Skip to content Skip to search Skip to footer. We're here to help you enable work from anywhere. View resources. Watch video Contact Cisco. Get a call from Sales. Contact Sales via Email. What does a router do? Why do you need a router? How do modems differ from routers? Get started with a free trial of Cisco Meraki cloud networking. You may also like: What is a switch vs a router?
How to set up a router How to setup a network How does a router work. Videos Getting to know the RV Router. Getting to know the RV Router. What are the different types of routers? Wired routers Wired routers usually connect directly to modems or wide-area networks WANs via network cables. Wireless routers Routers can also connect wirelessly to devices that support the same wireless standards.
How routers route data Routing, defined Routing is the ability to forward IP packets—a package of data with an Internet protocol IP address—from one network to another. Speeding data across networks Routers figure out the fastest data path between devices connected on a network, and then send data along these paths. Without the router, the data wouldn't end up at the right device. A command to print a document is useless if it ends up on your smartphone or a Google Home speaker—it needs to go to your printer.
Speaking of Google Home, routers are even more essential when it comes to connecting your smart home. Since a smart home is also a local network of devices, without a router they can't talk to each other.
Depending on the device, you might still need an internet connection if services are cloud-hosted. But ultimately, the router coordinates these data packages. A local network can exist without the internet or a modem, but it cannot exist without a router.
The difference between a wireless and wired router is what type of connections each device allows. A wired router only has LAN cable ports, while a wireless router also known as a Wi-Fi router includes antennae and a wireless adapter that allows devices to connect without a cable.
Most routers and modems nowadays include both LAN ports and antennae. There are a few points you should keep in mind before you select which Wi-Fi router to buy to make sure that you select the right one for your situation. Now you know what a router does and the role it plays in connecting your devices to the internet. It's a good idea to understand the hardware that makes up your home network and internet setup so that you know what you need when replacing or upgrading devices.
Understanding these differences can save you the hassle of buying redundant devices or purchasing hardware with additional features that you don't need. Just bought your first ever router? Upgraded your old one to a new one? What actually makes up the Internet? Let's look at another diagram: Diagram 3 Here we see Diagram 1 redrawn with more detail.
The physical connection through the phone network to the Internet Service Provider might have been easy to guess, but beyond that might bear some explanation. The ISP maintains a pool of modems for their dial-in customers.
This is managed by some form of computer usually a dedicated one which controls data flow from the modem pool to a backbone or dedicated line router.
This setup may be refered to as a port server, as it 'serves' access to the network. Billing and usage information is usually collected here as well. From here the packets will usually journey through several routers and over several backbones, dedicated lines, and other networks until they find their destination, the computer with address 5. But wouldn't it would be nice if we knew the exact route our packets were taking over the Internet?
As it turns out, there is a way This one is called traceroute and it shows the path your packets are taking to a given Internet destination. Like ping, you must use traceroute from a command prompt. In Windows, use tracert www. From a Unix prompt, type traceroute www. Like ping, you may also enter IP addresses instead of domain names.
Traceroute will print out a list of all the routers, computers, and any other Internet entities that your packets must travel through to get to their destination. If you use traceroute, you'll notice that your packets must travel through many things to get to their destination.
Most have long names such as sjc2-core1-h These are Internet routers that decide where to send your packets. Several routers are shown in Diagram 3, but only a few. Diagram 3 is meant to show a simple network structure. The Internet is much more complex. Internet Infrastructure The Internet backbone is made up of many large networks which interconnect with each other. These networks peer with each other to exchange packet traffic. NAPs were the original Internet interconnect points.
Below is a picture showing this hierarchical infrastructure. Diagram 4 This is not a true representation of an actual piece of the Internet. None of the physical network components are shown in Diagram 4 as they are in Diagram 3. This is because a single NSP's backbone infrastructure is a complex drawing by itself. Most NSPs publish maps of their network infrastructure on their web sites and can be found easily. To draw an actual map of the Internet would be nearly impossible due to it's size, complexity, and ever changing structure.
Does every computer connected to the Internet know where the other computers are? Do packets simply get 'broadcast' to every computer on the Internet? The answer to both the preceeding questions is 'no'. No computer knows where any of the other computers are, and packets do not get sent to every computer. The information used to get packets to their destinations are contained in routing tables kept by each router connected to the Internet.
Routers are packet switches. A router is usually connected between networks to route packets between them. Each router knows about it's sub-networks and which IP addresses they use. The router usually doesn't know what IP addresses are 'above' it.
Examine Diagram 5 below. Linux reports a gateway of 0. It says that anything on the Host-specific routes are also reported, including one that means "If anything tries to send a packet to So, let's say that host01 wants to send a packet to host It resolves the hostname host02 to the IP address So, yes, it's directly connected!
Both host02 and router receive that ARP request; router ignores it, but host02 should respond. And, host01 will keep the MAC address for The same logic would apply if host01 were sending a packet to router. But what if host01 wants to send a packet to, say, Is there a network-specific route, a routing table entry for, say, Good news, no routing error. Do what that route specifies, which means making it the problem of the router.
Routers tend to know more about network topology, and they tend to have default routes. When you get to the core of the Internet, the backbone routers, they have enormous routing tables because they have to know at least generally where everything is. Here is a more realistic situation, where host1 wants to send a packet to remote host2.
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