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Versions: (draft-eastlake-trill-channel-tunnel) 00 01 02 03 04 05 06 07 08 09 10 11 RFC 7978

INTERNET-DRAFT                                           Donald Eastlake
Updates: 7178                                                     Huawei
Intended status: Proposed Standard                        Mohammed Umair
                                                              IPinfusion
                                                               Yizhou Li
                                                                  Huawei
Expires: December 14, 2015                                 June 15, 2015

                 TRILL: RBridge Channel Tunnel Protocol
                <draft-ietf-trill-channel-tunnel-06.txt>


Abstract

   The IETF TRILL (Transparent Interconnection of Lots of Links)
   protocol includes an optional mechanism, called RBridge Channel, that
   is specified in RFC 7178, for the transmission of typed messages
   between TRILL switches in the same campus and between TRILL switches
   and end stations on the same link. This document specifies two
   optional extensions to the RBridge Channel protocol: (1) A standard
   method to tunnel a variety of payload types by encapsulating them in
   an RBridge Channel message; and (2) A method to support security
   facilities for RBridge Channel messages. This document updates RFC
   7178.


Status of This Memo

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

   Distribution of this document is unlimited. Comments should be sent
   to the authors or the TRILL working group mailing list:
   trill@ietf.org

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html. The list of Internet-Draft
   Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.






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Table of Contents

      1. Introduction............................................3
      1.1  Terminology and Acronyms..............................3

      2. Channel Tunnel Packet Format............................5

      3. Channel Tunnel Payload Types............................8
      3.1 Null Payload...........................................8
      3.2 Ethertype Without Addresses............................8
      3.2.1 Tunneled RBridge Channel Message.....................9
      3.2.2 Tunneled TRILL Data Packet...........................9
      3.2.3 Tunneled TRILL IS-IS Packet.........................10
      3.3 Ethertype With Addresses..............................11

      4. Security, Keying, and Algorithms.......................14
      4.1 Basic Security Format.................................14
      4.2 Authentication and Encryption Coverage................15
      4.3 Derived Keying Material...............................16
      4.4 SType None............................................16
      4.5 RFC 5310 Based Authentication.........................16
      4.6 DTLS Based Security...................................17
      4.7 RFC 5310 Based Encryption and Authentication..........18

      5. Channel Tunnel Errors..................................20
      5.1 SubERRs under ERR 6...................................20
      5.2 Nested RBridge Channel Errors.........................20

      6. IANA Considerations....................................21
      6.1 RBridge Channel Protocol Number.......................21
      6.2 Channel Tunnel Crypto Suites..........................21

      7. Security Considerations................................22

      Normative References......................................23
      Informative References....................................24

      Appendix Z: Change History................................25

      Acknowledgements..........................................27
      Authors' Addresses........................................28











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1. Introduction

   The IETF TRILL base protocol [RFC6325] has been extended with an
   optional RBridge Channel [RFC7178] facility to support transmission
   of typed messages (for example BFD (Bidirectional Forwarding
   Detection) [RFC7175]) between two TRILL switches (RBridges) in the
   same campus and between RBridges and end stations on the same link.
   When sent between RBridges in the same campus, a TRILL Data packet
   with a TRILL header is used and the destination RBridge is indicated
   by nickname. When sent between a RBridge and an end station on the
   same link in either direction a native RBridge Channel messages
   [RFC7178] is used with no TRILL header and with the destination port
   or ports indicated by a MAC address. (There is no mechanism to stop
   end stations on the same link, from sending native RBridge Channel
   messages to each other; however, such use is outside the scope of
   this document.)

   This document updates [RFC7178] and specifies extensions to RBridge
   Channel that provide two additional facilities as listed below.  Use
   of each of these facilities is optional, except that if Channel
   Tunnel is implemented there are two payload types that MUST be
   implemented.

      (1) A standard method to tunnel a variety of payload types by
          encapsulating them in an RBridge Channel message.

      (2) A method to provide security facilities for RBridge Channel
          messages.

   Both of the above facilities can be used in the same packet. In case
   of conflict between this document and [RFC7178], this document takes
   precedence.



1.1  Terminology and Acronyms

   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].

   This document uses terminology and acronyms defined in [RFC6325] and
   [RFC7178].  Some of these are repeated below for convenience along
   with additional terms and acronyms.

      AES - Advanced Encryption Standard.

      CCM - Counter with CBC-MAC (Cypher Block Chaining - Message
         Authentication Code).



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      CT-CCM - Channel Tunnel CCM.

