Is a router necessary between a modem and a switch?

3

Is it possible to change our internet setup from this:

Cable Modem -> Wi-fi Router -> (via wired connection) Unmanaged Switch -> CAT 5e Server Rack -> Wall Ethernet Port -> Computers

To This:

Cable Modem -> Unmanaged Switch -> CAT 5e Server Rack -> Wall Ethernet Port -> Computers?

Additional Info: Our company has a shared server room on another floor than ours, and our wi-fi router is far out of range to be of any use to us in that server room. We are looking to eliminate this router since its a rental from an ISP we just switched from that we will need to return anyways. Is the wi-fi router a necessary component in order to have internet sent through our switch?

Josh979

Posted 2016-06-22T22:03:50.120

Reputation: 153

What is the make and model of your cable modem? – David Schwartz – 2016-06-23T01:09:40.867

Answers

5

Yes and no. The router provides a local network, and distributes local IP addresses to all the computers connected to it, while only using 1 external IP provided by your ISP.

Without the router, that switch is going to try to give each PC on the network, it's own external facing IP address. I doubt it will work out well for you since I'm sure your ISP would have some sort of limit to how many IPs you can get. For me, it is 3. I have my cable modem running into an unmanaged switch, and the switch has 2 PCs connected to it, each with their own unique IP address, and then I have another port connecting to a junky old router, which I share between my two PCs. That setup is working fine for me, but if this is a business, I would highly recommend getting some sort of router, or a managed switch that will allow you to set up DHCP on it.

Twitch_Vikerish

Posted 2016-06-22T22:03:50.120

Reputation: 66

Thanks for your answer. This is a business, but we fortunately happen to have a "junky old router" on hand as well. Perhaps we'll throw this in to replace the existing one, I'm just hoping this won't limit our possible max download speeds though. – Josh979 – 2016-06-22T22:31:41.930

if you want to avoid that bottleneck, you may be able to get another unmanaged switch and (after checking your max number of ip addresses) create something like: modem-->unmanaged switch--> 2 different routers that service different floors or something. May be worth looking into buying high bandwidth devices though. Depends on your use case – Blaine – 2016-06-22T23:20:23.927

1This answer doesn't make sense. Unmanaged switches don't give IP addresses. Do you mean the modem? – David Schwartz – 2016-06-23T01:09:25.790

1@DavidSchwartz Up to just before his last sentence, I think he means that the ISP is going to provide IP(s) and each computer if it retrieves the IP via DHCP will receive it from the ISP, through the modem and switch, that being external IP(s). In contrast a NAPT router will hand out private IPs for internal use only. – barlop – 2016-06-29T06:38:09.523

2“Without the router, that switch is going to try to give each PC on the network, it's own external facing IP address.” This is wrong. The modem (in bridging mode) (also: not the switch) usually doesn’t waste an IP address. It doesn’t participate in in-band communication at all. Everything, including assigning IP addresses (usually only one!) is handled by the ISP. – Daniel B – 2016-07-08T06:51:59.160

4

It depends on your network diagram.

A simplest network configuration—a computer linked directly to a modem which is in turn linked through a phone line/cable/fiber optic uplink to the individual’s internet service provider. In this case, you don't need a router, but you can not access the internet with a Wi-Fi device. This situation is only advisable for home usage.

If for business, a router is needed, because a router performs the function of IP sharing, Network Address Translation (NAT), Dynamic Host Configuration, Firewall. The following picture shows a network diagram with a switch and a router.

enter image description here

Mark Twain

Posted 2016-06-22T22:03:50.120

Reputation: 244

2

If you got that setup to work properly, you'd have a very insecure network as all of the computers would have to be directly linked to the internet to work, (public IPs). However that might get costly as the costs for public IPs can get expensive. The simple solution here would be to just go and buy a router and replace the one you don't want. You could also potentially leave out the first switch in your equation if it's only bridging the connection between the router and the rack switch.

Cable Modem -> New Router -> CAT 5e Server Rack -> Wall Ethernet Port -> Computers

A somewhat decent router for basic usage can be from $100-$200 online depending on what all you want. If it's in a shared location, then you'll probably just want one that has a single WAN port as well as a single LAN. That's really not a good option though as moving the router into your office space would be better. The cable that goes from the closet to your space, (if it's a standard LAN cable) is the one that you should plug directly into the modem and then have your router at the other end. This will give you more control to as the routers tend to lock up more than modems in my personal experience.

Blerg

Posted 2016-06-22T22:03:50.120

Reputation: 1 094

Thank you for your helpful response! I'd upvote, but I haven't reached the min rep for that yet... We did get a new router, we just wanted to use it on our floor instead of in the server room so we could hook up wireless printers and such to it like you were saying. The switch in use powers about 16 computers via eithernet ports. – Josh979 – 2016-06-22T22:45:18.197

2

The WiFi portion of your WiFi router is probably not necessary, but in your case a router is in most cases to allow for security, firewalling, and basic network services such as DHCP and perhaps DNS caching. You probably need more horsepower, how much would vary on the number of devices, speed of your internet, and how you use your network.

At first glance I would say the setup should be...

Cable Modem -> New Router -> Ummanaged Switch -> Cat5 Server Rack -> Wall Jack -> Computer

Just like you have it, except with a new router... and to fix the WiFi dead spots, you use a Wireless Access Point, which give you WiFi where you need it physically by bridging the Ethernet network to WiFi, you can connect this at perhaps the Unmanaged switch or plugged into a spare wall jack somewhere. Access Points (APs) do not normally do any routing, they just bridge the network to WiFi and add encryption and authentication.

acejavelin

Posted 2016-06-22T22:03:50.120

Reputation: 5 341

2

Yes.

The router is the component that connects two different networks (your local area network or LSN and the internet). The switch only handles connections within the LAN while the modem translates the signals through the air or wires.

Joey Miller

Posted 2016-06-22T22:03:50.120

Reputation: 121

1

A modem is provided by the Internet Service Provider (ISP) and provides a network access to the internet. A router is the "traffic director" of a network. It takes information provided by the modem or ONT and routes it to the various devices that are connected, and creates internal IP address for the devices so they can be accessed. A switch is used to provide additional ports, expanding the capability of the router. A switch will not provide routing capability and should not be connected directly to the modem or ONT unless a DHCP Server is present elsewhere on the network. So the connection should be modem—router-switch.

katiesi

Posted 2016-06-22T22:03:50.120

Reputation: 155