MS-ring Ethernet redundancy access algorithm

The invention discloses an MS-ring Ethernet redundancy access algorithm and relates to a technique to expand existing networks in an industrial Ethernet and maintain redundant link backup between the existing networks and newly-accessed networks. The technique is mainly applied to a two-layer Ethernet switch to enable two physical connections to exist between two Ethernets, one is main connection, another is backup connection, by default, communication of the two Ethernets is performed through the main connection, the backup connection serving as a backup of the main connection does not perform data transmission, and when the main connection fails, the backup connection can immediately execute functions of the main connection after the main connection is detected to be in a failure. All protocol messages designed by the MS-ring Ethernet redundancy access algorithm are transmitted only in one Ethernet, the newly-accessed networks and basic networks can independently execute ring network protocol algorithms of