Welcome back everyone. Did you think you were going to get away with not getting into spanning tree? Did you I mean, switch is the switch. So you know, spanning tree has to be a part of it. Okay. So now, we already know more or less what ICP does.
We should know at this stage, but they want you to make sure right, so first let's review a little bit how switches work. Okay, you know, probably discussed it already. Let's discuss it again. Switches by nature, they forward, they forward information. That's their job. They take their learning addresses, write source addresses, they get it, they float out.
They don't, it's not in the MAC address table. They float out all the other ports. So they started learning learning. That's how they create their MAC address table. Right? But they don't stop forwarding.
They don't stop forwarding. Nice okay. Don't have any redundant links. All right, but you know, like it says they're in a more verbose network robust network, you want to have redundant links in your network. So that causes a problem if you ever done a link to your network, and switches for by nature, and one of the 14 Bridge protocol data units BPD use. So Cisco came up with this Spanning Tree Protocol, right Spanning Tree Protocol to have a loop free topology loop free.
So one of those ports, or several of those ports, depending how big your network is and how much redundancy you have. It will block block several ports or just one or what have you. All right, to stop it from forwarding now listening, stop it from forwarding. All right, and here just put a header on here. We're also going to go ahead and discuss the other types of Spanish that exists in oh two one D is the most commonly known everybody you know normally is the one that was used PVS T and then PVS t plus all these are Cisco proprietary Cisco proprietary protocols right in order to prevent a loop free environment now they all do different things obviously as you go down the list they're more enhanced they do more things in order to make your network you know more net mega mega better they can tweak it a lot better.
So this is what we're going to talk about now is spanning tree spanning tree okay and I know that it may like oh my god not again Bo Yes, but you need to know spanning tree because I guarantee you. I guarantee you you will be seeing questions on spanning tree. Okay, just remember that we know spanning tree is a loop free. That's its purpose to prevent loops and switching whether it's layer three switching or loop To switching, that's his purpose. Okay. And then we'll take a look at the other ones.
All right, but definitely, you have to have redundancy. You know, you can't get away from that you have to have, we don't know. So without that, I'll see you in the next one.