A switch will let you plug the modem in the other computers will esentially be "on the internet" directly. If you use a router, the Cable Modem or DSL comes in at its IP address and through NAT (Network Address Translation) the IP trafic is routed to the workstations on a local subnet like 192.168.x.x or 10.x.x.x which are IP subnets that don't exist on the internet. This provides at least a minimal amount of firewall which should prevent your machines from some hacker activity.
Some cable companies do not really support the use of routers howerver, and there can be some work getting it set up. Most DSL works great with a router.

Modem: Device that initiates comunication from one network to another.
 
Hub: Device that lets multiple PCs converse with each other when connected. Device permits broadcasting of packets across all ports. Rated speed is divided amongst all ports.
 
Switch: Similar in function as hub, except it does not permit broadcasting across all ports, hence less traffic. Rated speed is available to each port, not just across the entire unit. No broadcasting combined with great per-port bandwidth equals faster transfer speeds.
 
Router: Device for connecting 2 networks. In the case of TCP/IP routers, they are used for connecting different subnets.
 
Most of the devices that you see for sale, like the Linksys BEFSR41, are routers with built-in switches. On one "end" (node) of the unit, you connect the modem. On the other end, you connect the PCs/hubs/switches that you need for your local network. Some of the units can be purchased with no internal hub or switch, which would make the unit cheaper to purchase, but would need an external hub/switch to connect more than one PC to it.
 
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Regards,
 
clutch
 
[This message has been edited by clutch (edited 26 March 2001).]

Just wanted to make a few other points clear just for informations sake
 
Differences between hub/switch, switch/router
 
HUB- Works on the Physical layer of the OSI(open systems interconnect). It works by re-broadcasting all packets passed through it to every wire on the network until another physical interface(transiever on your NIC) accepts the packet. So, the action is: computer sends broadcast to hub; Hub takes it, re-broadcasts it out to entire network; recieving computer (matching address) accepts packet.
 
SWITCH- Works on Data Link Layer of OSI. The switch actually analyzes the packet header retrieves the address and broadcasts the signal to just that computer. Action: PC sends broadcast to switch; switch breaks the packet down and looks at the destination header; switch re-encapsulates packet(leaving the originating address) sends it to destination address only. PC accepts packet.
 
ROUTER- a router works on the Network level of the OSI. The main difference between a router and a switch, at least the one you should be concerned with is.. When the router gets to the section where it is analyzing the packet and reading the destination address, it checks against its table of routes(gee wiz Capt. Obvious strikes again). It then finds the fastest route to its destination address and sends it that way(doesnt just blindly send it to that address). Another difference in a router is, when a packet passes through it and it is re-routed, it goes through a re-encapsulation stage like a switch. The difference is when it leaves the router it has the routers address on it as the source address. Hope this will clear some stuff up for you.
 
-cheers
 
Moniker
 
[This message has been edited by Moniker (edited 27 March 2001).]

NOpe
 
gotta disagree with you
 
the Switch operates on the Data Link LAyer, not the Network Layer
 
the Data Link layer deals with Mac Addresses--which is what a switch uses
 
the Network layer deals with IP addresses, which is what routers use
 
and if I'm wrong, then I'm wasting my money on these CISCO Cert courses and this entire past semester(where all we did was study the OSI model) was pointless

Switch is DLL, but I think the reason for the confusion is that the network layer is listed as "dealing with packet switching" in some texts that you will see. Kinda confusing terminology if you get stuck having to wade through it.
 

 
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Regards,
 
clutch

Okay one more question... I had my PC connected directly from the Cable modem, just before I got a switch, then when I bought the switch and hooked it up to my Mac and re-routed the Ethernet cable to the PC via the Switch, all Internet connections to the PC stoppped. Could this be a hardware or software problem. I'm running 98 on the PC and MAcOS 9.1 on my Mac. I doubt that this could be an OS conflict, because I tried even connecting it directly back to my pC and the damn thing still doesn't want to work! Help help.... Thanks you networking masters!!!!
 
Moose

You have to connect your modem to a router/proxy BEFORE you can connect it to your network (switch or hub). So, it goes wall>modem>router>switch>PCs and Mac if you want network support from your cable modem. If you just want to throw another NIC into a PC, and set it up as a router (or proxy), then you can forgo buying the seperate router.
 
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Regards,
 
clutch

INFERNO2000- you are absolutely right. Thank you for correcting me. We wouldnt want to misinform anyone. I guess I better start confirming stuff before I ramble things off. I changed it in my post so if people read it they wont be "cornfused"
 
-moniker