Network Host Status
ARPANET host availability report for April 1972
Westheimer, E., "Network Host Status", RFC 332, DOI 10.17487/RFC0332, April 1972, <https://www.rfc-editor.org/info/rfc332>.
@misc{rfc332,
series = {Request for Comments},
number = 332,
howpublished = {RFC 332},
publisher = {RFC Editor},
doi = {10.17487/RFC0332},
url = {https://www.rfc-editor.org/info/rfc332},
author = {E. Westheimer},
title = {{Network Host Status}},
pagetotal = 4,
year = 1972,
month = apr,
} RFC text
Network Working Group Ellen Westheimer
NIC #9925 BBN
RFC #332 25 April 1972
Categories: F, G.3
Updates: RFC #330
Obsoletes: None
NETWORK HOST STATUS
This RFC reports on the status of most Network Hosts from April
10 to April 21. During this interval the IBM 360/44 at the University
of Southern California (Network Address 23) was connected to the
Network; also, a Terminal IMP was installed in Omaha, Nebraska at
Global Weather Central (Network Address 152) on April 18.
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
2) Hosts which are currently intended to be users only. Included here
are the Terminal IMPs, which are presently in the Network (AMES,
MITRE, NBS, ETAC, USC, GWC, 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
23 USC IBM-360/44
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 Server 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(TENEXA) PDP-10 Server Dan Murphy
133 BBN(TENEXB) 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-360/155 Server Bob Long
9 HARVARD PDP-10 Server Bob Sundberg
*73 HARVARD PDP-1 Server 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 CARNEGIE PDP-10 "Soon" Hal VanZoeren
*15 AMES ILLIAC Server 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
*148 ETAC TIP User Only
USC IBM-360/44 "Soon"
*151 USC TIP User Only
*152 GWC 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)
---- ---- -----------------------
4/10 4/11 4/12 4/13 4/14 4/17 4/18 4/19 4/20 4/21
1400 1700 1630 1400 1630 1330 1400 1630 1700 1300
1 UCLA-NMC O O T O O D O O T O
65 UCLA-CCN O O O O O D O O D D
2 SRI-ARC H D D D D O D O O D
66 SRI-AI O D D D O O O D O D
3 UCSB-MOD75 O O O O O O O O O O
4 UTAH-10 O O T D O O D D O O
69 BBN-TENEX O O O D O O D T O O
133 BBN-TENEXB #D #D #D #D #D #D #D #D #D #D
6 MIT-MULTICS D O O O O O R O O D
70 MIT-DMCG F O O F O T F O O F
71 RAND-CSG O D O T O O O H D O
8 SDC-ADEPT #D D H #D #D #D #D #D D #D
9 HARVARD-10 O O O O O D O O D T
10 L.L.-360 H H H H T D D H D D
74 L.L.-TX-2 O O #D O O O O O O O
11 STANFORD-AI D D D D D D D D D D
14 CMU-10 D H O D D D O D O O
15 AMES-ILLIAC O T T T T D T T T T
16 AMES-67 D 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.)
F = Full (Destination Host opened a connection, informed user that all
Network ports were in use, and immediately closed the connection.)
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 BBN Corp. under the ]
[ direction of Alex McKenzie. 12/96 ]
AI ELI5
On this page
§1Host Status Reporting
RFC 332 reports the network host status for April 10-21, 1972, covering most ARPANET hosts during this period. This was part of regular monitoring by the Network Control Center at BBN to track which hosts were available and functioning.
The report covers a time when the USC IBM 360/44 was newly connected to the network (April 10) and a Terminal IMP was installed at Global Weather Central in Omaha (April 18).
Each day, someone called each computer and noted whether it answered. This report shows the results for two weeks.
§2Host Categories
Hosts fell into different categories: regular servers (always expected to be available), hosts not yet expected to function as servers, and user-only hosts (including Terminal IMPs at AMES, MITRE, NBS, ETAC, USC, and GWC). User-only hosts could not serve requests from other sites; they could only send requests themselves.
The Network Control Center computer itself was marked user-only because it was used solely for gathering network statistics.
Some computers were like restaurants, waiting to serve other people. Others were like customers, just asking for service. The report said which was which.
§3Status Codes
The report used status codes to describe each host's behavior during a daily test:
O(Open): Host opened a connection and was accessible to users.D(Dead): Host was dead or inaccessible from the test point.T(Half Open): Host opened a connection but then closed it immediately or did not respond further.H(Half Open variant): Alternative notation for half-open states.F(Full): Host opened a connection but reported all ports were in use.R(Refused): Host sent a CLS (close) in response to the test.
O meant the computer answered and worked. D meant it did not pick up. T and H meant it started to answer but then hung up. F meant all its lines were busy. R meant it said no thanks.
§4Publication and Use
These status reports were published regularly by Ellen Westheimer at BBN. Network users would consult them to find available hosts and to understand why they could not reach a particular site. The reports also helped network operators spot recurring problems and plan maintenance.
The reports let users plan their work: if one computer was broken, they could use a different one.