A collapsed backbone (inverted backbone, backbone-in-a-box) is a type of backbone network architecture.
The traditional backbone network goes over the globe to provide interconnectivity to the remote hubs. In most cases, the backbones are the links while the switching or routing functions are done by the equipment at each hub. It is a distributed architecture.
In the case of a collapsed or inverted backbone, each hub provides a link back to a central location to be connected to a backbone-in-a-box. That box can be a switch or a router. The topology and architecture of a collapsed backbone is a star or a rooted tree.
The main advantages of the collapsed backbone approach are
- ease of management since the backbone is in a single location and in a single box, and
- since the backbone is essentially the back plane or internal switching matrix of the box, proprietary, high performance technology can be used.
However, the draw back of the collapsed backbone is that if the box housing the backbone is down or there are reachability problem to the central location, the entire network will crash. These problems can be minimized by having redundant backbone boxes as well as having secondary/backup backbone locations.