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Still not getting the Router/Switch difference

Last response: in Networking
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September 5, 2006 8:51:00 PM

OK so I've read numerous pages on the difference between switches and routers. I know that switches support massive bandwith and about how they conduct packet sending smartly, etc. And I know how routers do the same thing only more intelligently, yada yada. So I ask...how does this effect their use in the real world? I know that all major networks use switches. Why? Is it because of the sheer # of ports that they have?
Aside from that, would there be any point to use a switch at home instead of a router from your Modem?
September 6, 2006 3:43:58 PM

Switches and routers do completely different functions. Switches physically connect PCs to the network. Routers move traffic between networks. For example, the Internet and your LAN at home are two different IP networks which get linked by a router. For all intents and purposes you can think of switches as much the same thing as hubs, although that is a greatly simplified explanation.
September 6, 2006 8:16:43 PM

The router does a NAT function that the switches do not do.

Example:

You have more than 1 pc you want to connect. A router creates a seperate network for your home. It then acts like a trafic cop. When one pc request data from the www (WAN Port/modem) it make node of where the request came from and where it is going. This way it know when the reply comes back it know where to direct it to.

Switches can not preform this function.

Switch are used to expand networks, For each subnet you can have 254 devices.
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September 6, 2006 8:24:39 PM

Ok so once I connect a router and 2 pC's to my modem, it creates this separate network then links to the WAN. So say if I have only one PC, or two PCs together with a switch, then I'm directly connected to the WAN and there is no additional (private) network? Does this benefit a home user in anyway or not really?
September 6, 2006 8:55:04 PM

Quote:
So say if I have only one PC, or two PCs together with a switch, then I'm directly connected to the WAN and there is no additional (private) network? Does this benefit a home user in anyway or not really?


Will not work. Your ISP only provides 1 IP address for your system. Some will allow you to buy additional IP's.

Another benefit of the router's NAT, is that it provides a built-in Firewall. A switch does not have a firewall, your pc's are exposed to all of the www bad stuff. With out a software firewall, Adware and AV your life expectency is less than 1 minute before you are discovered.
September 6, 2006 9:22:55 PM

I thought if you enable your computer to share the net connection with other computers that it'll work? It kinda acts like a server that way yes no? Not saying thats what I want to do by any means (because I have a router already) I'm just curious.
September 6, 2006 9:51:36 PM

MS ICS is not in play. Infact from what I have read it only works with 1 pc. It can not work as a DHCP device.

But then the switch is not connected to the modem.
September 8, 2006 1:01:24 AM

Long time since I got my ccna but anyway. If I remember correctly, switches work at layer 2 while routers work at layer 3. Switches direct packets between computers on the same network/subnet. Routers connect different networks/subnets and vlans. Routers are also used to change the kind of cabling used. Hubs work similar to switches in that they connect computers on the same network but they dont direct packets to the correct computer. 1 packet will get sent to every port on the hub. Each device/computer determines if the packet is for it or not. If not it ignores it. Hubs are slow and only work at half duplex. Switches will work at full duplex.
September 8, 2006 3:26:32 PM

Quote:
Long time since I got my ccna but anyway. If I remember correctly, switches work at layer 2 while routers work at layer 3. Switches direct packets between computers on the same network/subnet. Routers connect different networks/subnets and vlans. Routers are also used to change the kind of cabling used. Hubs work similar to switches in that they connect computers on the same network but they dont direct packets to the correct computer. 1 packet will get sent to every port on the hub. Each device/computer determines if the packet is for it or not. If not it ignores it. Hubs are slow and only work at half duplex. Switches will work at full duplex.


This is correct, except I'm not sure what you mean when saying routers are used to change the cabling type. I would say that's what a media converter does. A router can change the type of cabling, for example from serial to ethernet, but it does a lot more than just change the type of cabling.
September 8, 2006 9:22:09 PM

Basically you can't hook a switch to a modem, unless it's a modem/router ( which some DSL companies provide). As someone said before a home DSL or cable connection usually gets one IP address from the modem ( the modem also has an external IP address to connect to the outside world ). If you put say a wireless router on the modem it gets assigned that single internal IP address and it creates in effect a second network which it can give out IP address to. The router's network can have lots of computers connected to it, it does the translation work and then sends all of the information out to the ISP as if it came from a single IP address.

Switches themselves are pretty dumb ( or cheap ones are ) and all they do is send data out to each port to a computer with an IP address. They don't assign IP's, and they dont translate... they really only echo data from one port to another ( I know that's a simple answer )

If you have a modem with multiple RJ45 ethernet ports on it, then it is probably a router too, and those ports are like a switch connected to the router. If DHCP is enabled on the router/modem you can hook a PC to each port. If you need more ports you just daisy chain another switch off one of those ports.

I hope that helps and doesn't cloud the issue.
September 11, 2006 7:04:15 PM

In the beginning I also could not work out the difference, This was a while back :) , But I think what confused me was a Router was called a ROuter when in fact it was a Switch/Modem and Router all in one. You have to think of these 3 items as different functions.

A router in simple terms is a device used to seperate different subnets as you cannot talk to 10.0.0.1 if your on 192.168.0.1, there is no way. If you have a device (Computer) for example with 2 IP Addresses, maybe physically 2 NIC's or Virtual Adapters as it were both have an IP address on both subnets so it can let traffic flow between them.

A modem is simply how you are allowed to ride the telephone lines as it were, modulate into analogue and demodulate back into digital hence MO - DEM.

The switch of course connect the computer PHYSICALLY by the use of MAC Addresses or in the case of a hub simply forwarding data throughout all of the ports (Multi-Port repeater)

Hope my 2 cents added something :) 

ATLANT3AN ^^
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