If you have a network of leased lines, you have options for how many sites you connect. Sites can communicate directly or through intermediate sites. 

a. In a full mesh, every pair of sites will be directly linked by a leased line. If there are N sites, there will be N*(N−1)/2 connections. In Figure 10-13, how many leased lines would be used in a full mesh?

b. In a hub-and-spoke network, there is a central site, and a leased line radiates from it to each other site. In Figure 10-13, how many leased lines would be used in a hub-and-spoke network with the hub located at Site A?

c. What is the benefit of full mesh networks over hub-and-spoke networks?

d. What is the advantage of hub-and-spoke networks over full mesh networks?

e. How would you use this information about advantages to advise a company about what to do when it installs a network of leased lines?