Electrical computers and digital processing systems: multicomput – Computer network managing – Network resource allocating
Reexamination Certificate
1997-03-31
2001-11-06
Dinh, Dung C. (Department: 2153)
Electrical computers and digital processing systems: multicomput
Computer network managing
Network resource allocating
C709S225000, C709S227000, C370S216000, C370S241000, C370S401000, C370S408000, C370S431000, C380S044000
Reexamination Certificate
active
06314464
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a communication control method and, more particularly, to a communication control method suitable for use in, for example, multicast communication.
2. Description of the Related Art
Recently, in distributed processing environments in which computers are interconnected over a network, multimedia applications, such as electronic teleconferencing and video on demand systems, have attracted attention. Characteristics of communications performed by such multimedia applications are that there is a real-time limitation upon data transfer, for example, data must be transmitted at a fixed rate or within a fixed time, and the same data must be efficiently transferred to a plurality of receivers at the same time.
Several protocols for reserving resources corresponding to multicast have already been proposed. Here, the resources are CPU (Central Processing Unit) processing time, a network band, a data buffer and the like. For example, ST-II (Internet Stream Protocol, Version 2) is a protocol for establishing a one-to-multiple connection. A sender proposes an optimum FlowSpec (Flow Specification) and multicasts a connection establishment request to all the receivers. Here, FlowSpec indicates data transfer properties, such as data transfer rate or permissible transmission delay, and the quantity of resources required for data transfer is calculated on the basis of a specified FlowSpec.
Each receiver sends back to the sender a maximum FlowSpec which can be ensured over the route to the sender. The sender selects a minimum-level FlowSpec from among the FlowSpecs gathered from all the receivers and transmits a connection establishment request again. In the second connection establishment request, resources are actually reserved, and an identical FlowSpec connection is established for all the receivers. This connection establishment procedure is performed each time a receiver joins or leaves.
Further, in RSVP (Resource ReSerVation Protocol), by periodically sending a tree construction request in advance using conventional multicast, a multicast tree managed by RSVP is constructed. A newly joining receiver establishes a connection with the sender by sending a connection establishment request by backtracking the constructed tree. In this method, since connection establishment is performed for each receiver, it is possible to set a different FlowSpec to each receiver. In RSVP, the established connection is reestablished dynamically rather than statically in accordance with a tree construction request which is periodically received.
However, in a conventional network protocol, since time required for data transfer varies according to the quantity of resources which can be used during data transfer, it is difficult to satisfy the real-time characteristic of data transfer. Therefore, a protocol is required by which a connection is established between the sender and the receiver, and necessary resources are reserved beforehand in accordance with a transfer request before starting transmission.
In particular, in multicast communication (one-to-multiple communication), a plurality of receivers are involved, and the connection dynamically varies during data transfer as receivers join or leave. For this reason, there is a demand for a real-time multicast protocol by which a path is shared and a connection can be established dynamically in response to a request from a receiver by setting up a connection between the sender and the receiver on a tree.
The summarized features of the above-described two protocols ST-II and RSVP are shown in FIG.
11
. As shown in
FIG. 11
, in ST-II, since a resource reservation is repeated from a sender each time a receiver joins, the load of the connection establishment request when the receiver joins concentrates on the sender, and scalability of the number of members in the group is a problem. Further, transfer level of each receiver is adjusted to the lowest transfer level among the receivers.
Therefore, in RSVP, by. transmitting a connection establishment request from a receiver, the above-described problems are solved. However, since the route varies dynamically, ensurance of an established connection is not sufficient. Further, although handling of requests from each receiver is attempted, it is not possible to select an optimum route appropriate for the request from each receiver because the route selection itself is made by the sender.
As described above, the problems of the conventional protocol are thought to occur from the fact that route selection can be made only by the sender because the route control and resource reservation mechanisms are considered to be completely independent. However, in the existing multicast route control algorithm, in an internal process, it is possible to select a route to the sender from the receiver.
SUMMARY OF THE INVENTION
The present invention has been achieved in view of the above-described circumstances. The present invention aims to make it possible to effect route control and to establish a connection in accordance with a request from each receiver by determining an interface between a route control mechanism and a resource reservation mechanism and integrating the mechanisms.
To these ends, according to a first aspect of the present invention, there is provided a communication control method for establishing a connection between a plurality of senders and a plurality of receivers over a network and controlling communications between the senders and the receivers, the method comprising the steps of: selecting a route between the senders and the receivers on the basis of a request from the receiver; defining an interface between the route selection mechanism for establishing a connection and the resource reservation mechanism for reserving the resources of the route; and integrating the route selection mechanism and the resource reservation mechanism.
According to a second aspect of the present invention, there is provided a communication control method for establishing a connection between a plurality of senders and a plurality of receivers over a network and controlling data transfer from the sender to the receiver, the method comprising the steps of: establishing a connection from a receiver to each sender on the basis of a sender list held by each sender; when the plurality of senders share the connection, limiting the number of the senders who transmit data via the connection at the same time to below a predetermined number on the basis of the quantity of the resources reserved for the connection; and accepting a request for joining the network from a new sender or receiver when a QOS (Quality of Service) request of the sender and the receiver between which there has been an established connection is ensured even when the new sender or receiver joins the network.
According to a third aspect of the present invention, there is provided a communication control method for establishing a connection between a plurality of senders and a plurality of receivers over a network and controlling communications between the senders and the receivers, the method comprising: a step for making a connection establishment request to a first upper node from a new receiver; a step for temporarily reserving resources on the basis of the connection establishment request; a step for selecting a route suitable for the connection establishment request from the receiver; a step for confirming the establishment of a connection between the first upper node and a higher upper node and reserving the resources when it is confirmed that the request of the receiver is satisfied; and a step for establishing a connection to a lower node from said second node when the resources are reserved.
According to a fourth aspect of the present invention, there is provided a communication control method for establishing a connection between a plurality of senders and a plurality of receivers over a network and controlling communications between the senders and the receivers, the meth
Murata Seiji
Shionozaki Atsushi
Bell Boyd & Lloyd LLC
Dinh Dung C.
Le Hien C.
Sony Corporation
LandOfFree
Communication control method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Communication control method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Communication control method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2611565