Patent ID: 7957380

Claim:
A method for communicating between a first router and a second router over a unidirectional communication link, the method comprising: initiating, by the first router, establishment of an adjacency between the first router and the second router by sending one or more point-to-point intermediate system-to-intermediate system (IS-IS) hello (IIH) messages over the unidirectional communication link, the unidirectional communication link connecting the first router to the second router, the one or more IIH messages containing three-way handshake information to transition the adjacency between the first router and the second router to an INIT state; applying a flooding rule to one or more additional unidirectional communication links on a return path between the second router and the first router to cause the one or more additional unidirectional communication links to pass link state packets (LSPs even when an adjacency on the one or more additional unidirectional communication links is not UP; receiving, by the first router, one or more LSPs containing three-way handshake information that includes a state of the adjacency between the first router and the second router, and, in response thereto, transitioning the adjacency between the first router and the second router from the INIT state to an UP state; and sending, by the first router, to the second router, one or more sequence number packets.