The architecture and mode of the APS group. The values mean: onePlusOne The 1+1 architecture permanently bridges the working line to the protection line. oneToN The 1:n architecture allows one protection channel to protect up to n working channels. When a fault is detected on one of the n working channels that channel is bridged over the protection channel. Note: onePlusOne and oneToN are mutually exclusive. revertive When the condition that caused a switch to the protection line has been cleared the signal is switched back to the working line. If this bit is clear it indicates a non-revertive system which remains on the protection line until another switch request is received. bidirectional The bi-directional mode provides protection in both directions. If this bit is clear it indicates unidirectional mode which provides protection in one direction. The default for 1:n is bidirectional. The default for 1+1 is unidirectional. extraTrafficAllowed Extra traffic may be carried on the protection channel in a 1:n architecture if this flag is set. It may be necessary to disable this in order to interwork with other SONET network elements that don't support extra traffic. onePlusOneOptimized If this bit is set it indicates that the protocol is: G.783 Annex B - 1+1 bidirectional switching optimized for a network using predominantly 1+1 bidirectional switching. When this bit is set set all other bits should be cleared. Multiplex section protection (MSP)1+1 optimized protocol pathProtection The path protection provides a protection in the SONET path layer. yCable Y Cable connects each port to two ports on the other device, transmissiion from both interfaces of the Y cable is forbidden when one of the interfaces has LOS and the other one doesn't a switch should be carried out. This object may not be modified if the associated apsConfigRowStatus object is equal to active(1).