      Data Label - VLAN or FGL.

      DTLS - Datagram Transport Level Security [RFC6347].

      FCS - Frame Check Sequence.

      FGL - Fine Grained Label [RFC7172].

      HKDF - Hash based Key Derivation Function [RFC5869].

      IS-IS - Intermediate System to Intermediate Systems [IS-IS].

      PDU - Protocol Data Unit.

      RBridge - An alternative term for a TRILL switch.

      SHA - Secure Hash Algorithm [RFC6234].

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

      TRILL switch - A device that implements the TRILL protocol
         [RFC6325], sometimes referred to as an RBridge.



























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2. Channel Tunnel Packet Format

   The general structure of an RBridge Channel message between two TRILL
   switches (RBridges) in the same campus is shown in Figure 2.1 below.
   The structure of a native RBridge Channel message sent between an
   RBridge and an end station on the same link, in either direction, is
   shown in Figure 2.2 and, compared with the first case, omits the
   TRILL Header, inner Ethernet addresses, and Data Label. A Protocol
   field in the RBridge Channel Header gives the type of RBridge Channel
   message and indicates how to interpret the Channel Protocol Specific
   Payload [RFC7178].

                      +-----------------------------------+
                      |           Link Header             |
                      +-----------------------------------+
                      |           TRILL Header            |
                      +-----------------------------------+
                      |      Inner Ethernet Addresses     |
                      +-----------------------------------+
                      |      Data Label (VLAN or FGL)     |
                      +-----------------------------------+
                      |      RBridge Channel Header       |
                      +-----------------------------------+
                      | Channel Protocol Specific Payload |
                      +-----------------------------------+
                      |   Link Trailer (FCS if Ethernet)  |
                      +-----------------------------------+

                   Figure 2.1 RBridge Channel Packet Structure


                      +-----------------------------------+
                      |       Ethernet Link Header        |
                      +-----------------------------------+
                      |      RBridge Channel Header       |
                      +-----------------------------------+
                      | Channel Protocol Specific Payload |
                      +-----------------------------------+
                      |                FCS                |
                      +-----------------------------------+

                     Figure 2.2 Native RBridge Channel Frame


   The RBridge Channel Header looks like this:







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                           1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         0x8946                | CHV=0 |   Channel Protocol    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Flags         |  ERR  |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               /
      /                             Channel Protocol Specific Data    /
      /-+-+-+-+-+-                                                    /

                      Figure 2.3 RBridge Channel Header

   where 0x8946 is the RBridge Channel Ethertype and CHV is the Channel
   Header Version. This document is based on RBridge Channel version
   zero.

   The extensions specified herein are in the form of an RBridge Channel
   protocol, the Channel Tunnel Protocol.  Figure 2.4 below expands the
   RBridge Channel Header and Protocol Specific Payload above for the
   case of the Channel Tunnel Protocol.

                           1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    RBridge Channel Header:
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         0x8946                | CHV=0 | Tunnel Protocol =TBD  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Flags         |  ERR  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Channel Tunnel Protocol Specific: | SubERR| RESV4 | SType | PType |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Security Information, variable length (0 length if SType = 0)
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |      Tunneled Data, variable length
      |  ...

                Figure 2.4 Channel Tunnel Header Structure

   The RBridge Channel Header field specific to the RBridge Channel
   Tunnel Protocol is the Protocol field. Its contents MUST be the value
   allocated for this purpose (see Section 6).

   The RBridge Tunnel Channel Protocol Specific Data fields are as
   follows:

      SubERR: This field provides further details when a Channel Tunnel
         error is indicated in the RBridge Channel ERR field. If ERR is
         zero, then SubERR MUST be sent as zero and ignored on receipt.
         See Section 5.


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      RESV4: This field MUST be sent as zero. If non-zero when received,
         this is an error condition (see Section 5).

      SType: This field describes the type of security information and
         features, including keying material, being used or provided by
         the Channel Tunnel packet. See Section 4.

      PType: Payload type. This describes the tunneled data. See Section
         3 below.

      Security Information: Variable length information. Length is zero
         if SType is zero. See Section 4.

   The Channel Tunnel protocol is integrated with the RBridge Channel
   facility.  Channel Tunnel errors are reported as if they were RBridge
   Channel errors, using newly allocated code points in the ERR field of
   the RBridge Channel Header supplemented by the SubERR field.



































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3. Channel Tunnel Payload Types

   The Channel Tunnel Protocol can carry a variety of payloads as
   indicated by the PType field. Values are shown in the table below
   with further explanation after the table.

