Patent ID: 7502376

Claim:
A method to provide a loop-free telecommunication network wherein end-user stations (U 1 ; U 2 ) are interconnected through at least one Virtual Private LAN Service VPLS-network (VPLS 1 ; VPLS 2 ) and Layer-2 networks (L2N 1 ; L2N 2 ), the Layer-2 networks including bridges (K; L), said VPLS-network comprising nodes (A, B, C; P, Q, R) with external node ports (pA 3 , pB 3 , pC 3 ; pP 3 , pQ 3 , pR 3 ) coupled to said Layer-2 networks, each node further having internal node ports (pA 1 , pA 2 , pB 1 , pB 2 , pC 1 , pC 2 ; pP 1 , pP 2 , pQ 1 , pQ 2 , pR 1 , pR 2 ) interconnecting the nodes inside a same VPLS-network, said bridges comprising external bridge ports (pK 1 , pK 2 ; pL 1 , pL 2 ) coupled to external ports of nodes or of other bridges, each port being associated to a predetermined weight factor, the method comprising the step of using a predetermined protocol to prevent loops through the interconnected nodes and bridges, said method further comprises the steps of: grouping the internal node ports (pA 1 , pA 2 , pB 1 , pB 2 , pC 1 , pC 2 ; pP 1 , pP 2 , pQ 1 , pQ 2 , pR 1 , pR 2 ) of each node (A, B, C; P, Q, R) of the VPLS-network (VPLS 1 ; VPLS 2 ) into a distinct port arrangement (mpA, mpB, mpC; mpP, mpQ, mpR), setting the weight factors associated to the port arrangements to the value zero, defining one of the nodes or bridges as a root bridge, calculating, for each of said external node ports (pA 3 , pB 3 , pC 3 ; pP 3 , pQ 3 , pR 3 ) of the nodes of said VPLS-network, the sum of the weight factors from this external node port towards the root bridge, selecting the node of which an external node port has the lowest sum of weight factors as primary node for the VPLS-network, and cutting, towards external ports of said root bridge, the coupling of external node ports that have a sum of weight factors that is higher than the sum of weight factors of the external ports of said primary node towards said root bridge.