IMP/TIP preventive maintenance schedule
A 1974 table of the monthly maintenance windows for every ARPANET IMP and TIP.
McKenzie, A.M., "IMP/TIP preventive maintenance schedule", RFC 638, DOI 10.17487/RFC0638, April 1974, <https://www.rfc-editor.org/info/rfc638>.
@misc{rfc638,
series = {Request for Comments},
number = 638,
howpublished = {RFC 638},
publisher = {RFC Editor},
doi = {10.17487/RFC0638},
url = {https://www.rfc-editor.org/info/rfc638},
author = {A.M. McKenzie},
title = {{IMP/TIP preventive maintenance schedule}},
pagetotal = 4,
year = 1974,
month = apr,
} RFC text
Network Working Group Alex A. McKenzie
Request for Comments: 638 BBN-NET
NIC: 30538 April 25, 1974
IMP/TIP Preventive Maintenance Schedule
This RFC corrects numerous inaccuracies in RFC #633. Rather than
trying to list all the changes, I urge all Liaisons and other
interested parties to look carefully at the times now listed for
the sites they are interested in.
This note presents the current IMP/TIP Preventive Maintenance
schedule. Preventive Maintenance is scheduled on a monthly basis and
a given machine is normally scheduled at the same time each month;
wherever possible the time is chosen to coincide with the PM time for
the Host(s) at the site.
It is sometimes necessary to reschedule PM's because of network
connectivity considerations or for other reasons. Whenever this is
necessary we will follow the usual procedure for scheduling down time
with our "primary contact" at the site. Permanent changes to the
schedule will he announced via the RFC mechanism.
PM's normally do not require the IMP/TIP to be taken down. However,
machines must be taken down in some cases, so no one should rely on
the machine remaining available through the PM period.
PLEASE REMEMBER THAT TUESDAY MORNINGS FROM 7am TO 9am ARE RESERVED
FOR NETWORK SOFTWARE MAINTENANCE.
All times shown below are Eastern Time.
First Monday (of each month)
5 BBN IMP [0830-1130]
40 NCC TIP [1130-1430]
47 WRIGHT-PATTERSON [1300-1700]
First Tuesday
30 BBN TIP [0830-1130]
3 UCSB [1130-1430]
First Wednesday
14 CARNEGIE [0830-1130]
2 SRI [1200-1500]
First Thursday
26 SDAC [0830-1130]
4 UTAH [1030-1330]
41 NORSAR [0830-1130]
42 LONDON [0830-1130]
Second Monday
6 MIT-MAC [0830-1130]
44 MIT-IPC [1200-1500]
25 DOCB [1030-1330]
Second Tuesday
17 MITRE [0830-1130]
23 USC [1130-1430]
Second Wednesday
31 CCA [0830-1130]
11 STANFORD [1200-1500]
32 XEROX [1400-1700]
18 RADC [0900-1200]
Second Thursday
27 BELVOIR [0830-1130]
35 UCSD [1130-1430]
37 RML [0930-1230]
Second Friday
43 TYMSHARE [1200-1500]
Third Monday
9 HARVARD [0830-1130]
1 UCLA [1000-1300]
48 KIRTLAND [1600-1900]
Third Tuesday
7 RAND [1130-1430]
8 SDC [1530-1830]
Third Wednesday
12 ILLINOIS [0930-1230]
28 ARPA [1700-2000]
15 AMES IMP [1200-1500]
16 AMES TIP [1300-1600]
36 HAWAII [1430-1730]
45 MOFFETT [1400-1700]
Third Thursday
20 ETAC [0830-1130]
33 FNWC [1300-1600]
Third Friday
21 LLL [1230-1530]
Fourth Monday
13 CASE [0830-1130]
Fourth Tuesday
19 NBS [0830-1130]
Fourth Wednesday
10 LINCOLN [0830-1130]
46 RUTGERS [1000-1400]
Fourth Thursday
24 GWC [1500-1800]
22 ISI [1300-1600]
29 ABERDEEN [1300-1600]
[ 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. 2/2000 ]
AI ELI5
On this page
§1Purpose and Corrections
This RFC corrects numerous inaccuracies in RFC 633. The author does not list the changes and instead urges all liaisons and other interested parties to check the times listed for their sites.
The old timetable had many mistakes, so everyone should check their own entry.
§2How Preventive Maintenance Works
Preventive Maintenance (PM) is scheduled monthly, and a given machine is normally serviced at the same time each month. Where possible the time matches the PM time of the hosts at the site.
Sometimes a PM must be rescheduled, for network connectivity or other reasons. BBN then follows the usual procedure for scheduling down time with its primary contact at the site. Permanent changes are announced through the RFC mechanism.
PMs normally do not require the machine to be taken down, but sometimes they must be, so no one should rely on the machine being available during the PM period. Tuesday mornings from 7am to 9am are reserved for network software maintenance.
Each box gets a monthly checkup at the same time. Most of the time it keeps working, but sometimes it has to be switched off, so do not count on it.
§3The Schedule
All times are Eastern Time. Each entry has the IMP or TIP number, the site name and a time window, grouped by the weekday and week of the month. For example, on the first Monday of each month the BBN IMP (number 5) is serviced from 0830 to 1130, the NCC TIP (40) from 1130 to 1430 and WRIGHT-PATTERSON (47) from 1300 to 1700.
The list continues through the fourth week. On the first Tuesday the BBN TIP (30) is scheduled from 0830 to 1130 and UCSB (3) from 1130 to 1430, and the last entries are the fourth Thursday windows for GWC, ISI and ABERDEEN.
Every site has its own slot, like a class timetable: a day of the week, which week of the month and a time of day.