         PType  Section  Description
         -----  -------  -----------
            0             Reserved
            1     3.1     Null
            2     3.2     Ethertype Without Addresses
            3     3.3     Ethertype With Addresses
         4-14             (Available for assignment by IETF Review)
           15             Reserved

                       Table 1. Payload Type Values

   While implementation of the Channel Tunnel protocol is optional, if
   it is implemented PType 1 (Null) and PType 2 (Ethertype without
   addresses) with the RBridge Channel Ethertype MUST be implemented.
   PType 2 for any Ethertypes other than the RBridge Channel Ethertype
   MAY be implemented. PType 3 MAY be implemented.

   The processing of any particular Channel Protocol message and its
   payload depends on meeting local security and other policy at the
   destination TRILL switch or end station.



3.1 Null Payload

   The Null payload type (PType = 1) is intended to be used for testing
   or for messages such as key negotiation or the like. It indicates
   that there is no payload. Any data after the Security Information
   field is ignored. If the Channel Tunnel feature is implemented, Null
   Payload MUST be supported. Any particular use of the Null Payload
   should specify what VLAN or priority should be used when relevant.



3.2 Ethertype Without Addresses

   A PType of 2 indicates that the payload of the Channel Tunnel message
   begins with an Ethertype. A TRILL switch supporting the Channel
   Tunnel RBridge Channel protocol MUST support a PType of 2 with a
   payload beginning with the RBridge Channel Ethertype as describe in
   Section 3.2.1. Other Ethertypes, including the TRILL and L2-IS-IS
   Ethertype as described in Section 3.2.2 and 3.2.3, MAY be supported.




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3.2.1 Tunneled RBridge Channel Message

   A PType of 2 with an initial RBridge Channel Ethertype indicates an
   encapsulated RBridge Channel message payload. A typical reason for
   sending an RBridge Channel message inside a Channel Tunnel message is
   to provide security services, such as authentication or encryption.

   This payload type looks like the following:

                           1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    RBridge-Channel (0x8946)   | CHV=0 | Tunnel Protocol = TBD |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  | SubERR| RESV4 | SType |  0x2  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Possible Security information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    RBridge-Channel (0x8946)   | CHV=0 |  Channel Protocol     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
      |                Channel Protocol Specific Data ...             /
      /                                                               /

           Figure 3.1 Tunneled RBridge Channel Message Structure



3.2.2 Tunneled TRILL Data Packet

   A PType of 2 and an initial TRILL Ethertype indicates that the
   payload of the Tunnel protocol message is an encapsulated TRILL Data
   packet as shown in the figure below.  If this Ethertype is supported
   for PType = 2 and the message meets local policy for acceptance, the
   tunneled TRILL Data packet is handled as if it had been received by
   the destination TRILL switch on the port where the Channel Tunnel
   message was received.














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                           1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    RBridge-Channel (0x8946)   | CHV=0 | Tunnel Protocol = TBD |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  | SubERR| RESV4 | SType |  0x2  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Possible Security information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        TRILL (0x22F3)         | V |A|C|M| RESV  |F| Hop Count |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Egress Nickname         |      Ingress Nickname         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Optional Flags Word                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Inner.MacDA                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Inner.MacDA continued      |          Inner.MacSA          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Inner.MacSA (cont.)                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Inner Data Label (2 or 4 bytes)
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |  TRILL Data Packet payload
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...

       Figure 3.2 Nested TRILL Data Packet Channel Tunnel Structure

   The optional flags word is only present if the F bit in the TRILL
   Header is one [rfc7180bis].



3.2.3 Tunneled TRILL IS-IS Packet

   A PType of 2 and an initial L2-IS-IS Ethertype indicates that the
   payload of the Tunnel protocol message is an encapsulated TRILL IS-IS
   PDU packet as shown in the figure below. If this Ethertype is
   supported, the tunneled TRILL IS-IS packet is processed by the
   destination RBridge if it meets local policy. One possible use is to
   expedite the receipt of a link state PDU (LSP) by some TRILL switch
   or switches with an immediate requirement for the link state
   information.  Since they can be transmitted directly on the link, a
   link local IS-IS PDU (Hello, CSNP, or PSNP [IS-IS]; MTU-probe or MTU-
   ack [RFC7176]; or circuit scoped FS-LSP, FS-CSNP or FS-PSNP
   [RFC7356]) would not normally be sent via this Channel Tunnel method
   except possibly to encrypt it.





