Switch vs. router

[Mr. Laser Beam]

I am a bit confused about this computer-related topic:

What is the difference between a switch and a router? Based on my admittedly limited understanding, they both appear to do the same thing: share one 'net connection amongst multiple devices. How are switches different from routers?

 

[GalaxyX]

Well, the two as it stands today are becoming very similar to each other, however, originally as Switch was basically just a device to plug several network devices (like PC's and Network Printers) to one box that would broadcast a network signal to every single port (and only the computer it was meant for would reply to it).

A Router is meant to go further in that will it actually read the network signal being send (for example, TCP/IP, which contains information about where it's going) and realize the signal is not meant to go anywhere within it's own network, but rather outside, and then it sends the broadcast outside of it's domain.

So in a way, Routers are smarter Switches.

 

[Mr. Laser Beam]

So if I understand this correctly, a switch can't be used to share one 'net connection among multiple computers, but a router can?

 

[GalaxyX]

Well, if you mean multiple computers as in multiple networks, then yes, an individual switch is usually not going to be able to connect to another network, but a router can.

 

[Kaziarl]

GalaxyX said:
Well, the two as it stands today are becoming very similar to each other, however, originally as Switch was basically just a device to plug several network devices (like PC's and Network Printers) to one box that would broadcast a network signal to every single port (and only the computer it was meant for would reply to it)

A Router is meant to go further in that will it actually read the network signal being send (for example, TCP/IP, which contains information about where it's going) and realize the signal is not meant to go anywhere within it's own network, but rather outside, and then it sends the broadcast outside of it's domain.

So in a way, Routers are smarter Switches.

Actually, you're thinking of a hub. There the ones that broadcast to everyone. Switches were the first device to use and address scheme to say "Hey, that email is for bob, so I'll send it only to him."

Routers are known as "Gateway Devices" The do the same thing, but on a much larger scale, and are what connect you to the internet. Many of you I'm sure have a Cable or DSL router/modem from your ISP.

In both cases they use an address scheme, so that they don't have to send it out every port.

 

[Mr. Laser Beam]

GalaxyX said:
Well, if you mean multiple computers as in multiple networks, then yes, an individual switch is usually not going to be able to connect to another network, but a router can.

I was referring to sharing an Internet connection from a cable modem.

 

[Kaziarl]

Two computer hooked to a switch, then the switch connected to the router will allow you to share the connection. Or to make it more simple, connect the two computers to the router and basically do the same thing. Either way, you need a router to connect to the internet.

 

[Mr. Laser Beam]

So what is it about a router that makes *it* able to share an internet connection, but a switch can't?

 

[Kaziarl]

Design mainly. Routers typically have a dedicated port with a much higher bandwidth then the rest. This allows the computers to share the higher bandwidth, while not slowing the rest down. The higher port connects to the internet, and is divided into lower ports for individual devices. It's just the breakdown of devices thats generally accepted in networking.

 

[Kaziarl]

Also, if your cable modem is anything like the one I got from comcast, it doesn't recognize a switch as a valid device. They also don't like linux.

 

[Mr. Laser Beam]

^ Cable modems vs. Linux? That's news to me.

 

[Kaziarl]

My cable modem, from ComCast, doesn't like linux. I have to use a router to be able to connect. And thats for just one computer.

 

[Lindley]

That's all about drivers, I suspect. There's no network reason why operating system should matter.

According to Wikipedia, a router (in the usual sense) is what's termed a "Layer-3 switch". A layer-1 switch is a simple hub; a layer-2 switch attempts to learn the addresses of local machines and to appropriate forwarding, which is good for small networks but not very scalable; a layer-3 switch contains the ability to link a local network to a much larger one through specialized protocols. Layer-4 switches differentiate themselves through the inclusion of security services.

Each progressive type of switch has to have a higher-level understanding of each bit of data it receives, and is thus more complex and more expensive.

 

[Alpha_Geek]

Hubs blindly repeat everything.

Switches determine where packets should go based on tables with hardware MAC addresses in them, creatiug seperate collision domains for IP packets(This part is unimportant in small home networks).

Routers make a similar decision, but based on IP addresses. Since routers understand TCP/IP, they can usually do more to interact with the traffic flowing through them, such as allow traffic on ceertain ports, allow multiple PCs behind them to appear to have one public IP address, etc, etc etc.

