Question

Given a class C network address 201.45.68.0 and the following subnet requirements:

a. Subnet A: must support 14 hosts
b. Subnet B: must support 28 hosts
c. Subnet C: must support 2 hosts
d. Subnet D: must support 10 hosts
e. Subnet E: must support 45 hosts

Draw the topology of the internetwork showing the main gateway router at the exit point of the internetwork, routers at the exit point of each subnet, and each of these routers connecting to the main gateway router (similar to the examples from the lectures). The above requirement does not include router interfaces, or the extra networks created by router interconnections (that is, you have to add them and account for them).

Design the subnetting scheme using VLSM.

Answer 1

The question involves creating a VLSM subnetting scheme for a class C network and drawing a network topology for five subnets. Subnet masks are calculated based on the number of hosts required for each subnet, with the largest being a /26 for 45 hosts and the smallest a /30 for 2 hosts. The topology includes the main gateway router and individual subnet routers connected to each segment.

Step-by-step explanation:

The question asks for a subnetting scheme using Variable Length Subnet Mask (VLSM) for a given class C network address. The scheme must accommodate five subnets with varying numbers of hosts. Network topology and subnet calculations are required.

Firstly, we calculate the necessary subnet masks based on the number of hosts needed for each subnet. We start with Subnet E which requires support for the largest number of hosts:

• Subnet E: Supports 45 hosts, thus needing a subnet mask that provides at least 6 bits for host addresses (2^6=64 addresses, providing 62 usable addresses). The appropriate mask would be 255.255.255.192 or /26.
• Subnet B: Supports 28 hosts, requires a subnet mask of 255.255.255.224 or /27.
• Subnet A: Supports 14 hosts, requires a subnet mask of 255.255.255.240 or /28.
• Subnet D: Supports 10 hosts, requires a subnet mask of 255.255.255.240 or /28.
• Subnet C: Supports 2 hosts, requires a subnet mask of 255.255.255.252 or /30.

Now, considering we need to include router interfaces, we need additional subnets for those connections. For simplicity, assume each router interface requires at least 2 host addresses, this means a subnet mask of /30 for each router interface.

To draw the topology, place the main gateway router at the center with connections to each of the subnet routers. Each subnet router will then connect to its respective subnet.