Maximum coupling links between two coupled rings in case of a failure in one of the coupled rings. If there is no connection starting from the switch in slave or local operational state over the route of the coupled rings or nets to oneself the slave or the local mode want to set the coupling port in forwarding after a timeout period. basicRedundancy(1) prevents the slave or the local mode from setting its coupling port into forwarding in case of the described failure. In this case the segment which is connected to this coupling port is unreachable until the failure is eliminated. In extendedRedundancy(2) the coupling port and the partner coupling port are allowed to be in forwarding.