Partial Mesh Topology

Let's take a figure as an example:

Let's suppose A frequently communicates with D then let's make a link between them. For suppose B frequently communicates with C then make a link between both of them, and if C does not frequently communicate with anyone so if C want's to send something it can go through headquarter. Notice that at this time we have got 6 links and this is called partial mesh topology. It is a subset of a full mesh. In partial mesh topology links are strategically added based on traffic patterns.