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                           1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    RBridge-Channel (0x8946)   | CHV=0 | Tunnel Protocol = TBD |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  | SubERR| RESV4 | SType |  0x2  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Possible Security information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |  L2-IS-IS (0x22F4)            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  0x83     | rest of IS-IS PDU
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-...

             Figure 3.3 Tunneled TRILL IS-IS Packet Structure



3.3 Ethertype With Addresses

   If PType is 3, the Tunnel Protocol payload is an Ethernet frame as
   might be received from or sent to an end station except that the
   tunneled Ethernet frame's FCS is omitted, as shown in Figure 3.4.
   (There is still an overall FCS if the RBridge Channel message is
   being sent on an Ethernet link.) If this PType is implemented and the
   message meets local policy, the tunneled frame is handled as if it
   had been received on the port on which the Channel Tunnel message was
   received.

   The priority of the RBridge Channel message can be copied from the
   Ethernet frame VLAN tag, if one is present, except that priority 7
   SHOULD only be used for messages critical to adjacency and priority 6
   SHOULD only be used for other important control messages.



















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                           1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    RBridge-Channel (0x8946)   |  0x0  | Tunnel Protocol = TBD |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  | SubERR| RESV4 | SType |  0x2  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Possible Security information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             MacDA                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         MacDA (cont.)         |             MacSA             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          MacSA (cont.)                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Any Ethernet frame tagging...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+=+-+-...
      |  Ethernet frame payload...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...

            Figure 3.4 Ethernet Frame Channel Tunnel Structure

   In the case of a non-Ethernet link, such as a PPP (Point-to-Point
   Protocol) link [RFC6361], the ports on the link are considered to
   have link local synthetic 48-bit MAC addresses constructed as
   described below.  These constructed addresses MAY be used as a MacSA.
   If the RBridge Channel message is link local, the source TRILL switch
   will have the information to construct such a MAC address for the
   destination TRILL switch port and that MAC address MAY be used as the
   MacDA. By the use of such a MacSA and either such a unicast MacDA or
   a group addressed MacDA, an Ethernet frame can be sent between two
   TRILL switch ports connected by a non-Ethernet link.

   These synthetic TRILL switch port MAC addresses for non-Ethernet
   ports are constructed as follows: 0xFEFF, the nickname of the TRILL
   switch used in TRILL Hellos sent on that port, and the Port ID that
   the TRILL switch has assigned to that port, as shown in Figure 3.5.
   (Both the nickname and Port ID of the port on which a TRILL Hello is
   sent appear in the Special VLANs and Flags sub-TLV [RFC7176] in that
   Hello.)  The resulting MAC address has the Local bit on and the Group
   bit off [RFC7042]. Since end stations are connected to TRILL switches
   over Ethernet, there will be no end stations on a non-Ethernet link
   in a TRILL campus. Thus such synthetic MAC addresses cannot conflict
   on the link with a real Ethernet port address.








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                           1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            0xFEFF             |            Nickname           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Port ID            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 3.5 Synthetic MAC Address











































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4. Security, Keying, and Algorithms

   The following table gives the initial assigned values of the SType
   field and their meaning.

         SType  Section  Meaning
         -----  -------  -------
           0     4.4     None
           1     4.5     [RFC5310] Based Authentication
           2     4.6     DTLS Based Security
           3     4.7     [RFC5310] Based Encryption and Authentication
          4-14           Available for assignment by IETF Review
          15             Reserved

                           Table 3. SType Values



4.1 Basic Security Format

   When SType is zero, there is no Security Information after the
   Channel Tunnel header and before the payload.  For all SType values
   except zero, the Security Information starts with a byte of flag bits
   and a byte of remaining length as follows:

         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
         |A|E|    RESV   |     Size      |   More Info
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...

                  Figure 4.1 Security Information Format

   The fields are as follows:

   A: Zero if authentication is not being provided. One if it is.

   E: Zero if encryption is not being provided. One if it is.

   RESV: Six reserved bits that MUST be sent as zero and ignored on
      receipt. In the future, meanings may be assigned to these bits and
      those meanings may differ for different STypes.

   Size: The number of bytes, as an unsigned integer, of More Info in
      the Security Information after the Size byte itself. Thus the
      maximum possible length of Security Information is 257 bytes for a
      Size of 255 plus the flags and Size bytes.

   More Info: Additional Security Information of length Size. Contents
      depends on the SType.

   The A and E bits are intended as hints and to assist in debugging.


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   They are not guaranteed to be correct. They can be interpreted as
   follows:

       A E     Comments
      -----   ----------

       0 0    Neither authentication nor encryption is being provided.

