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Reduntant Topoligies / Redundant switched topologies

Redundant Topoligies
7.1.2 This page will explain the concept and benefits of a redundant topology.
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 a 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. 
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.   
The next page will describe redundant switched topologies.
Redundant switched topologies
7.1.3 This page will explain how switches operate in a redundant topology.
Networks with redundant paths and devices allow for more network uptime. Redundant topologies eliminate single points of failure. If a path or device fails, the redundant path or device can take over the tasks of the failed path or device. 
If Switch A fails, traffic can still flow from Segment 2 to Segment 1 and to the router through Switch B.
Switches learn the MAC addresses of devices on their ports so that data can be properly forwarded to the destination. Switches flood frames for unknown destinations until they learn the MAC addresses of the devices. Broadcasts and multicasts are also flooded. 
A redundant switched topology may cause broadcast storms, multiple frame copies, and MAC address table instability problems.
The next page will discuss broadcast storms.

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