Questions on RFC 2317

[Brian {Hamilton Kelly}]

On 28 Sep, in article <37f0f692.73333098 at news.swbell.net>
     chrisl at tourneyland.com "Chris" wrote:

> I just read RFC 2317, in the hopes that it would explain how to do
> what I want. However, I didn't reallt understand it. For starters, I
> can't decipher this . . .
> 
>         
> " Let us assume we have assigned the address spaces to three different
> parties as follows:
> 
>            192.0.2.0/25   to organization A
>            192.0.2.128/26 to organization B
>            192.0.2.192/26 to organization C"
> 
> Sounds silly, but what do those slashes mean? They seem crucial to the
> whole RFC, but they have me lost.

They denote how many bits (from the more significant end) are counted as
denoting the *network*, leaving 32-<that number> bits for differentiating
between individual hosts.

So the first would cover all hosts in the range 192.0.2.0 to 192.0.2.127;
the second 192.0.2.128 to 192.0.2.191, and the last the rest to
192.0.2.255.

The old concept of Class A, B and C addresses has been defunct many years
(albeit that Microsoft, in their infinite wisdom, still expect fledgling
sysadmins to know all about them in order to "gain" the accolade of MCSE)
and the nomenclature upon which you've remarked has replaced it.

-- 
Brian {Hamilton Kelly}                                         bhk at dsl.co.uk
    "But we're a university.  We /have/ to have a library!..."said Ridcully,
         "What sort of people would we be if we didn't go into the library?"
    "Students", said the Senior Wrangler, morosely. [TP: The Last Continent]