One-Way Link

　A unidirectional link refers to a set of redundant channels In the constructed point-to-point transmission mode information network, the local device can receive messages sent by the peer device through the link layer, but the peer device cannot receive messages from the local device.

There are two situations in which unidirectional links are generated: one is optical fiber crossover connection, the other is that one of the two optical fibers is not connected or is faulty. Unidirectional links can cause a series of problems, such as loops in spanning tree topology.

One-way link phenomenon In the actual networking process, in order to ensure the high availability and stability of the network, redundant transmission channel deployment is usually used in the backbone network construction process, that is, between equipment and equipment. Interconnection is not just through a single optical fiber channel, but there are two or more optical channels that jointly form a transmission channel, that is, multiple physical links jointly form a logical link to achieve communication purposes, resulting in multi-link Issues with channel status detection.