Transmission system, bandwidth management apparatus, and bandwidth management method

A transmission system comprising a transmission line, plural communication apparatuses connected to the transmission line, and a bandwidth management apparatus for managing bandwidths on the transmission line, wherein

• a communication apparatus included in the plural communication apparatuses, when performing isochronous data transmission by using an allocated resource on the transmission line, outputs a resource allocation request to the bandwidth management apparatus before the isochronous data transmission, and outputs the resource allocation request again upon receipt of a free resource increase notification, when a negative acknowledgement is sent to the communication apparatus in response to the resource allocation request, and wherein
• the bandwidth management apparatus manages resources on the transmission line, sends the negative acknowledgement to the communication apparatus when resource allocation for the resource allocation request from the communication apparatus is impossible, and notifies all the communication apparatuses that free resources are increased, by broadcast, when the allocated resource is released.

A transmission system comprising a transmission line, plural communication apparatuses connected to the transmission line, and a bandwidth management apparatus for managing bandwidths on the transmission line, wherein

• a communication apparatus included in the plural communication apparatuses, when performing data transmission by using an allocated resource on the transmission line, outputs a resource allocation request including a priority to the bandwidth management apparatus before the data transmission, and wherein
• the bandwidth management apparatus manages resources on the transmission line in such a way that it releases resources allocated for other communication apparatuses and allocates the resources for the resource allocation request, when resource allocation for the resource allocation request from the communication apparatus is impossible and the priority of the resource allocation request is the highest.

A bandwidth management apparatus for managing resources on a transmission line and processing a resource allocation request including information indicating a minimum bandwidth and a maximum bandwidth, said bandwidth management apparatus comprising:

• an allocated-resource request table for storing plural allocated-resource requests;
• and
• resource management means which decides whether or not a sum of minimum bandwidths of all allocated-resource requests stored in the allocated-resource request table and a minimum bandwidth of the resource allocation request is allocatable from the resources on the transmission line when receiving the resource allocation request as an input, allocates a resource for each of the all allocated-resource requests and the resource allocation request such that a bandwidth between a corresponding minimum bandwidth and a corresponding maximum bandwidth is allocated when deciding that the sum is allocatable, and writes the minimum bandwidth and an allocated bandwidth of the resource allocation request in the allocated-resource request table as an allocated-resource request.

A bandwidth management apparatus for managing resources on a transmission line and processing a resource allocation request, comprising:

• means for broadcasting a free resource increase notification through the transmission line when an allocated resource is released.

A bandwidth management apparatus for managing resources on a transmission line and processing a resource allocation request including a priority, comprising:

• means which releases an allocated resource when resource allocation for the resource allocation request is impossible and the priority of the resource allocation is the highest, and performs resource allocation for the resource allocation request.

A bandwidth management method for managing resources on a transmission line by using an allocated-resource request table for storing plural allocated-resource requests, said method comprising the steps of:

• deciding whether or not a sum of minimum bandwidths of all allocated-resource requests stored in the allocated-resource request table and a minimum bandwidth of the resource allocation request is allocatable from the resources on the transmission line when receiving the resource allocation request as an input;
• and
• allocating a resource for each of the all allocated-resource requests and the resource allocation request such that a bandwidth between a corresponding minimum bandwidth and a corresponding maximum bandwidth is allocated when deciding that the sum is allocatable, and writing the minimum bandwidth and an allocated bandwidth of the resource allocation request in the allocated-resource request table as an allocated-resource request.

A bandwidth management method for managing resources on a transmission line to which plural communication apparatuses are connected, wherein

• when an allocated resource is released, all of the plural communication apparatuses are notified by broadcast that free resources are increased.