In the previous video, we have created 2 topology like this. Here we have room 1 and here we have room 2. 2
In the room 1, we have 2 vlan, which is vlan 10 for accounting and vlan 20 for marketing. 3
In the room 2, we also have same vlan, which is vlan 10 for accounting and vlan 20 for marketing. 4
Until now, we know that between different vlan can not communicate yet. 5
So PC in vlan 10 can not communicate with PC in vlan 20. But communication inside 6
vlan should be ok. Let’s say here PC 1 should be able to communicate with PC 2. 7
Now the question is, how if two PC in the same vlan, 8
but in the different room. Can they communicate each others? 9
For example, here we want to communicate from vlan 10 in the room 1 with vlan 10 in the room 2. 10
Now let’s try to connecting switch 1 and switch 2. Okay now here room 1 is connected to room 2. 11
Now let’s try to ping from vlan 10 in room number 1 to vlan 10 in room number 2. 12
Okay here we can see that the result is failed. Let’s try again, 13
okay still failed. 14
Why this is failed? This is because the interface that connecting between switch 15
is not in the vlan 10. Let’s verify it, enable, and then show vlan brief. 16
Oh I am sorry, here we can see that fa0/5 and fa0/6 is in the vlan 10, 17
this is because our configuration in the previous video. Now let’s set this two 18
interface to the vlan 1 again. Remember that by default, all interface is in the vlan 1. 19
Conf t, interface range fa0/5-6, switchport access vlan 1. Now let’s verify it, do show vlan brief. 20
Okay here we can see that fa0/5-6 is in the default vlan, which is vlan 1. 21
Now let’s see in the switch 2. 22
Enable, show vlan brief. Here we can see that fa0/5 is in the vlan 1. 23
This is why vlan 10 in the room 1 and vlan 10 in the room 2 can not communicate each others. 24
Because interface that connecting this two switch is in the vlan 1, 25
so vlan 10 can not passing this interface. Because this interface only allow vlan 1 to pass. 26
Here also same with vlan 20, vlan 20 in the room 1 27
also can not communicate with vlan 20 in the room 2. 28
So the question is, how we can communicate between vlan 10 in the room 1 to vlan 10 in room 2? 29
Here we can assign interface fa0/5 in both of switch to vlan 10. 30
So here let’s go to interface fa0/5, switchport mode access, and then switchport access vlan 10. 31
Now let’s verify it, do show vlan brief. Okay here we can see that fa0/5 now is in the vlan 10. 32
Next let’s configure in the switch 2. Conf t, go to interface fa0/5. 33
Switchport mode access, and then switchport access vlan 10. 34
Let’s verify it, do show vlan brief. Okay here we can see that now fa0/5 is in the vlan 10. 35
Now, vlan 10 in the room 1 should be able to communicate with vlan 10 in room 2. Let’s try it. 36
Okay here is still failed, let’s try again. 37
and here we can see that now is successful. 38
This is because interface between switch is in the vlan 10. So vlan 10 can pass this interface. 39
But the question is, how about vlan 20? 40
Let’s try it. 41
Okay here the result is failed. Why? Because interface between switch now Is in the vlan 10. 42
Absolutely vlan 20 can not pass this interface. 43
We can assign the interface between switch to vlan 20, 44
but vlan 10 will not able to communicate between rooms. 45
So the solution for this problem is we can 46
use trunk. We will configure the interface that connecting this two switch become trunk. 47
If we configure the interface to trunk, 48
so the interface can pass any packet from any vlan. So vlan 10 can pass the interface, 49
vlan 20 can pass the interface, and all of vlan can pass the interface. 50
Let’s try it. Open switch 1, interface fa0/5, and then switchport mode trunk. Okay this is how we 51
can configure trunk in cisco switch. Easy right? Now let’s move to switch 2, 52
interface fa0/5, switchport mode trunk. And now Let’s verify, 53
to verify the trunk, we can use command do show interface trunk 54
Here we can see that we have trunk interface, which is fa0/5. 55
Now let’s try to ping from vlan 10 room 1 to vlan 10 room 2. 56
Okay here we can see that the result is success. Let’s try for vlan 20. Okay here also success. 57
So now, same vlan between room can communicate each others. 58
Because we already configure trunk between switch. Okay I think enough for this video. 59
I hope you understand the function of trunk. 60
Thankyou for watching and see you on the next video.