> On Oct 5, 2017, at 4:14 PM, William Herrin <[email protected]> wrote:
>
> On Thu, Oct 5, 2017 at 1:32 PM, Jerry Cloe <[email protected]> wrote:
>
>> Several years ago I remember seeing a mathematical justification for it,
>> and I remember thinking at the time it made a lot of sense, but now I can't
>> find it.
>>
>
> Hi Jerry,
>
> If there's special ASIC-friendly math here, beyond what was later
> generalized with CIDR, it's not obvious.
>
> 10.0: 0000 1010 0000 0000
>
> 172.16: 1010 1100 0001 0000
>
> 172.31: 1010 1100 0001 1111
>
> 192.168: 1100 0000 1010 1000
>
> AFAIK, it was simply one range each from classes A, B and C.
As mentioned in one of the links posted earlier, 10.0.0.0/8 was the original
ARPANET class A assignment. (See RFC 970, which brings back a lot of
memories.) Once the ARPANET was shut down in 1990 that block was no longer
used, so it became available for reuse in RFC1918.
I have a vague recollection of parts of 192.168.0.0/16 being used as default
addresses on early Sun systems. If that's actually true, it might explain that
choice.
Steve
