RFC449

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Network Working Group Dave Walden RFC # 449 BBN-NET NIC # 14133 Jan. 6, 1973 Updates RFC 442


          The Current Flow-control Scheme for IMPSYS.


While Vint's notes on IMPSYS flow-control from the March 16, 1972,

meeting (RFC 442) seem reasonably accurate and while he does cite our Quarterly Technical Report #13, he might have done better to cite BBN's two formal publications relevant to the IMPSYS flow-control scheme:

1.  McQuillan et al, Improvements in the Design and Performance of
    the ARPA Network, Proceedings AFIPS 1972 FJCC, pp. 741-754.
2.  BBN Report 1822, Specifications for the Interconnection of a
    Host and an IMP, December 1972 Revision, section 3, pp. 17-35.

Reference 2 is particularly important reading for NCP programmers - things have recently changed somewhat.

The inter-IMP acknowledgement mechanism, described in the last

section of Vint's RFC 442, is also described in reference 1 and an almost identical mechanism is described in Appendix F of reference 2. The acknowledgement is of only intellectual interest to most Hosts as it is transparent to network users. However, the description in reference 2 is of vital interest to so-called Very Distant Hosts.






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