Whats the difference between a switch and router?

A switch merely makes an ethernet connection between different devices.

A router connects 2 networks together (usually a cable/DSL line to an ethernet network) and many common ones these days offer DHCP services for sharing an internet connection.

Hub:
no network traffic regulation. For example, if 2 computer tries to send data through at the same time, one will go through, another will bounce back and be sent again 'til it goes through.

Switch:
regulated traffic. It resolves collisions, and I guess has an internal queue. In a very small network (2-4 computers), not much if any speed difference between Hub and Switch, some may even say Hub is faster since there will be more hardware delays in the Switch. Anything beyond 4 computer network, Switch is probably more advantageous.

To connect multiple computers to the internet through Hub or Switch, each computer requires it's own "real" IP. Generally, ISPs are going to charge extra for each IP...universities tend to not care as much. I use a hub to share my university's connection.

Router:
Take the single "real" IP your ISP assigns, create a bunch of "fake" IPs, and put all the computers behind the router on those "fake" IPs. 192.168.x.x and 10.0.x.x are dedicated "fake" IPs for routers.

Why use routers? as mentioned above, ISPs will charge extra per IP, and unless you want to pay for multiple modems, you need to get a hub/switch anyway. Since routers are MUCH cheaper now, around the $100 mark, it's probably the best way to go in a SOHO setting.

thanks for the info .. very useful

I'm using a 4 port Linksys DSL router for my home network. I have a line going to my son's room. If I want to network a second computer there can I use that same line with a hub and hook both NICs up to that one line?

Thanks!

Bob

yep, sure will Low end 4 port and 8 port hub/switch are not that much different in price, might as well get an 8 port, if you wanna share network printers 'n such later, there'll be enough room.

Not quite true, Gelly...

What you're describing is a NAT device. Admittedly, many 'home' routers (i.e. DSL, Cable, etc.) will also perform NAT to allow connection sharing, but NAT is *not* a router function.

The definition of a router is a device that accepts incoming traffic and decides the best path to route that connection to get to its destination.

In a home environment, this almost exclusively means taking traffic from an internal host and routing it to your ISP (maybe also performing NAT at the same time), but that's a small part of routing in general, simply because you only have one way out of your network.

On the other hand, ISPs (especially large ISPs) may have multiple connections to multiple points/upstream providers. Your ISPs routers have to decide whether each packet you send to them is best routed out through, say, this T3 circuit to UUNet, this OC-3 circuit to Sprint, or some other circuit through another provider.

In other words, routers have intelligence designed to optimize traffic flows over a wide area network. Switches, on the other hand, can only handle local area traffic (even though 'local' could mean several thousand hosts in a large corporate environment).

For a home network, the only router that matters is the one that links you to your ISP. If you don't have a router somewhere on your network, you can't talk to the outside world at all.