CIDR ref table comes in handy http://www.krytosvirus.com/text/cidr.txt On Tuesday 15 May 2007 21:40, Erik Anderson wrote: > On 5/15/07, G J <iipreca at hotmail.com> wrote: > > This obviously isn't totally linux related but I was wondering if you > > guys could shed any light for me. > > I am currently working on a cisco 2600 router and I am not sure of the > > IOS version off the top of my head. I am trying to configure Access > > Control Lists and I need to specify a range of IP addresses, basically > > I'm splitting a subnet in half so I need to be able to filter the top > > half from the bottom half. Any help would be greatly appreciated. > > With the lack of specific details, it's hard to give an example I know > will be of use to you, but here - I'll propose a simple example and > you should be able to extrapolate... > > Let's say you have 192.168.0.0/24 and you want to split it into two > halves. You'd do something like this: > > ip access-list standard list1 > permit 192.168.0.0 0.0.0.127 > > ip access-list standard list2 > permit 192.168.0.128 0.0.0.127 > > this would give you the following two subnets: > 192.168.0.1 -> 192.168.0.126 > and > 192.168.0.129 -> 192.168.0.254 > > As you can see, inverse subnet masks are used in these ACLs. The > "standard" subnet mask for these is 255.255.255.128. > > By the way, this site incredibly valuable for this sort of thing: > http://www.subnetmask.info/ > > HTH. > > -erik > > _______________________________________________ > TCLUG Mailing List - Minneapolis/St. Paul, Minnesota > tclug-list at mn-linux.org > http://mailman.mn-linux.org/mailman/listinfo/tclug-list