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Network Working Group Request for Comments: 39

E. Harslem J. Heafner RAND 25 March 1970

COMMENTS ON PROTOCOL RE: NWG/RFC #36 We offer the following suggestions to be considered as additions to the April 28th 1970 protocol grammar specifications. ERROR MESSAGES It is desirable to include debugging aids in the initial protocol for checking out Network Control Programs, etc. There are three classes of errors--content errors, status errors, and resource allocation or exhaustion. specifies the class and the offending member of the class. The command is returned to the sending NCP for identification and analysis. Examples of status errors are: messages sent over blocked links and attempts to unblock an unblocked link. Examples of content errors are: an invalid RFC complete; a message sent on a link not connected; closing of an unconnected link; and an attempt to unblock an unconnected link. Examples of resource errors are: a request for a non-existent program and connection table over- flow, etc. Resource errors should be followed by a in response to the . QUERIES <>



Queries provide an extension to the facility as well as limited error recovery, thus avoiding re-initialization of an NCP. The first command requests the remote NCP connections to the user specified by the The second is the reply; contains information. If an NCP wants the status remote HOST, the is zero. to supply the status of all user number in . the connection status of all connections to a

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RFC 39

COMMENTS ON PROTOCOL RE: NWG/RFC #36

March 1970

PROGRAM TERMINATION NOTIFICATION This command supplements rather than communication between a program and which it is connected. This command handled by multiple commands. user number. HOST STATUS These messages (HOST coming up and HOST voluntarily going down) are compatible with asynchronous, interrupt-driven programs, as opposed to the more conventional post/poll method. TRANSMIT AND BROADCAST Unlike the previous commands, these are not sent over the control link, but rather over links assigned to user programs. The prefix of or indicates, to the receiving NCP, the disposition of the message body. indicates a message to be passed to a single process. specifies to the destination NCP that the message is to be distributed over all receiving connections linked to the sender. In response to a system call by the user to an NCP requesting , the NCP generates one to each HOST to which the sender is connected. RFC AND DYNAMIC RECONNECTION This protocol is complex; it queues (to become associated artificially imposed via the discounts the situation where knowledge that slave process reconnection. The , April 28th course, not April 28th, studied the proliferates control messages; it causes with re-entrant procedures) that are protocol (remote AEN assignment); and only controlling process "A" has "B" should be "rung out" in a dynamic replaces . It those programs in a performs what would contains severs all given HOST to otherwise be the sender's

etc., are suggestions for inclusion protocol specifications. The above intended to affect modification of nor to reflect on those who planned problem. It is meant, however, to

as additions in the criticism is, of the RFC structure by it. We have not voice our concern

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RFC 39

COMMENTS ON PROTOCOL RE: NWG/RFC #36

March 1970

about complexity and resulting response times. This is a difficult problem and it deserves more study after we have exercised the current RFC specifications. We hope to offer constructive suggestions with respect to the RFC in the future.

JFH:hs

[ This RFC was put into machine readable form for entry ] [ into the online RFC archives by Mario Vitale 08/99 ]

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