4.2 Fault Tolerance

1. Exam Points

• Fault-tolerance
  • What: When a system can support failures and still continue to function, it is called fault-tolerant.
  • How: Provide multiple paths between devices to achieve fault-tolerance.
• Characteristics and benefits of routing redundancy - Reliability. The system still works when some network devices or connections fail.
• Find the minimum number of connections to remove in a network to disconnect two devices. (cut, and find the cut with the least connections.)

2. Knowledge Points

(1) Fault Tolerance

• The Internet has been engineered to be fault-tolerant(容错的), with routing and transmitting data.
• Redundancy(冗余) is the inclusion of extra components(Ex. devices) 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(容错的).
• Redundancy within a system often requires additional resources but can provide the benefit of fault tolerance.
• The redundancy of routing(路由冗余) options between two points increases the reliability of the Internet and helps it scale to more devices and more people.
• Find the minimum number of connections to remove in a network to disconnect two devices.
  • Trick: Cut necessary connections, and find the cut with the least connections.
    
    

3. Exercises

• Practice
• Solution