Congestion notification method, device, system and network equipment

The invention provides a congestion notification method, a congestion notification device, a congestion notification system and network equipment. The method comprises that: first layer three network equipment resolves a first congestion notification message (CNM) transmitted by a congestion point to acquire an Internet protocol (IP) address of a congestion source, wherein the first layer three network equipment is in the same network segment as the congestion point; the first layer three network equipment re-encapsulates the first CNM according to the IP address of the congestion source to generate an IP message and transmits the IP message; and second layer three network equipment receives the IP message, recovers the IP message according to a protocol type identifier in an IP message to generate a second CNM, and transmits the second CNM to the congestion source, wherein the second layer three network equipment is in the same network segment as the congestion source. By the technical scheme provided by the invention, the cross-three layer network equipment transmission of the CNM is realized, and the problem of congestion in a layer three network is solved.