Enterprise Networking with VLANS

Networking in the Enterprise Environment can be very challenging. With hundreds of devices on a network, broadcasts can get of control. Fortunately, there are methods to design a network to virtually eliminate the adverse effects of too many computers on the network.

VLANS, or Virtual LANS, are the building blocks to a better Enterprise Network. A VLAN is a logical network provisioned on a switch. This effectively segments the traffic on the network ports of the switch. A single switch can have hundreds of VLANS or may have just a few, or even as little as one. The network switches in production today have a very robust feature set to enable the configuration of VLANS.

Enabling a VLAN is a simple process and typically can be done in very little time. Once a switch has multiple VLANS configured you would need to add in some sort of router to enable traffic between the VLANS. Years ago, at the first introduction to VLAN technology and managed switches, the routing had to be done with an actual router. This could be a router that was just attached with a single connection or a router switch module installed in a chassis switch. Cisco’s Catalyst 4000 was one of these switches. The advantage to the chassis switch was the high speed backplane that the switch modules communicated on. This made the routing happen at near wire speed. Todays layer three and four switches perform the routing function as part of its feature set. These high speed switches can route packets at wire speed.

Best practice network design includes separate VLANS for at least the networking equipment, servers and users. This will reduce processor utilization of the servers and allow for a protected management network for the switches. This can be taken much further and VLANS for departments, printers, wireless and other groups can also be provisioned.

The next step in the design of an Enterprise network will be the ACL list. This is a security list that a switch, router or firewall uses to allow or deny traffic. Once a solid VLAN design is implemented ACLS can be applied to enhance the network’s performance and security.

Stay tuned, next month I will talk about ACL configuration in the Enterprise network.

Howard Cathcart
Director of Enterprise Services