Packet ring network system, packet forwarding method and node

Abstract

Nodes 901 and 902 have the same address. Upon reception of a broadcast packet whose TTL value is not zero from a ringlet 910 a , a forwarding circuit 51 of each of the nodes 901 and 902 copies and transits the packet, and an address table 60 of each node learns the address based on the copied broadcast packet. Upon reception of a unicast packet whose destination is an address common to the two nodes from the ringlet 910 a , the forwarding circuit 51 of one node 901 copies and transits the packet, while the forwarding circuit 51 of the other node 902 strips the packet, and each address tables learns the address. A filter circuit of the node 902 prohibits the passage of the packet from the ringlet 910 a.

1 . A packet ring network system comprising:
 a plurality of nodes;
 a plurality of ringlets all of which respectively connect the nodes; 
 a virtual redundant node which includes a combination of plural nodes having a same address; and 
   a client device which is connected to the plural nodes of the virtual redundant node respectively through links,
 wherein the client device distributes packets to transmit to the plural nodes. 
   
     
     
         2 . The packet ring network system according to  claim 1 , wherein
 each of the node included in the virtual redundant node comprises:   two receivers respectively corresponding to the two ringlets and each of which receives a packet from a corresponding ringlet;   an address storage unit which stores a corresponding relationship between an address of the client device and an address of the node connected to the client device;   a sender for client device, which sends a packet to the client device; and   a filter unit which permits or prohibits output of the packet received by the each of the receivers to the sender for client device.   
     
     
         3 . The packet ring network system according to  claim 2 , wherein:
 of the receivers which receive a packet from a ringlet, in the two nodes included in the virtual redundant node,   a receiver which first receives the packet
 sends a broadcast control packet to a next node without subtraction of TTL value and generates a same packet as the received broadcast control packet, upon reception of the broadcast control packet whose the TTL value is not zero, and 
 sends a unicast control packet to a next node, and generates a same packet as the received unicast control packet, upon reception of the unicast control packet whose destination is an address of its own node; and 
   a receiver which afterward receives the packet
 sends a broadcast control packet to a next node after subtracting one from TTL value, and generates a same packet as the received broadcast control packet, upon reception of the broadcast control packet whose the TTL value is not zero, and 
 takes a unicast control packet from the ringlet, upon reception of the unicast control packet whose destination is an address of its own node. 
   
     
     
         4 . The packet ring network system according to  claim 2 , wherein:
 of the receivers which receive a packet from a ringlet, in the two nodes included in the virtual redundant node,   a receiver which first receives a packet
 sends a broadcast data packet to a next node without subtraction of TTL value, and generates a same packet as the received broadcast data packet, upon reception of the broadcast data packet whose the TTL value is not zero, and 
 sends a unicast data packet to a next node, and generates a same packet as the received unicast data packet, upon reception of the unicast data packet whose destination is an address of its own node; and 
   a receiver which afterward receives a packet
 sends a broadcast data packet to a next node after subtracting one from TTL value, and generates a same packet as the received broadcast data packet, upon reception of the broadcast data packet whose the TTL value is not zero, and 
 takes a unicast data packet from the ringlet, upon reception of the unicast data packet whose destination is an address of its own node. 
   
     
     
         5 . The packet ring network system according to  claim 4 , wherein
 the storage unit included in each node of the virtual redundant node learns and stores the corresponding relationship between an address of the client device and an address of the node connected to the each client device, based on the packet generated as the same packet as the broadcast data packet or unicast data packet received by the receiver of the same node, or based on the unicast data packet taken from the ringlet.   
     
     
         6 . The packet ring network system according to  claim 2 , wherein:
 the filter unit in one node which first receives a packet from one ringlet, of the two nodes included in the virtual redundant node
 permits output of a packet forwarded from the one ringlet to the sender for client device, and prohibits output of a packet forwarded from other ringlet to the sender for client device; and 
   the filter unit in other node which first receives a packet from other ringlet, of the two nodes included in the virtual redundant node
 permits output of a packet forwarded from the other ringlet to the sender for client device, and prohibits output of a packet forwarded from the one ringlet to the sender for client device. 
   
