Abstract: Spanning tree bridge is devised to minimize the service interruption time after occurrence of a fault in a network or in a component of the network by enabling faster recovery from the fault and by limiting tree reconstruction to a smallest possible area. In a bridged LAN formed of a plurality of LANs, a plurality of spanning trees are defined in one bridge such that a spanning tree is divided without dividing a LAN segment. To enable this, a plurality of spanning tree management units are provided in one bridge and are given unique bridge IDs for spanning tree management units. The arrangement is such that ports can be assigned to the spanning tree management units in a predetermined relationship. Therefore each management unit can independently perform spanning tree construction processing to divide a spanning tree in one LAN segment into a plurality ones, and a bridged LAN in which a plurality of spanning trees can exist in one LAN segment can be formed.

Abstract: A method is disclosed for setting transmission routes in which the transmission bandwidth is expanded by incorporating in a virtual concatenation signal those protection paths that are in a normal standby state. A protection control means selects paths to use in accordance with the state of each path in a redundancy configuration that is realized by prescribed working paths and protection paths. A bandwidth management means receives the states of working paths and protection paths from the protection control means. The bandwidth management means then incorporates protection paths in a virtual concatenation signal that includes working paths if the protection paths are in a normal standby state. If the protection paths are in an unusable state or in a used state, the bandwidth management means constructs the virtual concatenation signal with only paths that can be used in virtual concatenation.

Abstract: Spanning tree bridge is devised to minimize the service interruption time after occurrence of a fault in a network or in a component of the network by enabling faster recovery from the fault and by limiting tree reconstruction to a smallest possible area. In a bridged LAN formed of a plurality of LANs, a plurality of spanning trees are defined in one bridge such that a spanning tree is divided without dividing a LAN segment. To enable this, a plurality of spanning tree management units are provided in one bridge and are given unique bridge IDs for spanning tree management units. The arrangement is such that ports can be assigned to the spanning tree management units in a predetermined relationship. Therefore each management unit can independently perform spanning tree construction processing to divide a spanning tree in one LAN segment into a plurality ones, and a bridged LAN in which a plurality of spanning trees can exist in one LAN segment can be formed.

Abstract: In a fault evaluating system for a transmission apparatus having four packages which are mutually duplexed in both transmission and reception directions and bridged to oppose each other, each package includes a fault detection unit, a fault information extraction unit, a fault information insertion unit, and a fault evaluating unit. The fault detection unit individually detects an abnormality in signals transmitted from duplexed opposing packages. The fault information extraction unit individually extracts fault information representing a fault package, which is contained in the signals transmitted from the duplexed opposing packages. The fault information insertion unit generates fault information representing the fault package in accordance with a detection output from the fault detection unit, inserts the generated fault information and the fault information extracted by the fault information extraction unit in a signal to be transmitted, and sends back the signal to the duplexed opposing packages.