Network Host Status
A snapshot of which ARPANET computers were working in mid-February 1972.
Westheimer, E., "Network Host Status", RFC 315, DOI 10.17487/RFC0315, March 1972, <https://www.rfc-editor.org/info/rfc315>.
@misc{rfc315,
series = {Request for Comments},
number = 315,
howpublished = {RFC 315},
publisher = {RFC Editor},
doi = {10.17487/RFC0315},
url = {https://www.rfc-editor.org/info/rfc315},
author = {E. Westheimer},
title = {{Network Host Status}},
pagetotal = 4,
year = 1972,
month = mar,
} RFC text
Network Working Group Ellen Westheimer
Request for Comments: 315 BBN
NIC: 9345 March 8, 1972
Updates: 306
NETWORK HOST STATUS
This RFC reports on the status of most Network Hosts from February 14
to February 25. On February 21 Massachusetts celebrated Washington's
Birthday. During these two weeks the MIT Artificial Intelligence
(MIT-AI) PDP-10, Network address 134, became a Network User.
Several Hosts are currently excluded from the daily testing. These
Hosts fall into two categories:
1) Hosts which are not expected to be functioning on the Network
as servers (available for use from other sites) on a regular basis
for at least two weeks. Included here are:
Network
Address Site Computer
------- ---- --------
134 MIT-AI PDP-10
13 Case PDP-10
15 Ames/(Paoli) ILLIAC/(B6500)
2) Hosts which are currently intended to be users only. Included
here are the Terminal IMP's which are presently in the Network
(AMES, MITRE, NBS and BBN*). This category also includes the
Network Control Center computer (Network Address 5) which is used
solely for gathering statistics from the Network. Finally,
included among these Hosts are the following:
Network
Address Site Computer
------- ---- --------
7 Rand IBM-360/65
73 Harvard PDP-1
12 Illinois PDP-11
19 NBS PDP-11
The tables on the next two pages summarize the Host status for this
period.
_____
*The BBN Terminal IMP (Network Address 158) is a prototype and as
such is frequently not connected to the Network, but being used to
refine and debug the Terminal IMP programs.
"STATUS OR
SITE PREDICTIONS"
ADDRESS SITE COMPUTER STATUS OR PREDICTION OBTAINED FROM
------- ---- -------- -------------------- --------------
1 UCLA SIGMA-7 Server #Limited Jon Postel
65 UCLA IBM-360/91 NETRJS now Bob Braden
(Telnet in April)
2 SRI(NIC) PDP-10 Server John Melvin
66 SRI(AI) PDP-10 "Soon" Len Chaiten
3 UCSB IBM-360/75 Server Jim White
4 UTAH PDP-10 Server Barry Wessler
*5 BBN(NCC) DDP-516 Never Alex McKenzie
69 BBN(TENEX-A) PDP-10 Server Dan Murphy
*133 BBN(TENEX-B) PDP-10 Server(Exper.) Dan Murphy
6 MIT(Multics) H-645 Server Mike Padlipsky
70 MIT(DM) PDP-10 Server Bob Bressler
*134 MIT(AI) PDP-10 User Now Jeff Rubin
*7 RAND IBM-360/65 User only Eric Harslem
71 RAND PDP-10 Server Eric Harslem
*8 SDC IBM-370/15 Server Bob Long
9 HARVARD PDP-10 Server Bob Sundberg
*73 HARVARD PDP-1 User Only Bob Sundberg
10 LINCOLN IBM-360/67 "Soon" Joel Winett
74 LINCOLN TX-2 Server Will Kantrowitz
11 STANFORD PDP-10 "Soon" Andy Moorer
*12 ILLINOIS PDP-11 User Only John Cravits
*13 CASE PDP-10 June Charles Rose
14 CANERGIE PDP-10 "Soon" Hal VanZoeren
*15 AMES/(PAOLI) ILLIAC September John McConnell
(B6500)
16 AMES IBM-360/67 "Soon" Wayne Hathaway
*144 AMES TIP User Only
*145 MITRE TIP User Only
*19 NBS PDP-11 User Only Robert Rosenthal
*147 NBS TIP User Only
*158 BBN TIP User Only
(Prototype)
_____
*Host not included in daily testing.
