Change Network topology while working:

There is a flat network with more than 300 nodes and all servers and clients on the same VLAN. You know that default subnet class C not support more than 254 nodes so you should switch to Subnetting/VLAN not for supporting more IP but also increasing performance and security in the network.

There are 2 choices to achieve VLAN on existing LAN:

• Doing on off day while nobody working on the LAN, so define and configuring Subnet/VLAN. In this way you have enough time to test the new topology before clients using the LAN.
• The second way is doing process (changing topology) on the live LAN, there is a risk to do that, but there is no need to doing on the holiday (you can have fun with your family or friends on holidays).

I did this way successfully. Here is the summary of how I did it:

First define Subnet and assign them to each VLAN on the paper.

You need 2 NIC cards on the servers. The second NIC card will be used for the new topology. Assign new IP address to the second NIC.

Configure each access switch as DHCP server for the New IP address (each IP pool for one VLAN)

Configure layer 3 switch (distribute layer) for VLAN routing.

Connect and configure Trunking between each access switch and switch Layer 3(use the second uplink).

Assign each access switch’s port (that connected to the client) to the proper VLAN.

Now ready, restart client PC to receive the new IP address and will be in the proper VLAN.

At the end test the connection between each clients and servers, if that is OK, unplug the first connections (disable server’s first NIC, unplug first Uplink between access switch and layer 3 switch)

If you need more information or questions just send me an Email, I will answer you ASAP.