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> > It's called CIDR, Classless Internet Domain Routing.
> >
> > All the ones in the mask must be on the more-significant
> > side of any zeroes. No zeroes are allowed between the ones
> > and no ones between the zeroes in the netmask.
> >
>
> Well thats not the rfd standard ! Go Read the standard !
>
> The mask is valid but non-continous .. Not to mention You
> can do anything You want on a private network
On the one hand you mention standards, on the other you say you can do what
you want. :)
It is not a valid netmask. .Using CIDR or Classful you can never get to a
253 netmask If you don't believe me, try doing the math with paper and
pencil. A little demonstration will go a long way to clearing up
misconceptions.
An IP address is divided into two portions: Network and Host.
When subnetting, you are moving host bits and moving them to the network
bits. Bits are moved left to right of the host portion, in order, to the
network section. So for instance a /24 has 24 bits in the network portion
and 8 bits in the host portion. To subnet this into two networks, you take
one bit and move it to the network portion and you now have a /25 and 7 bits
for hosts. Network 0 has 128 IPs and network 1 has 128 IPs (we can forget
about network and broadcast addresses for the purpose of this discussion)
When supernetting you are doing the opposite. Moving network bits to host
bits. The bits to be moved are taken right to left of the network portion,
and they must all be taken in order. So the /22 I proposed takes 2 bits or 4
networks. I had to memorize all this junk so I do it in my head, but you
can just look it up and see that a /22 is a 252 netmask. The next netmask
down /23 is 254. So, 192.168.0.0/22 includes the range 192.168.0.0 -
192.168.3.255.
I will try and find some decent sites on subnetting and post URLs here for
ya. You can start by checking out Cisco though.
--
Wolf
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