Patent ID: 7076559

Claim:
A method for establishing a label switched path across multiple autonomous systems without the use of a multi-label stack, wherein each one of the multiple autonomous systems includes at least one border router and a plurality of interior routers, the method comprising: storing, in a memory at a border router coupling a first autonomous system to a second autonomous system, a mapping of a first label associated with a last hop forwarding equivalency class (FEC) of the first autonomous system to a second label associated with a first hop in the second autonomous system, the second label associated with the last hop FEC of the first autonomous system; receiving from an interior router in said first autonomous system a protocol message including a single label stack comprised of said first label; replacing said first label in the single label stack with said second label in said protocol message; and forwarding said single label stack protocol message to a downstream neighboring (next hop) interior router in said second autonomous system.