Hosts using the IMP Going Down message
Asking hosts to warn users when the local IMP is going down.
Walden, D.C., "Hosts using the IMP Going Down message", RFC 548, DOI 10.17487/RFC0548, August 1973, <https://www.rfc-editor.org/info/rfc548>.
@misc{rfc548,
series = {Request for Comments},
number = 548,
howpublished = {RFC 548},
publisher = {RFC Editor},
doi = {10.17487/RFC0548},
url = {https://www.rfc-editor.org/info/rfc548},
author = {D.C. Walden},
title = {{Hosts using the IMP Going Down message}},
pagetotal = 1,
year = 1973,
month = aug,
} RFC text
Network Working Group D. Walden
RFC # 548 BBN-NET
NIC # 17794 August 16, 1973
Hosts Using the IMP Going Down Message
As given in BBN Report 1822 (Specifications for the Interconnection
of a Host and an IMP), IMP to Host message type 2 specifies that the IMP
local to the Host is going down; the message further says when the IMP
is going down, for how long, and why.
When the IMP goes down after sending the IMP Going Down message to
the Host, the Host's network users and local users of the network will
not, in general, be forewarned unless the Host sends a message to these
users. We therefore urge all Hosts to warn their network users and
users of the network of impending IMP downs; just logging the received
IMP Going Down message on a logging teletype, as many Hosts currently
do, seems insufficient.
Incidentally, please remember that Tuesday mornings from 7 a.m. to 9
a.m. (Eastern Time) are reserved for Network Software Maintenance, as
announced in RFC #440.
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On this page
§1The Problem
BBN Report 1822, which specifies how hosts connect to IMPs, defines IMP-to-Host message type 2 as the IMP Going Down message. This message tells the Host that the local IMP is going down, specifies when it will go down, for how long, and why. However, many Hosts receiving this message were only logging it to a teletype rather than actively notifying their users. This meant that network users would be unprepared when their connectivity suddenly disappeared without warning.
The network hardware warns your computer before it shuts down for maintenance, but your computer wasn't telling the people using it about this planned outage.
§2What Should Happen
RFC 548 urges all Hosts to actively warn their network users (both users logging in remotely and local users of network services) when an IMP Going Down message is received. Rather than merely logging the information passively, Hosts should display the message to their users, giving them time to finish work, disconnect gracefully, or make other arrangements. The RFC notes that planned network maintenance occurs every Tuesday morning from 7 a.m. to 9 a.m. Eastern Time, as had been announced in RFC 440.
Hosts should show a message to all their users saying the network is about to go down, so people know to save their work.
§3Why This Matters
When an IMP Going Down message is received but users are not notified, network connectivity will be lost without warning. This can lead to lost work, interrupted computations, and user frustration. By warning users in advance, Host administrators give them time to save their work, gracefully close network connections, and prepare for the outage. This simple practice of communication improves the user experience during scheduled maintenance windows.
If you do not tell people the network will go down, they might lose their work. A simple warning gives them time to save and prepare.