       1 0    Authentication only. The payload should be parsable by a
              security ignorant receiver if it understands the payload
              format. The Size field permits skipping the More Info
              field.

       0 1    Encryption only, perhaps some form of opportunistic
              security [RFC7435].

       1 1    Authentication and Encryption.



4.2 Authentication and Encryption Coverage

   Authentication in the RBridge Channel case (see Figure 2.1) is
   computed across the inner Ethernet Addresses, Data Label, relevant
   Channel Tunnel header information, and the payload.  To be more
   precise, the covered area starts with the byte immediately after the
   TRILL Header ingress nickname unless the optional flag word
   [rfc7180bis] is present in which case it starts after the flag word,
   and extends to just before the TRILL Data packet link trailer, for
   example just before the FCS for Ethernet. If an authentication value
   is included in the More Info field shown in Section 4.1, it is
   treated as zero when authentication is calculated. If an
   authentication value is included in a payload after the security
   information, it is calculated as provided by the SType and security
   algorithms in use.

   Authentication in the native RBridge Channel case (see Figure 2.2),
   is as specified in the above paragraph except that it starts with the
   RBridge Channel Ethertype, since there are no TRILL Header, inner
   Ethernet address, or inner Data Label.

   If encryption is provided, it covers the payload from right after the
   Channel Tunnel header Security Information through to just before the
   TRILL Data packet link trailer.








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4.3 Derived Keying Material

   In some cases, it is possible to use keying material derived from
   [RFC5310] IS-IS keying material. In such cases, the More Info field
   shown in Figure 4.1 includes a two byte Key ID to identify the IS-IS
   keying material. The keying material actually used in Channel Tunnel
   security is derived from the IS-IS keying material as follows:

      HKDF-Expand-SHA256 ( IS-IS-key, "Channel Tunnel" | 0x0S, L )

   where "|" indicates concatenation, HKDF is as in [RFC5869], SHA256 is
   as in [RFC6234], IS-IS-key is the input keying material, "Channel
   Tunnel" is the 14-character [RFC20] string indicated, 0x0S is a
   single byte where S is the SType for which this key derivation is
   being used, and L is the length of output keying material needed.



4.4 SType None

   No security services are being invoked. The length of the Security
   Information field (see Figure 2.4) is zero.



4.5 RFC 5310 Based Authentication

   The Security Information (see Figure 2.4) is the flags and Size bytes
   specified in Section 4.1 with the value of the [RFC5310] Key ID and
   Authentication Data as shown in Figure 4.2.

                              1 1 1 1 1 1
          0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |1|0|    RESV   |     Size      |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |           Key ID              |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                               |
         +
         | Authentication Data (Variable)
         +
         |
         +-+-+-+-+-+-+-+-+-+-+-+-+-...

                  Figure 4.2 SType 1 Security Information

   o  RESV: Six bits that MUST be sent as zero and ignored or receipt.

   o  Size: Set to 2 + the size of Authentication Data in bytes.


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   o  Key ID: specifies the same keying value and authentication
      algorithm that the Key ID specifies for TRILL IS-IS LSP [RFC5310]
      Authentication TLVs. The keying material actually used is derived
      as shown in Section 4.3.

   o  Authentication Data: The authentication data produced by the key
      and algorithm associated with the Key ID acting on the packet as
      specified in Section 4.2. Length of the authentication data
      depends on the algorithm.



4.6 DTLS Based Security

   DTLS supports key negotiation and provides both encryption and
   authentication. This optional SType in Channel Tunnel uses DTLS 1.2
   [RFC6347]. It is intended for pairwise use. The presumption is that
   in the RBridge Channel case (Figure 2.1) the M bit in the TRILL
   Header would be zero and in the native RBridge Channel case (Figure
   2.2), the Outer.MacDA would be individually addressed.

   TRILL switches that implement the Channel Tunnel DTLS SType SHOULD
   support the use of certificates for DTLS. In this case the Size field
   shown in Section 4.1 MUST be zero and the Security Information is as
   shown in Figure 4.3.

   Also, if they support certificates, they MUST support the following
   algorithm:

   o  TLS_RSA_WITH_AES_128_CBC_SHA256 [RFC5246]


                      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                      |1|1|   RESV    |       0       |
                      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Figure 4.3 DTLS Cert or Special Pre-shared Key Security Information


   TRILL switches that support the Channel Tunnel DTLS SType MUST
   support the use of pre-shared keys for DTLS. The Size field as shown
   in Section 4.1 MUST be either zero or 2. If Size is zero as shown in
   Figure 4.3, a pre-shared key specifically associated with Channel
   Tunnel DTLS is used. If Size is 2 as shown in Figure 4.4, a two byte
   [RFC5310] Key ID is present and the pre-shared key is derived from
   the secret key associated with that Key ID as shown in Section 4.3.

