摘要 |
Methods, systems, and apparatus, including computer programs encoded on computer storage media, for determining image search results. One of the methods includes storing data representing a collection of predetermined paths through a network of devices. One or more packets are transmitted along each of the predetermined paths, wherein each packet includes instructions for forwarding the packet along a distinct path of the predetermined paths. One or more of the transmitted packets are received. Two or more problem paths are identified using the transmitted packets and the received packets. A problem link between two network devices is determined based on a comparison of the problem paths. |