Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1998-01-16
2001-04-03
Olms, Douglas (Department: 2661)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S465000
Reexamination Certificate
active
06212200
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technology for combining real time communications which processes multimedia data, etc., with non-real time communications which processes other data, and controlling the combination in a network such as a packet network, etc., and more particularly to a technology for effectively performing non-real time communications in which a bandwidth is restricted, on a network where resources are reserved with higher priority for real time communications and where its bandwidth is to be secured.
2. Description of the Related Art
When multimedia applications for performing communications of multimedia data such as audio data and video data are used on a network such as a packet network, etc., and when the transfer of these data are delayed due to heavy traffic on the network, users feel disturbed, since the continuity of sound and pictures is interrupted. To prevent this situation it is important that the bandwidth of real time communications is guaranteed on a network for processing multimedia data.
Conventionally, a technology is known to guarantee the bandwidth of the real time communications for preferentially assigning network resources to the real time communications for processing multimedia data, etc., by restricting the use of the network resources by the non-real time communications.
In fact, the bandwidth determined by subtracting the bandwidth assigned for the real time communications from that assigned for the whole network is assigned to each node apparatus. Each node apparatus restricts the bandwidth of the non-real time communications in such a way this bandwidth does not exceed the bandwidth which is assigned to each node apparatus.
However, the above-described prior art is not originally provided with a means for estimating necessary bandwidth based on the current used status of the non-real time communications and for updating the bandwidth limit value of the non-real time communications of each node apparatus according to the current used status. As a result, in the above-described prior art, since the non-real time communications cannot use the network resources effectively, a status occurs in which the delay of transfer of the non-real time communications increases, etc., which makes users feel disturbed when the used status of the non-real time communications by users changes. This is a problem of the prior art.
Although a method for deciding the assignment of the network resources based on its used result by observing the used status of the non-real time communications over a long period of time, is considered to be a method for estimating necessary bandwidth based on the current used status of the non-real time communications, this method has the problem that the network resources cannot be effectively assigned when the non-real time communications having strong data burst characteristics, occur.
Even if a means by which the occurrences of the non-real time communications having strong data burst characteristics are detected and even if the reassignment of the bandwidth of the non-real time communications can be requested based on it, a heavy traffic is caused on the network when the bandwidth of the non-real time communications is reassigned to all the node apparatuses at the time of the occurrence of the request for its reassignment. This increases the load of each node apparatus composing the network and causes the functioning of the network to deteriorate. This is another problem of the prior art.
SUMMARY OF THE INVENTION
The present invention is made in the above-described background. It is an object of the present invention to realize a means by which the bandwidth limit value of each node apparatus can be immediately updated when traffic occurs which exceeds its bandwidth limit value, and when the increase of its allowable bandwidth is required.
The present invention is based on a communications system for securing the necessary bandwidth of real time communications by transferring the packets of the non-real time communications through a queue (NRT queue
110
) and by adjusting the bandwidth of the non-real time communications.
First, one of a plurality of node apparatuses on the network is operated as a master apparatus (master apparatus
101
), while the other node apparatuses and/or the master apparatus itself are operated as client apparatuses (client apparatus
102
).
Then, the communications system comprises a non-real time communications status monitor unit (NRT communications status monitor unit
107
), and a non-real time communications bandwidth request unit (request generator unit
108
and NRT bandwidth request unit
109
).
The non-real time communications status monitor unit monitors the used status of the bandwidth of the non-real time communications in the queue of the client apparatus. For example, when the current output bandwidth in the queue reaches its bandwidth limit value set for the queue, the non-real time communications status monitor unit calculates an increment of the bandwidth of the non-real time communications according to the total packet length or the remaining time length of the packets remaining in the queue. For example, when the current output bandwidth in the queue reaches its bandwidth limit value set for the queue, and when the packet whose length is restricted by a size of a window is not remaining in the queue, the non-real time communications status monitor unit calculates an increment of the bandwidth of the non-real time communications, according to the total packet length of the packets remaining in the queue. When the current output bandwidth in the queue reaches its bandwidth limit value set for the queue, and when the packet whose length is restricted by a size of a window, is remaining in the queue, it calculates the increment of the bandwidth of the non-real time communications according to a value obtained by adding a value corresponding to the window control to the total packet length of the packets remaining in the queue. Or, for example, when the current output bandwidth in the queue reaches its bandwidth limit value set for the queue, the non-real time communications status monitor unit calculates an increment of the bandwidth of the non-real time communications according to the input bandwidth of the queue.
Next, when the non-real time communications status monitor unit judges that it is necessary to increase the bandwidth of the non-real time communications, the non-real time communications bandwidth request unit send outs a request for increasing the bandwidth of the non-real time communications to the master apparatus.
The master apparatus further comprises a non-real time communications bandwidth collector unit
104
, a non-real time communications bandwidth reassignment unit
105
, and a non-real time communications bandwidth notifier unit
106
.
The non-real time communications bandwidth collector unit decreases the bandwidth limit value of the queue inside a client apparatus in which the current bandwidth in the queue is less than the bandwidth limit value set for the queue, by regularly inquiring the use status of the bandwidth in each non-real time communications status monitor unit in each client apparatus, and at the same time stores the decreased value as a collected bandwidth.
Then, when the non-real time communications bandwidth distributor unit has received an increase request for the non-real time communications bandwidth from the non-real time communications bandwidth request unit in any client apparatus, it redistributes a new bandwidth limit value corresponding to the increase request within the range of the collected bandwidth stored by the non-real time communications bandwidth collector unit.
Then, the non-real time communications bandwidth notifier unit notifies the client apparatus which sent out the increase request and sets it to the new bandwidth limit value which is reassigned by the non-real time communications bandwidth reassignment unit.
In the above-described way, the master appa
Iizuka Fumiyuki
Yuhara Masanobu
Fujitsu Limited
Olms Douglas
Pizarro Ricardo M.
Staas & Halsey , LLP
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