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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: RFCchannel                                            Yizhou Li
Intended status: Proposed Standard                                Huawei
Expires: June 4, 2014                                   December 5, 2013

                 TRILL: RBridge Channel Tunnel Protocol
                <draft-ietf-trill-channel-tunnel-00.txt>


Abstract

   The IETF TRILL (Transparent Interconnection of Lots of Links)
   protocol includes an optional mechanism, called RBridge Channel, 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 optional extensions to RBridge Channel that
   provides three facilities: (1) A mechanism to send such messages
   between a TRILL switch and an end station in either direction, or
   between two end stations, when the two devices are in the same campus
   but not on the same link; (2) A method to support security facilities
   for RBridge Channel messages; and (3) A method to tunnel a variety of
   payload types by encapsulating them in an RBridge Channel message.


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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INTERNET-DRAFT                             TRILL: RBridge Channel Tunnel


Table of Contents

      1. Introduction............................................3
      1.2.  Terminology and Acronyms.............................3

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

      3. Tunnel Payload Types....................................8
      3.1 Null Payload...........................................8
      3.2 RBridge Channel Message Payload........................8
      3.3 TRILL Data Packet......................................9
      3.4 TRILL IS-IS Packet....................................10
      3.5 Ethernet Frame........................................11

      4. Channel Tunnel Scopes..................................13
      4.1 End Station to RBridge(s).............................14
      4.2 RBridge to End Station................................15
      4.3 End Station to End Station............................16

      5. Security, Keying, and Algorithms.......................18
      5.1 Authentication Coverage...............................18
      5.2 SType None............................................19
      5.3 RFC 5310 Based Authentication.........................19
      5.4 DTLS Based Security...................................20

      6. Channel Tunnel Errors..................................21
      6.1 SubERRs under ERR 6...................................21
      6.2 Nested RBridge Channel Errors.........................21

      7. IANA Considerations....................................22
      8. Security Considerations................................22

      Normative References......................................23
      Informative References....................................23
      Acknowledgements..........................................25
      Authors' Addresses........................................26
















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1. Introduction

   The IETF TRILL protocol [RFC6325] includes an optional RBridge
   Channel [RFCchannel] facility to support transmission of typed
   messages (for example BFD [RFCbfd]) between two RBridges in the same
   campus and between RBridges and end stations on the same link.  This
   document specifies optional extensions to RBridge Channel that
   provides three facilities:

      (1) A mechanism to send RBridge Channel messages between a TRILL
          switch (RBridge) and an end station in either direction, or
          between two end stations, when the two devices are in the same
          campus but not on the same link. This mechanism requires the
          cooperation of a TRILL switch that is on the same link as the
          end station or stations involved.

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

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

   Any one, two, or all three of these facilities can be use in the same
   message.

   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.



1.2.  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 the acronyms defined in [RFC6325] and [RFCchannel]
   supplemented by the following additional acronym:

      Data Label - VLAN or FGL.

      FGL - Fine Grained Label [RFCfgl].

      Primary Nickname - If a TRILL switch holds two or more nicknames,
         the one it holds with the highest priority is the primary
         nickname. If two or more are held with the same priority, the
         one with the lowest value, considered as a 16-bit unsigned
         integer in network byte order, is the primary nickname.



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      RBridge - An alternative term for a TRILL switch.

      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 on a link between
   TRILL switches (RBridges) is shown in Figure 1 below. When a native
   RBridge Channel message is sent between an RBridge and an end station
   on the same link, in either direction, the TRILL Header (including
   the inner Ethernet addresses and Data Label) is omitted as shown in
   Figure 2. The type of RBridge Channel message is given by a Protocol
   field in the RBridge Channel Header that indicates how to interpret
   the Channel Protocol Specific Payload [RFCchannel].

                      +-----------------------------------+
                      |           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 1. RBridge Channel Packet Structure


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

                     Figure 2. Native RBridge Channel Frame


   The RBridge Channel Header looks like this:








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       0                   1                   2                   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  |   Channel Protocol    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Flags         |  ERR  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Channel Protocol Specific Data
      |

                       Figure 3. RBridge Channel Header

   where 0x8946 is the RBridge Channel Ethertype and CHV is the Channel
   Header Version, currently zero.