   The following cryptographic algorithms MUST be supported for use with
   pre-shared keys:



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   o  TLS_PSK_WITH_AES_128_CBC_SHA256 [RFC5487]


                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     |1|1|   RESV    |       2       |
                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     |           Key ID              |
                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 4.4 DTLS Derived Pre-shared Key Security Information


   When DTLS security is used, the entire payload of the Channel Tunnel
   packet, starting just after the Security Information and ending just
   before the link trailer, is a DTLS record [RFC6347].



4.7 RFC 5310 Based Encryption and Authentication

   This SType is based on pre-existing [RFC5310] keying material but
   does not use any algorithm that may be associated with a Key ID under
   [RFC5310].  Instead it uses the derived key as specified in Section
   4.3 with the algorithm specified by a Crypto Suite ID as shown in
   Figure 4.5. Key negotiation is not provided and this SType is
   intended for use in securing multi-destination packets. The
   presumption is that in the RBridge Channel case (Figure 2.1) the M
   bit in the TRILL Header would be one and in the native RBridge
   Channel case (Figure 2.2), the Outer.MacDA would be group addressed.

                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     |1|1|   RESV    |       4       |
                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     |           Key ID              |
                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     |     Crypto Suite ID           |
                     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 4.5 DTLS Derived Pre-shared Key Security Information


   4.7.1 Channel-Tunnel-CCM

   The initially specified Crypto Suites is called CT-CCM-128 (Channel
   Tunnel Counter with CBC-MAC using AES-128), and is designed by Crypto
   Suite ID 0x0001.

   CT-CCM is based on [RFC3610] using AES-128 as the encryption
   function. The minimum authentication field size permitted is 8
   octets.  There is additional authenticated data which is the


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   authenticated data indicated in Section 4.2 up to but not including
   any of the Tunneled Data (Figure 2.4). The message size is limited to
   2**16 - 2**8 bytes so 2 bytes are used for the length of message
   field. There are thus 13 bytes available for nonce [RFC3610]. Since
   it is possible that the same Key ID could be used by different TRILL
   switches, the nonce MUST include an identifier for the originating
   TRILL switch. It is RECOMMENDED that this be the first 6 bytes of its
   IS-IS System ID as these will be unique across the campus.  The
   remaining 7 bytes (56 bits) need to be such that the nonce is always
   unique for a particular key, for example a counter for which care is
   taken that it is always incremented after each use and its value is
   preserved over TRILL switch crashes, re-starts, and the like. Should
   there be a danger of exhausting such a counter, the TRILL switch MUST
   take steps such as causing re-keying of the [RFC5310] key ID it is
   using and/or changing to use a different Key ID.





































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5. Channel Tunnel Errors

   RBridge Channel Tunnel Protocol errors are reported like RBridge
   Channel level errors. The ERR field is set to one of the following
   error codes:

         ERR   Meaning
         ---  ---------
          6    Unknown or unsupported field value
          7    Authentication failure
          8    Error in nested RBridge Channel message

                      Table 4. Additional ERR Values



5.1 SubERRs under ERR 6

   If the ERR field is 6, the SubERR field indicates the problematic
   field or value as show in the table below.

         SubERR  Meaning (for ERR = 6)
         ------  ---------------------
            0    Reserved
            1    Non-zero RESV4 nibble
            2    Unsupported SType
            3    Unsupported PType
            4    Unsupported Crypto Suite ID
            5    Unknown Key ID
            6    Unknown Ethertype with PType = 2

                    Table 5. SubERR values under ERR 6



5.2 Nested RBridge Channel Errors

   If
      a Channel Tunnel message is sent with security and with a payload
      type (PType) indicating a nested RBridge Channel message
   and
      there is an error in the processing of that nested message that
      results in a return RBridge Channel message with a non-zero ERR
      field,
   then that returned message SHOULD also be nested in an Channel Tunnel
   message using the same type of security. In this case, the ERR field
   in the Channel Tunnel envelope is set to 8 indicating that there is a
   nested error in the message being tunneled back.




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6. IANA Considerations

   This section list IANA Considerations.



