5.  Discriminators and Packet Demultiplexing

   The processing in Section 3.2 of [RFC7175] generally applies except
   that the test on the M bit in the TRILL Header is reversed.  If the M
   bit is zero, the packet MUST be discarded.  If the M bit is one, it
   is processed.

   After the Section 3.2 of [RFC7175] processing, the tail demultiplexes
   incoming BFD packets based on a combination of the source address and
   My Discriminator as specified in [I-D.ietf-bfd-multipoint].  In
   addition to this combination, TRILL P2MP BFD requires that the tail
   use the Data Label, which is either the inner VLAN or the Fine
   Grained Label [RFC7172], for demultiplexing.  If the tail needs to
   notify the head about the failure of a multipath, the tail is
   required to send unicast BFD Control packets using the same Data
   Label as used by the head.

6.  Tracking Active Tails

   According to [I-D.ietf-bfd-multipoint], the head has a session of
   type MultipointHead that is bound to a multipoint path.  Multipoint
   BFD Control packets are sent by this session over the multipoint
   path, and no BFD Control packets are received by it.  Each tail
   dynamically creates a MultipointTail per a multipoint path.
   MultipointTail sessions receive BFD Control packets from the head
   over multipoint paths.

   An example use is when a multicast tree root needs to keep track of
   all the receivers as in [I-D.ietf-trill-resilient-trees]; this can be
   done by maintaining a session of type MultipointClient per receiver
   that is of interest, as described in [I-D.ietf-bfd-multipoint-active-
   tail].  See [I-D.ietf-bfd-multipoint-active-tail] for detail
   operations of tracking active tails.

7.  Security Considerations



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   Multipoint BFD provides its own authentication but does not provide
   encryption (see Security Considerations in [I-D.ietf-bfd-
   multipoint]). As specified in this document, the point-to-multipoint
   BFD payloads are encapsulated in RBridge Channel messages which have
   been extended by [RFC7978] to provide security. [RFC7978] provides
   encryption only for point-to-point extended RBridge Channel messages
   so its encryption facilities are not applicable to this draft.
   However [RFC7978] provides stronger authentication than that
   currently provided in BFD. Thus, there is little reason to use the
   BFD security mechanisms if [RFC7978] authentication is in use. It is
   expected that a future TRILL document will provide for group keying;
   when that occurs, the use of [RFC7978] RBridge Channel security will
   be able to provide both encryption and authentication.

   For general multipoint BFD security considerations, see
   [I-D.ietf-bfd-multipoint].

   For general RBridge Channel security considerations, see [RFC7178].

8.  IANA Considerations

   IANA is required to allocate a number from the Standards Action range
   of the RBridge Channel Protocols registry which is part of the
   Transparent Interconnection of Lots of Links (TRILL) Parameters. The
   number to be allocated is as follows:

          Protocol          Number
          ----------------  ------
          P2MP BFD Control  TBD

9.  Acknowledgements

   Authors would like to thank the comments and suggestions from Gayle
   Noble and Donald Eastlake.

10.  References

10.1.  Normative References

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

   [I-D.ietf-bfd-multipoint-active-tail]
              Katz, D., Ward, D., and J. Networks, "BFD Multipoint
              Active Tails.", draft-ietf-bfd-multipoint-active-tail
              (work in progress).




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   [RFC7978]  Eastlake 3rd, D., Umair, M., and Y. Li, "Transparent
              Interconnection of Lots of Links (TRILL): RBridge Channel
              Header Extension", RFC 7978, DOI 10.17487/RFC7978,
              September 2016, <http://www.rfc-editor.org/info/rfc7978>.

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

   [RFC6325]  Perlman, R., Eastlake, D., Dutt, D., Gai, S., and A.
              Ghanwani, "Routing Bridges (RBridges): Base Protocol
              Specification", RFC 6325, July 2011.

   [RFC7172]  Eastlake, D., Zhang, M., Agarwal, P., Perlman, R., and D.
              Dutt, "Transparent Interconnection of Lots of Links
              (TRILL): Fine-Grained Labeling", RFC 7172, May 2014.

   [RFC7175]  Manral, V., Eastlake, D., Ward, D., and A. Banerjee,
              "Transparent Interconnection of Lots of Links (TRILL):
              Bidirectional Forwarding Detection (BFD) Support", RFC
              7175, May 2014.

   [RFC7176]  Eastlake, D., Senevirathne, T., Ghanwani, A., Dutt, D.,
              and A. Banerjee, "Transparent Interconnection of Lots of
              Links (TRILL) Use of IS-IS", RFC 7176, May 2014.

   [RFC7177]  Eastlake, D., Perlman, R., Ghanwani, A., Yang, H., and V.
              Manral, "Transparent Interconnection of Lots of Links
              (TRILL): Adjacency", RFC 7177, May 2014.

   [RFC7178]  Eastlake, D., Manral, V., Li, Y., Aldrin, S., and D. Ward,
              "Transparent Interconnection of Lots of Links (TRILL):
              RBridge Channel Support", RFC 7178, May 2014.

   [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>.

10.2.  Informative References

   [RFC6213]  Hopps, C. and L. Ginsberg, "IS-IS BFD-Enabled TLV", RFC
              6213, April 2011.

   [I-D.ietf-trill-resilient-trees]
              Zhang, M., Senevirathne, T., Pathangi, J., Banerjee, A.,
              and A. Ghanwani, "TRILL Resilient Distribution Trees",
              draft-ietf-trill-resilient-trees (work in progress).





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Authors' Addresses


   Mingui Zhang
   Huawei Technologies
   No.156 Beiqing Rd. Haidian District
   Beijing  100095
   P.R. China

   Email: zhangmingui@huawei.com


   Santosh Pallagatti
   India

   Email: santosh.pallagatti@gmail.com


   Vengada Prasad Govindan
   Cisco Systems

   Email: venggovi@cisco.com





























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