   The extensions specified herein are in the form of an RBridge Channel
   protocol, the Channel Tunnel Protocol.  Figure 4 below expands the
   RBridge Channel Header and Protocol Specific Payload above for the
   case of the Channel Tunnel Protocol.

       0                   1                   2                   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                |  0x0  | Tunnel Protocol(0x00?)|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Flags         |  ERR  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Channel Tunnel Protocol Specific: | SubERR| Scope | SType | PType |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Scope Information, variable length (0 length if Scope=0)
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |  Security information, variable length (0 length if SType = 0)
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |      Tunneled Data, variable length
      |  ...

                 Figure 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 7).

   The RBridge Tunnel Channel Protocol Specific fields are as follows:

      SubERR: This field provides further details when a Tunnel Channel
         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 6.



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      Scope: This field describes the transport scope of the instance of
         Channel Tunnel. See Section 4.

      SType: This field describes the type of security information and
         features, including keying material, being provided. See
         Section 5.

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

   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.
   Additional RBridge Channel Header flags are specified and used by
   Channel Tunnel.




































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3. Tunnel Payload Types

   The RBridge 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     RBridge Channel message
           3      3.3     TRILL Data packet
           4      3.4     TRILL IS-IS packet
           5      3.5     Ethernet Frame
         6-14            (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 PTypes 1 (Null) and 2 (RBridge Channel message)
   MUST be implemented. PTypes 3, 4, and 5 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 is intended to be used for messages such as key
   negotiation or the like. It indicates that there is no payload. Any
   data after the possible Scope Information and Security Information
   fields is ignored.



3.2 RBridge Channel Message Payload

   A PType of 2 indicates that the payload of the Channel Tunnel message
   is an encapsulated RBridge Channel message without the initial
   RBridge Channel Ethertype. Typical reasons for sending an RBridge
   Channel message inside a Channel Tunnel message are to provide
   security services, such as authentication or encryption, or to
   forward it through a cooperating border TRILL switch in either
   direction between an end station and a TRILL switch not on the same
   link.

   This looks like the following:



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       0                   1                   2                   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| Scope | SType |  0x2  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Possible Scope Information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |  Possible Security information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  0x0  |  Channel Protocol     |          Flags        |  ERR  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Channel Protocol Specific Data ...                    |
      |

        Figure 5. Tunneled Channel Message Channel Tunnel Structure



3.3 TRILL Data Packet

   A PType of 3 indicates that the payload of the Tunnel protocol
   message is an encapsulated TRILL Data packet without the initial
   TRILL Ethertype as shown in the figure below. If this PType is
   implemented, 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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       0                   1                   2                   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| Scope | SType |  0x3  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Possible Scope Information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |  Possible Security information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | V | R |M|Op-Length| Hop Count |      Egress Nickname          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Ingress Nickname         |        Inner.MacDA            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Inner.MacDA continued                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Inner.MacSA                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Inner.MacSA (cont.)        |     Inner Data Label ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      | TRILL Data Packet payload
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...

        Figure 6. Nested TRILL Data Packet Channel Tunnel Structure



3.4 TRILL IS-IS Packet

   A PType of 4 indicates that the payload of the Tunnel protocol
   message is an encapsulated TRILL IS-IS packet without the initial
   L2-IS-IS Ethertype as shown in the figure below. If this PType is
   implemented, the tunneled TRILL IS-IS packet is processed by the
   destination RBridge if it meets local policy. The intended use is to
   expedite the receipt of a link state PDU by some TRILL switch with an
   immediate requirement for the enclosed link state data. It is
   RECOMMENDED that any link local IS-IS PDU (Hello, xSNP, MTU-x)
   received via this channel tunnel payload type be discarded.













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       0                   1                   2                   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|| Scope | SType |  0x4
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Possible Scope Information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |  Possible Security information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |      0x83     | rest of IS-IS PDU
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...

              Figure 7. Tunneled TRILL IS-IS Packet Structure



3.5 Ethernet Frame

   If PType is 5, 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 8.
   (There is still an overall FCS if the RBridge Channel message is
   being sent on an Ethernet link.) If this PType is implemented, the
   tunneled frame is handled as if it had been received on the port on
   which the Tunnel Protocol message was received.