6.1 RBridge Channel Protocol Number

   IANA is requested to assign TBD as the RBridge Channel protocol
   number for the "Channel Tunnel" protocol from the range assigned by
   Standards Action.

   The added RBridge Channel protocols registry entry on the TRILL
   Parameters web page is as follows:

         Protocol   Description    Reference
         --------  --------------  ---------

           TBD     Tunnel Channel   [this document]



6.2 Channel Tunnel Crypto Suites

   IANA is requested to create a subregistry in the TRILL Parameters
   registry as follows:

   Name: RBridge Channel Tunnel Crypto Suites
   Registration Procedures: Expert Review
   Reference: [this document]

    Value    Description      Reference
   -------  -------------    -----------
        0    Reserved
        1    CT-CCM          [this document]
   2-65534   available for assignment
     65535   Reserved















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7. Security Considerations

   The RBridge Channel tunnel facility has potentially positive and
   negative effects on security.

   On the positive side, it provides optional security that can be used
   to authenticate and/or encrypt RBridge Channel messages. Some RBridge
   Channel message payloads, such as BFD [RFC7175], provide their own
   security but where this is not true, consideration should be given,
   when specifying an RBridge Channel protocol, to recommending or
   requiring use of the security features of the Tunnel Protocol.

   On the negative side, the optional ability to tunnel various payload
   types and to tunnel them between TRILL switches and to and from end
   stations can increase risk unless precautions are taken.  The
   processing of decapsulating Tunnel Protocol payloads is not a good
   place to be liberal in what you accept. This is because the tunneling
   facility makes it easier for unexpected messages to pop up in
   unexpected places in a TRILL campus due to accidents or the actions
   of an adversary. Local policies should generally be strict and only
   process payload types required and then only with adequate
   authentication for the particular circumstances.

   While simple [RFC5310] based authentication as specified in Section
   4.5 is better than nothing, in general it is RECOMMENDED that DTLS
   based security, as specified in Section 4.6, be used for all point-
   to-point Channel Tunnel messages and [RFC5310] based encryption and
   authentication, as specified in Section 4.7, be used for all multi-
   destination Channel Tunnel messages. If IS-IS authentication is not
   being used, then [RFC5310] keying information would not normally be
   available but that presumably represents a judgment by the TRILL
   campus operator that security is not needed.

   In connection with the use of DTLS for security as specified in
   Section 4.5, see [RFC7457].

   See [RFC7178] for general RBridge Channel Security Considerations and
   [RFC6325] for general TRILL Security Considerations.














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Normative References

   [IS-IS] - ISO/IEC 10589:2002, Second Edition, "Information technology
         -- Telecommunications and information exchange between systems
         -- Intermediate System to Intermediate System intra-domain
         routeing information exchange protocol for use in conjunction
         with the protocol for providing the connectionless-mode network
         service (ISO 8473)", 2002.

   [RFC20] - Cerf, V., "ASCII format for network interchange", STD 80,
         RFC 20, October 1969, <http://www.rfc-editor.org/info/rfc20>.

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

   [RFC3610] - Whiting, D., Housley, R., and N. Ferguson, "Counter with
         CBC-MAC (CCM)", RFC 3610, September 2003, <http://www.rfc-
         editor.org/info/rfc3610>.

   [RFC5246] - Dierks, T. and E. Rescorla, "The Transport Layer Security
         (TLS) Protocol Version 1.2", RFC 5246, August 2008,
         <http://www.rfc-editor.org/info/rfc5246>.

   [RFC5310] - Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
         and M. Fanto, "IS-IS Generic Cryptographic Authentication", RFC
         5310, February 2009.

   [RFC5487] - Badra, M., "Pre-Shared Key Cipher Suites for TLS with
         SHA-256/384 and AES Galois Counter Mode", RFC 5487, March 2009,
         <http://www.rfc-editor.org/info/rfc5487>.

   [RFC5869] - Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-
         Expand Key Derivation Function (HKDF)", RFC 5869, May 2010,
         <http://www.rfc-editor.org/info/rfc5869>.

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

   [RFC6347] - Rescorla, E. and N. Modadugu, "Datagram Transport Layer
         Security Version 1.2", RFC 6347, January 2012, <http://www.rfc-
         editor.org/info/rfc6347>.

   [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, May 2014.

   [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, May 2014,


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         <http://www.rfc-editor.org/info/rfc7176>.

   [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, May 2014.

   [RFC7356] - Ginsberg, L., Previdi, S., and Y. Yang, "IS-IS Flooding
         Scope Link State PDUs (LSPs)", RFC 7356, September 2014,
         <http://www.rfc-editor.org/info/rfc7356>.

