VLSM - Variable Length Subnet Mask

Packet Tracer Exercise 8.2.1.4

If there are subnets with different ammounts of hots needed, VLSM is used. In this exercise you recive one of three different setups. You have to design a VLSM addressing scheme and configure the devices using the addressing scheme.

In one of the setups you need:

• One LAN with 14 hosts (ASW-1)
• One LAN with 30 hosts (ASW-2)
• One LAN with 6 hosts (ASW-3)
• One LAN with 60 hosts (ASW-4)

To get the IP-Addresses for the subnets you first need to sort the networks from subnets with most to least hosts.

• ASW-4 (60 hosts) - 6 bits needed to display
• ASW-2 (30 hosts) - 5 bits
• ASW-1 (14 hosts) - 4 bits
• ASW-6 (6 hosts) - 3 bits

To understand what values you need for the subnetmask the picture below shows the number of hosts for one subnet and the network-addresses.

Over the whole square you have 256 values (8 bit). In 1/4 of the square you have 64 values (6 bit). In 1/8 of the square we have 32 values (7 bit). . .

The network is always the first address in the subnet so now we can see where the first addresses in the subnet are.