Date   : Sat, 18 Jul 2009 14:41:08 +0100
From   : zeem.uk@... (Alex Taylor)
Subject: Master Ethernet upgrade

On 18/07/2009, samwise <samwise@...> wrote:

>  A router learns which machines are attached to which port and after an
>  initial burst of traffic, will automatically route each of the
>  addressed packets to the correct port - which means devices on other
>  ports won't see the communications.  This is more secure and can
>  increase the throughput on the network ...

That also sounds rather a lot like a switch, which does the same thing
as a hub but with more intelligence.

I've done most of a Cisco CCNA but seem to have forgotten how to
describe what I'm thinking, so correct me if this is wrong. A router
involves two or more interfaces and routes packets between them - such
as linking a LAN with a WAN. It operates as Layer 3 of the OSI model,
in other words an IP router knows about IP and routes packets between
the interfaces according to IP addresses and destination networks. The
extra ports on the kind of router found at home will be a switch
attached to one of the interfaces. So that'll be a WAN interface to
connect to the cable modem or ADSL line, and a LAN interface with an
integrated 4-port switch.

A switch operates at Layer 2 so all it knows about is MAC addresses.
It learns which MACs are attached to which ports so it can send
Ethernet packets to the correct machine, increasing network throughput
and security.

As described already, a hub just retransmits what comes in on one port
out of all the others. Also described as a "multi-port repeater".


-- 
Alex Taylor