Subnetting

Before we get into segmentation, let’s discuss subnetting. It is easy to confuse subnetting and segmentation. Yes, most likely your network has multiple subnets, but this is not segmentation. Subnets ensure the broadcast domain of devices on the network is smaller. A broadcast domain is essentially the set of all devices on a network subnet that can reach each other by broadcasts at the data link layer (Layer 2 of the OSI model). When your computer connects to the network, your network interface card typically performs certain network discovery operations that involve broadcasting or multicasting. For example, it might use Address Resolution Protocol (ARP) broadcasts to resolve IP addresses to MAC addresses within its subnet. When a network is divided into subnets, each subnet forms its broadcast domain. This means broadcasts sent by a device in one subnet are not propagated to devices in other subnets. If a network has large subnets, then potential network congestion...