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rfc:rfc8564

Internet Engineering Task Force (IETF) M. Zhang Request for Comments: 8564 Huawei Technologies Updates: 7175, 7177 S. Pallagatti Category: Standards Track Vmware ISSN: 2070-1721 V. Govindan

                                                         Cisco Systems
                                                            April 2019

Support of Point-to-Multipoint Bidirectional Forwarding Detection (BFD)

      in Transparent Interconnection of Lots of Links (TRILL)

Abstract

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

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 https://www.rfc-editor.org/info/rfc8564.

Zhang, et al. Standards Track [Page 1] RFC 8564 P2MP BFD for TRILL April 2019

Copyright Notice

 Copyright (c) 2019 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
 (https://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  . . . . . . . . . . . . . . . . . . . . . . . .   2
 2.  Acronyms and Terminology  . . . . . . . . . . . . . . . . . .   3
   2.1.  Acronyms  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
 3.  Bootstrapping . . . . . . . . . . . . . . . . . . . . . . . .   3
 4.  A New RBridge Channel Message for P2MP BFD  . . . . . . . . .   4
 5.  Discriminators and Packet Demultiplexing  . . . . . . . . . .   4
 6.  Tracking Active Tails . . . . . . . . . . . . . . . . . . . .   5
 7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
 8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
 9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
   9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
 Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   7
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1. Introduction

 TRILL supports multicast forwarding.  Applications based on TRILL
 multicast may need quick detection of multicast failures using P2MP
 BFD [RFC8562].  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 [TRILL-TREES], the head needs to track the
 active status of tails [RFC8563].  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

Zhang, et al. Standards Track [Page 2] RFC 8564 P2MP BFD for TRILL April 2019

 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 Sections 4 and 5.

2. Acronyms and Terminology

2.1. Acronyms

 Data Label:  VLAN or Fine-Grained Label [RFC7172].
 BFD:   Bidirectional Forwarding Detection
 P2MP:  Point to Multipoint
 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 reads:
    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.

Zhang, et al. Standards Track [Page 3] RFC 8564 P2MP BFD for TRILL April 2019

 Now it should read:
    If an RBridge supports BFD (see [RFC7175] and [RFC8564]), 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.
 In addition, a normative reference to this document is added to RFC
 7177 as a result of this update.

4. A New RBridge Channel Message for P2MP BFD

 RBridge Channel protocol number 0x002 is defined for TRILL point-to-
 point BFD Control packets in [RFC7175].  That RFC states that if the
 M bit of the TRILL Header of the RBridge Channel packet containing a
 BFD Control packet is nonzero, the packet is generally dropped.  In
 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 message (P2MP BFD Control), whose protocol code point is
 0x007, 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 Link State PDUs (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 processing per Section 3.2 of [RFC7175], the tail
 demultiplexes incoming BFD packets based on a combination of the
 source address and My Discriminator as specified in [RFC8562].  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.

Zhang, et al. Standards Track [Page 4] RFC 8564 P2MP BFD for TRILL April 2019

6. Tracking Active Tails

 According to [RFC8562], 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 [TRILL-TREES]; this can be done by
 maintaining a session of type MultipointClient per receiver that is
 of interest, as described in [RFC8563].  See [RFC8563] for detailed
 operations of tracking active tails.

7. Security Considerations

 Multipoint BFD provides its own authentication but does not provide
 encryption (see the Security Considerations in [RFC8562]).  As
 specified in this document, the point-to-multipoint BFD payloads are
 encapsulated in RBridge Channel messages that 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 document.  However,
 [RFC7978] provides stronger authentication than that currently
 provided in BFD.  Thus, there is little reason to use the BFD
 security mechanisms if authentication per [RFC7978] is in use.  It is
 expected that a future TRILL document will provide for group keying;
 when that occurs, the use of RBridge Channel security [RFC7978] will
 be able to provide both encryption and authentication.
 For general multipoint BFD security considerations, see [RFC8562].
 For general RBridge Channel security considerations, see [RFC7178].

