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Routers

Routers are network devices responsible for forwarding packets toward their destination by determining the best path at each step along the way. Each router in the path examines the destination IP address and decides the next hop until the packet reaches its target.

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About this video

Routers are network devices whose primary function is to forward packets toward their intended destinations. When a device needs to communicate with a remote server, it sends traffic to its default gateway, which is typically the first router in the path. That router examines the destination IP address and determines the next best route for the packet, then forwards it accordingly. Every router the packet encounters along the way repeats this same decision-making process, each one determining only the next hop rather than the full end-to-end path. This distributed, hop-by-hop forwarding model is fundamental to how data travels across networks, allowing packets to traverse multiple interconnected routers before reaching their final destination. Understanding how routers evaluate destination addresses and make routing decisions is a foundational concept in networking and underpins more advanced topics such as routing protocols, subnetting, and network troubleshooting.

What you'll learn

What's covered

Routers

Aligned to

Cisco CCNA
3.2 Determine how a router makes a forwarding decision by default
Cisco CCST Networking
4.4 Explain basic routing concepts
CompTIA Network+
2.1 Explain characteristics of routing technologies
CompTIA A+ Core 1
2.6 Compare and contrast common network configuration concepts

Key terms

Router
A network device that forwards data packets between networks based on IP addresses.
Packet
A unit of data formatted for transmission over a network, containing a header, payload, and sometimes a trailer.
Default Gateway
The router that a device uses to send traffic to destinations outside its local network.
IP Address
A numerical label assigned to each device connected to a network that uses the Internet Protocol.
Hop
A single step in the path a packet takes through the network, specifically the transit from one router to the next closest router toward the destination. The number of hops a packet must travel is used as a routing metric by distance-vector protocols like RIP.

Transcript

Routers start getting really cool, because we're going to start seeing how everything is coming together to make this communication happen, and routers are a big key to all of this.

A router's function is to forward packets, to route packets. That's what a router is doing: it is routing packets.

In this scenario right here, we have a machine and it's communicating to a server over here. What it needs to do is it needs to send it to its default gateway, so it gets it to this router. The job of that router then is to figure out, where do I need to go next? What route does it need to take? So this router says, I'm going to need to figure out what route it's going to take. And then it sends it along its way.

Every router along the way does the same process. This router right here is going to say, "Okay, where do I need to send that? What is the destination IP address? And where do I need to send it next?"

Each one of these is called a hop. So this router is concerned with what is the next hop. This router is concerned with what is the next hop. And then this router sends it on to that server right there.

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