A local area network is a number of devices, typically PC's, fileservers and printers, connected to one or more "segments" of cable.

The cabling today would be Category 5/5E structured cabling. Previously it has been co-axial, or 10-Base-2, or thick Ethernet (10-Base-5). Most organisations deploy Ethernet, although some still use token ring.

A hub is the centre of a small sized network, which is a multi-port repeater, replicating the signal received on a port to all the other ports, this means that every station hears all the traffic on the network, it will just ignore traffic not destined for itself by reading addressing at higher layers. Where this traffic becomes a problem, a switch would be used, which is effectively a multi-port bridge. The switch "learns" the Ethernet (MAC) address(es) of the device(s) connected to each port. Incoming Ethernet frames are read by the switch to determine the destination MAC address, and only forwarded to the appropriate port.

In a busy network, with numerous servers and workstations, a switch can greatly improve performance.

Further problems can occur when networks get to a certain size with broadcast traffic. Many applications use broadcasting to find services, such as Microsoft networking. The problem occurs with so many stations broadcasting, every node has to read a certain amount of the inbound packet to determine whether it is intended for itself. This behavior can have dramatic performance deficits on servers, and workstations. The answer to this is to split the network into separate broadcast domains, or Virtual LAN's, VLAN's.

A VLAN is configured in one or more switches, which effectively creates separate physical networks, each of which has a different layer 3 network address. This means that routers must be used to transfer between the different VLAN's. This can be done with a multi port Ethernet router, but generally would be done with a card installed in a core switch, to allow switching across the backplane, which is generally several times faster than the speed of the LAN.

Talk to GGR about your Local Area Network needs to find the best solution for your company.