Abstract: A system and a method for providing an emulated network including a plurality of emulated networking devices, in which a number of network node executable images are employed. Each of the network node executable images corresponds to one of the emulated networking devices. The emulated networking devices represent physical networking devices, such as optical switches. A portion of each of the network node executable images is operable to execute without modification on a physical networking device.

Abstract: Each span of a communication network, such as a BLSR ring, is assigned a unique span ID. When a node of the network detects a failure in a span (including a straddling span) of the network, the node exchanges commands, according to an automatic protection switching (APS) protocol, that request other nodes of the network to switch network traffic from a working span (including a straddling span) to a protect span. The commands specify the working span by its span ID, without necessarily specifying a source node ID or a destination node ID for the commands. The span ID occupies fewer bits in the commands than a combination of the source node ID and the destination node ID. Consequently, the messages can accommodate span IDs larger than four bits, and networks can have more than 16 nodes. Alternatively, the commands specify a destination node ID without a span ID or a source node ID, or the commands specify a source node ID without a span ID or a destination node ID.

Abstract: A shared protect link extends between adjacent nodes that are shared by two or more adjacent BLSR rings. The shared protect link obviates the need for separate protect links between the adjacent nodes for each of the rings. A composite BLSR controller resides in each of the adjacent nodes. The composite BLSR controllers coordinate usage of the shared protect link, for example as a result of a span switch or a ring switch request. The composite BLSR controllers also coordinate transmission of signaling information for each of the rings over the common span between the adjacent nodes. In one embodiment, the signaling information is sent over separate channels of the common span. In another embodiment, the signaling information is multiplexed over the shared protect link. Each ring can be assigned a ring ID. The communication protocol between the adjacent nodes can be modified to tag the signaling information with the appropriate ring ID.