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New Member

Subnetting an existing network

I currently work for a company that uses a class b address with the default subnet mask. It's one big happy flat network.

I am upgrading the network with new equipment (Catalyst 4507R) and I want to establish VLANS (currently there are none in place). My question is, is there a way to subnet the existing network out without causing problems and how should I go about this? I basically want to impose a class C subnet mask on the class B address so I have 254 networks.

Any help is appreciated.


New Member

Re: Subnetting an existing network

I went through a similar situation not too long ago. We did it in two steps. The first step on the flat network was to set up on DHCP server on the flat network. That way I could get each workstation setup to support DHCP as I could.

Once that was done I set up my plan to create VLANS. I broke my campus environment up into Zones. Each zone was a Vlan. You can handle this any way you want. I had one DHCP server per Vlan.

Once I got the Everything ready. Including Routing plans, WINS, DNS, etc I took a weekend shut down the system, and rebuilt.

When everyone came to work on Monday the system was ready they logged in they got a new address in their new vlan, and were ready to go. There were a few hitches, and this is realy a simple explanation it may send you in the proper direction.

I would be happy to help you more with this if you need.

New Member

Re: Subnetting an existing network

Thanks for the reply. I decided to just setup a second network and migrate to it. It's easier on the existing infrastructure and probably in the long run a better choice.

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