Mesh networks and link density
All mesh networks are not the same. One important attribute of a mesh network is the link density, defined as “number of links implemented” divided to “maximum number of links that can be implemented” for the nodes of the network.
To find the theoretical maximum number of links, we use simple mathematics as following: for a network consisting of N nodes, the theoretical maximum number of links that can be created in a mesh network is N*(N-1)/2. This maximum is reached when all nodes are interconnected, thus each of the N nodes is connected to the rest N-1 nodes.
For example, in a small network consisting of 7 nodes, if we implement a full mesh architecture we can have a theoretical maximum number of 21 links (=7*6/2). So, if we implement only 8 links, then the network link density will be 8/21=0,38.
Let’s see another interesting example to understand why link density is important. In a medium size network consisting of 50 nodes, we see that the maximum number of links is 1225 (=50*49/2). This is a very big number that in real life will never be implemented due to investment cost. A more realistic scenario would be to implement 74 links, arranged in a tree topology, with maximum link length = 5 km, scattered around a 30 × 30 km region. In this case the link density 74/1225=0,06.
It seems obvious that the higher the link density, the more capable the NMS will become to re-route traffic to maximize bandwidth utilization. But as we see in the two above examples, the bigger the network, the smaller the link density that is can be achieved in the real world.
So how do we select which nodes to interconnect?