Technique for enhancing effectiveness of cache server

Abstract

A path calculating section obtains a path suitable for carrying out an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on QoS path information that includes network path information and path load information obtained by a QoS path information obtaining section. An automatic cache updating section, a link prefetching control section, and a cache server cooperating section carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, by utilizing the path obtained. For example, the path calculating section obtains a maximum remaining bandwidth path as the path.

1 . A network system comprising: 
 at least one priority controllable router capable of controlling a priority of transmitting a packet to a link, based on priority information added to the packet; and    at least one cache server for carrying out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, wherein a priority given to a packet, to be used for communications generated by at least one of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, is lower than a priority given to a packet to be used for communications generated by a cache operation.    
   
   
       2 . The network system according to  claim 1 , wherein 
 said at least one cache server comprises:    a priority providing section for providing a priority request source with a priority predetermined for each priority-request source, when a request for providing a priority occurs;    a priority information adding section for adding priority information showing a priority to a packet, when the priority and the packet to be transmitted to the network have been received; and    a cache operating section, a link prefetching control section, an automatic cache updating section, and a cache server cooperating section, which request the priority providing section to provide a priority when a transmission packet has occurred, and pass the transmission packet and the priority provided by the priority providing section to the priority information adding section.    
   
   
       3 . The network system according to  claim 2 , further comprising: 
 a QoS path information obtaining section for obtaining QoS path information including network path information and path load information,    wherein the priority providing section determines a priority based on a priority-request source and QoS path information obtained by the QoS path information obtaining section, when a request for providing a priority has occurred.    
   
   
       4 . A network system comprising: 
 at least one priority controllable router, wherein said at least one priority controllable router provides priority information to a packet associated with a specific communication flow by identifying this communication flow, and controls a priority of transmitting a packet to a link based on the priority information provided to the packet; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information including network path information and path load information,    a priority providing section for obtaining a priority variable for each link of the network suitable for carrying out an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section,    a router priority setting section for requesting the priority controllable router to set a priority to a specific communication flow, based on a result obtained by the priority providing section, wherein a priority set for a packet generated by at least one of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation is set lower than a priority for a packet to be used for communications generated by a cache operation, and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation by using the path obtained by the priority controllable router.    
   
   
       5 . A network system comprising: 
 at least one priority controllable router, wherein said at least one priority controllable router controls a priority of transmitting a packet to a link based on priority information provided to the packet; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information,    a path calculating section for obtaining a path suitable for carrying out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section, and for providing priority information lower than priority information of a packet to be used for communications generated by a cache operation, to a packet to be used for communications generated by the automatic cache updating operation, the link prefetching operation, or the cache server cooperating operation, and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, using the path by the path calculating section and using the packet of the priority provided by the path calculating section.    
   
   
       6 . A network system comprising: 
 at least one priority controllable router, wherein said at least one priority controllable router provides priority information to a packet associated with a specific communication flow by identifying this communication flow, and controls a priority of transmitting a packet to a link based on the priority information provided to the packet; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information, a path calculating section for obtaining a path suitable for carrying out an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section, and for obtaining a priority variable for each link of the network suitable for carrying out the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation,    a router priority setting section for requesting the priority controllable router to set a priority to a specific communication flow, based on a result obtained by the path calculating section, wherein a priority set for a packet generated by at least one of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation is set lower than a priority for a packet to be used for communications generated by a cache operation, and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation.    
   
   
       7 . A network system comprising: 
 at least one router, wherein said at least one router is allowed to control a priority of transmitting a packet to a link, based on priority information provided to the packet, and to set a requested path on the network; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information,    a path calculating section for obtaining a path suitable for carrying out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section, and for providing priority information lower than priority information of a packet to be used for communications generated by a cache operation, to a packet to be used for communications generated by the automatic cache updating operation, the link prefetching operation, or the cache server cooperating operation,    a path setting section for requesting the router to set the path obtained by the path calculating section, and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, by using the packet of the priority provided by the path calculating section.    
   
   
       8 . A network system comprising: 
 at least one router, wherein said at least one router provides priority information to a packet associated with a specific communication flow by identifying this communication flow, controls a priority of transmitting a packet to a link based on the priority information provided to the packet, and sets a requested path on the network; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information,    a path calculating section for obtaining a path suitable for carrying out an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section, for obtaining a priority variable for each link of the network suitable for carrying out the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, and for providing priority information lower than priority information of a packet to be used for communications generated by a cache operation,    a router priority setting section for requesting a router to set a priority to a specific communication flow, based on a result obtained by the path calculating section,    a path setting section for requesting the router to set a the path obtained by the path calculating section, and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, by using the path set by the router.    
   
