Join the existing LAN with a wireless router

[James Wilkinson]

Thomas Taylor wrote:
> Question:  Are you using a "switch box" or a "multi-port switch"?
> 	What I know as a "switch box" is for switching things like printers
> 	or serial modems.

Agreed, although I'd probably call it an "old-fashioned parallel (or
serial) switch box..."

>  A "multi-port switch" is a router, able to work across different
>  subnets.  There's also a "hub" whose function is similar to the
>  switch except it won't work over different subnets.

That isn't the normal terminology...

A port is somewhere you plug in an Ethernet cable (or a serial device,
or whatever). A (non-wireless) hub, switch or router with only one port
is technically known as Useless: the whole point is it connects more
than one device.

A hub is an Ethernet box which connects various computers via Ethernet.
Everything that comes in goes out on all ports. It doesn't understand
TCP/IP: it just passes along Ethernet packets (which probably contain
TCP/IP packets). So everything connected to a hub has to be on the one
TCP/IP subnet, for example 192.168.1.0/24.

A switch is an intelligent hub: it learns which port network devices are
on (by their hardware Ethernet MAC address) and will only route traffic
out the right port for the destination. This means it can carry multiple
full-speed connections at once. It still won't understand TCP/IP (except
possibly for management purposes), and everything has to be on the one
TCP/IP subnet.

(These days, the chips inside switches are so cheap that no-one makes
plain hubs any more.)

A router *does* understand TCP/IP. Its purpose in life is to connect two
(or more) TCP/IP sub-nets. For example, an office might have four
floors, each with a separate subnet (say 192.168.1.0/24 to
192.168.4.0/24) and another subnet (say 192.168.10.0/24) for servers.
You would have a router to send traffic from one subnet to another
appropriately.

These days, most people will encounter routers as "Internet routers",
"broadband routers", or "ADSL routers". They will commonly do other
tasks: many will have a built-in switch for the "local" side of the
router. They will almost certainly be able to do Network Address
Translation and firewalling.

A good example is the WRT54G mentioned up-thread. In this case, one
might connect the "Internet" side to whatever provides the Internet
connectivity, up to three devices to the four built-in Ethernet ports,
and the fourth port to a switch connected to the rest of the local
network.

Hope this helps,

James.

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E-mail address: james | The winds, however, get very lazy that time of year;
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