     
     
         7 . The packet ring network system according to  claim 6 , wherein:
 when a failure has occurred in one of the links connected to the respective two nodes included in the virtual redundant node, the client device sends a packet to the node connected thereto through the link without occurrence of the failure; and   the filter unit of each node included in the virtual redundant node permits output of a packet forwarded from any ringlets to the sender for client device, when a failure has occurred in a link between the client device and other node of the virtual redundant node.   
     
     
         8 . The packet ring network system according to  claim 1 , wherein:
 of the two nodes included in the virtual redundant node, one node which first receives a packet from one ringlet includes
 a multiplexer which multiplexes packets so as to send them to other ringlet, and 
 a packet generator which generates a packet to be forwarded to a ringlet based on a packet received from the client device; 
   of the two nodes included in the virtual redundant node, one node which first receives a packet from the other ringlet includes
 a multiplexer which multiplexes packets so as to send them to the one ringlet, and 
 a packet generator which generates a packet to be forwarded to a ringlet based on a packet received from the client device; 
   of the two nodes included in the virtual redundant node, one node which first receives a packet from the one ringlet includes
 a destination switch which outputs a packet to the multiplexer of the other node, when the packet generated based on the packet received from the client device is a packet to be sent to the one ringlet, and outputs a packet to the multiplexer of its own node, when the packet generated based on the packet received from the client device is a packet to be sent to the other ringlet; 
   of the two nodes included in the virtual redundant node, one node which first receives a packet from the other ringlet includes
 a destination switch which outputs a packet to the multiplexer of the other node, when the packet generated based on the packet received from the client device is a packet to be sent to the other ringlet, and which outputs a packet to the multiplexer of its own node, when the packet generated based on the packet received from the client device is a packet to be output to the one ringlet. 
   
     
     
         9 . The packet ring network system according to  claim 1 , wherein each of the nodes included in the virtual redundant node includes:
 a first multiplexer which multiplexes and sends packets to one ringlet;   a second multiplexer which multiplexes and sends packets to other ringlet;   a packet generator which generates a packet to be forwarded to a ringlet based on a packet received from the client device; and   a destination switch which outputs a packet to the first multiplexer of its own node, when the packet generated based on a packet received from the client device is a packet to be sent to the one ringlet, and which outputs a packet to the second multiplexer of its own node, when the packet generated based on a packet received from the client device is a packet to be sent to the other ringlet.   
     
     
         10 . A packet forwarding method comprising:
 connecting a plurality of nodes circularly within a packet ring network system by each of a plurality of ringlets   combining plural nodes within a virtual redundant node, the plural nodes having a same address;   connecting a client device to the plural nodes of the virtual redundant node respectively through links; and   distributing packets for transmission, by the client device to the plural nodes.   
     
     
         11 . The packet forwarding method according to  claim 10 , comprising:
 of the two nodes included in the virtual redundant node and receiving a packet from a ringlet,   in a node which first receives a packet,
 sending a broadcast control packet to a next node without subtraction of TTL value and generating a same packet as the received broadcast control packet, upon reception of the broadcast control packet whose the TTL value is not zero; 
 sending a unicast control packet to a next node, and generating a same packet as the received unicast control packet, upon reception of the unicast control packet whose destination is an address of its own node; and 
   in a node which afterward receives a packet,
 sending a broadcast control packet to a next node after subtracting one from TTL value, and generating a same packet as the received broadcast control packet, upon reception of the broadcast control packet whose the TTL value is not zero, and 
 taking a unicast control packet from the ringlet, upon reception of the unicast control packet whose destination is an address of its own node. 
   
