TRILL Working Group                                            Lucy Yong
INTERNET-DRAFT                                           Donald Eastlake
Intended status: Proposed Standard                            Sam Aldrin
                                                     Huawei Technologies
                                                              Jon Hudson
Expires: April 19, 2014                                 October 20, 2013

                  Transport of TRILL Using Pseudowires


   This document specifies how to interconnect a pair of TRILL
   (Transparent Interconnection of Lots of Links) switch ports using
   pseudowires under existing TRILL and PWE3 (Pseudowire Emulation End-
   to-End) standards.

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Table of Contents

      1. Introduction............................................3
      1.1 Conventions used in this document......................3

      2. PWE3 Interconnection of TRILL Switches..................4
      2.1 PWE3 Type Independent Details..........................4
      2.2 PPP PWE3 Transport of TRILL............................5

      3. IANA Considerations.....................................6
      4. Security Considerations.................................6

      Appendix A: Use of Other Pseudowire Types..................7
      Appendix Z: Change History.................................8

      Normative References.......................................9
      Informative References.....................................9
      Authors' Addresses........................................11

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1. Introduction

   The IETF has standardized the TRILL (Transparent Interconnection of
   Lots of Links) protocol [RFC6325] that provides optimal pair-wise
   data frame routing without configuration in multi-hop networks with
   arbitrary topology. TRILL supports multipathing of both unicast and
   multicast traffic. Devices that implement TRILL are called TRILL
   Switches or RBridges (Routing Bridges).

   Links between TRILL Switches can be based on arbitrary link
   protocols, for example PPP [RFC6361], as well as Ethernet [RFC6325].
   A set of connected TRILL Switches together form a TRILL campus which
   is bounded by end stations and layer 3 routers.

   This document specifies how to interconnect a pair of TRILL Switch
   ports using a pseudowire under existing TRILL and PWE3 (Pseudowire
   Emulation End-to-End) standards.

1.1 Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

   Acronyms used in this document include the following:

      IS-IS - Intermediate System to Intermediate System [IS-IS]

      MPLS - Multi-Protocol Label Switching

      PPP - Point-to-Point Protocol [RFC1661]

      PW - Pseudowire [RFC3985]

      PWE3 - PW Emulation End-to-End

      RBridge - Routing Bridge, an alternative name for a TRILL Switch

      TRILL - Transparent Interconnection of Lots of Links [RFC6325]

      TRILL Switch - A device implementing the TRILL protocol

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2. PWE3 Interconnection of TRILL Switches

   When a pseudowire is used to interconnect a pair of TRILL Switch
   ports, a PPP [RFC4618] pseudowire is used as described below. The
   pseudowire between such ports can be auto-configured [RFC4447] or
   manually configured. In this context, the TRILL Switch ports at the
   ends of the pseudowire are acting as native service processing
   elements (NSP [RFC3985]) and, assuming the pseudowires are over MPLS
   or IP [RFC4023] networks, as label switched or IP routers at the
   TRILL Switch ports.

   Pseudowires provide transparent transport and the two TRILL Switch
   ports appear directly interconnected with a transparent link.  With
   such an interconnection the TRILL adjacency over the link is
   automatically discovered and established through TRILL IS-IS control
   messages [RFC6327bis].

   A pseudowire is carried over a packet switched network tunnel
   [RFC3985].  For example, an MPLS or MPLS-TP label switched path
   tunnel in MPLS networks. Either a signaling protocol or manual
   configuration can be used to configure a label switched path tunnel
   between two TRILL Switch ports. This application needs no additions
   to the existing pseudowire standards.

2.1 PWE3 Type Independent Details

   The sending pseudowire TRILL Switch port MUST copy the priority of
   the TRILL Data packets being sent to the 3-bit Traffic Class field of
   the pseudowire label [RFC5462] so the priority will be visible to
   pseudowire transit devices and they can take the priority into
   account. TRILL IS-IS PDUs critical to establishing and maintaining
   adjacency (Hello and MTU PDUs) SHOULD be send with Traffic Class 7
   while other TRILL IS-IS PDUs SHOULD be sent with Traffic Class 6.

   If a pseudowire supports fragmentation and re-assembly, there is no
   reason to do TRILL MTU testing on it and the pseudowire will not be a
   constraint on the TRILL campus wide Sz (see Section 4.3.1 [RFC6325]).
   If the pseudowire does not support fragmentation, then the available
   TRILL IS-IS packet payload size over the pseudowire (taking into
   account MPLS encapsulation with a control word) or some lower value,
   MUST be used in helping to determine Sz (see Section 5

   An intervening MPLS label switched router or similar packet switched
   network device has no awareness of TRILL. Such devices will not
   change the TRILL Header hop count.

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2.2 PPP PWE3 Transport of TRILL

   For a PPP pseudowire (PW type = 0x0007), the two TRILL Switch ports
   being connected are configured to form a pseudowire with PPP
   encapsulation [RFC4618]. After the pseudowire is established and
   TRILL use is negotiated within PPP, the two TRILL Switch ports appear
   directly connected with a PPP link [RFC1661] [RFC6361].

   If pseudowire interconnection of two TRILL Switch ports is auto-
   configured [RFC4447], the initiating TRILL Switch port MUST attempt
   the connection set-up with pseudowire type PPP (0x0007).

