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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Walden [Page 1]