Patent ID: 7385918
Filing Date: 2008-06-10
Classification: H04J,H04L

Abstract:
1. A method of packet protection in a ring network including a plurality of transmission devices, each of said plurality of transmission devices including a tributary port and are connected in a ring by an inner ring having a first packet transmission direction and an outer ring having a second packet transmission direction opposite said first packet transmission direction, said method of packet protection comprising: reversing an initial packet transmission direction of a Network to Network Interface (NNI) packet that would have passed through a transmission link on which a transmission failure occurs at a first of said plurality of transmission devices having said failed transmission link as an output link, thereby reversing transmission direction of said NNI packet to one of said inner and said outer ring in said ring network; receiving said NNI packet including a transmission destination address sent via said reversed transmission direction at a second of said plurality of transmission devices, said transmission destination address corresponding to said second of said plurality of transmission devices; outputting said received NNI packet to a tributary port of said second of said plurality of transmission devices based on said receiving said NNI packet sent via said reversed transmission direction at said second of said plurality of transmission devices; in one of two of said plurality of transmission devices having said failed transmission link as an input link, and connected to said transmission link in which said failure occurs, turning an NNI packet applied through one of said inner ring and said outer ring which fails to include said input link as a component back to one of said inner ring and said outer ring including said input link as a component; converting, at each of said plurality of transmission devices, a UNI packet including a transmission destination UNI address which is applied through the tributary port into an NNI packet including a transmission destination NNI address; sending the NNI packet to one of said outer ring and said inner ring; determining when the ring network enters a state which makes a UNI packet including a certain transmission destination UNI address to be non-transmittable; transmitting at each of said plurality of transmission devices a protection path search packet including said certain transmission destination UNI address to an other of said plurality of transmission devices; receiving the protection path search packet at each of said other of said plurality of transmission devices; determining whether said transmission device receiving said protection path search packet is connected to one of a terminal and a network including the transmission destination UNI address included in said protection path search packet; returning protection path search response packet including a determination result, in response to said determining whether said transmission device receiving said protection path search packet is connected to one of a terminal and a network, to one of said plurality of transmission devices as a transmission source of said protection path search packet; and after receiving said protection path search response packet at said one of said plurality of transmission devices, and at a time of converting a UNI packet including said transmission destination UNI address into an NNI packet, taking, as a transmission destination NNI address of the NNI packet, an NNI address applied to any one of said plurality of transmission devices as transmission sources of the protection path search response packet indicating that one of said terminal and said network including said transmission destination UNI address is connected.