   
       9 . A network system comprising: 
 at least one router, wherein said at least one router controls a priority of transmitting a packet to a link, based on priority information provided to the packet;    at least one relay server; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information,    a relay control section for selecting one of said at least one a relay servers suitable for carrying out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section, instructing the selected relay server about data to be relayed, and providing priority information lower than priority information of a packet to be used for communications generated by a cache operation, to a packet to be used for communications generated by the automatic cache updating operation, the link prefetching operation, or the cache server cooperating operation,    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, by using the packet of the priority provided by the relay control section, and    wherein the relay server relays the data according to an instruction received from the relay control section.    
   
   
       10 . A network system comprising: 
 at least one router, wherein said at least one router provides priority information to a packet associated with a specific communication flow by identifying this communication flow, and controls a priority of transmitting a packet to a link based on the priority information provided to the packet;    at least one relay server; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information;    a relay control section for selecting one of said at least one a relay servers suitable for carrying out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section, for instructing the selected relay server about data to be relayed, for obtaining a priority variable for each link of the network suitable for carrying out an automatic cache updating operation, a link prefetching operation, or a cache server cooperating operation, and for providing priority information lower than priority information of a packet to be used for communications generated by a cache operation,    a router priority setting section for requesting one of said at least one a routers to set a priority of a specific communication flow, based on a result obtained by the relay control section, and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation respectively, by using the packet of the priority provided by the relay control section, wherein said at least one relay server relays the data according to an instruction received from the relay control section.    
   
   
       11 . A network system comprising: 
 at least one router, wherein said at least one router controls a priority of transmitting a packet to a link, based on priority information provided to the packet;    at least one relay server; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information,    a relay control section for selecting a path and one of said at least one a relay servers, which are suitable for carrying out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section, for instructing the selected relay server about data to be relayed, for instructing the selected relay server to relay the data using the selected path, and for providing priority information lower than priority information of a packet to be used for communications generated by a cache operation, to a packet to be used for communications generated by the automatic cache updating operation, the link prefetching operation, or the cache server cooperating operation, and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation respectively, by using the packet of the priority provided by the relay control section, and wherein said at least one relay server relays the data according to an instruction received from the relay control section.    
   
   
       12 . A network system comprising: 
 at least one router, wherein said at least one router provides priority information to a packet associated with a specific communication flow by identifying this communication flow, and controls a priority of transmitting a packet to a link based on the priority information provided to the packet;    at least one relay server; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information,    a relay control section for selecting a path and one of said at least one a relay servers suitable for carrying out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section, for instructing the selected relay server about data to be relayed, instructing the selected relay server to relay the data using the selected path, for obtaining a priority variable for each link of the network suitable for carrying out an automatic cache updating operation, a link prefetching operation, or a cache server cooperating operation, and for providing priority information lower than priority information of a packet to be used for communications generated by a cache operation,    a router priority setting section for requesting the router to set a priority of a specific communication flow, based on a result obtained by the relay control section, and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation respectively, by using the packet of the priority provided by the relay control section, wherein said at least one relay server relays the data according to an instruction received from the relay control section.    
   
   
       13 . A network system comprising: 
 at least one router, wherein said at least one router controls a priority of transmitting a packet to a link, based on priority information provided to the packet, and sets a requested path on the network;    at least one relay server; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information,    a relay control section for selecting a path and one of said at least one a relay servers suitable for carrying out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section, instructing the selected relay server about data to be relayed, and providing priority information lower than priority information of a packet to be used for communications generated by a cache operation, to a packet to be used for communications generated by the automatic cache updating operation, the link prefetching operation, or the cache server cooperating operation,    a path setting section for requesting a router to set the path obtained by the relay control section, and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation respectively, by using the packet of the priority provided by the relay control section, wherein said at least one relay server relays the data according to an instruction received from the relay control section.    
   
