Multiring control method, node using the method, and control program

Abstract

The invention enables protection of a ring frame transferred via an inter-ring bridge ring node when a fault occurs at the node in a multiring. Ring nodes form a ring protection domain to enable one ring node to be bypassed by using other ring nodes when a fault occurs at this ring node. The TTL value of ring frame to be transferred through the bypass is set to a value obtained by adding the number of hops h to the faulty ring node to a common initial value A in the same two-fiber ring to enable detection of a characteristic TTL value at a bypassing ring node. The bypass for the ring frame is selected with reference to the characteristic TTL value at the bypassing ring node.

1 . A method of controlling a multi-two-media ring network in which a plurality of two-media ring networks constituted by ring nodes R 1  transmit and receive an NNI packet by using an inner ring or an outer ring and perform transmission and reception of the NNI packet with a terminal through a port connected by ring nodes R 2  which bridge the two-media ring networks, said method comprising:
 forming a ring protection domain of a plurality of the ring nodes R 2  bridging the two-media networks; and   a protection execution step of transferring the NNI packet via a bypass when a fault occurs at one of the plurality of ring nodes R 2 , the bypass being formed by at least another of the ring nodes R 2  other than the ring node R 2  at which the fault has occurred.   
   
   
       2 . The method according to  claim 1 , wherein said protection execution step includes:
 a bypassing step of transferring the NNI packet via the bypass in such a manner that a TTL value in the NNI packet is set to a value obtained by adding together an initial value common in the same two-media ring network and the number of hops to the faulty ring node R 2  to be able to be detected as a characteristic TTL value at the ring node R 2  forming the bypass, and the NNI packet is transferred via the bypass if the TTL value in the NNI packet coincides with the characteristic TTL value at the bypass ring node R 2 ; and   a TTL value updating step of making the bypass ring node R 2  set the TTL value in the NNI packet transferred via the bypass to a value obtained by adding together the initial value of the bypass-destination two-media ring network and the number of hops to the next bypass ring node R 2 .   
   
   
       3 . A ring node R 2  in a multi-two-media ring network in which a plurality of two-media ring networks constituted by ring nodes R 1  transmit and receive an NNI packet by using an inner ring or an outer ring and perform transmission and reception of the NNI packet with a terminal through a port connected by said ring node R 2  and other ring nodes R 2  bridging the two-media ring networks, a ring protection domain being formed by a plurality of the ring nodes R 2  bridging the two-media ring networks, said ring node R 2  comprising:
 first transport means of receiving the NNI packet which is transmitted from a transmission source ring node R 1  in the two-media ring network containing one of the ring nodes R 2  at which a fault has occurred, and in which the TTL value is updated, and transferring the NNI packet to the another of the two-media ring networks while updating the TTL value of the another of the two-media ring networks to which said ring node R 2  is connected; and   second transport means of receiving the NNI packet transferred from said first transport means, recognizing the NNI packet as a packet transferred via a bypass from the TTL value in the NNI packet, and transferring the NNI packet to still another of the two-media ring networks.   
   
   
       4 . A computer-readable medium encoded with data structure for making a computer execute a method of controlling a multi-two-media ring network in which a plurality of two-media ring networks constituted by ring nodes R 1  transmit and receive an NNI packet by using an inner ring or an outer ring and perform transmission and reception of the NNI packet with a terminal through a port are connected by ring nodes R 2  which bridge the two-media ring networks, a ring protection domain being formed by a plurality of the ring nodes R 2  bridging the two-media ring networks, said data structure causing the computer to execute:
 a protection execution step of transferring the NNI packet via a bypass when a fault occurs at one of the plurality of ring nodes R 2 , the bypass being formed by at least another of the ring nodes R 2  other than the ring node R 2  at which the fault has occurred.   
   
   
       5 . The medium according to  claim 4 , wherein said protection execution step includes:
 a bypassing step of transferring the NNI packet via the bypass in such a manner that a TTL value in the NNI packet is set to a value obtained by adding together an initial value common in the same two-media ring network and the number of hops to the faulty ring node R 2  to be able to be detected as a characteristic TTL value at the ring node R 2  forming the bypass, and the NNI packet is transferred via the bypass if the TTL value in the NNI packet coincides with the characteristic TTL value at the bypass ring node R 2 ; and   a TTL value updating step of making the bypass ring node R 2  set the TTL value in the NNI packet transferred via the bypass to a value obtained by adding together the initial value of the bypass-destination two-media ring network and the number of hops to the next bypass ring node R 2 .