Network Working Group                                         E. Harslem
Request for Comments: 40                                      J. Heafner
                                                                    RAND
                                                              March 1970

               More Comments on the Forthcoming Protocol

We have recently discussed NWG/RFC Nos. 36 and 39 with Steve Crocker,
UCLA.  Steve has asked that we elaborate on the errors, queries, and
HOST status that were mentioned in NWG/RFC #39.

Please voice your opinions soon in order to affect the forthcoming
protocol specifications.

ERROR MESSAGES

        

 is an eight-bit field that specifies the error type.  The
assigned codes are shown below.   is a 16-bit integer
that indicates the length of the  in bits.  The
 is the spurious command.

The ranges of  are shown below in hexidecimal.

     00     Unspecified error types
     10-0F  Resource errors
     10-1F  Status errors
     20-2F  Content errors
     30-3F  Unused

Specific values of  are shown below with their meaning.

      value   Semantics

         00         Unspecified errors.
         01         Request for an invalid resource.
         02         Request for an exhausted resource, try later.
        03-0F       Unused.
         10         Invalid , i.e., link connected but unblocked.
         11         Invalid .
         12         Invalid , i.e., connected but no 
                      received.








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      value   Semantics

         13         Message received on blocked link.
        14-1F       Unused.
         20         Unknown command code.
         21         Message received on unconnected link.
         22         Invalid .
         23         Invalid .
         24         Invalid , i.e., link not connected.
         25         Invalid .
         26         Invalid .
         27         Invalid .
         28         Invalid , i.e., not connected.
        29-2F       Unused.
        30-FF       Unused.

QUERIES

      
or     

The  is the query indicated in NWG/RFC #39 and  is the reply.
The format of  is shown below; also refer to NWG/RFC #36, p. 3.

::= <16 bit count of relevant connection table entries>
          

::=
                                     
                                     
                                     

::=  
                                        
                                       
                                       















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HOST STATUS

     

An NCP may be up, down, pending, etc.  When an NCP changes its
state to UP it should send a  to each remote NCP which
indicates the NCP is available.  The sending NCP can then
construct a vector of HOST status from the RFNMs it receives.  An
NCP receiving a  can update the availability of the sending
NCP in its HOST status vector.



       [ This RFC was put into machine readable form for entry ]
         [ into the online RFC archives by Richard Ames 6/97 ]




































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