[ih] The history of "This" 0.0.0.0/8 network?

[Michael Kjörling]

On 12 Feb 2019 09:42 -0700, from internet-history at gtaylor.tnetconsulting.net (Grant Taylor):
>   - To me, "0.0.0.0" represents and as such implies IPv4.  So "early 
> IPv4 transition days" sounds like the transition /to/ IPv4.  Yet 0.0.0.0 
> is an IPv4 address to me.  So what are we transitioning from and to?

NCP. https://en.wikipedia.org/wiki/Network_Control_Program

The final transition from NCP to TCP/IP was in January 1983. RFC 801
may be of interest.


> Admittedly I'm not familiar with the addressing that was used on ARPAnet 
> prior to IPv4.  But I suspect that it's addressing did not take the form 
> of 0.0.0.0.

I wasn't around at the time, but the January 1970 RFC 33 says on page
6 that NCP addressing was 24 bits of "user number" plus 8 bits of
"host number" plus 8 bits of "another eight-bit number", 7 of which
seem like they function largely as what we today refer to as "ports";
one end of a connection was therefore identified by a total of 48
bits, 8 of which describe the host. I don't see anything obvious
actually specifying a format for how these addresses would be entered
by or displayed to a user, only hints that hexadecimal notation may
have been common.

This format allowed up to 2^8 hosts on the network, each with 2^24
users, each with 2^7 simultaneous active bidirectional connections.

Note that "port" in NCP seems to have been a very different concept
from "port" in TCP. My understanding is that NCP "ports" refer more to
the physical links than to a logical property of a data connection.

-- 
Michael Kjörling • https://michael.kjorling.se • michael at kjorling.se
  “The most dangerous thought that you can have as a creative person
              is to think you know what you’re doing.” (Bret Victor)