switch vs router dumb question

[jason210]

can you use a switch so multiple devices can share one modem? or do you have to have a router?

 

[ur6beersaway]

Router

 

[mbreslin1954]

It takes a router to make a network. A router understands multiple networks. When you have more than one device, by definition you have a network. Your modem just connects one device to the Internet, a series of networks. A switch creates a network, but does not hand out IP addresses nor does it have any intelligence to comprehend the idea that there are other networks. It just connects Ethernet ports. The router is aware of other networks through the modem, and can route packets from your network to the other networks that make up the Internet.

If you get to the point where you run out of connections to the router (say if it only has four local area network [LAN] ports and you have a fifth device), a switch will give you more ports for more devices on your network. But you need the router to route BETWEEN your home network and the rest of the world.

 

[Beachnative]

Jason there are no dumb questions when learning about networking.

The way you learn is by asking questions.

My first computer class I had to ask the teacher how to turn on my computer. She put her hand over my head and told the class, every one laughed at me and I was told my face was beet red from embarrasment. The cool thing was everyone in my class wanted to help me learn and everyday someone was giving me help.
The help part is what I like about Tom's, everyone helps one another

 

[thinslicedbread]

can you use a switch so multiple devices can share one modem? or do you have to have a router?

Depending on the type of modem you have YES, you can just connect a switch to it.

There are a lot of modems today that act as routers and have NAT and DHCP pools and other layer 3 functions - Even if they just have one port.

Most people would be surprised to find that if they looked at their WAN IP address on their router behind the modem it would be receiving a private NAT'd IP address from the modem (IE 192.168.x.x) because it is handing out private LAN addresses and not just bridging a public IP with no layer 3 functionality.

Hook up a switch and see if the device gets an IP address. If it does, then you're gold. If it doesn't, go get a router that fits your needs.

 

[Kewlx25]

A dumb switch uses broadcast packets to allow discovery of devices within the network, this is part of the Ethernet protocol. The Internet, or IP, is a routing protocol, so it doesn't "discover" devices, it forwards directly to them.

A discovery protocol works fine for smaller networks, but does not work for large networks, so you really need a routing protocol that knows where to send data without probing every device out there.

 

[Beachnative]

can you use a switch so multiple devices can share one modem? or do you have to have a router?

Did the installer leave you a wireless network set up?

If not and this is in the US if this is for a home then you will need a router and router allows one network to communicate with another.

The modem has a cable connector that sends data over the cable then the modem converts the signal into a connection over ethernet(the big phone port looking connector). The big phone port connector is called an RJ45 connector and you use an Ethernet cable to connect to it.
Your ISP has a large network covering a large area called a Wide Area Network(WAN) and at your house you have a small network that is called a Local Area Network(LAN). These boundaries of networks are neccesary for many reasons mainly security but that's another topic.
Your router has ports on the back of them the one port on the back identified as WAN or internet is for your connection to your modem. The other ports labeled LAN or numbered 1,2,3,4, are for your LAN (your home devices).

Your original question asked do you need a router or a switch? The answer is a router.
Your ISP will give the average home user one IP address to use for one device only. That one device can be a computer, any other network device, but most people use a router.
Your router will get one IP address and you can hide/use multiple devices behind it using Network Address Translation (NAT).
If you plugged in a switch directly to a modem then plugged in two devices only one would work, why?
Because the single IP address was given to one device. If the device then shuts down the other would work but not both at the same time...and you might have to get reboot the moden and switch for it to work.....a router makes it simple!
Jason210, this is a basic description of how things work.