Patent ID: 7543075

Claim:
A method of establishing a bi-directional Label Switched Path (LSP) in an optical network, comprising: a bi-directional LSP establishing request, an available upstream label subset and an available downstream label subset are sent from a first node to a terminal node of the bi-directional LSP in a node-by-node manner, wherein each node has available upstream and downstream label sets, each particular node except the first node receives portions of the available upstream and downstream label sets of the first node from an adjacent upstream node and then AND-matches the received portions with the available upstream and downstream label sets of that particular node to form AND-matched available upstream and downstream label subsets of that particular node, and each particular node except the first and terminal nodes sends corresponding AND-matched available upstream and downstream label subsets of that particular node to an adjacent downstream node, if either of the AND-matched available upstream or downstream label subsets obtained by the terminal node or obtained by other nodes before the terminal node is null, the bi-directional LSP can't be established, and if the bi-directional LSP establishing request is sent to the terminal node and if both the AND-matched available upstream and downstream label subsets are not null, the terminal node chooses an acceptable upstream label having a single upstream pathway inclusive between the first node and the terminal node and an acceptable downstream label having a single downstream pathway inclusive between the terminal node and the first node from the received AND-matched available upstream and downstream label subsets; and a bi-directional LSP establishing response, and the chosen upstream and downstream labels are sent from the terminal node to foregoing nodes of the bi-directional LSP in a node-by-node manner, and each foregoing node, except the first node, chooses upstream and downstream labels to a respective adjacent upstream node till the first node in accordance to the AND-matched available upstream and downstream label subset provided by the terminal node.