TRILL: RBridge Channel Tunnel Protocol
draft-ietf-trill-channel-tunnel-02

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INTERNET-DRAFT                                           Donald Eastlake
Updates: 7178                                                  Yizhou Li
Intended status: Proposed Standard                                Huawei
Expires: June 7, 2015                                   December 8, 2014

                 TRILL: RBridge Channel Tunnel Protocol
                <draft-ietf-trill-channel-tunnel-02.txt>

Abstract

   The IETF TRILL (Transparent Interconnection of Lots of Links)
   protocol includes an optional mechanism, called RBridge Channel and
   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 protcol: (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.

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   and may be updated, replaced, or obsoleted by other documents at any
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   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
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D. Eastlake & Y. Li                                             [Page 1]
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Table of Contents

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

      2. Channel Tunnel Packet Format............................4

      3. Tunnel Payload Types....................................7
      3.1 Null Payload...........................................7
      3.2 RBridge Channel Message Payload........................7
      3.3 TRILL Data Packet......................................8
      3.4 TRILL IS-IS Packet.....................................9
      3.5 Ethernet Frame........................................10

      4. Security, Keying, and Algorithms.......................12
      4.1 Authentication Coverage...............................12
      4.2 SType None............................................13
      4.3 RFC 5310 Based Authentication.........................13
      4.4 xxx Based Security....................................13

      5. Channel Tunnel Errors..................................14
      5.1 SubERRs under ERR 6...................................14
      5.2 Nested RBridge Channel Errors.........................14

      6. IANA Considerations....................................15
      7. Security Considerations................................16

      Normative References......................................17
      Informative References....................................18

      Appenxid Z: Change History................................19

      Acknowledgements..........................................20
      Authors' Addresses........................................21

D. Eastlake & Y. Li                                             [Page 2]
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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 [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 the destination port or ports is 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 provides two additional facilities as listed below.
   Implementation and use of each of these facilities is optional,
   except that there are two payload types that MUST be implemented.
   Both of these facilities can be used in the same packet.

      (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.

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 the acronyms defined in [RFC6325] and [RFC7178]
   supplemented by the following additional acronym:

      Data Label - VLAN or FGL.

      FGL - Fine Grained Label [RFC7172].

      RBridge - An alternative term for a TRILL switch.

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

D. Eastlake & Y. Li                                             [Page 3]
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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, inner
   Ethernet addresses, and Data Label are 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 [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 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:

D. Eastlake & Y. Li                                             [Page 4]
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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 =tbd1 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Flags         |  ERR  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Channel Tunnel Protocol Specific: | SubERR| RESV4 | SType | PType |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  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 6).

   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 5.

      RESV4: This field MUST be sent as zero. If non-zero when received,

D. Eastlake & Y. Li                                             [Page 5]
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         this is an error condition (see Section 4).

      SType: This field describes the type of security information and
         features, including keying material, being provided. See
         Section 4.

      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 (see Section 6).

D. Eastlake & Y. Li                                             [Page 6]
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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 testing or messages
   such as key negotiation or the like. It indicates that there is no
   payload. Any data after the 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 payload type looks like the following:

D. Eastlake & Y. Li                                             [Page 7]
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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 =tbd1 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  | SubERR| RESV4 | SType |  0x2  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  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 as shown in the figure
   below. (There is no TRILL Ethertype before the inner TRILL Data
   packet because that is just part of the Ethernet link header for a
   TRILL Data packet, not part of the TRILL header itself.)  If this
   PType is implemented 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.

D. Eastlake & Y. Li                                             [Page 8]
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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 =tbd1 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  | SubERR| RESV4 | SType |  0x3  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  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 PDU 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. One possible use is to
   expedite the receipt of a link state PDU by some TRILL switch or
   switches with an immediate requirement for the enclosed link state
   PDU.  Any link local IS-IS PDU (Hello, CSNP, or PSNP [IS-IS]; MTU-
   probe, MTU-ack [RFC7176]; or circuit scoped FS-LSP, FS-CSNP or FS-
   PSNP [RFC7356]) received via this channel tunnel payload type MUST be
   discarded.

D. Eastlake & Y. Li                                             [Page 9]
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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 =tbd1 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  | SubERR| RESV4 | 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 and the
   message meets local policy, the tunneled frame is handled as if it
   had been received on the port on which the Tunnel Protocol message
   was received.

       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 =tbd1 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  | SubERR| RESV4 | SType |  0x5  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Possible Security information
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             MacDA                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         MacDA (cont.)         |             MacSA             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          MacSA (cont.)                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Any Ethernet frame tagging...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
      |  Ethernet frame payload...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...

             Figure 8. Ethernet Frame Channel Tunnel Structure

D. Eastlake & Y. Li                                            [Page 10]
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   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.
   This constructed address MAY be used as the MacSA and, 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.

   These MAC addresses are constructed as follows: 0xFEFF, the nickname
   of the TRILL switch used in TRILL Hellos on that port, and the Port
   ID that the TRILL switch has assigned to that port, as shown in
   Figure 9. Both the nickname and Port ID appear in the Special VLANs
   and Flags sub-TLV [RFC7176].  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.

       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             |            Nickname           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Port ID            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 9. Synthetic MAC Address

D. Eastlake & Y. Li                                            [Page 11]
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4. Security, Keying, and Algorithms

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

         SType  Section  Meaning
         -----  -------  -------
           0     4.2     None
           1     4.3     [RFC5310] Based Authentication
           2     4.4     xxx 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.

4.1 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.

D. Eastlake & Y. Li                                            [Page 12]
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4.2 SType None

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

4.3 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.

                              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.

4.4 xxx Based Security

   xxx - permits key negotiation, provides both encryption and
   authentication ...

D. Eastlake & Y. Li                                            [Page 13]
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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
         (more TBD?)

                         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    Non-zero RESV4 nibble
            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

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.

D. Eastlake & Y. Li                                            [Page 14]
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6. IANA Considerations

   IANA has assigned tbd1 as the RBridge Channel protocol number the
   "Channel Tunnel" protocol from the range assinged by Standards
   Action.

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

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

           tbd1    Tunnel Channel   [this document]

D. Eastlake & Y. Li                                            [Page 15]
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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 provide their own security [RFC7175] but
   where this is not true, consideration should be give to 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 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 [RFC7178] for general RBridge Channel Security Considerations.

   See [RFC6325] for general TRILL Security Considerations.

D. Eastlake & Y. Li                                            [Page 16]
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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.

   [FIPS-180] - "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

   [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.

   [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.

   [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,
         <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>.

D. Eastlake & Y. Li                                            [Page 17]
INTERNET-DRAFT                             TRILL: RBridge Channel Tunnel

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.

D. Eastlake & Y. Li                                            [Page 18]
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Appenxid 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.

   x. Other Editorial changes.

D. Eastlake & Y. Li                                            [Page 19]
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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.

D. Eastlake & Y. Li                                            [Page 20]
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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

D. Eastlake & Y. Li                                            [Page 21]
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Copyright, Disclaimer, and Additional IPR Provisions

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   document authors. All rights reserved.

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D. Eastlake & Y. Li                                            [Page 22]