A goal of redundant topologies is to eliminate network outages caused by a single point of failure. All networks need redundancy for enhanced reliability.

A network of roads is a global example of a redundant topology. If one road is closed for repair there is likely an alternate route to the destination.

Consider an outlying community separated by a river from the town center. If there is only one bridge across the river there is only one way into town. The topology has no redundancy.

If the bridge is flooded or damaged by an accident, travel to the town center across the bridge is impossible.

Building a second bridge across the river creates a redundant topology. The suburb is not cut off from the town center if one bridge is impassable.

Web Links Understanding Spanning-Tree Protocol – the Fundamental Bridging Algorithm http://www.oreillynet.com/pub/a/ network/2001/03/30/ net_2nd_lang.html