What Is a Router in Networking? Core Function Explained

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A core element of internet connectivity, a router is a device that allows multiple devices to connect to the internet and facilitates the forwarding of data packets to their respective destination addresses. Using dynamic routing techniques, a router examines the data and selects the most effective route for information flow among the various available paths.

What exactly does a router do?

The primary function of a router is forwarding (or routing) data packets between networks. In networking, data packets are the fundamental information units that are transferred over the internet. Every data packet contains a source IP address and a destination IP address. A router’s job is to efficiently route an IP packet from the source station to its destination station without any hindrances.

Routers have various other functions as well, including:

• Simplifying management: Given the limited number of available IP addresses, routers use Network Address Translation (NAT), which allows several devices to share a single public IP address. NAT also improves network security and simplifies network management.
• Packet filtering: Routers monitor incoming and outgoing packets for suspicious traffic using filtering techniques. They decide whether to allow or disallow packets based on screening filters like port numbers, IP addresses, and Internet Control Message Protocol (ICMP) messages.
• Dynamic routing: In dynamic routing, routers adapt to changes in networks and take the best path based on real-time conditions. If a router detects a failure in a network’s section, it consults its routing table and reroutes the traffic to an alternate path.
• Classifying traffic: With the help of Quality of Service (QoS), routers prioritize which traffic will receive more preferential treatment.

How do routers work?

When a router receives a data packet, it reads its IP header to understand where it is headed. To begin with, it checks its routing table with the details of paths to various network destinations. These routing tables use algorithms that help pick the best path to reach that destination.

The router then sends packets to the next node until they reach the destination, allowing for smooth data transmission.

Components of a network router

A network router comprises both internal and external components. The internal components are:

• CPU: Routers have CPUs that can efficiently determine the most optimal route for packets while keeping track of them.  
• Memory: A router uses different types of memory like RAM, Read Only Memory (ROM), Flash, and non-volatile RAM (NVRAM).
  • RAM: RAM is the main memory in routers, but only temporarily stores data. If the router is turned off, all data is erased.
  • Flash: Flash memory is a type of non-volatile memory designed for storing a router’s operating system. The content stored in flash memory is not affected even when the router is shut down.
  • NVRAM: NVRAM is a kind of non-volatile RAM that can save data even after a router has been turned off.
• Interfaces/ports: Routers support multiple interfaces/ports like Ethernet and Serial to connect to various wires. In Ethernet, the router supports FastEthernet and GigabitEthernet, while Serial supports HDLC, PPP, and Frame Relay.

The external components of a router include:

• WAN Port: The WAN port connects to the wide area network or the internet.
• LAN Port: The LAN port connects to the local area network, enabling communication between connected devices.

Main types of routers

Routers used to be essentially the same: a piece of hardware that allowed devices to communicate with each other across a network. But today, routers can take many different forms. Here are some of the most common:

• Wired router: The original router type, wired routers use physical Ethernet cables to share data over networks.
• Wireless router: Wireless routers allow Wi-Fi internet connections through built-in access points. These routers are widely used in homes and small offices and can support multiple devices simultaneously.
• Edge router: An edge router is a specialized wire or wireless router that resides at the boundary of a network. These routers don’t communicate with internal networks; instead, they communicate with external networks.
• Virtual router: Virtual routers are a type of software that allows computers to function as efficiently as physical routers. They work similarly to physical routers by sharing data packets and can be scaled up quickly when required. As a result, they are an excellent option for businesses looking for high-performance networking solutions.
• Core router: Core routers are another form of specialized routers that forward data within the core of the network. They are ideal for large organizations and are designed to handle high traffic.

What are the most common router issues?

Routers can face many issues. Below are common router issues and how to troubleshoot them:

Slow network

It is common to encounter slow networks where several clients are attempting to connect to a router that may or may not have enough capacity to accommodate all of them. In such cases, the router may slow down internet speed on one or more of the connected devices.

To troubleshoot a slow network, you can unplug the router and wait 30 seconds before plugging it back in.

Weak signal

If your router is old or placed in an unsuitable location, it may block the Wi-Fi signal. In addition to that, physical interferences, such as large appliances or thick walls, can also result in low signal strength.

For a strong Wi-Fi signal, remove obstructions between your router and wireless devices. Also, place your router on a high surface and keep it updated. In a large area, you may need to use one or more Wi-Fi extenders.

You get locked out

There are a few ways you can get locked out of your router. Perhaps you have forgotten your password, or it may have been hacked.

Regardless of the cause, if you get locked out, you can reset your router password by pressing the reset button for at least 10 seconds.

Router protocols

Routers use routing protocols to build routing tables that contain details about the paths available to different networks. With this information, the router can determine the most optimal route for each data packet.

Types of router protocols

There are various types of router protocols. Here are some of the most common:

Routing Information Protocol (RIP)

One of the oldest routing protocols, RIP is an interior gateway protocol that uses a distance vector algorithm to route packets to their destination. Distance vector routing determines the best path for data packets with a simple calculation of how many routers the packet has to pass through (or “hop”) to reach its destination.

However, RIP is not the best option for large and complex networks. That’s because it is designed to only broadcast updates every 30 seconds — which was enough in the early days of networks, but can’t support modern network traffic volumes — and only supports up to 15 hops.

The newer version of this protocol, RIPv2 (and its IPv6 extension, RIPng), improves on the shortcomings of RIP and provides additional features like multicasting, password authentication, variable length subnet masking, poison reverse, and more — but it’s still limited to a maximum hop count of 15.

Open Shortest Path First (OSPF)

OSPF is a link-state routing protocol designed for TCP/IP environments. It calculates the best path the packets should take to reach their destination using Dijkstra’s algorithm.

Border Gateway Protocol (BGP)

BGP is a gateway protocol developed to replace EGP. Its primary function is to transfer data packages between autonomous systems (AS) using the best path selection algorithm. Prominent features are support for next-hop, Classless Inter-Domain Routing (CIDR), Transmission Control Protocol (TCP), and efficient network bandwidth utilization.

Immediate System-to-Immediate System (IS-IS)

IS-IS is a link state and classless protocol that uses the Dijkstra algorithm to find the optimal path for data transmission. It is used for routing in autonomous systems.

Router vs. switch vs. modem

While a router, switch, and modem might look similar, each is used differently, combining to facilitate internet connectivity for homes, businesses, and other organizations.

Bottom line: Routers facilitate efficient network communication

A router is a literally essential component of modern network computing — without it, most network connectivity would be impossible. A good router ensures fast, reliable, and secure data transmission across networks.

Network administrators should have a comprehensive understanding of routers, including their types and uses. This knowledge will help them decide which router to choose for their organization and optimize their network’s performance.

Get to know the best enterprise Wi-Fi solutions and providers to maximize efficiency and uptime on your organization’s network.