   
       14 . A network system comprising 
 at least one router, wherein said at least one router provides priority information to a packet relating to a specific communication flow by identifying this communication flow, controls a priority of transmitting a packet to a link based on the priority information provided to the packet, and sets a requested path on the network;    at least one relay server; and    at least one cache server comprising:    a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information,    a relay control section for selecting a path and a relay server suitable for carrying out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section, for instructing the selected relay server about data to be relayed, and for obtaining a priority variable for each link of the network suitable for carrying out an automatic cache updating operation, a link prefetching operation, or a cache server cooperating operation,    a router priority setting section for requesting the router to set a priority of a specific communication flow, based on a result obtained by the relay control section, and for providing priority information lower than priority information of a packet to be used for communications generated by a cache operation,    a path setting section for requesting the router to set the candidate path selected by the relay control section, and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation respectively, by using the packet of the priority provided by the relay control section, wherein said at least one relay server relays the data according to an instruction of the relay control section.    
   
   
       15 . A cache server provided in a network system having a priority controllable router for controlling a priority of transmitting a packet to a link based on priority information provided to the packet, wherein 
 the cache server carries out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, and provides priority information to a packet to be used for communications generated by the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, wherein the priority information is lower than priority information of a packet to be used for communications generated by a cache operation.    
   
   
       16 . The cache server according to  claim 15 , further comprising: 
 a priority providing section for providing a priority request source with a priority predetermined for each request source, when there has been a request for providing a priority;    a priority information adding section for adding priority information showing the priority to a packet, when the packet to be transmitted to the network and the priority have been received; and    a cache operating section, a link prefetching control section, an automatic cache updating section, and a cache server cooperating section, each of which requests the priority providing section to provide a priority when a transmission packet has been generated, and passes the priority provided by the priority providing section and the transmission packet to the priority information adding section.    
   
   
       17 . A cache server on a network provided with at least one priority controllable router that provides priority information to a packet associated with a specific communication flow by identifying this communication flow, and controls a priority of transmitting a packet to a link based on the priority information provided to the packet, the cache server comprising: 
 a QoS path information obtaining section for obtaining QoS path information that includes network path information and path load information;    a priority providing section for obtaining a priority variable for each link of the network suitable for carrying out an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained by the QoS path information obtaining section;    a router priority setting section for requesting at least one priority controllable router to set a priority to a specific communication flow, based on a result obtained by the priority providing section wherein the priority set is lower than a priority of a packet to be used for communications generated by a cache operation; and    at least one of an automatic cache updating section, a link prefetching control section, and a cache server cooperating section, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation respectively, by utilizing a path set by the priority controllable router.    
   
   
       18 . A method for controlling a cache server provided on a network system having at least one priority controllable router capable of controlling a priority of transmitting a packet to a link based on priority information provided to the packet, the method comprising: 
 a) carrying out at least one of an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation; and    b) providing priority information to a packet to be used for communications generated by the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, wherein the priority information is lower than priority information of a packet to be used for communications generated by a cache operation.    
   
   
       19 . A method for controlling a cache server provided on a network system including at least one priority controllable router which provides priority information to a packet associated with a specific communication flow by identifying this communication flow and controls a priority of transmitting a packet to a link based on the priority information provided to the packet, the method comprising: 
 a) obtaining QoS path information that includes network path information and path load information;    b) obtaining a priority variable for each link of the network suitable for carrying out an automatic cache updating operation, a link prefetching operation, and a cache server cooperating operation, based on the QoS path information obtained at the step (a);    c) requesting at least one priority controllable router to set a priority, based on a result obtained at the step (b), wherein the at least one priority set is lower than a priority of a packet to be used for communications generated by a cache operation; and    d) providing at least one of an automatic cache updating step, a link prefetching control step, and a cache server cooperating step, which carry out respective ones of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, by utilizing a path set by the priority controllable router.    
   
   
       20 . A recording medium storing a program for use in a computer of a cache server provided on a network system having at least one priority controllable router that controls a priority of transmitting a packet to a link based on priority information provided to the packet, the program instructing the computer to function as: 
 a priority providing section for providing a priority request source with a priority predetermined for each request source, when there has been a request for providing a priority;    a priority information adding section for adding priority information showing a priority to a packet, when the packet to be transmitted to the network and the priority have been received; and    a cache operating section, a link prefetching control section, an automatic cache updating section, and a cache server cooperating section, which request the priority providing section to provide a priority when a transmission packet has been generated, and pass the priority provided by the priority providing section and the transmission packet to the priority information adding section, where in a priority given to a packet to be used for communications generated by at least one of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation is lower than a priority given to a packet to be used for communications generated by a cache operation.