4.2 Fault Tolerant

Enduring Understanding

Computer systems and networks facilitate the transfer of data.

Learning Objective

For fault-tolerant systems, like the Internet:

a. Describe the benefits of fault tolerance

b. Explain how a given system is fault-tolerant.

c. Identify vulnerabilities to failure in a system. 

Essential Knowledge

The Internet has been engineered to be faulttolerant, with abstractions for routing and transmitting data.

Redundancy is the inclusion of extra components that can be used to mitigate failure of a system if other components fail.

One way to accomplish network redundancy is by having more than one path between any two connected devices.

If a particular device or connection on the Internet fails, subsequent data will be sent via a different route, if possible.

When a system can support failures and still continue to function, it is called fault-tolerant. This is important because elements of complex systems fail at unexpected times, often in groups, and fault tolerance allows users to continue to use the network.

Redundancy within a system often requires additional resources but can provide the benefit of fault tolerance.

The redundancy of routing options between two points increases the reliability of the Internet and helps it scale to more devices and more people.