Re: difference between repeater,hub,switch,etc
A repeater is specific hardware designed to overcome signal attenuation, it usually has only two ports and is designed to pure boost or amplify a signal.
A hub is very similar to a repeater. It allows for multiple machines to connect to the same network, by broadcasting traffic to all of its ports. ie traffic from a machine on port 1 going to a machine on port 3 will also be sent to any device connected to ports 2, 4, and 5. The most practical implication of this is that only one device can send data at a time, otherwise a collision occurs. Hubs implement a collision detection multiple access method to detect when two machines attempt to send data at the same time.
So far, both a repeater and a hub work at the physical layer of the network. A switch classically works at layer 2 or the data-link layer of a network (although multi-layer switches exist).
A switch works by keeping track of which MAC addresses are attached to each port. It inspects traffic and only sends it to the port that the destination device is on (based on the destination MAC address). A switch had a finite amount of memory in which it can store MAC addresses, smaller switches such as ones intended for desktop use have less memory then larger ones that may form part of an enterprise networks backbone. When a switches memory becomes full of active MAC addresses it will often revert to functioning like a hub and broadcast traffic to all ports.
So in summary, a repeater boosts signal, a hub connects multiple network devices by broadcasting all traffic down all ports, and a switch connects multiple network devices by intelligently sending traffic to the ports that require it.
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Last edited by Jerry K : 08-31-2010 at 12:50 PM.