[ale] IP Calculations

Matt Shade mshade at threekay.com
Sat Dec 15 00:59:23 EST 2001


oh man, don't complicate things!

matt shade
www.threekay.com


----- Original Message -----
From: "Mark E. Schill" <Mark.Schill at cmschill.net>
To: ale at ale.org
To: "'Matt Shade'" <mshade at threekay.com>; <ale at ale.org>
Sent: Saturday, December 15, 2001 00:57
Subject: RE: [ale] IP Calculations


> Now what happens when you introduce IPv6?? :)
>
>
>
> -----Original Message-----
> From: Matt Shade [mailto:mshade at threekay.com]
> Sent: Saturday, December 15, 2001 12:47 AM
> To: ale at ale.org
> Subject: Re: [ale] IP Calculations
>
> I'm not exactly sure what's being meant as "classless" and "classful",
> but
> basically, you have "default" subnet masks for Class A, B, C networks.
> Your
> default subnet masks are:
> 255.0.0.0        Class A networks - 0-127.x.x.x
> 255.255.0.0     Class B networks - 128-191.x.x.x
> 255.255.255.0 Class C networks - 192-223.x.x.x
>
> These give you your basic Class networks. You can SUBnet these networks
> using non-default subnets.
>
> Subnet 255.255.255.4 is an odd subnet, but not incorrect. You basically
> need
> all the binary digits to be zeros on the right side, for example:
>
> 11111111.11111111.11111111.11000000
> subnet mask of 255.255.255.192
>
> 11111111.11111111.11111111.11111100
> subnet mask of 255.255.255.4
>
> 11111111.11111111.11111111.11110010
> incorrect, since all the numbers to the right of the last contiguous 1
> is
> not a zero
>
> You figure out how many nodes are available on a subnet by adding up all
> the
> zeros.
> On a Class C network subnetted with 255.255.255.240
> (11111111.11111111.11111111.11110000) you would figure the 0000 part,
> and
> get 15 nodes.
>
> That's the basics of subnetting. Next class, we'll learn super-netting!
>
> matt shade
> www.threekay.com
>
>
> ----- Original Message -----
> From: "Joseph A Knapka" <jknapka at earthlink.net>
> To: <kenn at refriedgeek.com>
> Cc: <ale at ale.org>
> Sent: Friday, December 14, 2001 14:19
> Subject: Re: [ale] IP Calculations
>
>
> > Ken Nagorski wrote:
> > >
> > > OK, there is something you need to know.
> > >
> > > Is it classless or classful? if it is classful then
> > >
> > > 0-127 is a class A ( first bit 0)
> > > 128-191 is in the clash B (first bits 10 )
> > > 192-223 class C ( fist bits 110 )
> > >
> > > However mostly the world uses VLSM or CIDR, (classless) In this case
> you
> > > need to know how many bits are on for subnetting,
> > >
> > > Lets say 24 (255.255.255.0) bits are on... Then you have 8 bits left
> for
> the
> > > network
> > >
> > > You need to calculate 2^8 - 2 = 254 ( this is the amount of useable
> hosts )
> > >
> > > The network will be the lowest IP ( before you minus 2 )
> > > The broadcast is the last IP in the block
> > >
> > > Ken
> >
> > Is it not true that a classess network may have any netmask
> > whatsoever? That is, you could have a netmask with lower-order
> > bits == 1 and higher-order bits == 0, like 255.255.255.4, or
> > something? I seem to remember encountering a network that
> > had such a netmask, but the details are hazy.
> >
> > Cheers,
> >
> > -- Joe
> >
> > ---
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> >
>
>
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