Patent ID: 7733856

Claim:
A method for obtaining path information related to a virtual private local area network services (VPLS) based network comprising: generating layer 2 (L2) trace-request frames; setting the source media access control (MAC) addresses of the L2 trace-request frames to trace values; forwarding the L2 trace-request frames in a VPLS-based network, wherein the forwarding defines a traversed path; comparing the source MAC addresses of the L2 trace-request frames to filter MAC addresses; generating trace-reply frames in response to the comparing of the source MAC addresses of the L2 trace-request frames to the filter MAC addresses, wherein the trace-reply frames are generated in response to matches between the source MAC addresses and the filter MAC addresses; collecting path information that identifies the traversed paths of the L2 trace-request frames and embedding the path information into a payload portion of the trace-reply frames; and forwarding the trace-reply frames in the VPLS-based network, wherein the path information embedded in the payload portion of the trace-reply frames is used to learn the traversed paths of the corresponding L2 trace-request frames; wherein the trace values are values that enable L2 frames to be identified as trace-request frames through the comparisons of the source MAC addresses to the filter MAC addresses.