In the previous video, we already done doing subnetting calculation with different case. 2
Next in this video, we are going to learn about the concept of block subnet. In the previous video, 3
I said that block subnet is just like a room. This is the result of our calculation before. 4
Here we have block subnet 1, 2, 3 and so on. We can imagine that each block subnet is used in each room . 5
Let’s say we have a building and in the building we have room 1, 2 and 3. 6
So we can use the first block subnet for room number 1, 7
second block subnet for room number 2, and third block subnet for room number 3. 8
Let’s say in the room number 1 there are 15 pc, room number 2 also has 15 pc, and room number 9
3 also has 15 pc. 15 pc in the room number 1 can use ip range from first block subnet, 10
15 pc in the room number 2 can use ip range from second block subnet, 11
and finally 15 pc in the room number 3 can use ip range from the third block subnet. 12
One thing that you need to remember is that by default, each block subnet can't 13
communicate each others. So let’s say here we have PC 1 and PC 2. The ip address of PC 1 is 10.10.10.10 14
and the ip address of PC 2 is 10.10.10.20/27. 15
In this case, PC 1 and PC 2 can communicate each others, why? 16
Because these 2 pc is in the same block subnet. Which is first block subnet. 17
Here we can see that 10 is in the first block subnet, and 20 also in the first block subnet. 18
Okay, so PC 1 can communicate with PC 2 because they are in the same block subnet. 19
But how if the ip address of PC 1 is 10.10.10.15/27, and the ip address of PC 2 is 20
10.10.10.50/27? In this case, these 2 pc can not communicate each others. Why? 21
Because PC 1 is in the first block subnet but PC 2 in the second block subnet. 22
Okay let’s try it in the Cisco Packet Tracer. 23
Here we will configure the ip address as our calculation before. We will use the first case first. 24
The ip address of PC 1 is 10.10.10.10/27 and the ip address of PC 2 is 10.10.10.20/27. 25
Okay let’s configure the ip address of PC 1. Go to dekstop, ip configuration, 26
the ip address is 10.10.10.10, the subnetmask is 255.255.255.224. 27
remember that this subnetmask is the result of our calculation before for prefix /27. 28
Okay next, let’s configure the Ip address of PC 2. The ip address is 10.10.10.20, 29
and the subnetmask is 255.255.255.224. close this, and open the command prompt. 30
Here let’s try to ping to the PC 1. Which is 10.10.10.10, here we can see that the ping 31
from PC 2 to PC 1 is successful. 32
Next, let’s try the second case, so the ip address of PC 1 will be 10.10.10.15/27, 33
and the ip address of PC 2 will be 10.10.10.50/27. Go to PC 1, here let’s change the ip address to 15. 34
Next go to PC 2, and change this to 50. 35
Now let’s ping to PC 1. Which is 10.10.10.15. 36
Okay here we can see that the result is request timeout. This is means that PC 2 and PC 1 can not communicate each others. 37
Okay I hope you now understand the concept of block subnet. Remember that by default 38
each block subnet can not communicate each others. But some of you may be have a question, 39
how if we want to each block subnet can communicate each others? For that case, 40
we will need additional device, which is router. We will learn about router in the next video. 41
Okay I think enough for this video. Thankyou for watching and see you on the next video.