The topic of this paper is Ethernet redundancy for serial device servers. Three types of redundancy are available:
- Single-network redundancy includes STP/RSTP protocols for mesh-type topologies, and the proprietary Turbo Ring protocol for ring-type topologies. Turbo Ring for Moxa's NPort 6000 series of secure device servers supports a recovery time of under 100 milliseconds, compared to a recovery time of about 5 seconds for RSTP.
- Dual-network redundancy includes Moxa's Redundant COM mode, which has a recover time of "zero seconds" due to the fact that data is transmitted simultaneously over both networks.
- Multi-host redundancy is set up to transmit the same data simultaneously to up to four hosts. The device server duplicates the serial data and transmits the data to all of the hosts at the same time.
In addition, Moxa's DRDAS mode provides a combination of dual-network and multi-host redundancy.