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RFC 68 - Comments on Memory Allocation Control Commands: CEASE, ALL, GVB, RET, and RFNM

  • Status: Unknown
  • Published: 31 August 1970
  • Stream: Legacy
  • Errata: No Errata

Document Information​

  • RFC Number: 68
  • Title: Comments on Memory Allocation Control Commands: CEASE, ALL, GVB, RET, and RFNM
  • Authors: M. Elie (UCLA)
  • Date: 31 August 1970
  • Category: Unknown

Abstract​

RFC 68 argues that the buffer allocation scheme of the protocol is more complicated than it needs to be, because it requires two parallel mechanisms of which only one appears necessary, and proposes to replace it by a slightly different conception of the Request for Next Message (RFNM). Since the RFNM is sent back from the receiving imp before the whole message has been accepted by the receiving host, nothing insures that the message has arrived intact, and a sending foreign host that has already been unblocked can congest the imp's memory. The note therefore suggests that the RFNM be initiated by the receiving host as an acknowledgment of correct reception (ACK), taking either of the two forms ACK (CONTINUE) or ACK (CEASE), with a third kind, NAK(REPEAT), sent by the NCP to ask for retransmission. This would permit error detection redundancy such as check sum bits to be added to the message, would turn the whole arrangement into a very simple end-to-end point-to-point transmission procedure, and could also replace the memory allocation mechanism, since ACK (CONTINUE) and ACK (CEASE) correspond to the WABT of classic transmission procedures. It closes by noting that the solution does not immobilize the imp memory any longer than the present one, because it is the sending host, and not the imp, that has to repeat a message.

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