Route retrieval method, the path calculation unit, a path computation client and Systems

The present invention discloses a kind of path request, the method comprising: a stateful path computation element PCE receives Stateful path computation client PCC transmission path computation request message, the path computation request message including the first attribute information of the attribute information PCC for acquiring specify the request path; the Stateful PCE based on the first attribute information acquired path information in line with the PCC request; sending a path computation response message to the PCC, the path computation response message in compliance with the request path information to the PCC. Embodiments of the invention further provides a stateful path computation unit types and the path computation client. Embodiment of the present invention, for solving the prior art routing method is not flexible, limit the technical problem of network extension.