Patent ID: 7990888
Filing Date: 2011-08-02
Classification: H04L

Abstract:
1. A method of assessing a state of a remote node via a label switched path, the method comprising: receiving a response request message from an originator node at an autonomous system border router, the autonomous system border router included in a plurality of autonomous system border routers on the label switched path between the originator node and the remote node; transmitting the response request message to each successive one of the autonomous system border routers as the response request message traverses the autonomous system border routers on the label switched path to the remote node; accumulating, in a nondestructive manner at each successive one of the autonomous system border routers, an entry indicative of an identity of each successive one of the autonomous system border routers traversed on the label switched path to the remote node, wherein accumulating the entry indicative of the identity of each successive one of the autonomous system border routers further comprises building a stack of accumulated entries indicative of identities of the autonomous system border routers in the response request message; traversing the label switched path back to the originator node based on the stack of accumulated entries included in the acknowledgement response message; and forwarding messages at each respective one of the autonomous system border routers according to forwarding rules, the forwarding rules directing the respective one of the autonomous system border routers to: transmit the response request message, if the response request message is received, to a next route toward the remote node; redirect the acknowledgment response message, if the acknowledgment response message is received, to a next address on the stack of accumulated entries; and identify, if the response request message cannot reach the remote node, an autonomous system or the respective one of the autonomous system border routers encountering a condition of the response request message being unable to reach the remote node.