Time
15 hours 34 minutes
Difficulty
Intermediate
CEU/CPE
16

Video Description

Spanning Tree Protocol Lab For this lesson, we are looking at Spanning Tree Protocol display to examine the output data. For example, with the Root and Bridge ID data, for each component you'll learn how its calculated, what the calculation means, we'll demonstrate how to determine where the port and switch locations are, show you what dataset tells how long a switch holds on to the BPDU received on a port before the BPDU is discarded.

Video Transcription

00:04
So we're looking at art apology with switch one switched to switch three and switch for
00:09
this one's. I'm gonna first
00:11
log in to switch to
00:15
maximize this
00:17
and execute the command show spanning tree
00:22
and the villain we have. Let me shoot me as a reminder. Show reel and grief.
00:29
Remember, we created real and 1 50 yesterday
00:32
with names CCN eh?
00:36
So we're gonna check spanning tree for villain 1 50
00:40
So show standing. Three Villain. One
00:45
1 50
00:47
So here is your command output and I will go over it with you guys.
00:53
As you see, the priority does not see a 32 768 it saves 32 918
00:59
Why? Because, As I assured you, the priority field has been split into you have priority plus villain I D. So the priety is 32 +768 You add 1 50 to it. So 32 +768 plus 1 50 is 32 +918 The top portion
01:17
off this
01:18
command or the top stanza of this command, is all information pertaining to the root bridge.
01:25
So the priority of the root bridges 32 918
01:30
the Mac address of the route Bridge Is this guy here?
01:34
The number highlighted 0000164 a d o c. Nine
01:42
The cost. The route path cost to get to the root is 38.
01:49
So we at this point should be able to garner that the route is to switch is away
01:55
because the cost
01:57
for fast Internet All these links that we're running here are fast Internet links.
02:01
The cost for these links is 19. So when the cost is 38 you know that the BP do trance. First
02:09
two ports
02:10
enter two switches,
02:13
so the cost has been implemented locally from 19 to 38.
02:20
The hello time
02:22
or the time between bpd use is two seconds.
02:25
The four delay.
02:28
As I said, the time spent in listening and learning is 15 seconds, 15 seconds for listening and then 15 seconds for learning
02:37
the max each time. I would not worry about this at your level. The Max age is basically the number of seconds. Ah, switch will hold on to a B P. D. You received on a port before the bpd you is discarded. I said that once, but you don't really need to know what Max Ages at your level.
02:57
The bottom stanza of this command gives you information about the local switch about switch to
03:04
so switch to his priority is also 32 918
03:07
So why did this guy? Whoever this guy has become the route because it's Mac address was lower than switched two's Mac address,
03:15
even if the 1st 3 characters you see this guy, the Route bridge is 000 and
03:24
switched to is 00 d o. D is higher in hacks than zero
03:32
again. The hello time is set to or the time between bpd uses set to two seconds on the four. Delay is again 15 seconds is usually not recommended to mess with these timers.
03:45
Now, Port one
03:46
is alternate and remember, alternate ports are put in blocking, and the cost of that port is 19. Because it is a fast Internet link,
03:57
Port to
03:59
is also an alternate path to the route bridge. It's a non route, non designated port. Hence it was put in for blocking.
04:09
Don't worry about this number. This is the priority field for the port itself. It is the port priority. This does not come into play until you get to your C C in peace.
04:19
Port three, as you see, is your route port and it is put in forging.
04:25
So one route port, part non roots switch.
04:30
Port four is also alternate and blocking. So this is switched to
04:35
Let's go look at
04:38
switch one.
04:41
So switch one should be one Switch away from the root bridge since switch to was to two switches away and we have a total of four switches.
04:50
So when I say show spanning tree real and 1 50 the cost to the route bridge should say 19. See?
05:00
And there it is.
05:01
The cost to the route bridge
05:04
is 19
05:08
and the priority is 32 918 Same as you saw on switch to
05:14
the top stones again is information about the route
05:16
and the bottom stanza is information about switch one. The local switch Port three on switch one is the root port, and I will inform you that poor tree is connected to switch three. So switch three should be our route.
05:32
Port one is the designated port, which is connected to switch one.
05:38
So pulling up the topology.
05:41
Port one hair is connected to switch to show off course. This is the designated port or the downstream facing port.
05:47
And
05:48
I believe
05:53
port three
05:54
is your route port. And this is Port three up here where my r o. C. Which is connected to switch three. So let's go to switch three and check out
06:02
Check to see if that is the root shows man.
06:06
Phelan
06:10
1 50
06:18
and switch three Say's that this bridge is the root.
06:25
This is information Swiss trees providing about the route bridge. And this is information Switch three is private writing about about itself. However, you see the Mac address of the Route bridge and the Mac address off itself is the same. Which means switched three is the route bridge.
06:43
Also, as I said, all the ports on the route bridge will be designated ports. And you see that? That seems to be the case. All the ports on this switch, our designated and fording.
06:56
Now what if I wanted to make a switch? One. The route bridge.
07:01
Can I change which ones? So I'm back in switch wanted.
07:05
Can I change? Which one's Mac address? No, Mac addresses are hard coded.
07:11
Can I change its priority? Sure, I can.
07:15
So spanning tree
07:17
villain 1 50 And if I execute the help feature,
07:24
I see the option priority
07:27
so I can say priority.
07:30
And the default priority is 32 768 plus 1 50 which is 32 918 So I just need to set it to a number lower than this, and I believe 100 will do
07:42
so. Let's try and set it to 100
07:46
and it does not allow me to set the priority to 100.
07:49
Now, remember that number I asked you to remember on the villain I d field when the priority field has been broken into four bit priority and 12 villain I d. That first bit value for the villain I d part was 40 96. That wasn't it.
08:05
Hence, because just those four bits were designated as a villain, I d. You can only make changes to the priority field in increments off 40 96. So British priority must be in increments of 40 96 which is why I put the bit values on the board
08:24
to make sure you understood this.
08:26
This part
08:28
So can I make the priority? Zero. Sure I can.
08:31
And now if I said you show
08:35
span short for spanning tree villain 1 50
08:41
Switch one Say's that it is the root bridge,
08:46
and that concludes for now, the spanning tree lab.

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