Image Number 7 for United States Patent #6985447.
Label switched paths are installed in a label switched communications packet network. Paths are selected by defining and installing partial routes each having two or more paths such that an end-to-end route across the network can be defined as the concatenation of two partial routes. Signalling to select a path is effected by sending a path message from an end point to a first virtual router, determining a path from the end point to the virtual router, and forwarding an identity of the path to a second virtual router. The second virtual router determines a routing vector across the network, and returns information identifying the routing vector to the first virtual router.