   Behavior for TRILL with a PPP pseudowire continues to follow that of
   TRILL over PPP as specified in Section 3 of [RFC6361].

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3. IANA Considerations

   No IANA actions are required by this document. RFC Editor: Please
   remove this section before publication.

4. Security Considerations

   For PPP link TRILL security considerations, see [RFC6361].

   For security considerations introduced by carrying PPP TRILL links
   over pseudowires, see [RFC3985].

   Not all implementations need to include specific security mechanisms
   at the pseudowire layer, for example if they are designed to be
   deployed only in cases where the networking environment is trusted or
   where other layers provide adequate security.  A complete enumeration
   of possible deployment scenarios and associated threats and options
   is not possible and is outside the scope of this document.  For
   applications involving sensitive data, end-to-end security should
   always be considered, in addition to link security, to provide
   security in depth. In this context, such end-to-end security should
   be between the end stations involved so as to protect the entire path
   to, through, and from the TRILL campus.

   For general TRILL protocol security considerations, see [RFC6325].

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Appendix A: Use of Other Pseudowire Types

   This informational Appendix briefly discusses use of pseudowire types
   other than PPP.

   The use of Ethernet pseudowires [RFC4448] was examined by the authors
   and would be possible; however, they would require an additional 12
   or 16 bytes per packet.

   It would also be possible to specify a new pseudowire type for TRILL
   traffic but the authors feel that any efficiency gain over PPP
   pseudowires would be too small to be worth the complexity of adding
   such a specification. Furthermore using PPP pseudowire encoding means
   that any traffic dissector that understands TRILL PPP encoding
   [RFC6361] and understands PPP pseudowires [RFC4618] will
   automatically be able to recursively decode TRILL transported by

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Appendix Z: Change History

   From -00 to -01

   Add information on Traffic Classes that should be used for TRILL IS-
   IS PDUs.

   Other changes to resolve WG Last Call comments:

      Change title from "TRILL Over Psuedowires".

      Change "Class of Service" to "Traffic Class".

      Expand informational paragraph about the consideration of using
      other pseudowire types for the transport of TRILL and make that
      paragraph into Appendix A.

      Add this Change History Appendix Z.

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   Thanks for the valuable comments from the following:

      Yakov Stein

   The document was prepared in raw nroff. All macros used were defined
   within the source file.

Normative References

   [RFC1661] - Simpson, W., Ed., "The Point-to-Point Protocol (PPP)",
         STD 51, RFC 1661, July 1994.

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

   [RFC4447] - Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T., and
         G. Heron, "Pseudowire Setup and Maintenance Using the Label
         Distribution Protocol (LDP)", RFC 4447, April 2006.

   [RFC4618] - Martini, L., "Encapsulation Methods for Transport of
         PPP/High-Level Data Link Control (HDLC) over MPLS Networks",
         BCP 116, RFC 4618, September 2006.

   [RFC5462] - Andersson, L. and R. Asati, "Multiprotocol Label
         Switching (MPLS) Label Stack Entry: "EXP" Field Renamed to
         "Traffic Class" Field", RFC 5462, February 2009.

   [RFC6325] - Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
         Ghanwani, "Routing Bridges (RBridges): Base Protocol
         Specification", RFC6325, July 2011.

   [RFC6361] - Carlson, J., and D. Eastlake, "PPP Transparent
         Interconnection of Lots of Links (TRILL) Protocol Control
         Protocol", RFC6361, August 2011.

   [ClearCorrect] - Eastlake, D., M. Zhang, A. Ghanwani, V. Manral, and
         A. Banerjee, "TRILL: Clarifications, Corrections, and Updates",
         draft-ietf-trill-clear-correct, in RFC Editor's queue.

Informative References

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   [IS-IS] - International Organization for Standardization,
         "Intermediate system to Intermediate system intra-domain
         routing information exchange protocol for use in conjunction
         with the protocol for providing the connectionless-mode Network
         Service (ISO 8473)", ISO/IEC10589:2002, Second Edition, Nov

   [RFC3985] - Bryant, S., Ed., and P. Pate, Ed., "Pseudo Wire Emulation
         Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005.

   [RFC4023] - Worster, T., Rekhter, Y., and E. Rosen, Ed.,
         "Encapsulating MPLS in IP or Generic Routing Encapsulation
         (GRE)", RFC 4023, March 2005.

   [RFC4448] - Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron,
         "Encapsulation Methods for Transport of Ethernet over MPLS
         Networks", RFC 4448, April 2006.

   [RFC6327bis] - Eastlake 3rd, D., Perlman, R., Ghanwani, A., Howard,
         Y., and V. Manral, "TRILL: Adjacency", draft-ietf-trill-
         rfc6327bis, work in progress.

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Authors' Addresses

   Lucy Yong
   Huawei Technologies
   5340 Legacy Drive
   Plano, TX 75025 USA

   Phone: +1-469-227-5837

   Donald E. Eastlake, 3rd
   Huawei Technologies
   155 Beaver Street
   Milford, MA 01757 USA

   Phone: +1-508-333-2270

   Sam Aldrin
   Huawei Technologies
   2330 Central Expressway
   Santa Clara, CA 95050 USA

   Phone: +1-408-330-4517

   Jon Hudson
   130 Holger Way
   San Jose, CA 95134 USA

   Phone: +1-408-333-4062

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