RFC 308

ARPANET host availability data

📅 published March 1972, from ietf

RFC 308: ARPANET HOST AVAILABILITY DATA 💖

Network Working Group                   Marc Seriff
Request for Comments 308                MIT-DMCG
NIC 9259                                13 MARCH 1972
References: RFC 254

Okay so this one is by Marc Seriff from MIT-DMCG, it's RFC 308 (also NIC 9259), dated 13 March 1972, and it references RFC 254. 🎀 Heads up, it's an info-drop about a SURVEY service, so it's not a standard, and no obsoletes or updates are listed. ✨

Why this RFC exists 🦋

Okay so a few months before this, a SURVEY program got set up on the MIT-DMCG ITS PDP-10 system to help collect info on how available different ARPANET HOSTS are. 🧚 This RFC has three goals, bestie:

  1. Tell the Network Working Group the info-gathering service exists and how to get access to it,
  2. Share the SURVEY results from its first few months, and
  3. Fix any mistakes in our data or how we collected it. 🔥

How SURVEY works 💅

So basically, whenever the MIT-DMCG ITS Time-Sharing system is in normal operation, a SURVEY kicks off every 15 minutes. ⭐ It tries to connect to the LOGGER (socket 1) of every HOST on its table, and every result gets recorded for later. The Initial Connection Protocol gets aborted before the transmitted socket number is read, so SURVEYed HOSTS do the least possible work. 🫶 If the LOGGER connection works, the HOST's average request-for connection response time (in seconds) gets updated. You can look at this info later in a bunch of formats through the MIT-DMCG server TELNET "NETWRK," which I'll explain below. 🌸

The five statuses 🌈

Every test ends with one of these five statuses, no cap:

  1. LOGGER available - connection completed. ✨
  2. LOGGER not responding - RFC sent (HOST-HOST OK), but no response (20 seconds allowed). 😭
  3. LOGGER rejecting - CLOSE returned by NCP. 💀
  4. NCP not responding - RESET timed out (15 seconds allowed). 🙈
  5. HOST dead - host-dead status returned by IMP. 🥀

The big caveat 💜

Heads up bestie, SURVEY can only run when MIT-DMCG ITS Time-Sharing System is in normal operation and the MIT IMP is operational. So the current 94% figure for MIT-DMCG is inaccurate. 😬 It should actually be closer to 66%.

There are two more shortcomings we know about, periodt. 💅 First, SURVEY runs on a 24-hour basis and does not consider advertised up time. For example, MIT-DMCG will never be better than 67% on a Tuesday, since the machine is always unavailable from 4 p.m. to midnight. 🍓 Second, the Lincoln Lab's TX-2 shows as "never available." That's an as-yet undiagnosed problem that's being looked into right now. 🔍

Getting the data from DMCG 🎀

To get availability info from DMCG, you first have to follow the scenario in RFC 254. Once you're in NETWRK (the DMCG user-TELNET), there are seven commands that work with SURVEY data. Main character energy, literally. 👑

  • SUMMARY.OF.SURVEYS: summarizes the most recent info.
  • HISTORY.OF <host name>: gives a detailed recent history of the given host. This makes a LOT of output, so use it sparingly. 🙈
  • ACTIVE.HOSTS: lists the hosts that accepted a connection at least once in the last 24 hours.
  • BEST.SURVEY: lists the best of the recent surveys.
  • LONGTERM SUMMARY.OF.SURVEYS: summarizes all past info. This is what made the table further down. 📊
  • LONGTERM HISTORY.OF <host name>: gives a summary of the past history of the given host. It doesn't make as much output as the HISTORY command. ✨
  • LONGTERM ACTIVE.HOSTS: lists the hosts that accepted a connection at least once since December 13, 1971. 🧚

For all seven of these commands, "recent" means "within the last 24 hours or less." ⏰

Help and contact info 🫶

If you need help getting SURVEY data, or you have thoughts on making the admittedly limited SURVEY service better, reach out to:

     Marc Seriff
     M.I.T. - Project MAC
     545 Main Street
     Cambridge, Mass. 02139
     (617) 864-6900 ext. 1458

The data 📊

6528 Surveys from 09:55:18 on 12/13/71 to 08:50:41 on 03/20/72
--HOST-- -#- -%-UP- -RESP- *
ucla-nmc 001  064%   00.93
sri-arc  002  064%   02.96
ucsb-75  003  048%   00.53
utah-10  004  057%   03.23
bbn-ncc  005  000%   00.00
multics  006  047%   05.60
rand-rcc 007  000%   00.13
sdcadept 010  000%   02.60
harv-10  011  022%   00.23
ll-67    012  021%   03.70
su-sail  013  000%   00.00
ill-11   014  000%   00.06
case-10  015  000%   00.00
cmu-10   016  034%   00.23
burr     017  000%   00.00
ames-67  020  000%   00.00
radc-645 022  000%   00.00 **
nbs-11   023  000%   00.00 **
tink-418 025  000%   00.00 **
usc-44   027  000%   01.13 **
ncar7600 031  000%   00.00 **
ucla-ccn 101  070%   00.30
sri-ai   102  000%   02.26
tenex    105  060%   02.40
mit-dmcg 106  093%   01.10 ***
rand-csg 107  013%   02.96 **
harv-1   111  000%   00.23
ll-tx2   112  000%   01.76
ill-6500 114  000%   00.00
burrtest 117  000%   00.00 **
tenexb   205  018%   02.93
mit-ai   206  000%   00.00
harv-11  211  000%   00.00

* Remember that "UP is defined as "Logger Accepting connections."
** Surveyed only since February 18, 1972.
*** MIT-DMCG is actually up about 66% of the time.

Machine-readable note 🤖

       [ 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   ]
📦 where this page comes from