Network Topology

physical layout vs logical layout

Physical topology refers to the placement of nodes and what type of transmission media connects them to the network. Logical topology refers to the flow of data through the network. Networks that have different physical topologies can have the same logical topology. For example, in a network where two nodes are connected via a single Ethernet cable and another network where both nodes are connected to a network switch, even though the physical layout (the physical topology) is different, the logical topology is the same since the end result is the same - the nodes can communicate with each other.

In the simplest type of topology, a single link is established between two nodes and is called a point-to-point link. P2P links can be either a physical or logical topology. For example, in an enterprise WAN, two router appliances can address each other privately, even when the data being sent between each other jumps between several intermediate networks and forwarding devices. In the end, it's the 1:1 relationship that defines the P2P link.