There are a lot of different types of devices in computer networking. However, the two core devices are end-user devices such as your computer, laptop, phone, and router. Your end-user devices are obvious. Without devices to use, there’d be a minimal point in networking anything.
To some degree, everyone should be familiar with a router. Anyone with a home internet connection will have one in their home after all. But it’s easy to have misconceptions. One of the most common misconceptions is that a router connects you to the internet. Technically it doesn’t.
Key Features
The singular defining feature of a router is that it connects two or more networks. Other networking hardware, such as hubs, switches, and access points, simply extends access to a single network. Technically, end-user devices can be connected to multiple networks. However, they can’t be used to route traffic between them without specialized software.
A router directs the network traffic it receives based on the destination IP address. To do this, it keeps a table of which physical connections have preferred connections to IP address ranges. The routing table is made up of dynamically learned routes, communicated by a routing protocol, and static routes, which include a default route.
The router identifies the destination IP address for every network packet that comes in. It then checks to see if the IP address falls in one of its specific routing ranges. If it does, it forwards the packet down the associated cable; if there is no specific related entry, the router will forward the packet down its default route. Hoping that the next router will know where to send the traffic.
Home Routers
A home router is a complex combination of devices, almost always being a two or even three in one device. The vast majority of home routers will offer both ethernet ports and a wireless Wi-Fi network. The third possible device is the modem. Historically modems have been separate devices. However, many recent models include an integrated modem. The modem is also why the router doesn’t technically connect you to the internet.
The modem translates the electrical signals from your ISP into a format that can be understood by a router. This means that the modem connects your router to the internet, though routers with integrated modems complicate this. From a networking perspective, it’s also almost easier to ignore modems because they’re essentially transparent boxes sitting on a cable. It’s the routers that do the actual work.
At the end of the day, the router is the heavy hitter. It provides network connectivity to all your devices, wired and wirelessly. It also then allows access to the internet via your ISP and modem. To do this, it checks to see if any network traffic is supposed to go to other devices on your home network, then forwards all other traffic to your ISP. Network traffic from the internet is routed to your network’s relevant device by your router.
Corporate and ISP Networks
Routers’ operation is basically the same in large networks, such as those in corporate environments and ISPs. However, the details are a little more complex. Often, router functionality is located in specific hardware, with functionality such as wireless access points being broken out to separate devices. These routers may also not have a direct connection to the internet, instead forming an internal network of routers that may have one or more actual internet connections.
Internal networks of routers may connect many Local Area Networks or LANs via a Wide Area Network or WAN. The difference is generally defined as LANs are for devices with physical proximity, and WANs cover LANs over large areas. In this layout, routers may need to forward network traffic to another router in the WAN without actually going to the internet.
Routers in these environments will typically be located in server racks and offer much higher performance, bandwidth, and connectivity than home routers. Often, connectivity for devices will be provided via switches, as even rack routers don’t have enough network ports for a medium-sized business.
Note: Rack-mounted routers, also called blade routers, may have ethernet ports and fiber-optic ports for ultra-high-speed networking.
Secondary Functions
After the internet was invented, there were plenty of IP addresses to go around for a long time. At this point, almost every end-user device got its own public IP address and could be individually communicated with. Eventually, though, it was clear there would soon be enough devices that there wouldn’t be enough IP addresses to go around. While a new addressing scheme, IPv6, was developed, it’s seen low levels of adoption, despite the current pressure on IPv4 addresses being immense.
One holding technique implemented to buy more time to switch to IPv6 is called NAT, though there’s also related PAT. These stand for Network Address Translation and Port Address Translation, respectively. In these two schemes, only your router gets assigned an IP address. It then keeps careful track of all incoming and outgoing network connections and maps them to specific connected devices. While primarily meant as a stopgap measure, it also acts as an effective security measure, preventing unintended direct communication to end-user devices.
Conclusion
A router is a computer networking device that connects multiple networks together. Home routers connect your home networks to the internet via an Internet Service Provider and a modem. In Corporate and ISP environments, etc., routers may not necessarily provide a direct connection to the internet and may not only have two connected networks. Here they often connect many internal networks together and connect to other routers.
In British English, router is pronounced like “rooter,” with the “ou” in “route” being pronounced like the roots of trees. Whereas in American English, router is pronounced “rowter” with the “ou” in “route” being pronounced like the traditional exclamation of pain “ow.” Both pronunciations refer to the same device. Don’t forget to leave your thoughts in the comments.
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