Current flow-control scheme for IMPSYS
A note directing readers to formal sources on IMPSYS flow control.
Walden, D.C., "Current flow-control scheme for IMPSYS", RFC 449, DOI 10.17487/RFC0449, January 1973, <https://www.rfc-editor.org/info/rfc449>.
@misc{rfc449,
series = {Request for Comments},
number = 449,
howpublished = {RFC 449},
publisher = {RFC Editor},
doi = {10.17487/RFC0449},
url = {https://www.rfc-editor.org/info/rfc449},
author = {D.C. Walden},
title = {{Current flow-control scheme for IMPSYS}},
pagetotal = 1,
year = 1973,
month = jan,
} RFC text
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. [ This RFC was put into machine readable form for entry ] [ into the online RFC archives by Alex McKenzie with ] [ support from GTE, formerly BBN Corp. 9/99 ]
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§1Comment on RFC 442
Dave Walden says the notes on IMPSYS flow control in RFC 442 seem reasonably accurate and cite a BBN quarterly technical report. He says BBN's two formal publications would have been better references.
The unit metadata says RFC 449 updates RFC 442.
The author considers the earlier notes reasonably accurate. He adds two formal sources that readers should consult.
§3Inter-IMP Acknowledgements
The inter-IMP acknowledgement mechanism discussed in the last section of RFC 442 is also described in the first publication. An almost identical mechanism appears in Appendix F of BBN Report 1822.
Walden says most Hosts need only understand the mechanism intellectually because it is transparent to network users, while the Report 1822 description is important to Very Distant Hosts.
Most Hosts do not expose the acknowledgement mechanism to users. The RFC says the details matter to Very Distant Hosts.