RFC 730 20 May 77 Extensible Field Addressing Network Working Group Jon Postel Request for Comments: 730 USC-ISI NIC: 40400 20 May 1977
Host Name Host IMP old # new # -------------------------------------- SRI-ARC 0 2 2 2 UCLA-CCN 1 1 65 65537 ISIA 1 22 86 65558 ARPA-TIP 2 28 156 131100 BBNA 3 5 197 196613
At ISI, we have the capability of emulating computers using the PRIM system [7]. For many applications it is desirable to add the emulated host to the network. Since the emulation is carried out under control of a program operating under Tenex, we have a host within a host. Extensible addressing of hosts would provide the necessary handle.
SCRL once had a PDP-11 connected by VDH to an IMP at UCSB. It became necessary to add a second PDP-11 to the network. The two PDP-11s were already physically connected and it would have been a simple matter to have the first serve as a multiplexor for both. However, because of the limitations in the network addressing structure, there was no way to identify the two hosts to other sites on the network. A new IMP had to be installed!
In many other cases, it is desirable to have two hosts share the same front end to the network. With the current limitation, one IMP port must be consumed for each host.
Definitions:
<address> ::= <field-name> ":" <fields> <field-name> ::= "NET" | "IMP" | "HOST" | "MESSAGE-ID" <fields> ::= <field> | <field> "/" <fields> <field> ::= a decimal number
Examples:
NET:1/3/5/7 names message-id 7 at host 5 on imp 3 in network 1.
HOST:6 names host 6 on whatever imp this message originates on.