Difference between Switch and Router

[FordLorider]

I have set-up many router networks and have always used a router over a switch. I just moved in with my new roomates and we have DSL and they used a switch instead of a router last year. I have been doing some online reading to see how set-up will differ from using a router and I have not come up with anything that really makes sense. Basically can you guys help me out with what to expect and why. I am splitting the net acess between 4 computers. We have a Linksys switch. Thanks for the help!

 

[Confused]

A switch works at layer 2 of the OSI model, and deals with MAC addresses.

A router works at layer 3 of the OSI model, and deals with IP addresses.


A switch would be used to share an internet connection if you are using some sort of ICS (internet connection sharing) running on 1 machine which is always on and connected to both the network and the internet. A switch would also be used to share an internet connection if you have more than one IP address available to you, one for each computer. The outside world would see x number of IP addresses and therefore x number of computers.

A router would be used if you only have 1 IP address to connect to the internet, but more than 1 computer. The router would use NAT (network address translation) to allow all computers within the LAN to connect to the internet, using only 1 IP. The outside world would see 1 IP address and therefore 1 computer, no matter if you have just 1 computer on the inside, or 1000.


Hope this helps. There also might be some more information in the FAQs


Confused

 

[alkemyst]

A router can be a switch....it all depends at what network layer it's operating.

The switch and bridge are Layer 2 devices. These devices divide the network into separate segments, providing fewer users per segment. Each segment is a single collision domain. Broadcast traffic goes to all segments, so only one broadcast domain exists.

Routers operate at Layer 3. They provide paths to all networks in the internetwork. The router segments the network into separate collision domains and broadcast domains.

There is a lot more but simple reading in the Cisco Interconnecting Cisco Network Devices (ICND). Stop by a book store and check out pages 16-28, 30-31.

Hope this helps.

 

[pm]

Probably better asked in the Networking forum.

If you are using a switch, then you have 4 IP addresses for the DSL connection? One for each of the four computers? Isn't that a little expensive? I would think you could save some money by cancelling all of the IP's and just using one IP and a router. If it's not a cost issue (ie. the extra IP's are included in the DSL package), and you have 4 IP's, and everything is working fine, then why change over to a router? There wouldn't be a performance advantage. There's a minor security benefit to using a router but you can achieve the same thing with software firewalls.

 

[Kingofcomputer]

Apple and orange.

Simply saying,
Switch is just for connecting the LAN computers together.
Router has NAT to provide internet sharing.

You cannot replace a router by a switch or vice versa.

Some routers have built-in switch, that can replace a switch plus a router. This is banana.
You could use such router as a switch if you want to.

apple + orange = banana.

 

[Technonut]

Apple and orange. Simply saying, Switch is just for connecting the LAN computers together.
Router has NAT to provide internet sharing. You cannot replace a router by a switch or vice versa. Some routers have built-in switch, that can replace a switch plus a router. This is banana.
You could use such router as a switch if you want to. apple + orange = banana.

Damn, I have not had breakfast yet. I am looking at my Linksys BEFVP41, (Banana) and it is making me hungry.

 

[FordLorider]

Thanks for the info .

 

[CZroe]

Originally posted by: alkemyst
A router can be a switch....it all depends at what network layer it's operating.

A rounter must "decide" where a packet goes, therefore it must read it into memory, process it, store and retrieve the data to and from the routing tables, process that then transmit the packet. A switch isn't "dumb" like a hub but technically it's just as dumb compared to a router. Using a router as a switch will add latency to the packet, just like any "hop" will. A switch does not store and forward like a router, and can therefore begin transmitting the packet as a soon as the destination address is received in a process known as "cut through switching." This lowers latency to nearly that of a hub, and is better than a hub because the packet is only transmitted to the network segment that it was intended for, saving bandwidth. The segment transmitted to is judged by the segments directly connected to the switch, unlike a router, so if the destination of the packet is on a segment that is not directly connected to the switch, it is transmitted to all segments except the originating segment. A switch can not take the place of a router, only a hub. There is no NAT, so it can't share an Internet connection unless a hub would be able to in the same situation (My ISP is configured wrong and I can lease as many IP addresses as I want through a normal hub!).