   In the case of a non-Ethernet link, such as a PPP link [RFC6361], the
   ports on the link are considered to have link local synthetic 48-bit
   MAC addresses constructed by concatenating three 16-bit quantities:
   0xFEFF, the primary nickname of the TRILL switch (see Section 1.2),
   and the Port ID that the TRILL switch has assigned to that port, as
   shown in Figure 9. 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 an end station address.














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       0                   1                   2                   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| Scope | SType |  0x5  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Possible Scope Information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |  Possible Security information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             MacDA                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         MacDA (cont.)         |             MacSA             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          MacSA (cont.)                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Any Ethernet frame tagging...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |  Ethernet frame payload...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...

             Figure 8. Ethernet Frame Channel Tunnel Structure

       0                   1                   2                   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             |        Primary Nickname       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Port ID            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 9. Synthetic MAC Address



















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4. Channel Tunnel Scopes

   The Channel Tunnel protocol extends the RBridge Channel facility to
   optionally support typed messages between an end station and a TRILL
   switch, in either direction, or between two end stations, when these
   devices are part of the same TRILL campus but not on the same link.
   The scopes specified in this document are as follows:

         Scope  Symbol  Section  From-To
         -----  ------  -------  -------
           0     NORM            Normal
           1     ESRB    4.1     End Station to RBridge
           2     RBES    4.2     RBridge to End Station
           3     ESES    4.3     End Station to End Station
          4-14          Available for assignment by IETF Review
          15            Reserved

                           Table 2. Scope Values

   If the Channel Tunnel protocol is supported, then the NORM scope MUST
   be supported. Other scopes MAY be supported. In cases where a
   sequence of steps is given below, other processing sequences
   producing the same result are allowed.

   NORM: This is the normal scope of an RBridge Channel message; thus it
      is either between two TRILL switches in the same campus or between
      a TRILL switch and an end station on the same link in either
      direction. The base RBridge Channel mechanisms apply [RFCchannel].
      The scope dependent addressing information is of zero length. This
      scope is typically used when just the security and/or payload type
      features of the Tunnel Protocol are desired. If a TRILL switch
      supports the Channel Tunnel facility, it MUST support NORM scope.

   ESRB: From end station to RBridge(s) not on the same link. The scope
      dependent address information is eight bytes long. See Section 4.1
      for further details. This scope MAY be supported.

   RBES: From RBridge to end station(s) not on the same link. The scope
      dependent address information is eight bytes long. See Section 4.2
      for further details. This scope MAY be supported.

   ESES: From end station to end station(s) not on the same link. The
      scope information is twelve bytes long. See Section 4.3 for
      further details. This scope MAY be supported.

   It is an implementation option and may depend on local policy whether
   or not an edge TRILL switch that has been requested to forward a
   Channel Tunnel protocol message due to a non-NORM Scope examines the
   SType and, if it does examine the SType, whether it verifies any
   authentication.


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4.1 End Station to RBridge(s)

   The ESRB scope additional information is as follows:

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Scope Destination Nickname   |                    (2 bytes)
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
     |  Scope Source MAC Address                       |  (6 bytes)
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+

                     Figure 10. ESRB Scope Information

   To support the case where an end station originates a multi-
   destination RBridge Channel message to all the TRILL switches
   advertising interest in a Data Label, the BR (Broadcast) bit is the
   RBridge Channel Header Flags field is used (see Section 7).

   Steps by the source end station:

      If the RBridge Channel message is intended to a single destination
      RBridge, the source end station sets the Scope Destination
      Nickname to a nickname of that RBridge and ensures that the BR bit
      is zero. If the message is intended to be broadcast to the
      RBridges indicating interest in a Data Label, the end stations
      sets the BR bit, uses that Data Label as part of the TRILL Header
      information, and the contents of the Scope Destination Nickname
      field is ignored.

