CCNA Cisco subnetting (compute and assign addresses using VLSM)

The number and grouping of hosts are as follows:

Student LAN

Student computer: 460

Router (LAN Gateway): 1

Switch (Management): 20

Total student subnets: 481

Teacher LAN

Teacher Computer: 64

Router (LAN Gateway): 1

Switch (Management): 4

Total Teacher Subnets: 69

Administrator LAN

Administrator computer: 20

Servers: 1

Router (LAN Gateway): 1

Switch (Management): 1

Total administrator Subnets: 23

WAN

The Wan:2 between routers

WAN Total: 2

Calculate and assign addresses using VLSM

Use the VLSM allocation method to assign a smaller block of addresses to each network as needed.

Address Block 172.16.0.0/22 (subnet mask 255.255.252.0) has been assigned to the entire internetwork. 10 bits will be used to define the host address and subnet. The result is a 1024 IPv4 local address, ranging from 172.16.0.0 to 172.16.3.0.

Student LAN

The largest subnet is a student LAN that requires 460 addresses.

Use the formula available host number = 2^n-2, borrowing 9 bits as the host part, and 512-2 = 510 available host addresses. This quantity is in line with current requirements and there is little room for future development.

Using 9 master seats also leaves 1 bits available for locally defined subnet addresses. We use the smallest available address to derive the subnet address 172.16.0.0/23.

The mask for student subnets is calculated as follows:

Address: 172.16.0.0

Binary representation:

10101100.00010000.00000000.00000000

Mask: 255.255.254.0

Represents 23 bits in binary:

11111111.11111111.11111110.00000000

In the student network, the IPV4 host address range is:

172.16.0.1 to 172.16.1.254, broadcast address is 172.16.1.255.

Because these addresses are already assigned to student LANs, they can no longer be assigned to the rest of the subnets: Teacher LAN, Administrator LAN, and WAN. The 172.16.2.0 address is the address within the range of 172.16.3.255.

Teacher LAN

The second largest network is the teacher LAN. This network requires a minimum of 66 addresses. If you use 6 as an exponent in the power formula of 2, 2^6-2 can only provide 62 available addresses. Therefore, you must use an address block that has 7 master seats. The calculation 2^7-2 can draw an address block with 126 addresses. This leaves 25 bits to be assigned to the network address. The next available address block of the same size is the 172.16.2.0/25 network.

Address: 172.16.2.0

Binary representation:

10101100.00010000.0000010.00000000

Mask: 255.255.255.128

Represents 25 bits in binary:

11111111.11111111.1111111.10000000

The IPV4 host address range provided is:

172.16.2.1 to 172.16.2.126, broadcast address is 172.16.2.127.

From the original address block 172.16.0.0/22, assign the address 172.16.0.0 to 172.16.2.127. The remaining assignable addresses are 172.16.2.128 to 172.16.3.255.

Administrator LAN

The administrator LAN needs to support 23 hosts. Therefore, you need 6 master seats and use the calculation: 2^6-2.

The next available address block that can support these hosts is the 172.16.2.128/26 address block.

Address: 172.16.2.128

Binary representation:

10101100.00010000.0000010.10000000

Mask: 255.255.255.192

Represents 26 bits in binary:

11111111.11111111.1111111.11000000

The IPV4 host address range provided is:

172.16.2.129 to 172.16.2.190, broadcast address is 172.16.2.191.

The result is a 62 unique IPV4 address for the administrator LAN.

WAN

The last network segment is a WAN connection and requires 2 host addresses. Support WAN links with just 2 primary seats. 2^2-2 = 2.

This leaves 8 bits to define the local subnet address. The next available address block is 172.16.2.192/30.

Address: 172.16.2.192

Binary representation:

10101100.00010000.0000010.11000000

Mask: 255.255.255.252

Represents 30 bits in binary:

11111111.11111111.1111111.11111100

The IPV4 host address range provided is:

172.16.2.193 to 172.16.2.194, broadcast address is 172.16.2.195.

CCNA Cisco subnetting (compute and assign addresses using VLSM)