   [rfc7180bis] - Eastlake, D., Zhang, M., Perlman, R. Banerjee, A.,
         Ghanwani, A., and S. Gupta, "TRILL: Clarifications,
         Corrections, and Updates", Draft-ietf-trill-rfc7180bis, work in
         progress.



Informative References

   [RFC6234] - Eastlake 3rd, D. and T. Hansen, "US Secure Hash
         Algorithms (SHA and SHA-based HMAC and HKDF)", RFC 6234, May
         2011.

   [RFC6361] - Carlson, J. and D. Eastlake 3rd, "PPP Transparent
         Interconnection of Lots of Links (TRILL) Protocol Control
         Protocol", RFC 6361, August 2011

   [RFC7042] - Eastlake 3rd, D. and J. Abley, "IANA Considerations and
         IETF Protocol and Documentation Usage for IEEE 802 Parameters",
         BCP 141, RFC 7042, October 2013.

   [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,
         May 2014.

   [RFC7435] - Dukhovni, V., "Opportunistic Security: Some Protection
         Most of the Time", RFC 7435, December 2014, <http://www.rfc-
         editor.org/info/rfc7435>.

   [RFC7457] - Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing
         Known Attacks on Transport Layer Security (TLS) and Datagram
         TLS (DTLS)", RFC 7457, February 2015, <http://www.rfc-
         editor.org/info/rfc7457>.








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Appendix Z: Change History

From -00 to -01

   1. Fix references for RFCs published, etc.

   2. Explicitly mention in the Abstract and Introduction that this
      document updates [RFC7178].

   3. Add this Change History Appendix.

From -01 to -02

   1. Remove section on the "Scope" feature as mentioned in
      http://www.ietf.org/mail-archive/web/trill/current/msg06531.html

   2. Editorial changes to IANA Considerations to correspond to draft-
      leiba-cotton-iana-5226bis-11.txt.

   3. Improvements to the Ethernet frame payload type.

   4. Other Editorial changes.

From -02 to -03

   1. Update TRILL Header to correspond to [rfc7180bis].

   2. Remove a few remnants of the "Scope" feature that was removed from
      -01 to -02.

   3. Substantial changes to and expansion of Section 4 including adding
      details of DTLS security.

   4. Updates and additions to the References.

   5. Other minor editorial changes.

From -03 to -04

   1. Add SType for [RFC5310] keying based security that provides
      encryption as well as authentication.

   2. Editorial improvements and fixes.

From -04 to -05

   1. Primary change is collapsing the previous PTypes 2, 3, and 4 for
      RBridge Channel message, TRILL Data, and TRILL IS-IS into one by
      including the Ethertype. Previous PType 5 is renumbered as 3.



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   2. Add Channel Tunnel Crypto Suites to IANA Considerations

   3. Add some material to Security Considerations,

   4. Assorted Editorial changes.

From -05 to -06

   Fix editorials found during WG Last Call.











































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Acknowledgements

   The contributions of the following are hereby acknowledged:

         Gayle Noble

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












































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Authors' Addresses

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

      Phone: +1-508-333-2270
      EMail: d3e3e3@gmail.com


      Mohammed Umair
      IPinfusion

      EMail: mohammed.umair2@gmail.com


      Yizhou Li
      Huawei Technologies
      101 Software Avenue,
      Nanjing 210012, China

      Phone: +86-25-56622310
      EMail: liyizhou@huawei.com




























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Copyright, Disclaimer, and Additional IPR Provisions

   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
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.  The definitive version of
   an IETF Document is that published by, or under the auspices of, the
   IETF. Versions of IETF Documents that are published by third parties,
   including those that are translated into other languages, should not
   be considered to be definitive versions of IETF Documents. The
   definitive version of these Legal Provisions is that published by, or
   under the auspices of, the IETF. Versions of these Legal Provisions
   that are published by third parties, including those that are
   translated into other languages, should not be considered to be
   definitive versions of these Legal Provisions.  For the avoidance of
   doubt, each Contributor to the IETF Standards Process licenses each
   Contribution that he or she makes as part of the IETF Standards
   Process to the IETF Trust pursuant to the provisions of RFC 5378. No
   language to the contrary, or terms, conditions or rights that differ
   from or are inconsistent with the rights and licenses granted under
   RFC 5378, shall have any effect and shall be null and void, whether
   published or posted by such Contributor, or included with or in such
   Contribution.





















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