A “path” represents a pair of interfaces, a source interface and a destination interface through which traffic can flow from site to site. For example, eth1/router1 -- eth1/router2 is a path. Note, that there could be many paths through the same egress interface. The “path” does not refer to the actual network path the packet takes through the SP network. There could be multiple network paths in SP network from customer’s edge router to another edge router. Also, the network paths could change. A path is unidirectional and path characteristics is tracked in each direction.