Patent ID: 7697552

Claim:
A method for communication, comprising: in a communication network that includes multiple ring nodes arranged in at least first and second ring networks, which are connected by one or more of the ring nodes serving as interconnect nodes, accepting a data packet from a source user node served by a first ring node in the first ring network for forwarding to a destination user node served by a second ring node in the second ring network; attaching to the data packet in the first ring network an identifier that identifies an interconnect node in the first ring network though which the data packet is to be forwarded to the second ring network, and forwarding the data packet over the first ring network; wherein attaching the identifier comprises learning at the first ring node that the data packet is to be forwarded to the second ring network though the interconnect node based on a previous data packet which: originated in another source user node served by the second ring node, was addressed to another destination user node served by the first ring node, and was forwarded though the interconnect node; and accepting the data packet at the interconnect node, and responsively to the identifier, forwarding the data packet from the interconnect node to the second ring network; and forwarding the data packet over the second ring network to the destination user node.