Sunday, March 25, 2012


Hubs are used to build a LAN by connecting different computers in a star/hierarchal network topology, the most common type on LANs now a day. A hub is a very simple (or dumb) device, once it gets bits of data sent from computer A to B, it does not check the destination, instead, it forwards that signal to all other computers (B, C, D…) within the network. B will then pick it up while other nodes discard it. This amplifies that the traffic is shared.

There are mainly two types of hubs:

1. Passive: The signal is forwarded as it is (so it doesn’t need power supply).

2. Active: The signal is amplified, so they work as repeaters. In fact they have been called multiport repeaters. (use power supply)

Hubs can be connected to other hubs using an uplink port to extend the network.

OSI Model: Hubs work on the physical layer (lowest layer). That’s the reason they can’t deal with addressing or data filtering.