Network Host Status
Checking which network hosts were working in late April and early May 1972
Westheimer, E., "Network Host Status", RFC 342, DOI 10.17487/RFC0342, May 1972, <https://www.rfc-editor.org/info/rfc342>.
@misc{rfc342,
series = {Request for Comments},
number = 342,
howpublished = {RFC 342},
publisher = {RFC Editor},
doi = {10.17487/RFC0342},
url = {https://www.rfc-editor.org/info/rfc342},
author = {E. Westheimer},
title = {{Network Host Status}},
pagetotal = 4,
year = 1972,
month = may,
} RFC text
Network Working Group Ellen Westheimer
NIC #10421 BBN
RFC #342 15 May 1972
Categories: F. G.3
Updates: RFC #332
Obsoletes: None
NETWORK HOST STATUS
This RFC reports on the status of most Network Hosts from April
24 to May 5. During this interval the IBM 360/44 at the University
of Southern California (Network Address 23) 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
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.
SITE
NO. SITE DATE AND TIME (EASTERN)
---- ---- -----------------------
4/24 4/25 4/26 4/27 4/28 5/1 5/2 5/3 5/4 5/5
1700 1600 1300 1430 1700 1300 1300 1700 1430 1430
1 UCLA-NMC O O D O O O O O O O
65 UCLA-CCN* O O D O O D O O O O
2 SRI-ARC O O O O O O T D O O
66 SRI-AI D D D D D O D D D D
3 UCSB-MOD75 O H O O O O O O O O
4 UTAH -10 O D O D T T O T T O
69 BBN-TENEX O O T T O O O O O O
133 BBN-TENEXB #D #D #D #D #D #D #D #D #D T
6 MIT-MULTICS R D O O O O D O D O
70 MIT-DMCG O O F F O F O O O F
71 RAND-CSG O O O T O #O! D O O O
8 SDC-ADEPT D #D #D #D D #D D #D D #D
9 HARVARD-10 O O O O O O O O #D D
10 L.L.-360 D D D H H D D H D D
74 L.L-TX-2 O T #D O O O O #D O O
11 STANFORD-AI D D D D D D D T D D
14 CMU-10 O O D O D D D D O O
15 AMES-ILLIAC T D T T D T T T D 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.
!Rand opened a connection but requested users to logout immediately.
"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 June)
2 SRI(NIC) PDP-10 Server Jim White
66 SRI(AI) PDP-10 Server Len Chaiten
3 UCSB IBM-360/75 Server Ron Stoughton
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-370/65 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 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
*23 USC IBM-360/44 User Now James Pepin
*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.
[ 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
§1Introduction
RFC 342 reports on host status from April 24 to May 5, 1972. During this interval, the IBM 360/44 at USC (Network Address 23) became a new network user, expanding the operational ARPANET. BBN conducted daily tests from the Terminal IMP to determine each host's accessibility and responsiveness.
BBN kept checking which big computers connected to the ARPANET were working. More computers were joining the network during this time.
§2Host Categories and Status Codes
Like previous reports, hosts were divided into two categories for testing: non-server hosts (such as MIT-AI and Case, expected to join later) and user-only hosts including Terminal IMPs and machines at Rand, Harvard, Illinois, NBS, and USC. The 1972 network also introduced a new status code: F (Full), indicating a host opened a connection but reported all network ports in use.
The full set of codes used were: O (Open), D (Dead), H (Half Open), T (Timed out), R (Refused), and F (Full). The testing revealed varying reliability across the network, with some machines like SRI-AI remaining consistently dead throughout the period.
Some computers only received data (user-only), while others let other sites use them. The new F code meant a computer was so busy it wouldn't accept more connections. Different computers had different reliability.
§3Network Growth
The status tables across this period show a maturing network. Major servers like UCLA, SRI, UCSB, UTAH, MIT-Multics, RAND CSG, SDC, Harvard, and Carnegie were becoming more consistently available. The addition of USC and the expected addition of MIT-AI and Stanford (which had not yet become servers) showed the network expanding to new institutions.
Performance issues persisted: AMES-67 remained dead throughout, and other hosts showed intermittent problems. Despite these issues, the network was stabilizing into a core of reliable servers that researchers could depend on.
More places were joining and sharing computers. Some computers were very reliable, but some were always down or often had problems. The network was growing and getting better over time.