WAN Topology Types

Point-to-point

One dedicated link joins two sites, such as a leased line between a head office and a branch. It is simple and predictable. The link is the single point of failure, and it does not scale: each new site needs its own link.

Hub-and-spoke

Every branch has one link to a central site, the hub. This needs only as many links as there are branches, which keeps it cheap, and it puts policy and security in one place. Traffic between two branches passes through the hub, which adds delay, and if the hub fails, every branch loses its path to the others and to central services.

Partial mesh and full mesh

A partial mesh adds direct links between selected sites, usually where traffic is heavy or resilience matters. A full mesh connects every site to every other, which gives the shortest paths and the most resilience at the highest cost.

Choosing a WAN shape

Match the topology to where traffic really flows. If branches mostly talk to head office and data centres, hub-and-spoke fits. If branches talk to each other a lot, add direct links where that traffic is. Reserve full mesh for a handful of critical sites. Whatever shape you choose, give important sites a second path, because the WAN link is the part you do not own. The same shapes appear again with VPNs and SD-WAN, where tunnels replace leased lines.

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