Method and system for controlling communication network and router used in the network

Abstract

The present invention provides a communication network comprising a host network, a plurality of base stations, at least a mobile host capable of establishing links to the base stations, and a hierarchy-network of plural routers which are improved in transferring performances for ensuring continuous operations with a reduced load without packet loss.

What is claimed is: 
     
         1 . A communication network system comprising:
 a plurality of base stations; and   a router that transmits a packet with a label value which indicates a sequence of transmission of a packet to at least one of the plurality of base stations; and   wherein, when the router transmits the packet to a first base station, the router transmits the packet to an second base station which is an adjacent of the first base station.   
     
     
         2 . The communication network system as claimed in  claim 1 , further comprising:
 a queuing unit that queues the packets transmitted to the second router.   
     
     
         3 . The communication network system as claimed in  claim 2 ,
 wherein the first base station transmits the packet with the label value,   wherein the queuing unit selects the packet from packets in the queuing unit, comparing each of label values of the packets in the queuing unit with a label value of the packet which the first base station transmits last, and transmits the selected packet to the second base station.   
     
     
         4 . The communication network system as claimed in  claim 1 ,
 wherein the router is positioned at a branch point of between a first route to the first base station and a second route to the second base station.   
     
     
         5 . The communication network system as claimed  1 , further comprising:
 a mobile node that links to at least one of the plurality of base stations   wherein the first base station transmits the packet to the mobile node,   wherein, when the mobile node starts to link to the second base station, the mobile node sends the label value of the packet which the mobile node receives last to the queuing unit.   
     
     
         6 . The communication network system as claimed in  claim 5 ,
 wherein, when the mobile node can receive the packet from both the first and second base station, the mobile node discards the receiving packet based on the label value of the receiving packet.   
     
     
         7 . A mobile node that at least one of a plurality of base stations;
 the first unit that receives a packet with a label value which indicates a sequence of transmission of the packet from a first base station,   the second unit that sends the label value of the packet which the mobile node receives form the first base station last when the mobile node starts to link to a second base station which is an adjacent of the first base station.   
     
     
         8 . The mobile node as claimed in  claim 7 , further comprising:
 the third unit that discards the packet based on the label value of the packet when the mobile node can receive the packet from both the first and second base station.   
     
     
         9 . A method of controlling a communication network system comprising a plurality of base stations, comprising the step of:
 transmitting a packet with a label value which indicates a sequence of transmission of the packet to a first base stations; and   transmitting the packet to an second base station which is an adjacent of the first base station when the router transmits the packet to the first base station.   
     
     
         10 . The method as claimed in  claim 9 , further comprising the step of.
 queuing the packets transmitted to the second router.   
     
     
         11 . The method as claimed in  claim 10 , further comprising the step of:
 selecting the packet from the queuing packets comparing each of label values of queuing packets with a label value of the packet which the first base station transmits last; and   transmitting the selected packet to the second base station.   
     
     
         12 . The method as claimed in  claim 9  wherein the communication network system comprises a mobile node that links to at least one of the plurality of base stations, further comprising the step of:
 sending, by a mobile node, the label value of the packet which the mobile node receives last when the mobile node starts to link to the second base station. 
 
     
     
         13 . The method as claimed in  claim 12 , further comprising the step of:
 discarding, by a mobile node, the receiving packet based on the label value of the receiving packet when the mobile node can receive the packet from both the first and second base station.   
     
     
         14 . A method of controlling a mobile node that links to at least one of a plurality of base stations, comprising the step of
 receiving a packet with a label value which indicates a sequence of transmission of a packet from a first base station,   sending the label value of the packet which the mobile node receives last when the mobile node starts to link to a second base station which is an adjacent of the first base station.   
     
     
         15 . A method as claimed in  claim 14 , further comprising the step of:
 discarding the packet based on the label value of the packet when the mobile node can receive the packet from both the first and second base station.