S  EAP-FAST start
         R  Reserved (must be zero)


            L bit (length included) is set to indicate the presence of
            the four octet Message Length field, and MUST be set for the
            first fragment of a fragmented TLS message or set of
            messages.  The M bit (more fragments) is set on all but the
            last fragment.  The S bit (EAP-FAST Start) is set in an EAP-
            FAST Start message.







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      Ver

         This field contains the version of the protocol.  This document
         describes version 1 (001 in binary) of EAP-FAST.

      Message Length

         The Message Length field is four octets, and is present only if
         the L bit is set.  This field provides the total length of the
         message that may be fragmented over the data fields of multiple
         packets.

      Data

         In the case of a EAP-FAST Start request (i.e. when the S bit is
         set) the Data field consists of the A-ID described in
         Section 4.1.1.  In other cases when the Data field is present
         it consists of an encapsulated TLS packet in TLS record format.
         An EAP-FAST packet with Flags and Version fields but with zero
         length data field to used to indicate EAP-FAST acknowledgement
         for either a fragmented message, a TLS Alert message or a TLS
         Finished message.

4.1.1  Authority ID Data

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Type (0x04)          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ID
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


      Type

         0x04 for Authority ID

      Length

         The Length filed is two octets, which contains the length of
         the ID field in octets.

      ID

         Hint of the identity of the server.  It should be unique across
         the deployment.




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4.2  EAP-FAST TLV Format and Support

   The TLVs defined here are standard Type-Length-Value (TLV) objects.
   The TLV objects could be used to carry arbitrary parameters between
   EAP peer and EAP server within the protected TLS tunnel.

   The EAP peer may not necessarily implement all the TLVs supported by
   the EAP server.  To allow for interoperability, TLVs are designed to
   allow an EAP server to discover if a TLV is supported by the EAP
   peer, using the NAK TLV.  The mandatory bit in a TLV indicates
   whether support of the TLV is required.  If the peer or server does
   not support a TLV marked mandatory, then it MUST send a NAK TLV in
   the response, and all the other TLVs in the message MUST be ignored.
   If an EAP peer or server finds an unsupported TLV which is marked as
   optional, it can ignore the unsupported TLV.  It MUST NOT send an NAK
   TLV for a TLV that is not marked mandatory.

   Note that a peer or server may support a TLV with the mandatory bit
   set, but may not understand the contents.  The appropriate response
   to a supported TLV with content that is not understood is defined by
   the individual TLV specification.

   EAP implementations compliant with this specification MUST support
   TLV exchanges, as well as processing of mandatory/optional settings
   on the TLV.  Implementations conforming to this specification MUST
   support the following TLVs:

      Result TLV
      NAK TLV
      Error TLV
      EAP-Payload TLV
      Intermediate-Result TLV
      Crypto-Binding TLV
      Request-Action TLV

4.2.1  General TLV Format

   TLVs are defined as described below.  The fields are transmitted from
   left to right.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |M|R|            TLV Type       |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              Value...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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      M

         0  Optional TLV
         1  Mandatory TLV

      R

         Reserved, set to zero (0)

      TLV Type

         A 14-bit field, denoting the TLV type.  Allocated Types
         include:

         0  Reserved
         1  Reserved
         2  Reserved
         3  Result TLV
         4  NAK TLV
         5  Error TLV
         7  Vendor-Specific TLV
         9  EAP-Payload TLV
         10 Intermediate-Result TLV
         11 PAC TLV [I-D.cam-winget-eap-fast-provisioning]
         12 Crypto-Binding TLV
         18 Server-Trusted-Root TLV [I-D.cam-winget-eap-fast-
            provisioning]
         19 Request-Action TLV
         20 PKCS#7 TLV [I-D.cam-winget-eap-fast-provisioning]

      Length

         The length of the Value field in octets.

      Value

         The value of the TLV.

4.2.2  Result TLV

   The Result TLV provides support for acknowledged success and failure
   messages for protected termination within EAP-FAST.  If the Status
   field does not contain one of the known values, then the peer or EAP
   server MUST treat this as a fatal error of Unexpected_TLVs_Exchanged.
   The behavior of the Result TLV is further discussed in Section 3.3.2
   and Section 3.4.2.  An Result TLV indicating failure MUST NOT be
   accompanied by the following TLVs: NAK, EAP-Payload TLV, or Crypto-



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   Binding TLV.  Result TLV is defined as follows:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |M|R|         TLV Type          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Status            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


      M

         Mandatory, set to one (1)

      R

         Reserved, set to zero (0)

      TLV Type

         3 for Result TLV

      Length

         2

      Status

         The Status field is two octets.  Values include:

         1  Success
         2  Failure


4.2.3  NAK TLV

   The NAK TLV allows a peer to detect TLVs that are not supported by
   the other peer.  An EAP-FAST packet can contain 0 or more NAK TLVs.
   A NAK TLV should not be accompanied by other TLVs.  A NAK TLV MUST
   NOT be sent in response to a message containing a Result TLV, instead
   a Result TLV of failure should be sent indicating failure and an
   Error TLV of Unexpected_TLVs_Exchanged.  The NAK TLV is defined as
   follows:







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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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |M|R|         TLV Type          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Vendor-Id                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            NAK-Type           |           TLVs....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


      M

         Mandatory, set to one (1)

      R


         Reserved, set to zero (0)

      TLV Type

         4 for NAK TLV

      Length

         >=6

      Vendor-Id

         The Vendor-Id field is four octets, and contains the Vendor-Id
         of the TLV that was not supported.  The high-order octet is 0
         and the low-order 3 octets are the SMI Network Management
         Private Enterprise Code of the Vendor in network byte order.
         The Vendor-Id field MUST be zero for TLVs that are not Vendor-
         Specific TLVs.

      NAK-Type

         The NAK-Type field is two octets.  The field contains the Type
         of the TLV that was not supported.  A TLV of this Type MUST
         have been included in the previous packet.

      TLVs

         This field contains a list of TLVs, each of which MUST NOT have
         the mandatory bit set.  These optional TLVs are for future
         extensibility to communicate why the offending TLV was



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         determined to be unsupported.


4.2.4  Error TLV

   The Error TLV allows an EAP peer or server to indicate errors to the
   other party.  An EAP-FAST packet can contain 0 or more Error TLVs.
   The Error-Code field describes the type of error.  Error Codes 1-999
   represent successful outcomes (informative messages), 1000-1999