What exactly is a router?

[OrangeVixen]

I'm new to networking and I need this cleared up, I know it sounds obvious, but I'm reading a couple of network howtos on setting up a LAN so all my computers can use one dialup connection.

But they all seem to refer to a "router" differently, some seem to refer to it as a device you connect all the computers to with one connection that goes to the Internet. Other docs refer to the Linux box as the "router".

If I do a shopping search for routers I get pics of devices that appear to be "routers", so is it a computer or is it a separate device?

[drpjkurian]

For local area network (LAN) two devices are maimly required they are Modem and Router.
Modem ( Derived from Modulator-demodulator)is the device which converts the telephone signals to internet signals so that the computer can communicate with the web.
Router on other hand is a device which routes the signals from the modem to different computers (just like traffic control).
Nowadays some modems are having inbuilt router,

[haqking]

For local area network (LAN) two devices are maimly required they are Modem and Router.
Modem ( Derived from Modulator-demodulator)is the device which converts the telephone signals to internet signals so that the computer can communicate with the web.
Router on other hand is a device which routes the signals from the modem to different computers (just like traffic control).
Nowadays some modems are having inbuilt router,

there is no such thing as a Internet signal and a modem does not convert a signal for use on the Internet.

A modem modulates a signal to be sent to another modem which can demodulate it back into a language the attached computer can understand.

Modems were around and used before the www came about, they can dial straight into another computer without the use of the Internet.

What they do with the modulation/demodulation is to allow one computer to communicate with another often today involving Internet access.

This could be through POTS (plain old telephone system) or *DSL or Fibre or Cable.

At one time they simply converted a digital signal into a analogue one to allow the telephone lines to carry the information which would then be converted back to digital at the receiving modem.

[OrangeVixen]

Nowadays some modems are having inbuilt router,

What is confusing me is that a couple of howtos on IP masquerading (NAT) have different references to "router". Some are saying it's a Linux with a modem, others are describing it to something similar to what you described.

I have one Linux with a ppp0 interface using dialup. I'm not sure where the "router" goes.

I also found references to "switch" and "hub", I need to connect computers within the LAN to the Linux box with the dialup so they can access the net too. The Linux box has an ethernet card (a eth0 interface)

Do I connect the Linux box's eithernet card to a router or is the Linux box "is" the router in this case? where does the switch and hub come in?

[sanderj]

I'm new to networking and I need this cleared up, I know it sounds obvious, but I'm reading a couple of network howtos on setting up a LAN so all my computers can use one dialup connection.

dialup connection? Really? No DSL or cable?

[haqking]

A router "routes" traffic from one computer or network to another.

Modems and routers are not related.

A router may or may not be required on your home network.

If you have a ISP connection and one computer you may be able to hardwire to the modem and then connect directly to the Internet and you wont need a router, however all your Internet traffic will go through a Router on the Internet (a router is the Information Superhighways Traffic Cop directing packets to a destination based on where they came from (source address) to where they want to go (destination address)

A router is like a post office sorting office, it decides where something is going based on address/zip code etc.

If you wanted wireless/WiFi in your house then a Wireless Router will enable multiple connections to all connect to it and the traffic will be routed to other machines on the LAN or out to the Internet based on the packets source and destination address.

Routers can be specialised hardware devices or software running on a Linux or a Windows machine.

http://www.cisco.com/cisco/web/solut...tch/index.html

Also read about the OSI layers https://www.youtube.com/watch?v=p5i5ZE3Oquo

This explains packets, routing, etc very well https://www.youtube.com/watch?v=Ve7_4ot-Dzs

[sgage]

I'm new to networking and I need this cleared up, I know it sounds obvious, but I'm reading a couple of network howtos on setting up a LAN so all my computers can use one dialup connection.

But they all seem to refer to a "router" differently, some seem to refer to it as a device you connect all the computers to with one connection that goes to the Internet. Other docs refer to the Linux box as the "router".

If I do a shopping search for routers I get pics of devices that appear to be "routers", so is it a computer or is it a separate device?

The "separate device" really is a computer - a very special-purpose one. It runs software that makes it a... router. You can run software on your computer to make it a router, but of course you'd have to also have the hardware to present either ethernet connectivity or wireless to whatever other computers you wanted to share the connection with. When I was still on dial-up, I used to share my connection using my computer as a router, essentially.

Nowadays, a router often presents several ethernet ports plus a wireless capability. It also typically acts as a DHCP server, so that when you boot your computer, it can get an IP address from the router. Then the router keeps track of all the input/output from the various computers attached to it - it "routes" the traffic.

[lisati]

*cough* Simple explanation: A modem is a device which lets you transmit and receive computer signals via the phone line.

[haqking]

*cough* Simple explanation: A modem is a device which lets you transmit and receive computer signals via the phone line.

*cough* OP asked what a router was

[lisati]

*cough* OP asked what a router was

I noticed that, but wasn't satified with the modem part of the discussion.

+1 to the comparision with "Traffic Control" for the router.