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- NWG/RFC# 752 MRC 2-Jan-79 01:22 nnnnn
- A Universal Host Table
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- Network Working Group Mark Crispin
- Request for Comments 752 SU-AI
- NIC nnnnn 2 January 1979
-
- A Universal Host Table
-
- ABSTRACT:
-
- The network host table in use at MIT and Stanford is described.
- This host table is superior to the NIC and Tenex host tables in several
- ways. A binary file, compiled from this host table, is also described.
- This file is used by subsystems on MIT's ITS and Stanford's WAITS
- timesharing systems for efficiency in host and network lookups.
-
-
- HISTORY:
-
- As with many other sites on the Arpanet, we found the NIC's host
- table unsuited to our needs. Part of the problem was because the NIC
- host table was often inaccurate and all too often failed to include
- several nicknames in common usage in our communities. In addition, the
- NIC host table's format was awkward for user programs to use, especially
- those which wanted to have the host table mapped into memory in some
- sort of structured binary form for efficient lookups. Finally, the NIC
- host table neglects to include some essential information.
-
- The ITS host table was originally designed to be compiled along
- with a network handling program (MIDAS, the PDP-10 assembler used, has a
- pseudo-op to insert a file into an assembly). In order to make the host
- table palatable to the assembler, every comment line began with a
- semicolon, and every actual data line began with the word HOST. Each
- program which used the host table defined HOST as an assembly macro
- before inserting the host table into the assembly.
-
- This worked well for a long while, but as the network grew, hosts
- changed their status more frequently and more network programs required
- reassembly when the host table was updated. If the appropriate person
- for a particular subsystem was not around, it could be a while before
- that subsystem updated its host table.
-
- In the spring of 1977, design started on a binary file which would
- be placed on a system directory and which all subsystems which wanted to
- access host table information would read in. The format was carefully
- designed to be general enough to satisfy the needs of all the diverse
- subsystems. All of these subsystems required modification to use the
- new format but these modifications turned out to be trivial compared to
- the benefits from not having to recompile every subsystem.
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- Later the host table and binary file were imported to the WAITS
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- Mark Crispin [page 1]