#The NMC is a research site and would like to have prior arrangement
with each user.
SITE
NO. SITE DATE AND TIME (EASTERN)
---- ---- -----------------------
2/14 2/15 2/16 2/17 2/18 2/22 2/23 2/24 2/25
1830 1030 1730 1600 1200 1030 1500 1100 1500
1 UCLA-NMC O O O O 0 O D #D O
65 UCLA-CCN O D O O D D O O O
2 SRI-ARC O O O O D O O O O
66 SRI-AI D D D D D D D D D
3 UCSB-MOD75 D #D O O O #D O O O
4 UTAH-10 O D O O O D O O O
69 BBN-TENEX O O O O T T O O O
133 BBN-TENEXB #D #D #D #D #D #D #D #D #D
6 MIT-Multic O O T T O D D D D
70 MIT-DMCG O O O D T O H O D
71 RAND-CSG T T O T O H D O O
8 SDC-ADEPT #D #D H #D #D #D #D #D #D
9 HARVARD-10 #D D #D O O D #D #D #D
10 L.L.-67 H D H H H H H H H
74 L.L.-TX-2 #T O #D O O O #D O O
11 SU-AI D D D D D D D D D
14 CMU-10 D D H D H H H D D
16 AMES-67 D D D D D D D D D
where
D = Dead (Destination Host either dead or inaccessible [due to
network partitioning or local IMP failure] from the BBN Terminal
IMP.)
H = 1/2 Open (Destination Host opened a connection but then either
immediately closed it, or did not respond any further.)
O = Open (Destination Host opened a connection and was accessible to
users.)
R = Refused (Destination Host returned a CLS to the initial RFC.)
T = Timed out (Destination Host did not complete the ICP and open a
connection within 60 seconds.)
_____
*The only service currently offered by the UCLA IBM-360/91 is a
Network Job Service (NETRJS), however, the BBN Terminal IMP is not
equipped to test NETRJS. We are assuming that initial connection to
the NETRJS logger indicates that NETRJS is also functioning.
#These sites advertise that they may not have their system available
at these times.
[This RFC was put into machine readable form for entry]
[into the online RFC archives by H�l�ne Morin, Viag�nie, 12/99]
AI ELI5
On this page
§1Introduction
This RFC reports on the status of the ARPANET's host computers during the two weeks of February 14 to 25, 1972. During this period, MIT's Artificial Intelligence laboratory at address 134 joined the network as a new user.
The report explains which computers were tested daily and which ones were excluded from testing because they were not yet network servers or were not expected to respond.
This report is like a checklist of computers on the early network, saying which ones are ready to help and which ones are being worked on.
§2Excluded Hosts
Some hosts were not included in daily testing. The first category included machines expected to be unavailable: MIT-AI (address 134), Case (13), and AMES/Paoli (15). The second category included hosts that were users only, not servers: Terminal IMPs at several sites and the Network Control Center computer (address 5) that gathered statistics.
This distinction mattered for operations: the network did not expect to use these machines to host services for other sites.
Some machines were like students getting library cards instead of working at the library desk. They were just using the network, not offering a service to others.
§3Test Results
For two weeks, BBN's Terminal IMP tested connectivity to each host multiple times per day. The results used status codes: O (Open: connected and accessible), D (Dead: unreachable), T (Timed out: no response in 60 seconds), H (1/2 Open: connected but then closed immediately).
The report shows that reliability varied widely. Some hosts like UCLA-NMC and MIT-Multics were mostly open, while others like AMES and Stanford-AI were down nearly every day.
The test used simple letters to show each computer's condition: O meant it was awake and listening, D meant it was off or broken, and H meant it answered but then hung up.
§4Status Today
This RFC was replaced by RFC 319, which continued the weekly network status reporting. Network host status reports became a regular publication throughout the ARPANET era.
This report was only for two weeks. After that, someone else kept writing similar reports to help network users know which computers were working.