   Steps by the ingress TRILL switch on receiving the native RBridge
      Channel message from the end station:

      0. As with any RBridge Channel message, determine, as a matter of
         local policy, whether the native RBridge Channel message is
         acceptable and discard it if it is not. This test might take
         into account, for example, whether the message is authenticated
         (see Section 5), whether or not the BR flag is set, and whether
         or not the original native destination MAC address is All-Edge-
         RBridges.
      1. Store the native RBridge Channel message's source MAC address
         into the Scope Source MAC Address field.
      2. Clear the NA bit and set the MH bit in the RBridge Channel
         Header flags.
      3. Set the native RBridge Channel message's MAC destination
         address to All-Egress-RBridges.
      4. Set the native RBridge Channel message's MAC source address to
         the MAC address that the ingress RBridge normally uses as the
         Inner.MacSA for RBridge Channel messages it originates.
      5.a. If the BR flag is zero, ingress the modified native frame as
         a unicast TRILL RBridge Channel message with egress nickname
         set from the Scope Destination Nickname. If that Scope


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         Destination Nickname is unknown, the appropriate error SHOULD
         be returned (see Section 6).
      5.b If the BR flag is one, select a distribution tree and ingress
         the modified native frame as a multi-destination TRILL RBridge
         Channel message.
      5.c Regardless of the BR flag value, the Inner.VLAN is the VLAN ID
         reported by the ingress port or, if that port is configured for
         FGL, the Inner.Label is the FGL that VLAN maps to [RFCfgl].
      6. Process the resulting RBridge Channel message. Note that if it
         is unicast to the ingress TRILL switch as egress, it is then
         immediately egressed.  And if it is multi-destination and the
         ingress RBridge qualifies, a copy is egressed as well as a copy
         being sent on the selected distribution tree.



4.2 RBridge to End Station

   The RBES scope additional addressing information is as follows:

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
     |  Scope Destination MAC Address                  |  (6 bytes)
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
     |  Scope Source Nickname        |                    (2 bytes)
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 11. RBES Scope Information

   Steps by the source TRILL switch:

      The source RBridge must set the Scope Destination MAC Address
      field. It creates an RBridge Channel message, either unicast or
      multi-destination, based on that MAC address. (The Inner.MacDA
      cannot be used for this because it must be the All-Egress-RBridges
      MAC address.) The created RBridge Channel message is unicast if
      the Scope Destination MAC address is unicast and the creating
      RBridge knows the egress by which that MAC address is reachable.
      The created RBridge Channel message is multi-destination if the
      Scope Destination MAC Address is broadcast, multicast, or unknown
      unicast. The source TRILL switch sets the Inner.MacSA to the MAC
      address it usually uses for RBridge Channel messages and also
      selects the Inner Data Label.

   Steps by the egress RBridge(s):

      An egress RBridge stores the ingress nickname into the Scope
      Source Nickname and sets the NA bit in the RBridge Channel Header
      flags. It then egresses the frame as a native RBridge Channel
      message, setting the native frame's outer destination and source
      MAC addresses to the Scope Destination MAC Address and the egress


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      RBridge port's MAC address, respectively.

      If the original RBridge Channel message was multi-destination it
      might be egressed by more than one RBridge, each of which would
      perform the above transform. Whether such a multi-destination
      RBridge Channel Tunnel Protocol message would be accepted by any
      particular egress TRILL switch is a matter of local policy.



4.3 End Station to End Station

   The ESES scope additional addressing information is as follows:

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
     |  Scope Destination MAC Address                  |  (6 bytes)
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
     |  Scope Source MAC Address                       |  (6 bytes)
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+

                     Figure 12. ESES Scope Information

   Steps by the source end stations:

      If the RBridge Channel message is intended for a single
      destination end station, the source end station sets the Scope
      Destination MAC address to the MAC address of that end station and
      ensures that the BR bit is zero. If the message is intended to be
      broadcast to a set of end stations via a multicast MAC address or
      the broadcast MAC address, the end station sets the Scope
      Destination MAC address to that multicast or broadcast address and
      sets the BR bit. All of this is within the VLAN of the native
      RBridge Channel message or its Fine Grained Label (FGL) if the
      ingress port is configured to map to an FGL.

   Steps by the ingress RBridge:

      0. As with any RBridge Channel message, determine, as a matter of
         local policy, whether the native RBridge Channel message is
         acceptable and discard it if it is not. This test might take
         into account, for example, whether the message is authenticated
         (see Section 5), whether or not the BR flag is set, and whether
         or not the original Outer.MacDA is All-Edge-RBridges.
      1. Store the native RBridge Channel message's source MAC address
         into the Scope Source MAC Address.
      2. Clear the NA bit and set the MH bit in the RBridge Channel
         Header flags.
      3. Set the native RBridge Channel message's MAC destination
         address to All-Egress-RBridges.
      4. Set the native RBridge Channel message's MAC source address to


