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IMP System change notifications (RFC0271)

IP.com Disclosure Number: IPCOM000003304D
Original Publication Date: 1972-Jan-03
Included in the Prior Art Database: 2000-Sep-13
Document File: 2 page(s) / 4K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

B. Cosell: AUTHOR

Abstract

We are planning to install a new version of the IMP System, version 2514. The new version is scheduled for field installation Thursday, January 13, 1972 between noon and 1 PM EST, and will require the assistance of IMP-site personnel at each site.

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 70% of the total text.

Network Working Group Bernard Cosell

RFC # 271 BBN

NIC 7819 3 January 1972

Categories: B.1

Updates: None

Obsoletes: None

IMP System Change Notification

------------------------------

We are planning to install a new version of the IMP System,

version 2514. The new version is scheduled for field installation

Thursday, January 13, 1972 between noon and 1 PM EST, and will require

the assistance of IMP-site personnel at each site.

There were two principal problems with version 2513, both related

to the delay inserted between the time when a Host comes up and the

time when its IMP will accept the second packet from the Host. The

first was that the delay was lengthened to slightly over 40 seconds,

which caused hardware difficulties for some Hosts. The second was

that there was an ambiguity that could make the delay run as long as a

minute and a quarter. On the first point, the delay has been backed

off from 40 seconds to 30 seconds, as it was for IMP systems prior to

2513. On the second point, the ambiguity has been entirely removed.

(Note, however, that BBN Report No. 1822, on page 23, specifies that

the delay may range from 30 to 90 seconds, and that future versions

may require a longer delay.)

In summary, a Host may come alive in one of two ways, corres-

ponding to the two ways in which the Host can go down. If the Host

went down voluntarily (by sending a "Host going down" to the IMP), the

Host indicates his intention to come alive by sending the IMP

something. If the Host went down involuntarily (by dropping his ready

line), the Host indicates his intention to come alive by bringing his

ready line back up. In either case

the IMP will refuse to accept more than one packet from the Host for

30 seconds after the Host has indicated his intention to come alive.

Notice, however, that the Host must be prepared to accept all messages

from the Network from the instant that he indicates his intention to

come alive.* This particular point seems to have given many Hosts

difficulty in running through their standard initialization

procedures. Don't forget this simple and universal rule, that when

you are telling your IMP that you are alive, you must be prepared to

always take every- thing from the Network whether or not the Network

is taking any- thing from you.

Version 2514 will also incorporate a few other changes, mainly

related to the operation of the NCC. Since the Timeout is, for a

change, being made shorter, and the other modifications are minor,

there should be no appreciable ...