Seamless Redundancy

Frame Replication and Elimination for Reliability (IEEE P802.1CB)

To ensure robust and reliable communication, control systems must be tolerant to packet loss due to congestion, link failures, cable breakage and other faults. To minimize the impact of such faults, P802.1CB aims to send duplicate copies of critical traffic across disjoint paths in the network. If both frames reach their destination, the duplicate copy is discarded. If one copy fails to reach its destination, the duplicate message is still received, effectively providing seamless redundancy. 

 

To minimize network congestion, packet replication can be selected based upon address/traffic class and path information. Likewise, duplicate frame elimination can be based upon address/traffic class and timing. In other words, only critical traffic need be replicated. Best effort and other traffic tolerant to congestion loss can still be transmitted normally.