Comments on Memory Allocation Control Commands: CEASE, ALL, GVB, RET, and RFNM
M. Elie · 1970
Comments on memory allocation control commands CEASE, ALL, GVB, RET) and RFNMThe protocol provides a scheme for buffer allocation.This scheme is rather complicated because it necessitates two parallel mechanisms.It is not obvious that both are necessary.In fact it is suggested that this scheme could be probably replaced by a slightly different conception of the Request for Next Message (RFNM).Now the RFNM is sent back from the receiving imp after the message has been reconstituted and the first packet transmitted to the host.Nothing insures that the whole message has been accepted and correctly received by the host; also the design of the host imp interface permits the host to stop accepting data from the imp during any length of time; as the link has been already unblocked by sending back the RFNM another message may be transmitted by the sending foreign host which will congest the imp's memory.On the other hand it is probable that usually the host is able to accept data from the imp at a higher rate than it is transmitted on the network, e.g.200k bits/sec; thus the time to transmit a full message from the imp to the host would be approximately 1/20th of a second which is 10 times less than the average delay of transmission of a message over the network.This indicates that to send a RFNM after the reception of a full message by the host would not increase significantly the response time on the network.