ISP customer assignments

Tue Oct 13 18:54:36 UTC 2009

> I'm ok with teaching it to beginners to explain where we came from but that
> should be it.

But why does that have to be done first? Why can't they teach current best
practice in addressing, and then point out that historically it was
done different
but that caused problems which led to today's system?

>  That said I still occasionally refer to networks in classful terms
> and I can think of several network engineers who have years of enterprise
> experience that still don't understand CIDR.

I'm very careful about classful terminology because I work with a team
of engineers
who still occasionally must deal with a customer network (using very old gear)
which requires class C addressing.

For those who don't know what a Class C address is, it is an IP address in the
range 192.0.0.0 to 223.255.255.255, i.e. it begins with binary 110, and the
network prefix is fixed at /24. This means that 10.2.3/24 is not a class C
address, and 192.2/16 is not a legal address block.

--Michael Dillon