Response to RFC 597: Host status
Two questions about link counts and regional loops on an ARPANET map.
Burchfiel, J.D., "Response to RFC 597: Host status", RFC 603, DOI 10.17487/RFC0603, December 1973, <https://www.rfc-editor.org/info/rfc603>.
@misc{rfc603,
series = {Request for Comments},
number = 603,
howpublished = {RFC 603},
publisher = {RFC Editor},
doi = {10.17487/RFC0603},
url = {https://www.rfc-editor.org/info/rfc603},
author = {J.D. Burchfiel},
title = {{Response to RFC 597: Host status}},
pagetotal = 1,
year = 1973,
month = dec,
} RFC text
Network Working Group J.D. Burchfiel
RFC # 603 BBN-TENEX
NIC # 21022 31 December, 1973
Response to RFC # 597: Host Status
I have several questions about the November 1973 ARPANET
topographical map:
1. AMES is 4-connected, i.e. four network connections will go down
if the IMP fails. Is there some aspiration that IMPs should be
no more than three connected?
2. The seven IMPS in the Washington area are arranged into a loop.
This guarantees that local communication can take place even if
one connection fails, and is probably a worthwhile preparation
for area routing. On the other hand, for example, a break
between MIT-IPC and MIT-MAC will require them to communicate
through a 12-hop path through Washington. This can be remedied
by a short (inexpensive) connection between Harvard and Lincoln
Labs. Is there a plan to pull the Boston area, the San
Francisco area, and the Los Angeles area into loops like the
Washington area?
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ISO Plain Language
On this page
§1The Map Under Discussion
J. D. Burchfiel says he has several questions about the November 1973 ARPANET topographical map. RFC 603 is a short response to the host-status map in RFC 597.
The memo presents two questions about network connections. It does not define a protocol or establish rules for network design.
The author looked at an ARPANET map and raised two questions about how its connections were arranged. The memo does not prescribe a design.
§1How Many Connections Should an IMP Have?
The first question concerns AMES, described as four-connected. If its IMP fails, four network connections will go down. The author asks whether there is an aim for IMPs to have no more than three connections.
The author asks whether an IMP should have a limit on how many connections it serves. The example is AMES, where an IMP failure affects four connections.
§2Loops Between Network Areas
The seven IMPs in the Washington area are arranged in a loop. The author notes that local communication can continue if one connection fails, and says this may help prepare for area routing.
He contrasts this with a break between MIT-IPC and MIT-MAC, which he says would require a 12-hop route through Washington. He suggests a short connection between Harvard and Lincoln Labs and asks whether Boston, San Francisco and Los Angeles might also be arranged in loops.
The author asks whether more regions should have loops like Washington's. He notes that another connection could avoid a long route through Washington after a break.