VLSM and their configuration

To configure VLSM on a router, follow these steps:

Determine the network requirements: Identify the number of hosts required on each network segment and choose an appropriate subnet mask based on that number.

Assign IP addresses: Assign an IP address and subnet mask to each network segment. The subnet mask should be based on the number of hosts required on that network segment.

Configure routing protocols: Configure routing protocols such as OSPF or EIGRP to advertise the subnet masks and network addresses to other routers in the network.

Verify the configuration: Verify the VLSM configuration by checking the routing table on each router and verifying that the correct routes are present.

Here’s an example of configuring VLSM on a router:

Suppose we have the following network requirements:

Network 1: 20 hosts

Network 2: 50 hosts

Network 3: 100 hosts

We can use VLSM to allocate appropriate subnet masks to each network segment. For example:

Network 1: 192.168.1.0/27 (subnet mask of 255.255.255.224)

Network 2: 192.168.1.32/26 (subnet mask of 255.255.255.192)

Network 3: 192.168.1.96/25 (subnet mask of 255.255.255.128)

Once the IP addresses and subnet masks have been assigned to each network segment, we can configure routing protocols such as OSPF or EIGRP to advertise the subnet masks and network addresses to other routers in the network. Finally, we can verify the VLSM configuration by checking the routing table on each router and verifying that the correct routes are present. We can use the “show ip route” command on Cisco routers to view the routing table.