8. IANA Considerations

 IANA has allocated the following from the Standards Action [RFC8126]
 range of the "RBridge Channel Protocols" registry, which is part of
 the "Transparent Interconnection of Lots of Links (TRILL) Parameters"
 registry.
        Protocol          Number
        ----------------  ------
        P2MP BFD Control  0x007

Zhang, et al. Standards Track [Page 5] RFC 8564 P2MP BFD for TRILL April 2019

9. References

9.1. Normative References

 [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>.
 [RFC6325]  Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
            Ghanwani, "Routing Bridges (RBridges): Base Protocol
            Specification", RFC 6325, DOI 10.17487/RFC6325, July 2011,
            <https://www.rfc-editor.org/info/rfc6325>.
 [RFC7172]  Eastlake 3rd, D., Zhang, M., Agarwal, P., Perlman, R., and
            D. Dutt, "Transparent Interconnection of Lots of Links
            (TRILL): Fine-Grained Labeling", RFC 7172,
            DOI 10.17487/RFC7172, May 2014,
            <https://www.rfc-editor.org/info/rfc7172>.
 [RFC7175]  Manral, V., Eastlake 3rd, D., Ward, D., and A. Banerjee,
            "Transparent Interconnection of Lots of Links (TRILL):
            Bidirectional Forwarding Detection (BFD) Support",
            RFC 7175, DOI 10.17487/RFC7175, May 2014,
            <https://www.rfc-editor.org/info/rfc7175>.
 [RFC7176]  Eastlake 3rd, D., Senevirathne, T., Ghanwani, A., Dutt,
            D., and A. Banerjee, "Transparent Interconnection of Lots
            of Links (TRILL) Use of IS-IS", RFC 7176,
            DOI 10.17487/RFC7176, May 2014,
            <https://www.rfc-editor.org/info/rfc7176>.
 [RFC7177]  Eastlake 3rd, D., Perlman, R., Ghanwani, A., Yang, H., and
            V. Manral, "Transparent Interconnection of Lots of Links
            (TRILL): Adjacency", RFC 7177, DOI 10.17487/RFC7177, May
            2014, <https://www.rfc-editor.org/info/rfc7177>.
 [RFC7178]  Eastlake 3rd, D., Manral, V., Li, Y., Aldrin, S., and D.
            Ward, "Transparent Interconnection of Lots of Links
            (TRILL): RBridge Channel Support", RFC 7178,
            DOI 10.17487/RFC7178, May 2014,
            <https://www.rfc-editor.org/info/rfc7178>.
 [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, <https://www.rfc-editor.org/info/rfc7978>.

Zhang, et al. Standards Track [Page 6] RFC 8564 P2MP BFD for TRILL April 2019

 [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>.
 [RFC8562]  Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky,
            Ed., "Bidirectional Forwarding Detection (BFD) for
            Multipoint Networks", RFC 8562, DOI 10.17487/RFC8562,
            April 2019, <https://www.rfc-editor.org/info/rfc8562>.
 [RFC8563]  Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky,
            Ed., "Bidirectional Forwarding Detection (BFD) Multipoint
            Active Tails", RFC 8563, DOI 10.17487/RFC8563, April 2019,
            <https://www.rfc-editor.org/info/rfc8563>.

9.2. Informative References

 [RFC6213]  Hopps, C. and L. Ginsberg, "IS-IS BFD-Enabled TLV",
            RFC 6213, DOI 10.17487/RFC6213, April 2011,
            <https://www.rfc-editor.org/info/rfc6213>.
 [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
            Writing an IANA Considerations Section in RFCs", BCP 26,
            RFC 8126, DOI 10.17487/RFC8126, June 2017,
            <https://www.rfc-editor.org/info/rfc8126>.
 [TRILL-TREES]
            Zhang, M., Senevirathne, T., Pathangi, J., Banerjee, A.,
            and A. Ghanwani, "TRILL: Resilient Distribution Trees",
            Work in Progress, draft-ietf-trill-resilient-trees-09,
            January 2018.

Acknowledgements

 The authors would like to thank Gayle Noble and Donald Eastlake 3rd
 for their comments and suggestions.

Zhang, et al. Standards Track [Page 7] RFC 8564 P2MP BFD for TRILL April 2019

Authors' Addresses

 Mingui Zhang
 Huawei Technologies
 No.156 Beiqing Rd. Haidian District
 Beijing  100095
 China
 Email: zhangmingui@huawei.com
 Santosh Pallagatti
 Vmware
 Email: santosh.pallagatti@gmail.com
 Vengada Prasad Govindan
 Cisco Systems
 Email: venggovi@cisco.com

Zhang, et al. Standards Track [Page 8]

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