Patent ID: 7433318

Claim:
A received path trace detection apparatus provided with: a specific byte extracting/holding function unit receiving a path signal sent from another apparatus and extracting and holding once path information written for showing the path in specific bytes mapped in the received path signal at a predetermined sampling timing, a comparing function unit detecting if path information of previous specific bytes held in the specific byte extracting/holding function unit and path information of the currently received specific bytes match, a protecting function unit detecting that said match has continued for exactly a predetermined number of protection stages as a result of the comparison by said comparing function unit, and a forwarding function unit forwarding the held path information to an erroneous connection decision unit for enabling the erroneous connection decision unit to decide if values exhibited by path information of the specific bytes held at said specific byte extracting/holding function unit and predetermined expected values match when matches of a consecutive number of protection stages are detected by said protecting function unit.