Abstract: A capability is provided for computing paths to destinations in networks having link constraints. An improved Constrained Shortest Path First (CSPF) algorithm is provided for computing a path from a source node to a destination node through a network. The improved CSPF algorithm uses neighbor node lists, in addition to a tentative node list and a paths list, for computing a path. The improved CSPF algorithm, during path computation, maintains a tentative node list including nodes selected for inclusion within the path. The tentative node list specifies the computed path. The improved CSPF algorithm, for each node selected for inclusion within the tentative node list, uses a neighbor node list for the selected node, and selects a neighbor node from the neighbor node list for inclusion within the tentative node list.

Abstract: Path information is obtained in a VPLS-based network by generating special Layer 2 frames (referred to herein as “trace-request frames”), performing source MAC filtering to identify the trace-request frames, and generating a special frame (referred to herein as a “trace-reply frame”) when the source MAC filtering identifies a trace-request frame. Upon identifying a trace-request frame, path information is collected and embedded into the trace-reply frame. The trace-reply frame is then sent to the originating node where the path information is used to learn the path that the trace-request frame traversed. By sending multiple trace-request frames with different source MAC addresses, path information received from source MAC filtering at different nodes in the VPLS-based network can be collected and used to learn an entire path of interest.

Abstract: Path information is obtained in a bridged network by generating an L2 frame with a special MAC address in the header and a target MAC address embedded in the payload of the frame. The special MAC address in the header of the frame triggers the collection of path information as the frame traverses the bridged network while the target MAC address in the payload of the frame is used to forward the frame in the bridged network. In an embodiment, the destination MAC address of the frame is set to a special MAC address that identifies the frame as a “trace-path” frame, for example, a multicast MAC address.

Abstract: Path information is obtained in a VPLS-based network by generating special Layer 2 frames (referred to herein as “trace-request frames”), performing source MAC filtering to identify the trace-request frames, and generating a special frame (referred to herein as a “trace-reply frame”) when the source MAC filtering identifies a trace-request frame. Upon identifying a trace-request frame, path information is collected and embedded into the trace-reply frame. The trace-reply frame is then sent to the originating node where the path information is used to learn the path that the trace-request frame traversed. By sending multiple trace-request frames with different source MAC addresses, path information received from source MAC filtering at different nodes in the VPLS-based network can be collected and used to learn an entire path of interest.

Abstract: Path information is obtained in a bridged network by generating an L2 frame with a special MAC address in the header and a target MAC address embedded in the payload of the frame. The special MAC address in the header of the frame triggers the collection of path information as the frame traverses the bridged network while the target MAC address in the payload of the frame is used to forward the frame in the bridged network. In an embodiment, the destination MAC address of the frame is set to a special MAC address that identifies the frame as a “trace-path” frame, for example, a multicast MAC address.