Patent ID: 8165013

Claim:
A method of operating a computer that connects to a network through at least one gateway, the computer operating according to a layered network protocol, the layered network protocol having at least a connection or application layer, a path layer and a link layer, the method comprising: a) in response to a failure at the connection or application layer of a transmission attempt through a gateway, obtaining information from the link layer concerning connectivity of the computer over the network, wherein obtaining the information from the link layer comprises probing, at the link layer, through the gateway, for a neighbor device other than the gateway; and b) using the information to determine usability of the gateway, wherein using the information comprises: when the transmission attempt through the gateway fails and, in response to the probing, it is determined that the neighbor device is reachable by the computer through the gateway at the link layer, making another transmission attempt through the gateway; and when the transmission attempt through the gateway fails and, in response to the probing, it is determined that the neighbor device is not reachable by the computer through the gateway at the link layer, determining availability of at least one alternative gateway.