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Versions: 00 01 02 draft-ietf-trill-p2mp-bfd

TRILL                                                           M. Zhang
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                           S. Pallagatti
Expires: November 14, 2015                              Juniper Networks
                                                             V. Govindan
                                                           Cisco Systems
                                                            May 13, 2015


                TRILL Support of Point to Multipoint BFD
                     draft-zhang-trill-p2mp-bfd-02

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 an RBridge Channel.

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."

   This Internet-Draft will expire on November 14, 2015.

Copyright Notice

   Copyright (c) 2015 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



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Acronyms and Terminology  . . . . . . . . . . . . . . . . . .   2
     2.1.  Acronyms  . . . . . . . . . . . . . . . . . . . . . . . .   2
     2.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Bootstrapping . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  A New RBridge Channel 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  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   TRILL supports multicast forwarding.  Applications based on TRILL
   multicast may need quick detection of multicast failures using P2MP
   BFD.  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 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].  When the tail loses
   connectivity from the head, the tail should notify the head of the
   lack of multipoint connectivity with unicast BFD Control packets.
   These packets are transmitted using the existing RBridge Channel
   assigned to BFD Control [RFC7175].

2.  Acronyms and Terminology

2.1.  Acronyms

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

   BFD: Bidirectional Forwarding Detection




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   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", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

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

3.  Bootstrapping

   The TRILL adjacency mechanism bootstraps the establishment of the BFD
   session [RFC7177].  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 for P2MP BFD

   RBridge Channel 0x002 is defined for TRILL point-to-point BFD Control
   packets in [RFC7175].  If the M bit of the TRILL Header of the
   channeled packet containing the BFD Control packet is non-zero, the
   packet MUST be dropped [RFC7175].  While for P2MP BFD, the head is
   required to probe tails using multicast.  This means the M bit will
   be set to 1.  For this reason, a new RBridge Channel, whose code
   point is TBD, is specified in this document.  An RBridge that
   supports P2MP BFD MUST support the new RBridge Channel for P2MP BFD.
   The capability to support the RBridge Channel for P2MP BFD, and
   therefore support performing P2MP BFD, is announced within the
   "RBridge Channel Protocols Sub-TLV" in LSPs [RFC7176].






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   As specified in [RFC7178], when the tail receives TRILL Data packets
   sent on the channel, 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] applies except that the
   test on the M bit in the TRILL Header is reversed.  If the M bit is
   zero, the packet is 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 the tail to use
   the Data Label, which is either the inner VLAN or the Fine Grained
   Label [RFC7172], for demultiplexing.  If the tail need 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.

   If the head is keeping track of some or all of the tails
   [I-D.ietf-trill-resilient-trees], it has a session of type
   MultipointClient per tail that it cares about
   [I-D.ietf-bfd-multipoint-active-tail].  See
   [I-D.ietf-bfd-multipoint-active-tail] for detail operations of
   tacking active tails.

7.  Security Considerations

   P2MP BFD control packets can be encapsulated as the payload of the
   RBridge Channel Tunnel [I-D.ietf-trill-channel-tunnel].  In that
   case, the security option of RBridge Channel Tunnel can secure the
   transmission of BFD control packets.

   The demultiplexing of TRILL P2MP BFD at the tail is Data Label aware.
   This enhances the security of the dynamic creation of MultipointTail
   sessions at tails.  In order to forge BFD Control packets, the




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   attacker has to acquire the right Data Label that the head uses for
   P2MP BFD.

   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 one RBridge Channel protocol number from
   the Standards Action range, as follows:

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

9.  Acknowledgements

   Authors would like to thank the comments and suggestions from 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-06 (work in
              progress), May 2015.

   [I-D.ietf-bfd-multipoint-active-tail]
              Katz, D., Ward, D., and J. Networks, "BFD Multipoint
              Active Tails.", draft-ietf-bfd-multipoint-active-tail-00
              (work in progress), May 2015.

   [I-D.ietf-trill-channel-tunnel]
              Eastlake, D., Umair, M., and L. Yizhou, "TRILL: RBridge
              Channel Tunnel Protocol", draft-ietf-trill-channel-
              tunnel-05 (work in progress), April 2015.

   [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-02 (work in progress),
              December 2014.





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   [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.

10.2.  Informative References

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

Authors' Addresses

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

   Email: zhangmingui@huawei.com









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   Santosh Pallagatti
   Juniper Networks
   Embassy Business Park
   Bangalore  KA 560093
   India

   Email: santoshpk@juniper.net


   Vengada Prasad Govindan
   Cisco Systems

   Email: venggovi@cisco.com






































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