TechKnowSurge
Cisco CCNA 1.13 CompTIA Network+ 1.2 Cisco CCST Networking 4.5 CompTIA A+ Core 1 2.2 CompTIA Network+ 2.2
TechKnowSurge Catalog Videos Switches
VideoNetworkFree

Switches

Ethernet switches improve on hubs by directing frames only to their intended destination based on MAC addresses, increasing both security and network efficiency. This content covers how switches reduce collision domains and how to configure duplex and speed settings for different network environments.

⚑ Complete this video to capture a CTF flag worth 1 point.

About this video

Ethernet switches are the primary Layer 2 devices used to forward frames between nodes on a network, and they represent a significant advancement over the hub-based networks that preceded them. A hub broadcasts every incoming frame out all of its ports, meaning every connected device receives all traffic regardless of whether it was the intended recipient. This creates a single large collision domain where only one device can transmit at a time, introduces half-duplex limitations, and raises security concerns because any node can capture traffic meant for another. A switch eliminates these problems by reading the destination MAC address on each incoming frame and forwarding it only to the port associated with that address. Each port effectively becomes its own collision domain, so devices no longer compete for bandwidth, collisions are largely eliminated, and traffic stays between the sender and the intended recipient. The result is a faster, more secure, and more scalable network architecture capable of supporting simultaneous conversations across multiple port pairs. Beyond basic frame forwarding, switches provide per-port configuration options for duplex mode and link speed. Most modern switches default to full duplex and auto-negotiate speed with connected devices, handling the majority of deployment scenarios without manual intervention. However, certain legacy or specialized equipment may not support auto-negotiation, and mismatched settings can cause significant packet errors and degraded performance. Knowing when and how to manually set duplex and speed on a switch port is an important practical skill for maintaining reliable network connectivity across mixed hardware environments.

What you'll learn

What's covered

Ethernet Switches

Aligned to

Cisco CCNA
1.13 Describe switching concepts
CompTIA Network+
1.2 Compare and contrast networking appliances, applications, and functions.
2.2 Given a scenario, configure switching technologies and features.
Cisco CCST Networking
4.5 Explain basic switching concepts
CompTIA A+ Core 1
2.2 Compare and contrast common networking hardware.

Key terms

Collision Domain
A network segment where data packets can collide with each other when transmitted simultaneously.
Half Duplex
A communication mode that allows data to be transmitted in both directions but only one direction at a time.
Full Duplex
A communication mode that allows data to be transmitted in both directions simultaneously.
Switch
A network device that connects devices within a LAN and forwards traffic based on MAC addresses.
Media Access Control
MAC
A sublayer of the Data Link layer that controls how devices on a network gain access to a medium and transmit data.
Hub
A basic Layer 1 network device that receives a signal on one port and repeats it out every other port simultaneously, creating a single shared collision domain among all connected devices. Hubs have been replaced by switches in modern networks because they waste bandwidth and cause collisions.
Autonegotiation
A mechanism that allows network devices to automatically negotiate a common speed and duplex setting without manual configuration.

Transcript

So now we're going to talk about switches. Switches are what Ethernet uses to get information from one node to the next node.

From hubs to switches

Where things started out was using a hub. And in a hub situation, we already mentioned, when a frame comes into that switch, then that switch will forward it out all other ports to all other end nodes there. So that's the way a hub works. The problem with it is that all devices can listen to all traffic. So there is a security concern. Plus we have the issue with half duplex. So with a hub we get collisions.

So the difference with a switch is, when a device sends a frame and it has some sort of destination MAC address on it, that switch is going to determine where that frame needs to go and then send it out just that port to just that device. So it's getting sent just to that device. So we've added security plus efficiency. So now multiple devices can actually talk at the same time with the switch, because it's not contention-based.

Collision domains

When we add a switch to a network, we've now split this from one big contention-based model, or what we call a collision domain, into lots of smaller collision domains. So in this scenario, we wouldn't really have collisions, because all devices are on separate ports of this switch. So we don't have collisions, and we don't have to worry about that contention. Therefore, our system here is going to run much more efficiently, since we have a switch involved here.

Duplex and speed settings

Because a switch could actually be plugged into lots of different devices, or possibly even another hub — maybe it's connected into a hub or another switch — there are settings on the switch itself to set to full duplex or half duplex. And so this can change depending on what equipment is on the other side. So we do have a setting on switches to set it to either half duplex or full duplex. By default, most switches are set to full duplex nowadays. And so therefore, you won't have any issues, because most of our equipment is able to handle that. But there are times when you may need to go in there and set it to half duplex if you have certain equipment set on the other side.

So another setting that's on the switch is the speed settings. Once again, you don't know what equipment is on this other side, and so you can set up the switch to have different speed settings on the different ports. Now, usually nowadays, equipment can autonegotiate. So they autonegotiate whatever speed they're going to communicate at, and you don't really need to worry about this. But there are times when you plug it into equipment where the speed needs to be set on it. And if you don't set that, then communication can be hindered, and you can have a bunch of errors on your switch. So just be watching out for that. There could be some older equipment that you plug into that you will have to manually set the speed on.

About TechKnowSurge

TechKnowSurge builds IT and cybersecurity professionals through hands-on, concept-first training built around real understanding — not memorization. Free interactive tools, structured programs, and 25+ years of real-world experience, all in one place.

Explore free tools and programs →