As others have said, the distinction between router and switches is becoming hazy as both become more capable due to technology improvements.


If your ISP dosen't like Linux, tell them "Windows NT 4.0".

AG

 

[Marc]

Alpha_Geek said:
As others have said, the distinction between router and switches is becoming hazy as both become more capable due to technology improvements.

AG

think I have disagree a bit here. Switches only direct traffic between computers on a network where as a router has the ability to direct traffic outside of the network.

It provides the mean to send data from your internal IP address range to computers on another address range.

While the switch works at a higher level than a hub it's still working at the network level (layer2) but router is working with networking protocols coming in at layer 3.

A switch won't give a damn if you're using IPX, NetBUI or TCP/IP but a router will (not the NetBUI is routable).

 

[Meredith]

Here is a Chart:




SIMPLE <---------+------------> COMPLEX
CHEAP <----------+------------> EXPENSIVE

<HUB> ---------<SWITCH>--------<ROUTER>


Personally I use a Switch instead of a Hub because a HUB can slow things down on a network if more that 2 machines are talking at the same time. A router is good when interfacing two different networks together, ie. "The Internet +-----Router----+ Your Home Network"


Imagine playing the game "telephone"

Bob needs to talk to Alice.

Hub: Bob yells his message to everyone one in the room and Alice can hear his message, but so does everyone else, everyone else ignores Bob's message.

Switch: Bob instead of yelling tells the message to Steve (switch) who recognises where Alice is and walks around everyone else and talks directly to Alice, only giving her the messsage.

Router: Bob is in a large conference room (internet), he tells Steve his message, he runs down the hallways to a small room containing Alice and tells the message to Alice.

 

[Kaziarl]

Meredith said:
Here is a Chart:




SIMPLE <---------+------------> COMPLEX
CHEAP <----------+------------> EXPENSIVE

<HUB> ---------<SWITCH>--------<ROUTER>


Personally I use a Switch instead of a Hub because a HUB can slow things down on a network if more that 2 machines are talking at the same time. A router is good when interfacing two different networks together, ie. "The Internet +-----Router----+ Your Home Network"


Imagine playing the game "telephone"

Bob needs to talk to Alice.

Hub: Bob yells his message to everyone one in the room and Alice can hear his message, but so does everyone else, everyone else ignores Bob's message.

Switch: Bob instead of yelling tells the message to Steve (switch) who recognises where Alice is and walks around everyone else and talks directly to Alice, only giving her the messsage.

Router: Bob is in a large conference room (internet), he tells Steve his message, he runs down the hallways to a small room containing Alice and tells the message to Alice.

I like that. This is a very simple, and very accurate description. Thank you for saying what I was trying to over complicate. It's a really bad habit of mine.

 

[jkladis]

Marc said:
think I have disagree a bit here. Switches only direct traffic between computers on a network where as a router has the ability to direct traffic outside of the network.

It provides the mean to send data from your internal IP address range to computers on another address range.

While the switch works at a higher level than a hub it's still working at the network level (layer2) but router is working with networking protocols coming in at layer 3.

A switch won't give a damn if you're using IPX, NetBUI or TCP/IP but a router will (not the NetBUI is routable).

The distinction has never changed, but layer 3 switches have become increasingly more common. They are still switches, but with routing engines built in to support multiple networks separated at layer 1 (other switch/hub) or layer 2 with 802.1q VLANs.

Baba, study the OSI model. Understand it, and the roles of routers and switches will make more sense.

 

[Marc]

jkladis said:

Marc said:
think I have disagree a bit here. Switches only direct traffic between computers on a network where as a router has the ability to direct traffic outside of the network.

It provides the mean to send data from your internal IP address range to computers on another address range.

While the switch works at a higher level than a hub it's still working at the network level (layer2) but router is working with networking protocols coming in at layer 3.

A switch won't give a damn if you're using IPX, NetBUI or TCP/IP but a router will (not the NetBUI is routable).

The distinction has never changed, but layer 3 switches have become increasingly more common. They are still switches, but with routing engines built in to support multiple networks separated at layer 1 (other switch/hub) or layer 2 with 802.1q VLANs.

Baba, study the OSI model. Understand it, and the roles of routers and switches will make more sense.

Just don't do my trick and forget it. Lost count of the times I've gone over the OSI model for uni studies int he past couple of years but it come post exams I quickly forget it.