rfc54.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

   A NOP command is included for convenience.  It is coded as zero to
   facilitate command message construction.

   Finally, an ERR command is included for notifying a foreign host it
   has (apparently) made an error.  At present, no specific list of
   errors is defined, and no action is defined for the receipt of ERR
   commands.  Hosts should log ERR commands upon receipt so that system
   programmers can diagnose the trouble.  A host may generate an ERR
   command at any time and for any reason, but it is advised that each
   host publish an exhaustive list of the ERR commands it may sent and
   their interpretations.

NETWORK CONTROL COMMANDS

   The following is a detailed description of the structure and format
   of each of the control commands.


   To facilitate and clarify socket descriptions, the following
   conventions have been adopted:

   <my socket> and <your socket> are used in the command descriptions.




Crocker, Postel, Newkirk & Kraley                              [Page 5]

RFC 54              An Official Protocol Proffering        18 June 1970


   <my socket> is local to the originator of the command.

   <your socket> is local to the receiver of the command.

CONTROL COMMAND FORMATS


   No Operation
                      _______
                     |       |
                     |  NOP  |
                     |_______|

   Request Connection, Receiver to Sender
                      ______________________________________________
                     |       |             |               |        |
                     |  RTS  |  my socket  |  your socket  |  link  |
                     |_______|_____________|_______________|________|

   Request Connection, Sender to Receiver
                      _____________________________________
                     |       |             |               |
                     |  STR  |  my socket  |  your socket  |
                     |_______|_____________|_______________|

   Close
                      _____________________________________
                     |       |             |               |
                     |  CLS  |  my socket  |  your socket  |
                     |_______|_____________|_______________|

   Allocate
                      __________________________
                     |       |        |         |
                     |  ALL  |  link  |  space  |
                     |_______|________|_________|

   Interrupt Sent by Receiving Process
                      _______________
                     |      |        |
                     | INR  |  link  |
                     |______|________|









Crocker, Postel, Newkirk & Kraley                              [Page 6]

RFC 54              An Official Protocol Proffering        18 June 1970


   Interrupt Sent by Sending Process
                     _______________
                    |      |        |
                    | INS  |  link  |
                    |______|________|

   Echo Request
                     ____________________________   _________
                    |       |                    \  \        |
                    |  ECO  |  length            /  /  text  |
                    |_______|____________________\  \________|

   Echo Reply
                     ____________________________   _________
                    |       |                    \  \        |
                    |  ERP  |  length            /  /  text  |
                    |_______|____________________\  \________|

   Error Detected
                     ____________________________   _________
                    |       |                    \  \        |
                    |  ERR  |  length            /  /  text  |
                    |_______|____________________\  \________|




   The host is specified in the leader.

   <link> is 8 bits

   <space> is 32 bits long and is an unsigned integer.

   <length> is an unsigned 16 bit integer.

   <text> is as long as the length.  The command is therefore 24 bits
   longer that the length.  Maximum length is one message, to facilitate
   command decoding and manipulation.


   All control command codes are 8 bit long:

             NOP = 0
             RTS = 1
             STR = 2
             CLS = 3
             ALL = 4
             INR = 5



Crocker, Postel, Newkirk & Kraley                              [Page 7]

RFC 54              An Official Protocol Proffering        18 June 1970


             INS = 6
             ECO = 7
             ERP = 8
             ERR = 9

   <my socket> and <your socket> are 32 bits long,
                     _______________________
                    |               |       |
                    |  User number  |  AEN  |
                    |_______________|_______|

   24 bits for user number and 8 bits for AEN.

III.  Conclusion

   Extensions to the Protocol

   Some issues have not been adequately treated in the current protocol.
   We have in mind the following topics to consider more thoroughly and
   perhaps experiment with.

   1. More Sophisticated Flow Control.

   As mentioned above, other schemes for flow control are still being
   considered.  Other than the necessity of providing some form of it,
   we are completely unsure of the nature of the problem.  It may turn
   out that the present scheme is completely adequate; it may also turn
   out that we will need a much more complex scheme.

   2. Error Detection and Recovery

   As we gain some experience with the network, we will develop a better
   understanding of what errors can occur and, perhaps more importantly,
   what to do about these errors.  We expect the protocol to change as
   we understand error control.

   3. Start Up and Shut Down Procedures

   We have not done enough thinking about the problem of the host which
   participates part-time in the network, which ceases normal network
   operation but remains on the network for special purposes, or which
   recovers from a system failure.  These issues are critical to robust
   network operation and are possibly our highest priority.  4. Query
   and Response

   A host-to-host status test would be a valuable tool, but it is not
   yet clear what is appropriate to provide.




Crocker, Postel, Newkirk & Kraley                              [Page 8]

RFC 54              An Official Protocol Proffering        18 June 1970


Coming onto the Network

   We suggest that hosts come onto the network gingerly.  First, each
   host should thoroughly exercise connections to itself.  Then it
   should arrange experiments with some other host who is already
   functioning.  Finally, it may begin to exercise the facilities of
   other hosts.  It is not clear at this time which host will be in the
   best position to help other hosts first, but UCLA will attempt to
   serve this function.

Private Networking

   A common ploy is to use the IMP to connect several local computers,
   one or more of which is not available to the whole network.  For
   example, Harvard is connecting its PDP-1 to its PDP-10 via an IMP;
   Lincoln Laboratories is connecting its TSP to the 360/67 and the TX2
   via an IMP; and UCLA is similarly connecting a XDS 920 to its Sigma-
   7.  In each of these cases, the small machine will not initially
   provide services to the network.

   Although there should be no unwanted traffic to any of these extra
   hosts, it is desirable that they conform minimally to the network
   protocol.  Provided that they never initiate a connection or send out
   spurious control commands, it is sufficient for a host to respond to
   CLS commands with acknowledging CLS commands, and to respond to ECO
   commands with ERP commands.

Acknowledgments

   The work presented above is only a small portion of the concurrent
   effort.  Most of the related effort will be reported in immediately
   forthcoming RFC's.  A number of people provided extremely valuable
   aid during the last two weeks.  We are particularly grateful to
   Professor George Mealy of Harvard for supporting four of his students
   to come westward to work on the network, to Robert Uzgalis for
   facilitating access to CCN at UCLA, and to the secretarial staff of
   the Computer Science Division of the University of Utah, and
   especially Peggy Tueller and Marcella Sanchez, for excellent help in
   preparing these documents.


       [ This RFC was put into machine readable form for entry ]
      [ into the online RFC archives by Eitetsu Baumgardner 3/97 ]









Crocker, Postel, Newkirk & Kraley                              [Page 9]