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         the MAC address that the ingress RBridge normally uses as the
         Inner.MacSA for RBridge Channel messages it originates.
      5.a. If the BR flag is zero, lookup the Scope Destination MAC
         Address and ingress the modified native frame as if it were a
         unicast native frame with that destination MAC address. This
         will result in either a unicast TRILL Data packet to the Scope
         Destination MAC Address or in unknown MAC flooding.
      5.b If the BR flag is one, select a distribution tree and ingress
         the modified native frame as a multi-destination TRILL RBridge
         Channel message.
      5.c Regardless of the BR flag value, the Inner.VLAN is the VLAN ID
         reported by the ingress port or, if that port is configured for
         FGL, the Inner.Lable is the FGL that VLAN maps to.
      6. Process the resulting RBridge Channel message. Note that if it
         is unicast to the ingress TRILL switch as egress, it is then
         immediately egressed.  And if it is multi-destination and the
         ingress TRILL switch qualifies, a copy is egressed as well as a
         copy being sent on the selected distribution tree. It is
         possible that the Scope Destination MAC is actually out a
         different or even the same port of the ingress TRILL switch as
         the port on which the native RBridge Channel message was
         received.

   Steps by the egress RBridge(s):

      The egress RBridge sets the NA bit in the RBridge Channel Header
      flags. It then egresses the frame as a native RBridge Channel
      message, setting the native frame's outer destination and source
      MAC addresses to the Scope Destination MAC Address and the egress
      RBridge port's MAC address, respectively.

      If the original RBridge Channel message was multi-destination it
      might be egressed by more than one TRILL switch, each of which
      would perform the above transform. Whether such a multi-
      destination RBridge Channel Tunnel Protocol message would be
      accepted by egress TRILL switches is a matter of local policy.
















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5. Security, Keying, and Algorithms

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

         SType  Section  Meaning
         -----  -------  -------
           0     5.2     None
           1     5.3     [RFC5310] Based Authentication
           2     5.4     DTLS Based Security
          3-14           Available for assignment on IETF Review
          15             Reserved

                           Table 3. SType Values

   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      |   Info
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...

                  Figure 12. 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.

   Size: The number of bytes, as an unsigned integer, of Info in the
      Security Information after the Size byte itself.

   Info: Variable length Security Information.



5.1 Authentication Coverage

   Authentication is computed across relevant Channel Tunnel header
   information and payload with the area when their authentication value
   is to be stored set to zero. To be more precise, the covered area
   starts just after the first byte of the RBridge Channel header flags
   and extends to just before the link trailer.  Thus RBridge Channel
   header flags bits 8 through 11 are protected by authentication while
   flag bits 0 through 7 are not.



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   Any Scope Information (see Figure 6) MUST be correctly filled in when
   the authentication value is computed or verified even when this is
   not required on the wire for correct routing, as follows:

   ESRB: (Section 3.1) Authentication value computation at the origin
      end stations MUST be done with the Source Scope MAC Address filled
      in (as well as the Scope Destination Nickname which is required
      for correct routing). Similarly, a TRILL switch ingressing an ESRB
      packet, which is required to set the Source Scope MAC Address in
      any case, will not be able to correctly validate the
      authentication value unless it is correctly set. There should be
      no problem at the egress TRILL switch as by the time the packet
      gets there, the Source Scope MAC Address should be correctly set.

   RBES: (Section 3.2) Authentication value computation at the origin
      TRILL switch MUST be done with the Source Scope Nickname filled in
      (as well as the Scope Destination MAC Address which is required
      for correct routing). Similarly, a TRILL switch egressing an RBES
      packet, which is required to update the Source Scope Nickname in
      any case, will not be able to correctly validate the
      authentication value unless that nickname is correctly set.

   ESES: (Section 3.3) Authentication value computation at the origin
      end stations MUST be done with the Source Scope MAC Address filled
      in (as well as the Scope Destination MAC Address which is required
      for correct routing). Similarly, a TRILL switch ingressing an ESES
      packet, which is required to update the Source Scope MAC Address
      in any case, will not be able to correctly validate the
      authentication value unless it is correctly set. There should be
      no problem at the egress TRILL switch as by time the packet gets
      there, the Source Scope MAC Address should be correctly set.



