13 hours 57 minutes
Hello and welcome back to I see anyone interconnecting Cisco networking devices. Part one,
this is Episode 2 to 4 of the Mac address Table
is always on Triton, dear. When I'm gonna be instructive for this course
the last video we went over how the switch learns the Mac address of its hosts and connected devices. And what happens when the broadcasts and unknown unique rats destination frames? What happens with those
this episode of recovering the Cisco Mac address table? What aging means and what the mag address table might look like with two. Switch is hooked up to it.
All right, learning objectives for this, we're gonna look at the show commands of the Mac address table
how the switch ages, the Mac entries and a live demonstration of the Mac address table.
And hopefully you guys excited as I am about actually breaking up this lab equipment. I remember when I was first learning. I was super excited when I was actually working on the equipment and using commands and counseling into it
and, you know, working with command line stuff. That was super fun to me. I had a ton of had a great time I was just stuck up in the office for hours. The wife loved it.
so I hope you guys are excited about this. I've had about 1/2 a pot of coffee. It's January in Michigan. It's actually sunny outside.
So I'm excited for this.
Are so quick. We're gonna do a throwback pre assessment here because we are going to connecting two switches together. What kind of cable is needed to connect the two switches? So I'll give you a few seconds to think about it. Consult your notes, see if you can get it going.
All right. It is D cross over cable, remember to like devices. They're gonna need that cross over now. If we connected a switch together with a computer or a router, we would use a straight through the roll over cable is the council cable that we currently have plugged into it in our party session and co axial is used for Cable modems
are so quick, lad. No, here as always. So I kinda expanded on it a little bit this time. Finally,
uh, so the SoHo router does have the Internet hooked up to it and also does have the rest of my network hooked up to it. Now, in your actual lab environment, I'm gonna suggest that you just keep some stuff hooked up to just the switches and routers not actually connected into your actual production or, you know, your home network.
so it's a very good idea at first when you're learning all this. I know I did. Every time I want to go do a lab, I would default configuration and write everything out.
Um, it's a very good way to learn how to do the commands and know what command you need to do
what you need to do to get it running. And the way that I did it was I had a
that had all my commands that I would use kind of as a base configuration for these devices so I'd have one for my switches, my routers, and we're gonna go over some. You know, we're gonna expand on all those commands in every episode.
So one that I'm gonna really enjoy getting out of the way
iss the helpful, useful commands it will hit the next lesson.
Uh, that one's gonna make. Using the switch is a little bit easier,
and you'll see some of the issues that we're gonna run into without those commands. So I've actually defaulted both of these switches. I have not put the villain I p addresses. And yet the only thing I've done has changed the host name.
That is that everything else is still just defaulted.
All right, so what about the Mac address table? That's the picture that you guys have been seeing for down a few episodes now.
So what I did was did a show Mac address table with that question mark. So it shows the next command that I can use the next war that can, Using that command. So what aging does is wanna frame with that source address comes in a switch. It's going to see. Is there an entry already for this Mac address? If it is, it's going to set that timer
back to zero.
If it doesn't have an entry, it's actually just gonna add it to the table and said it to zero as well.
But if it doesn't receive a frame from that device within
that, whatever that determined timer is, it's gonna remove that entry from the Mac address, table
extended, assumed that that connection is dead. So if you know, shut off your computer or something. Um, the default aging timer on the Cisco switches is 300 seconds or five minutes.
All right, so if it doesn't receive a frame for these devices for 300 seconds is gonna remove it from that Mac address table now off the table starts to fill up, and it still has some processing power left. There's ways to flood it, but
it is actually gonna remove some of the older ones. So if if you have a timer that's a 100 seconds, 200 seconds to 250 seconds, let's say the
the timer is that you know, you only can have three Mac addresses. Let's just say, for example, um, and then a couple more come in. It's going to start removing the older ones. That's going without 2 50 than the 200. And you know it's going to slow work his way back down the line unit. They haven't reached that Mac address table.
so we are gonna go ahead and do a quick demo of the Mac address. They won't bring up the party session
and see we're logged out because we don't have the exact time out set up. We're gonna go into a naval mode or privilege mode
and see what we currently have connected. Show Mac address table.
I'm gonna just couldn't do dynamic. It just makes makes a little cleaner. You avoid all CPU, Mac addresses.
So again, because I'm sure you guys can guess which port I have. My
so hot rodders plugged in to remember because it has a ton of the order
devices on there.
And we have port 24.
It is plugged into which one?
I support 24. It's plugged in to switch to
Port one has the a boon to server. And then I have port to plugged into my another laptop, just offhand.
so if we do a
aging, aging timer.
So I have the aging timer says 300 seconds right now.
Now, if you look at this some very useful things. Uh, let's say you have suits. You just happen to know the Mac address
of one of these.
And you have you know, 48 ports switch unless you stack five switches. You looking at
almost 250 addresses. You know, that's a huge Mac address table, and you don't want to go searching through that. What you can do is do a show, Mac address, table
address. And what does it want for the address? The 48 bit Mac address in this specific?
I think so. Let me go back up here and copy one
and paste it in.
It's going to show you exactly what port that's out
and you could do the same thing. If you're trying to trace trace back down a certain of ice,
you could do a show Mac address table in her face F a 01
I'll show you what devices on there.
So let's say you're you are having issues with duplicates and you just need to do it or kind of reload that Mac address. Still, we need to clear it out.
We're gonna do clear
Mac address, table
So all these show commands can actually, So I'm gonna go into disable,
and we're gonna do a show Mac address. So this is just showing that you that you don't have to be into
you don't have to be in privilege mode to run the show commands you could do. Show Mac
dressed Abel interface if it is your one.
Oh, my booty, sir. Must be sleeping.
so you don't actually need to do that, but to do it's a clear Mac dress table. It's not gonna let us
for the clearing of it. We do have to be an enable mode.
So you'll see me go back in here where it says incomplete. So if we hit the question mark
that we have to choose one of the options. So if you wanna dynamic and it question mark, we see the CR,
which means that that could be the end of the command. Okay,
when the race that
and we will get off Puddy
and we went to the post assessment.
All right. What is the default aging timer on the switch? Give me a few seconds.
All right. It is 300 seconds where the default is 300 seconds. There were five minutes
and again. Guys, remember, set up the switches, play with them. Um,
if you're gonna play with him, remember the one thing you can do to make sure they always kind of to do it. Don't do a copy. Running configuration started configuration or copyright start.
Um, you know, especially if you're playing with them. And you're just
I kind of see what you can D'oh.
Don't do a cop. You're a star. Because then if you get into a mode where you know, you broke something and
you could just unplug it, plug it back in
and it should go back to that base configuration.
Our guys in the next lesson, we're gonna go look at configuring basics. Which management?
All right. As always, if you have questions and help, go and shoot the message, I'll be happy to help. You know otherwise. Thank you for washing this lesson. Look forward to seeing you next one.
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