In a redundant ring network, a total failure of one of the ring switches is likely to mean that a connection to all of the nodes attached to that switch are lost. For this reason, some system designers use PCs and devices with dual Ethernet ports and attach the devices twice to the network. It can be difficult to manage dual attachment in this way, creating extra work at the application layer or complex configuration of redundant NIC pairs.
The ESD42 switches are designed to overcome these problems by providing an operating & standby connection to the network, switching over to the standby path automatically in the event of a failure.

See datasheet for the product types available or see the IPS42 datasheet for mains / high voltage powering options.