5.2 SType None

   No security services are being invoked. The length of the Security
   Information field (see Figure 6) is zero.



5.3 RFC 5310 Based Authentication

   The Security Information (see Figure 6) is the flags and Size bytes
   specified above together with the value of the [RFC5310] Key ID and
   Authentication Data as shown in Figure 13.






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                              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 13. SType 1 Security Information

   The Key ID specifies the same keying value and algorithm that Key ID
   specifies for core TRILL IS-IS LSP Authentication TLVs; however, to
   avoid using the same key for multiple purposes, the keying value
   actually used for Tunnel Channel messages with this SType is a value
   derived from that TRILL IS-IS value as follows:

      HMAC-SHA256 ( ( "Channel Tunnel" | Data Label ), IS-IS-key )

   where "|" indicates concatenation, HMAC-SHA256 is as in [FIPS-180]
   [RFC6234], "Channel Tunnel" is the 14 character [ASCII] string
   indicated, and Data Label is the Data Label in which Channel Tunnel
   message is being sent as either (1) a right justified 12-bit VLAN ID
   in two bytes with 4 zero high order bits or (2) three bytes of FGL.



5.4 DTLS Based Security

   TBD - permits key negotiation, provides both encryption and
   authentication [RFC6347]...
















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6. 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
         (more TBD?)

                         Table 4. Additional ERR Values



6.1 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    Unsupported Scope
            1    Unsupported SType
            2    Unsupported PType
            3    Unknown or reserved Scope Egress Nickname in an
                 ESRB scope Tunnel Channel message
            4    Unsupported crypto algorithm
            5    Unknown Key ID for SType 1
         (more TBD)

                       Table 5. SubERR values under ERR 6



6.2 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.


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7. IANA Considerations

   IANA is requested to allocate a new RBridge Channel protocol number
   from the range based on Standards Action for the "Channel Tunnel"
   protocol.

   IANA is requested to allocate a new RBridge Channel Header flag bit
   for the Broadcast (BR) flag with this document as reference. Bit 8 is
   suggest. In any case, this bit must be one of the low order 4 bit,
   that is, bits 8 through 11.



8. 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 channel messages. Some RBridge Channel
   message payloads provide their own security [RFCbfd] but where this
   is not true, careful consideration should be give to requiring use of
   the security features of the Tunnel Protocol.

   On the negative side, the ability to tunnel various payload types and
   to tunnel them not just between TRILL switches but to and from end
   stations can increase risk unless precautions are taking. The
   processing of decapsulated Tunnel Protocol payloads is not a good
   place to be liberal in what you accept as 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.

   See [RFCchannel] for general RBridge Channel Security Considerations.

   See [RFC6325] for general TRILL Security Considerations.














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Normative References

   [ASCII] - American National Standards Institute (formerly United
         States of America Standards Institute), "USA Code for
         Information Interchange", ANSI X3.4-1968, 1968.  ANSI X3.4-1968
         has been replaced by newer versions with slight modifications,
         but the 1968 version remains definitive for the Internet.

   [FIPS180] - "Secure Hash Standard (SHS)", United States of American,
         National Institute of Science and Technology, Federal
         Information Processing Standard (FIPS) 180-4, March 2012,
         http://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf

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

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

   [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.

   [RFCchannel] - D. Eastlake, V. Manral, Y. Li, S. Aldrin, D. Ward,
         "TRILL: RBridge Channel Support", draft-ietf-trill-rbridge-
         channel-08.txt, in RFC Editor's queue.

   [RFCfgl] - D. Eastlake, M. Zhang, P. Agarwal, R Perlman, D. Dutt,
         "TRILL: Fine-Grained Labeling", draft-ietf-trill-fine-labeling,
         in RFC Editor's queue.




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",


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INTERNET-DRAFT                             TRILL: RBridge Channel Tunnel


         BCP 141, RFC 7042, October 2013.

   [RFCbfd] - Manral, V., D. Eastlake, D. Ward, A. Banerjee, "TRILL
         (Transparent Interconnetion of Lots of Links): Bidirectional
         Forwarding Detection (BFD) Support", draft-ietf-trill-rbridge-
         bfd, in RFC Editor's queue.














































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Acknowledgements

   The contributions of the following are hereby acknowledged:

         TBD

   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


      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

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   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   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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   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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