Movatterモバイル変換

Network Working Group                                          B. CosellRequest for Comments: 209                        Bolt Beranek and NewmanNIC: 7187                                                 13 August 1971HOST/IMP Interface Documentation   On 25 June 1971 we put a new version of the IMP system, Version 2500,   up in the network.  Among other changes, the new system corrected the   problem of Hosts receiving spurious "Destination Dead" [Type 7]   messages.  The correction involved making the IMP refuse to accept   any messages from its Host for about 30 seconds after the Host   indicated its intention to come alive.  This delay has caused trouble   to a number of NCPs because they had imposed an upper limit on the   time an IMP may take to accept a message, and when that time was   exceeded the IMP was declared inoperative and the NCP shut itself   down, leaving the site personnel annoyed and perplexed.   We're sorry to have caused so much trouble, but we thought that the   new version modified no advertised property of the system.  To   prevent misunderstandings of this type in the future, the IMP/Host   interface should be well documented, well understood and invariant.   The only way to set up and maintain such an interface is to presume   that BBN Report No. 1822 is complete and correct.  We understand that   it is neither, but operating on the basis of this assumption is the   best way to force 1822 to improve.  In our view, the Hosts should   proceed under the constraint that anything not specifically   guaranteed by 1822 does not exist and should not be used.  If there   are problems using this approach, please don't "code around" the   problem or treat your IMP as a "black box" and extrapolate its   characteristics from a series of experiments.  Instead, send your   comments and problems to the NCC at BBN, and we will fix the IMP   system, or 1822, whichever is necessary.   We are, at the moment, working n an update to 1822.  It will reflect   the deletion of the "cease" mechanism [as per RFC #107].   We are also considering augmenting the IMP/Host protocol with a   mechanism to allow a Host to detect a change in the "version" of the   IMP system, and to provide the Hosts with status information as to   who is alive in the net.         [ This RFC was put into machine readable form for entry ]             [ into the online RFC archives by Ryan Kato 6/01]Cosell                                                          [Page 1]