Abstract: A change of switch plane operation is performed in a multi-plane cell switching node (20) which has a first switch plane (22); a second switch plane (24); and plural switch port interface units (26). In response to detection of a fault in the active switch plane, the passive switch plane sends a plane change cell to the plural switch port interface units, and stops egress traffic flow from the second switch plane. Upon receiving the plane change cell, each switch port interface unit redirects traffic cells sent from the active plane to the passive switch plane. Each switch port interface unit then determines when traffic cells destined thereto have been flushed from the first switch plane, and changes its active switch plane designation (so that the formerly passive switch plane becomes the active switch plane) so that egress traffic flow can begin from the formerly passive (now active) plane to the respective switch port interface units.

Abstract: The present invention provides interconnection links between modules in a switch node. A redundant physical link couples the modules and a dual state data packet routing tag is used to identify which link is active. A standard tag received from an application device is converted to the dual state data packet routing tag, after the data leaves the application device so the interconnection link routing is essentially invisible to the application layer.

Abstract: A cell switch node (20) has a first switch plane (22); a second switch plane (24); a sender switch port interface unit (26S); and a receiver switch port interface unit (26R). The sender switch port interface unit sends maintenance cells to the receiver switch port interface unit via the first switch plane and the second switch plane. The maintenance cells are applied to the first switch plane and the second switch plane in a predetermined sequence. The receiver switch port interface unit detects an erroneous switch plane when the maintenance cells from the sender switch port interface unit do not arrive in the predetermined sequence.