On Fri, Jun 6, 2008 at 9:07 AM, Todd Walton <[EMAIL PROTECTED]> wrote: > I'm trying to get a grasp on IP addressing concepts. What I > understand is that there used to be classes of IP addresses: A, B, and > C. All IP addresses had a network identifier and then a host. Then > they invented subnetting. An IP address was a network, a subnet, and > then a host. So The Internets could route to the network, and the > network would route to the subnet, which would then route to the host. > > So if I have a subnet I have to have a router for it. And I also have > to have a subnet mask. The subnet mask is either 255.255.255.0 (or > 255.255.0.0, etc) where the 0's indicate the portion for host > identification, or the subnet mask can be written at the network name > with a slash and then a number indicating the length of the network > identifier. For example: 63.98.246.161/8? That doesn't make sense to > me. How could I specify a whole address but then also have room for a > mask? Then there's the concept of variable length subnet masks, which > I don't have to worry about. Classless routing is called "CIDR". > > I'm in an environment with 67 subnets and I'm configuring a device > scanner for this environment. I'm defining one configuration file for > each subnet so that when I scan it will be one subnet at a time, > instead of just push and go and tear up the network. I've been given > a list of subnet addresses and their masks. Most of them are of the > type: > > 167.190.45.0 (address) and 255.255.255.0 (mask) > > which yields an IP range of 167.190.45.1 up to 167.190.45.254. That's > fine. But then some of them are of the type: > > 167.190.1.24 (address) and 255.255.255.248 (mask) > > which yields an IP range of... ?
167.190.1.25 - 167.190.1.30 > > Sometimes the mask is like 255.255.240.0 or 255.255.255.192. Aagh! 167.190.0.1 - 167.190.15.254 or 167.190.1.1 - 167.190.1.62 based on the scheme above. > What the heck is going on? Is there a calculator for this stuff? Ya just Google "subnet calculator". > > I would really appreciate it if one of you network brains could > explain this odd subnet masking or explain where the kink is in my > understanding. > > -todd > > > -- > KPLUG-List@kernel-panic.org > http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list > -- KPLUG-List@kernel-panic.org http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
