Welcome back. It's back to the basics. I'm Sean Barr. And today we are talking about broadcast domains versus collision domains. Yes. Everything happens at layer two. Let's go. [MUSIC] All right, we're back and we are talking about broadcast domain versus a collision domain. So what's the difference? Well, before we talk about differences, let's talk about what each of them are. They both happened. Let's talk about that broadcast and collision. They both happened at layer two, their data link. At the data link layer of the OSI model. The big difference is a broadcast domain is essentially who can hear you on this segment. So for example, in a switch, we have these things called VLANs, and those VLANs will segment the broadcast domain. So if I have ports one through ten on VLAN one, those ports are in a broadcast domain. And that means port one can talk to port two, or any of the ports one to ten. It could talk to them without going through a router. And so a router operates at layer three, and can connect multiple layer two segments together. So essentially the broadcast domain essentially is a VLAN. If you have a hub, hubs don't have the VLAN capabilities traditionally from a hub definition. So basically it's essentially a wire that connects all the machines together and that is a broadcast domain. So everything that connects into that hub well see everybody else and has the ability to talk to one another. So that's broadcast domain. Collision domain also happens at layer two, but that is really around this CSMA CD Carrier-Sense Multiple Access Collision Detect. And so this is where in a switch there is a port and a host and those are on the same collision domain, on a switch. In a hub, every single port is in the same collision domain, meaning if two hosts on the same hub talk at the same time, we're going to have a collision, meaning two people are trying to transmit on the wire at the same time. They both detected, they both back off a random amount of time using the back off algorithm and they start transmitting again in a switch. The collision domain is isolated to the port, so a host in a port. So really in a full duplex type of port, you shouldn't have collisions unless there's a cabling type problem on a switch. So, those are the big differences on a switch, collision domain is isolated to the port, and you also have the ability on a broadcast domain level to segment the switch ports in VLANs. In a hub, every single port is in the same collision domain and every single port is in the same broadcast domain. So those are the big difference between a switch and a hub. We talked about kind of the differences between a collision domain on a hub versus a collision domain on a switch. And we talked about the broadcast domain, how it's pervasive within a VLAN or within a total hub because you have no segmentation. That's kind of why people started looking at switches because there are more efficient and transmitting traffic, you have less collisions, less dropped packets, less people backing off, you could transmit more readily. And then also if one host is talking to another, and the Mac address the can table and the switches built. Those hosts will travel directly to each other and all the other ports in that switch segment, or in that collision, or that broadcast domain would not see that traffic in a hub. They all see the traffic. So it's just much more efficient on the machines, transmission to switch versus hub. And those are the difference between a broadcast domain and a collision domain. If I said anything in this video that you go, hey, I'd love to hear more about it. Make sure you leave a comment, like, subscribe. So you get more videos and content like this and thank you for watching. We'll see on the next one. See you. [MUSIC]
