Network host status
Checking which network hosts were working in February 1972
Westheimer, E., "Network host status", RFC 306, DOI 10.17487/RFC0306, February 1972, <https://www.rfc-editor.org/info/rfc306>.
@misc{rfc306,
series = {Request for Comments},
number = 306,
howpublished = {RFC 306},
publisher = {RFC Editor},
doi = {10.17487/RFC0306},
url = {https://www.rfc-editor.org/info/rfc306},
author = {E. Westheimer},
title = {{Network host status}},
pagetotal = 4,
year = 1972,
month = feb,
} RFC text
Contents
Network Working Group E. Westheimer
Request for Comments: 306 BBN
NIC: 9257 February 15, 1972
Obsoletes: None
NETWORK HOST STATUS
This RFC reports on the status of most Network Hosts from January 31
to February 11.
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 SITE COMPUTER
ADDRESS
133 BBN PDP-10 (B)
13 Case PDP-10
15 Ames/(Paoli) ILLIAC/(B6500)
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 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 SITE COMPUTER
ADDRESS
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 SITE COMPUTER STATUS OR PREDICTIONS"
ADDRESS 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
*7 RAND IBM-360/65 User only Eric Harslem
71 RAND PDP-10 Server Eric Harslem
*8 SDC IBM-370/155 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 Winnet
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 March Charles Rose
14 CARNEGIE 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 SITE DATE AND TIME (EASTERN)
NO. 1/31 2/1 2/2 2/3 2/4 2/7 2/8 2/9 2/10 2/11
1430 1530 1430 1630 1530 1830 1500 1730 1000 1230
1 UCLA-NMC H O O O O O O O O #D
65 UCLA-CCN O O O O D O O O D #D
2 SRI-ARC O O D O O O O T H O
66 SRI-AI D D D D D D D D D D
3 UCSB-MOD75 O O H O H D O O O O
4 UTAH-10 D O T O D D D O D D
69 BBN-TENEX T O O O O D O O O O
6 MIT-Multics O O D O O D R D O O
MIT-DMCG H D D D D D H D O O
71 RAND-CSG T T T D D D D D T T
8 SDC-ADEPT #D #D #D #D #D D #D D #D #D
9 HARVARD O O O O #D #T O O D #D
10 L.L.-67 T H H D H D H H H H
74 L.L.-TX-2 D D D T T #D O #D D #T
11 SU-AI D D D D D D D D D D
14 CMU-10 D H H H H D D D D H
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.)
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 = Time 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 10/99]
AI ELI5
On this page
§1Introduction
RFC 306 reports on host status for the ARPANET from January 31 to February 11, 1972. The network at this time consisted of a small number of university and research computers connected through Interface Message Processors (IMPs). BBN, a key network contractor, conducted daily testing to determine whether each host was accessible.
The report excludes certain hosts from daily testing: hosts not expected to function as network servers within two weeks (such as prototype systems and machines under development), and hosts that were user-only machines or Terminal IMPs reserved for gathering network statistics.
The ARPANET was just a few years old, and only a handful of computer centers were connected. BBN kept checking which ones were working each day so people would know where they could send their jobs.
§2Host Categories
The status tables exclude machines falling into two categories. The first category includes hosts not expected to serve the network regularly for at least two weeks, such as research prototype systems. The second category includes hosts intended to be users only: Terminal IMPs present in the network (at AMES, MITRE, NBS, and BBN), the Network Control Center (address 5) used for statistics gathering, and machines at RAND, Harvard, Illinois, and NBS configured as user-only systems.
Hosts like UCLA, SRI, UCSB, UTAH, MIT, Stanford, SDC, and others were the operational servers on the network during this period.
Some computers were set up just to receive data from the network (user-only), while others were ready to let other sites use them (servers). The report focused on the server machines.
§3Status Codes
The daily testing used five status codes to report each host's condition:
- O (Open): The host opened a connection and was accessible to users.
- D (Dead): The host was either dead or inaccessible from the BBN Terminal IMP, possibly due to network partitioning or local IMP failure.
- H (Half Open): The host opened a connection but then immediately closed it or did not respond further.
- R (Refused): The host returned a CLS to the initial RFC (connection establishment request).
- T (Time out): The host did not complete connection establishment (ICP) and open within 60 seconds.
O meant the computer was ready. D meant it was broken or unreachable. H meant it started to listen but then went quiet. R meant it said no. T meant it was too slow to answer.