Hello and welcome back to I C. Ndy one interconnecting Cisco networking devices. Part one
this is episode 333 Analyzing where it's Ethernet switches, son frames.
I am friend Arun. I'll be your instructor for this course in the last video, one over some basic troubleshooting commands and methodologies for miss configured switches.
This episode of recovering how to think like a switch in where they're gonna send the frames and where the
should be. Sending the frames,
learning objectives were gonna think back and think about the 14 path of switch uses.
Good pre assessment here. What does the switch use for forging frames? Give me a few seconds.
All right, Hopefully you got the mac address table
Are so pass of the frame here. The biggest thing you don't want to use. The first command here is the show Mac address table dynamic.
This is gonna tell you if the Mac address is on the run port or, um
right. Just think back to the original
lesson that house switches forward. Friends that use that Mac users table
s use of messages. So kind of the steps that's gonna dio is gonna receive that frame on the incoming interface is going to say, Is this a trunk or access port? Do I have a port security violation? You know
things of that nature. And from there, if it's an access port, it's gonna say Cool. I just got a frame on F A 02
for on the line and 10. This is unauthorized. Airport security is not enabled.
So I'm gonna go ahead and take a look at the destination address or Mac address
on the Mac address table. If I have that Mac address in there,
I'm gonna go ahead and just send that frame out. That one port.
So for the destination, if it doesn't know where it's at,
is he gonna say, Okay, send it out. All ports, except for the one that came in on.
And if it's also, if it's, ah, broadcast frame instead of a unique *** for being a one for one
broadcast being want all it's just gonna flood that frame. So it goes out. All friends, except for all ports, except for the one who came in up.
So quick. Demonstration Here. We got Bob with it up with a B B. A suit with A a B, B, B B
and the Sun mail server with a B B C. C.
So I think What? Bob, over here.
he's gonna send a frame, too?
But I was gonna send a frame down to sue. Couldn't come in here. Say, is this an access board or a trunk port?
Do I have port Security enabled? No. Okay, so I received a frame on F A zero to We're all in the line. 10.
So it says Okay, so I do have a spot in my Mac address. Deal over Sue. So I'm gonna go ahead. Just send that out the trunk port for F A 0 24
and where it's gonna add that v land tag. Since the villian 10 is not native V lane on these switches,
So it's going to send it down to here. Switch to is going to receive that frame.
So you think Is this an access port or trunk port? This is a trunk port. It has a V Lyon tag. So it's gonna go ahead and say, OK, this is Mentor v. Lyon to on Mac address A a B B B B B
and it's gonna strip that veal and tag off and send it out. That known interface F A 06 for Sue.
How it runs, remember, is gonna go in,
determine where it needs to go. If it needs to go out a trunk port or not
that it will send it out. It'll tag it with villain 10.
Remember the Eastern ETS header?
And then when it gets in here, it's gonna strip off that
header and just go back down to the Internet frame
Real simple, um, rolled down and dirty. So what we're gonna do, I'm gonna go ahead and just bring up the Mac address deal for one of my switches.
Okay, let's bring up buddy.
I just did a reload on it. So what's going on? Get logged in cyber? Very.
Mr in a show. Mac, address table dynamic and see what we got.
All right, so we only had two. And 60 currently we are switch one.
So if we were to send a frame from, let's say if a zero to phaser six, it would immediately just come in and say, Okay, I gotta I gotta pour for that
I'm gonna send it out. You know, I fe 06
If we go to send a brain too in our device has not recognized in the Magno stable is going to say OK, flood the frame all ports except for F A zero to the one that came in on
That's basically what you're gonna wanna look at.
Look, a trunk poor configuration. Look at whether it's in the Mac address table. It was not in the Mac address table. A quick way to push it into the Mac address table is to get on that device physically or logically, and, um, send a ping to someone on the network. It might fail.
but what is doing is pushing frames and pushing packets through that switch so it'll register. That's Mac address to the interface.
So when I go ahead and get back down putting,
we will move on to the post assessment. So it's going to throw back here. What is the default aging timer for the Mac address table?
See if you remember here,
all right. It is 300 seconds or five minutes
in the next episode, we're gonna look at trouble shooting port security.
And, as always, if you guys have questions, need some help. Feel free to shoot me. Message. Otherwise, thank you for watching this video before to see me the next one.