rfc1006.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

                         Session protocol     [ISO8327]       [X.225]


      The ISO transport service definition describes the services
      offered by the TS-provider (transport service) and the interfaces
      used to access those services.  This memo focuses on how the ARPA
      Transmission Control Protocol (TCP) [RFC793] can be used to offer
      the services and provide the interfaces.


      +-----------+                                       +-----------+
      |  TS-user  |                                       |  TS-user  |
      +-----------+                                       +-----------+
           |                                                     |
           | TSAP interface                       TSAP interface |
           |  [ISO8072]                                          |
           |                                                     |
      +----------+   ISO Transport Services on the TCP     +----------+
      |  client  |-----------------------------------------|  server  |
      +----------+              (this memo)                +----------+
           |                                                     |
           | TCP interface                         TCP interface |
           |  [RFC793]                                           |
           |                                                     |


      For expository purposes, the following abbreviations are used:

         TS-peer      a process which implements the protocol described
                      by this memo

         TS-user      a process talking using the services of a TS-peer







M. Rose & D. Cass                                               [Page 6]

RFC 1006                                                        May 1987


         TS-provider  the black-box entity implementing the protocol
                      described by this memo


      For the purposes of this memo, which describes version 2 of the
      TSAP protocol, all aspects of [ISO8072] are supported with one
      exception:

          Quality of Service parameters


      In the spirit of CCITT, this is left "for further study".  A
      future version of the protocol will most likely support the QOS
      parameters for TP by mapping these onto various TCP parameters.

      The ISO standards do not specify the format of a session port
      (termed a TSAP ID).  This memo mandates the use of the GOSIP
      specification [GOSIP86] for the interpretation of this field.
      (Please refer to Section 5.2, entitled "UPPER LAYERS ADDRESSING".)

      Finally, the ISO TSAP is fundamentally symmetric in behavior.
      There is no underlying client/server model.  Instead of a server
      listening on a well-known port, when a connection is established,
      the TS-provider generates an INDICATION event which, presumably
      the TS-user catches and acts upon.  Although this might be
      implemented by having a server "listen" by hanging on the
      INDICATION event, from the perspective of the ISO TSAP, all TS-
      users just sit around in the IDLE state until they either generate
      a REQUEST or accept an INDICATION.

























M. Rose & D. Cass                                               [Page 7]

RFC 1006                                                        May 1987


4.  The Primitives


      The protocol assumes that the TCP[RFC793] offers the following
      service primitives:

                                    Events

         connected       - open succeeded (either ACTIVE or PASSIVE)

         connect fails   - ACTIVE open failed

         data ready      - data can be read from the connection

         errored         - the connection has errored and is now closed

         closed          - an orderly disconnection has started

                                     Actions

         listen on port  - PASSIVE open on the given port

         open port       - ACTIVE open to the given port

         read data       - data is read from the connection

         send data       - data is sent on the connection

         close           - the connection is closed (pending data is
                           sent)


This memo describes how to use these services to emulate the following
service primitives, which are required by [ISO8073]:

                                 Events

         N-CONNECT.INDICATION
                          - An NS-user (responder) is notified that
                            connection establishment is in progress


         N-CONNECT.CONFIRMATION
                          - An NS-user (responder) is notified that
                            the connection has been established

         N-DATA.INDICATION
                          - An NS-user is notified that data can be
                            read from the connection





M. Rose & D. Cass                                               [Page 8]

RFC 1006                                                        May 1987


         N-DISCONNECT.INDICATION
                          - An NS-user is notified that the connection
                            is closed

                                Actions

         N-CONNECT.REQUEST
                          - An NS-user (initiator) indicates that it
                            wants to establish a connection

         N-CONNECT.RESPONSE
                          - An NS-user (responder) indicates that it
                            will honor the request

         N-DATA.REQUEST   - An NS-user sends data

         N-DISCONNECT.REQUEST
                          - An NS-user indicates that the connection
                            is to be closed

      The protocol offers the following service primitives, as defined
      in [ISO8072], to the TS-user:

                                    Events

         T-CONNECT.INDICATION
                          - a TS-user (responder) is notified that
                            connection establishment is in progress

         T-CONNECT.CONFIRMATION
                          - a TS-user (initiator) is notified that the
                            connection has been established

         T-DATA.INDICATION
                          - a TS-user is notified that data can be read
                            from the connection

         T-EXPEDITED DATA.INDICATION
                          - a TS-user is notified that "expedited" data
                            can be read from the connection

         T-DISCONNECT.INDICATION
                          - a TS-user is notified that the connection
                            is closed










M. Rose & D. Cass                                               [Page 9]

RFC 1006                                                        May 1987


                                Actions

         T-CONNECT.REQUEST
                          - a TS-user (initiator) indicates that it
                            wants to establish a connection

         T-CONNECT.RESPONSE
                          - a TS-user (responder) indicates that it
                            will honor the request

         T-DATA.REQUEST   - a TS-user sends data

         T-EXPEDITED DATA.REQUEST
                          - a TS-user sends "expedited" data

         T-DISCONNECT.REQUEST
                          - a TS-user indicates that the connection
                            is to be closed




































M. Rose & D. Cass                                              [Page 10]

RFC 1006                                                        May 1987


5.  The Protocol


      The protocol specified by this memo is identical to the protocol
      for ISO transport class 0, with the following exceptions:

            - for testing purposes, initial data may be exchanged
              during connection establishment

            - for testing purposes, an expedited data service is
              supported

            - for performance reasons, a much larger TSDU size is
              supported

            - the network service used by the protocol is provided
              by the TCP


      The ISO transport protocol exchanges information between peers in
      discrete units of information called transport protocol data units
      (TPDUs).  The protocol defined in this memo encapsulates these
      TPDUs in discrete units called TPKTs.  The structure of these
      TPKTs and their relationship to TPDUs are discussed in the next
      section.

      PRIMITIVES

         The mapping between the TCP service primitives and the service
         primitives expected by transport class 0 are quite straight-
         forward:

                   network service              TCP
                   ---------------              ---
                   CONNECTION ESTABLISHMENT

                       N-CONNECT.REQUEST        open completes

                       N-CONNECT.INDICATION     listen (PASSIVE open)
                                                finishes

                       N-CONNECT.RESPONSE       listen completes

                       N-CONNECT.CONFIRMATION   open (ACTIVE open)
                                                finishes

                   DATA TRANSFER

                       N-DATA.REQUEST           send data

                       N-DATA.INDICATION        data ready followed by



M. Rose & D. Cass                                              [Page 11]

RFC 1006                                                        May 1987


                                                read data

                   CONNECTION RELEASE

                       N-DISCONNECT.REQUEST     close

                       N-DISCONNECT.INDICATION  connection closes or
                                                errors

          Mapping parameters is also straight-forward:

                     network service             TCP
                     ---------------             ---
                     CONNECTION RELEASE

                         Called address          server's IP address
                                                 (4 octets)

                         Calling address         client's IP address
                                                 (4 octets)

                         all others              ignored

                      DATA TRANSFER

                         NS-user data (NSDU)     data

                      CONNECTION RELEASE

                         all parameters          ignored



      CONNECTION ESTABLISHMENT

          The elements of procedure used during connection establishment