Creating Subnets, DHCP Relay, Catalyst 6000, PIX, Catalyst 2948/2924

Hello All,

Fairly new to Cisco administering here and need some guidance on segmenting traffic on our flat network.


Internet Cisco 1800 router PIX Catalyst 6000 Catalyst 2948 and 2924

We're in a W2k3 environment with a dedicated DHCP server and one scope.

Currently the dorm users patch into a Cat2948 or Cat2924 for internet access. These users get their IP address from the DHCP server.


We'd like to separate or segment users in the dorm onto a different subnet. I'm thinking that this can be achieved by creating Vlans for the dorms, set the cat29xx's up as a DHCP relay, then create a new scope within DHCP for these vlans.

From what I see on google groups this can be done. However, I don't

know where to begin or how to achieve this. Can anyone give me some guidance on this and\\or point me to good documenation?

Thanks all!

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DHCP relay happens at the subnet border, and a Cat 29xx doesnt route - so doesnt need to do DHCP relay.

If your Cat 6k has L3 in it, then you should set up the DHCP relay there.

I havent done this for a long time, so dont remember the exact commands - but the cisco web site has a good search engine and should find examples there.

dont forget to add a scope per subnet to the DHCP server, or nothing is going to work.....

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The basic steps you will need are - 1. Build the new DHCP scope on the server. 2. Enable layer 3 routing between the new Segments. Note that your

6500 would need Layer 3 capability for this. 3. Enable DHCP relay on the 2848/24 that has the new IP segment, pointing it at the DHCP Server.

I assume steps 1 & 2 are pretty straight forward for you, and for step

3, search the Cisco Web site for "Configuring DHCP Relay".

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Thanks guys. This is helpful. STep 1 is straightforward indeed. Step 2 is unclear to me how to achieve but I'll reach out to cisco documentation for scripting.

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