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RFC 213 UNKNOWN INFRASTRUCTURE · ARPANET

IMP System change notification

An announcement of IMP system version 2505 with expanded capacity and improved monitoring

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PUBLISHED
August 1971
AUTHORS
B. Cosell
STREAM
Legacy
IMP VERSION
2505
HOST LIMIT
Increased from 3 to 4
NEW STATUS LIGHT
Light 8 for Host 4
TIMING UNIT CHANGE
100 to 800 microseconds
DOI
10.17487/RFC0213

RFC text

Original text · RFC Editor View on rfc-editor.org ↗ 
Network Working Group                              B. Cosell
Request for Comments:  #213                        BBN
NIC #7194                                          20 August 1971
Categories:  B.1
Updates:  None
Obsoletes:  None



                     IMP System Change Notification
                     ------------------------------


     During the week of 16 August, we installed a new version of
the IMP system, version 2505.  The new version incorporated three
principal changes:

     1)  The number of hosts the system can handle was increased
         from three to four. Although this caused a rather large
         internal change to the IMP, the only external effects of
         the change are the presence of a new status light [light
         8 monitors Host 4], and the lengthening of the 10-second
         and snapshot statistics.

     2)  The host handling routines were modified to gather more
         accurate and voluminous statistics on host usage of the
         network, and report them to NCC.

     3)  The 10-sec. statistics were changed to measure time for
         the host "round trip" statistic in units of 800 rather
         than 100 microseconds.

          It is not anticipated that the new system should have any
     direct effect on the hosts.





          [ 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
PROBLEMThe ARPANET's IMP switching system had limitations in how many hosts one IMP could serve, and the Network Control Center (NCC) needed better visibility into host usage patterns.
MECHANISMBBN deployed IMP system version 2505, which increased the number of hosts an IMP can handle from three to four, improved host statistics collection, and adjusted timing measurement units for more precise reporting.
WHAT CHANGEDThe system expansion was transparent to hosts. The only external changes were one new status light and longer statistics reports that would now track a fourth host and measure round-trip time in more precise units.

§1The Update

During the week of 16 August 1971, BBN installed a new version of the IMP system, version 2505. This update incorporated three principal changes to improve network capacity and monitoring.

The primary change was expanding the number of hosts the system could handle from three to four. Although this required significant internal changes to the IMP's host-handling routines, the only external effects were the presence of a new status light (light 8 monitors Host 4) and the lengthening of the 10-second and snapshot statistics reports.

An upgrade added room for one more computer to connect, with only a new indicator light to show the change on the outside.

§2Improved Statistics

The host-handling routines were enhanced to gather more accurate and voluminous statistics on host usage of the network and report them to the Network Control Center. This gave the NCC better insight into how hosts were using network resources.

Additionally, the 10-second statistics were changed to measure the host "round trip" statistic in units of 800 microseconds rather than 100 microseconds. This change provided more precise timing measurements while consuming less space in the statistics reports.

The system now keeps better track of what each computer is doing and measures time more precisely.

§3Impact on Hosts

BBN anticipated that the new system should have no direct effect on the hosts themselves. The expansion and improvements were internal to the IMP infrastructure and should be transparent to host software and users. Hosts would continue to operate normally with the same interface and behavior.

Everything works the same from the host's point of view. The changes are all behind the scenes.