Transmission system, delivery path controller, load information collecting device, and delivery path controlling method

A transmission system including a network having a plurality of delivery servers for delivering a content responding to a delivery request from a client device for receiving the content, the transmission system comprising:

• a database that stores server load states of the plurality of delivery servers, and respective individual link load states for a plurality of delivery paths defined between a plurality of delivery server side routers and a client side router;
• a first collecting unit capable of collecting the server load states of the plurality of delivery servers and updating the database;
• a second collecting unit capable of collecting the respective individual link load states and updating the database;
• a path control unit that determines a minimum load state delivery path having a minimum load state among the plurality of delivery paths, based on sums of the server load states and the respective individual link load states stored in the database updated by the first collecting unit and the second collecting unit, the path control unit using a virtual node connected to the plurality of delivery server side routers via virtual links;
• and
• a router control unit, which sets a connection to deliver the content, included in each of a plurality of routers provided in the minimum load state delivery path determined by the path control unit, wherein the path control unit replaces the server load states of the plurality of delivery servers with individual link load states in directions from the virtual node via the virtual links, respectively, to the client side router, and determines a set of a delivery server and a delivery path by using the individual link load states.

A delivery path controller in a transmission system having:

• a plurality of delivery server side routers which communicate with a plurality of delivery servers for delivering a content;
• and a client side router which communicates with a client device for receiving the content, the delivery path controller comprising:
• a database that stores server load states of the plurality of delivery servers, and respective individual link load states for a plurality of delivery paths defined between the plurality of delivery server side routers and the client side router;
• a path control unit that determines a minimum load state delivery path having a minimum load state among the plurality of delivery paths, based on sums of the server load states and the respective individual link load states stored in the database, the path control unit using a virtual node connected to the plurality of delivery server side routers via virtual links;
• and
• a router control unit, which sets a connection to deliver the content, included in each of a plurality of routers provided in the minimum load state delivery path determined by the path control unit, wherein the path control unit replaces the server load states of the plurality of delivery servers with individual link load states in directions from the virtual node via the virtual links, respectively, to the client side router, and determines a set of a delivery server and a delivery path by using the individual link load states.

A load information collecting device in a transmission system having:

• a plurality of delivery server side routers which communicate with a plurality of delivery servers for delivering a content;
• and a client side router which communicates with a client device for receiving the content, the load information collecting device comprising:
• a database that stores server load states of the plurality of delivery servers, and respective individual link load states for a plurality of delivery paths defined between the plurality of delivery server side routers and the client side router;
• and
• a path control unit that writes, into the database, the server load states collected from the plurality of delivery servers and individual link load states between adjacent routers collected from the adjacent routers among a plurality of routers, and the path control unit using a virtual node connected to the plurality of delivery server side routers via virtual links, wherein the path control unit replaces the server load states of the plurality of delivery servers with individual link load states in directions from the virtual node via the virtual links, respectively, to the client side router, and determines a set of a delivery server and a delivery path by using the individual link load states in directions from the virtual node via the virtual links, respectively, to the client side router.

A method for determining a delivery path in a transmission system having:

• a plurality of delivery server side routers which communicate with a plurality of delivery servers for delivering a content;
• and a client side router which communicates with a client device for receiving the content, the method for determining a delivery path comprising:
• collecting server load states of the plurality of delivery servers;
• collecting individual link load states between adjacent routers collected from the adjacent routers among a plurality of routers;
• calculating sums of the server load states and the individual link load states collected, by using a Dijkstra method;
• based on the sums, determining a minimum load state delivery path having a minimum load state among a plurality of delivery paths;
• setting a connection for delivering the content in each of a plurality of routers provided in the minimum load state delivery path determined;
• and
• replacing the server load states of the plurality of delivery servers with individual link load states in directions from a virtual node connected to the plurality of delivery server side routers via virtual links, respectively, to the client side router, and determining a set of a delivery server and a delivery path by using the individual link load states.