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New Member

Subnetting an IP LAN

Hi, this is Paul with a question. Inside our firewall, I use Cisco Catalyst 2924 XL and 3548 XL for our internal LAN. We use Class B private addressing on the internal LAN and only use one subnet currently. What do I have to do to add a second subnet for a particular group of PCs so that they're separate from the original subnet yet can still access the same Windows NT domain controllers for user authentication? Thank you.

New Member

Re: Subnetting an IP LAN

You would need to add a quick router or Layer 3 switch to separate the network into two segments. Once that is done, and you readdress one of the segments into another subnet, you will need to enable WINS services on the server(s) and clients. If you use DHCP to configure your clients, that will make things easier. Other than that, it's some learning and playing around, but that is roughly it.

Be sure to pick a routing/L3 device that can give you good throughput. You don't want to install a bottleneck!

New Member

Re: Subnetting an IP LAN

Well, first of all, you'll have to see some kind: maby you don't need a subnet, but another net. You'll see: if you want to subnet your current network, you'll have to change all configuration on your pc's.

Instead of that, you can add a new class a, b or c network (it must be in the range of private addresses). Well, you now have a switched enviroment (layer 2), and you will need a layer 3 device, to make the conmuting: a router. If you're managing vlans on your switches, maby you'll use ISL or 802.1q protocol. Well i hope i can help you, and sorry about my english, but i'm writing from Argentina. For more information, you can contact me at

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