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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This is a continuation of U.S. patent application Ser. No. 09 / 915,056, filed Jul. 25, 2001, in the name of Masayoshi Kobayashi, and entitled TECHNIQUE FOR ENHANCING EFFECTIVENESS OF CACHE SERVER.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a cache server and a network system having cache servers. The invention particularly relates to a technique of performing prefetching of linked information (link prefetching) and the like with enhanced effectiveness of a cache server in high probabilities without deteriorating a congestion status of the network. [0004] 2. Description of the Related Art [0005] A conventional network system having cache servers will be described with reference to FIG. 36 and FIG. 37. [0006]FIG. 36 is a block diagram showing an example of the configuration of a conventional network system having cache servers. Web servers S1 and S2 are the servers that exist within ...

AI Technical Summary

Benefits of technology

[0036] Based on provision of the above structure, it becomes possible to make a cache server perform the link prefetching operation, the automatic cache updating operation, and / or the cache server cooperating operation in higher probabilities than those of the prior art. This causes the efficiency of the cache server to be increased without deteriorating a congestion status of the network.

[0037] Further, in order to achieve the above object, according to another aspect of the present invention, there is provided a network system including a cache server in which a relay control section selects a relay server that is necessary for setting 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. The relay control section instructs the selected relay server about data to be relayed. The relay control section selects a relay server that is necessary for setting a relay path that does not include a congestion portion. According to this structure, it is possible to obtain the above-described advantages. Further, when a relay path including no congestion portion is not found, only a relay server that locates upstream from (preferably nearest to) the congestion portion is notified of data to be relayed, and the data is stored in that location of the relay path until the congestion status has disappeared. When the congestion status has disappeared, the relay control section issues a relay instruction to relay servers downstream from the location where the congestion had occurred. With this arrangement, it becomes possible to shorten the time taken for obtaining the data as compared with the case of obtaining the data from the original Web server after the congestion status has been released.

[0038] In addition to the above arrangement, a path setting section maybe provided in the cache server, and a path-settable router maybe used that can set a path according to an instruction of the path setting section, as a router. With this arrangement, it becomes possible to make a cache server carry out the link prefetching operation, the automatic cache updating operation, and the cache server cooperating operation in higher probabilities without deteriorating a congestion status of the network.

[0039] Further, in order to achieve the above object, according to still another aspect of the present invention, there is provided a network system that includes a priority controllable router for controlling the priority of sending a packet to a link based on priority information given to the packet, and a cache server for carrying out at least one of the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, and for giving priority information to a packet to be used for communications generated by the above three operations. According to this arrangement, it becomes possible to lower the priority of communications for the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation. Therefore, it becomes possible to execute the link prefetching operation, the automatic cache updating operation, and the cache server cooperating operation in higher probabilities, without deteriorating a congestion status of the network.

[0040] Further, in order to achieve the above object, according to still further aspect of the present invention, there is provided a network system that includes a priority controllable router designed to give priority information to a packet relating to a specific communication flow by discriminating this communication flow, and to control the priority of transmitting a packet to a link based on the priority information given to the packet. The network system further includes a cache server for obtaining priority, that can be changed for each link of the network, suitable for executing the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation, based on QoS path information. The cache server further requests the priority controllable router to set and cancel the priority to a specific communication flow. According to this arrangement, it becomes possible to lower the priority of communications for the automatic cache updating operation, the link prefetching operation, and the cache server cooperating operation. Therefore, it becomes possible to execute the link prefetching operation, the automatic cache updating operation,and the cache server cooperating operation in higher probabilities, without deteriorating a congestion status of the network.

Problems solved by technology

When the predicted content are not actually required, or when the content is updated more frequently at the Web server than the automatic cache updating operation, these operations are not effective.

Only the resources of the network are wasted.

Consequently, there has been a problem that the operations of (1), (2) and (3) are not carried out.

As a result, the prefetching of the content may further deteriorate the congestion status of the network.

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