Network partitioning is a situation, when a computer network is divided into two or more distinct and independent subnetworks.
Suppose, if there are network glitches causing the link/path between nodes 6 and 7, as well as 7 and 9, to break, then the network will be split into three partitions.
Partition 1: nodes 1, 2, 3, 4, 5 and 6
Partition 2: nodes 7, 8 and 9
Partition 3: nodes 10, 11 and 12
In the event of a network partition, applications on one side of the partition will be unable to communicate with applications on the other side, potentially resulting in issues such as data inconsistencies and data loss.
Common questions to address when designing partition-tolerant applications include:
a. What will happen once network failure is rectified, and connectivity is reinstated between these partitions?
b. Will these partitions merge into one again? If they do, how are the data conflicts resolved?
c. How are user requests handled during a network partition? What is the system's behaviour in such scenarios?
Reasons for network partitioning
a. Hardware failures, such as malfunctions in network components like switches and routers.
b. Software glitches within network software.
c. Errors in network configuration can contribute to the creation of partitions within the network.
d. Security attacks might cause a network partition.
e. In some cases, network partitioning is intentionally designed to check fault tolerant applications functionality.
Consequences of Network Partitioning
Breakdown in Communication: Nodes within one partition are unable to communicate with those in another partition. Applications on one side of the partition will be unable to communicate with those on the other side.
Inconsistency in Data: Independent updates to data in different partitions may result in inconsistencies when the partitions are subsequently merged.
Data Loss: Data in transit during a partition may be lost.
Degraded Performance: Overall performance of the distributed application may be degraded.
How to mitigate the effects of network partitions?
Redundancy: The incorporation of redundant network devices and pathways serves as a preventive measure against the occurrence of partitions.
For instance, by maintaining a pathway between nodes 5 and 8, as well as 8 and 10, disruptions in the network between nodes 6 and 7, as well as 7 and 11, do not affect the system.
Partition detection and recovery: Mechanisms can be implemented to identify network partitions and initiate automatic recovery processes.
Partition-tolerant applications: Applications should be designed to operate seamlessly even when they are partitioned from other sections of the network.
Understanding and effectively managing network partitioning is essential to guarantee the reliability, availability, and fault tolerance of distributed systems.
System Design Questions
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