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

    <ERR> <Code> <Command length> <Command in error>

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

The ranges of <Code> 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 <Code> are shown below with their meaning.

    <Code> value   Semantics

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








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    <Code> value   Semantics

        13         Message received on blocked link.
       14-1F       Unused.
        20         Unknown command code.
        21         Message received on unconnected link.
        22         Invalid <RFC>.
        23         Invalid <CLS>.
        24         Invalid <RSM>, i.e., link not connected.
        25         Invalid <FND>.
        26         Invalid <END>.
        27         Invalid <RDY>.
        28         Invalid <ASG>, i.e., not connected.
       29-2F       Unused.
       30-FF       Unused.

QUERIES

    <QRY> <My Socket>
or   <RPY> <Your Socket> <Text>

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

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

<relevant connection table entries>::=
                                    <relevant connection table entries>
                                    <a relevant connection table entry>
                                    <a relevant connection table entry>

<a relevant connection table entry>::= <local socket> <foreign socket>
                                      <link> <connection state>
                                      <flow state and buffer control>
                                      <reconnection control state>















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HOST STATUS

    <NOP>

An NCP may be up, down, pending, etc.  When an NCP changes its
state to UP it should send a <NOP> 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 <NOP> 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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