     
     
         12 . The packet forwarding method according to  claim 10 , comprising:
 of the two nodes included in the virtual redundant node and receiving a packet from a ringlet,   in a node which first receives a packet,
 sending a broadcast data packet to a next node without subtraction of TTL value and generating a same packet as the received broadcast data packet, upon reception of the broadcast data packet whose the TTL value is not zero, 
 sending a unicast data packet to a next node, and generating a same packet as the received unicast data packet, upon reception of the unicast data packet whose destination is an address of its own node; and 
   in a node which afterward receives a packet,
 sending a broadcast data packet to a next node after subtracting one from TTL value, and generating a same packet as the received broadcast data packet, upon reception of the broadcast data packet whose the TTL value is not zero, and 
 taking a unicast data packet from a ringlet, upon reception of the unicast data packet whose destination is an address of its own node. 
   
     
     
         13 . The packet forwarding method according to  claim 12 , comprising:
 in each of the nodes included in the virtual redundant node,   learning and storing the corresponding relationship between an address of the client device and an address of the node connected to the client device, based on the packet generated as the same packet as the received broadcast data packet or unicast data packet, or based on the unicast data packet taken from the ringlet.   
     
     
         14 . The packet forwarding method according to  claim 10 , comprising:
 in the node included in the two nodes of the virtual redundant mode and first receiving a packet from the one ringlet,
 permitting output of a packet forwarded from the one ringlet to a sender for client device, which sends a packet to the client device, and prohibiting output of a packet forwarded from the other ringlet to the sender for client device; and 
   in the node included in the two nodes of the virtual redundant mode and first receiving a packet from the other ringlet,
 permitting output of a packet forwarded from the other ringlet to the sender for client device, and prohibiting output of a packet forwarded from the one ringlet to the sender for client device. 
   
     
     
         15 . The packet forwarding method according to  claim 14 , comprising:
 when a failure has occurred in one of links for connecting between the two nodes included in the virtual redundant node and the client device,   sending a packet to the node connected to the link without occurrence of the failure, in the client device; and   permitting output of a packet forwarded from any ringlets to the sender for client device, in the node without occurrence of the failure in the link to the client device.   
     
     
         16 . The packet forwarding method according to  claim 10 , comprising:
 in the node of the two nodes included in the virtual redundant node and first receiving a packet from the one ringlet,
 generating a packet to be forwarded to a ringlet based on a packet received from the client device; 
 outputting the packet to the other node, and sending the packet to the other node, when the generated packet is a packet to be sent to the one ringlet; and 
 sending the packet from its own node, when the generated packet is a packet to be sent to the other ringlet; and 
   in the node of the two nodes included in the virtual redundant node and first receiving a packet from the other ringlet,
 generating a packet to be forwarded to a ringlet based on a packet received from the client device; 
 outputting the packet to the other node, and sending the packet to the other node, when the generated packet is one to be sent to the other ringlet; and 
 sending the packet from its own node, when the generated packet is one to be sent to the one ringlet. 
   
     
     
         17 . The packet forwarding method according to  claim 10 , further comprising:
 in each of the nodes included in the virtual redundant node,
 generating a packet to be forwarded to a ringlet based on a packet received from the client device; and 
 sending the generated packet from its own node, regardless of whether the generated packet is a packet to be sent to the one ringlet or to be sent to the other ringlet. 
   
     
     
         18 . A node which is applied to a packet ring network system including a plurality of nodes connected to each other through plural ringlets, and the node being used in a first usage state wherein the node is independently arranged by itself, in a second usage state wherein the node is combined with other node having a same address as an address of its own node and is so arranged as to receive a packet from one ringlet before the other node, or in a third usage state wherein the node is combined with other node having a same address as an address of its own node and is so arranged as to receive a packet from one ringlet after the other node, the node comprising:
 a first receiver which receives a packet from one ringlet;   a second receiver which receives a packet from other ringlet;   a sender for client device, which sends a packet to a client device; and   a filter unit which permits or prohibits output of the packet received by the first receiver or the second receiver to the sender for client device, wherein:   the first receiver
 implements a process corresponding to the received packet in accordance with a predetermined rule, in the first usage state, 
 upon reception of the broadcast packet whose TTL value is not zero, sends the broadcast packet to a next node without subtraction of its TTL value and generates a same packet as the received broadcast packet, and upon reception of the unicast packet whose destination is an address of its own node, sends the unicast packet to a next node, and generates a same packet as the received unicast packet, in the second usage state, and 
 upon reception of the broadcast packet whose TTL value is not zero, sends the broadcast packet to a next node after subtracting one from its TTL value and generates a same packet as the received broadcast packet, and, upon reception of the unicast data packet whose destination is an address of its own node, takes the unicast data packet from a ringlet, in the third usage state; 
   the second receiver
 implements a process corresponding to the received packet in accordance with a predetermined rule, in the first usage state, 
 upon reception of the broadcast packet whose TTL value is not zero, sends the broadcast packet to a next node after subtracting one from its TTL value and generates a same packet as the received broadcast packet, and, upon reception of the unicast data packet whose destination is an address of its own node, takes the unicast data packet from a ringlet, in the second usage state, and 
 upon reception of the broadcast packet whose TTL value is not zero, sends the broadcast packet to a next node without subtraction of TTL value and generates a same packet as the received broadcast packet, and, upon reception of the unicast packet whose destination is an address of its own node, sends the unicast packet to a next node and generates a same packet as the received unicast packet, in the third usage state; and 
   the filter unit
 permits output of the packet received by both of the first receiver and the second receiver to the sender for client device, in the first usage state, 
 permits output of the packet received by the first receiver to the sender for client device, and prohibits output of the packet received by the second receiver to the sender for client device, in the second usage state, 
 prohibits output of the packet received by the first receiver to the sender for client device, and permits output of the packet received by the second receiver to the sender for client device, in the third usage state. 
   
     
     
         19 . The node according to  claim 18 , further comprising:
 a packet generator which generates packets to be forwarded to a ringlet based on a packet received from the client device;   a first multiplexer which multiplexes at least the packets generated by the packet generator so as to send them to one ringlet;   a second multiplexer which multiplexes at least the packets generated by the packet generator so as to send them to other ringlet; and   a destination switch which outputs the packet generated by the packet generator to the first multiplexer or second multiplexer of its own node or the other node, wherein   the destination switch
 outputs the packet generated by the packet generator to the first multiplexer or second multiplexer of its own node, in accordance with a target ringlet to which the packet is sent, in the first usage state, 
 outputs the packet generated by the packet generator to the first multiplexer included in the other node when the packet is a packet to be sent to the one ringlet, and outputs the packet generated by the packet generator to the second multiplexer included in its own node when the packet is a packet to be sent to the other ringlet, in the second usage state, 
 outputs the packet generated by the packet generator to the first multiplexer included in its own node when the packet is a packet to be sent to the one ringlet, and outputs the packet generated by the packet generator to the second multiplexer included in the other node when the packet is a packet to be sent to the other ringlet, in the third usage state. 
   
     
     
         20 . The node according to  claim 18 , further comprising:
 a packet generator which generates packets to be forwarded to a ringlet based on a packet received from the client device;   a first multiplexer which multiplexes at least the packets generated by the packet generator so as to send them to one ringlet;   a second multiplexer which multiplexes at least the packets generated by the packet generator so as to send them to other ringlet; and   a destination switch which outputs the packets generated by the packet generator to the first multiplexer or second multiplexer in its own node corresponding to a target ringlet to which the packet is sent, and wherein   the first receiver sends, upon reception of a packet whose source address is an address of its own node from the other node, the packet to a next node as is, in the third usage state, and   the second receiver sends, upon reception of the packet whose source address is an address of its own node from the other node, the packet to a next node as is, in the second usage state.