Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1998-06-08
2002-10-22
Luther, William (Department: 2664)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S477000
Reexamination Certificate
active
06470029
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bandwidth control method and a bandwidth control system in a network that interconnects by way of a plurality of trunk nodes each of a plurality of subscriber nodes that in turn accommodate a plurality of subscribers.
2. Description of the Related Art
RSVP (ReSource reservation Protocol) has been used as a communication control method for reserving bandwidth. In this communication control method, a bandwidth request (a request to reserve a transmission bandwidth) from a terminal is transmitted by way of, for example, an interposed router to the server that is the communication partner. Upon receiving the bandwidth request from the terminal, the interposed router transfers the request on to the next router while reserving a transmission bandwidth on the path. In this way, the entire transmission bandwidth on the path is reserved from the terminal to the server. Upon receiving the request signal from the terminal, the server determines whether acceptance is possible, and if acceptance is possible, sends a response signal indicating this state on the path for which the transmission bandwidth is reserved. This response signal follows the path taken by the request signal to reach the terminal at which the request originated.
Another method is a bandwidth reserving method used in an ATM (A synchronous Transfer Mode) network. Explanation of this method is presented with reference to a typical network shown in FIG.
1
.
The network shown in
FIG. 1
is made up of subscribers
11
-
13
,
21
-
23
,
31
-
33
, and
41
-
43
(for example, residential and company subscriber servers); subscriber nodes
10
,
20
,
30
, and
40
that accommodate these subscribers; and trunk nodes
50
,
60
,
70
, and
80
that connect these subscriber nodes to each other.
Subscribers
11
-
13
are accommodated within subscriber node
10
, subscribers
21
-
23
are accommodated within subscriber node
20
, subscribers
31
-
33
are accommodated within subscriber node
30
, and subscribers
41
-
43
are accommodated within subscriber node
40
. Subscriber nodes
10
and
20
are link ed to each other by way of trunk node
50
, subscriber nodes
30
and
40
are linked to each other by way of trunk node
60
, and trunk nodes
50
and
60
are linked to each other by way of trunk nodes
70
and
80
.
As an example, when guaranteeing a line of bandwidth Wa from subscriber node
10
to subscriber node
40
by the bandwidth control of the prior art, a virtual channel of bandwidth Wa is set at subscriber node
10
on each of links (trunk line)
51
,
75
,
78
,
86
, and
64
up to subscriber node
40
. In this way, bandwidth is guaranteed by placing in correspondence subscriber node pairs (pairs of transmission source subscriber nodes and destination subscriber nodes) and defining a virtual channel within each link that joins the trunk nodes.
However, the above-described prior art has several problems as described herein below.
In a method in which bandwidth is reserved between subscribers by using RSVP, determination of whether a bandwidth is assigned or not is realized on the subscriber's server and thus cannot be managed on the network side. As a result, there is the problem that, even if it is desired, a particular subscriber cannot reserve network resources such as the bandwidth of a transmission line if the resources are already reserved by another subscriber.
Moreover, a fee-charging service has been difficult to establish using RSVP because authority such as bandwidth management is entrusted to subscribers. Due to the above-described points, RSVP has been difficult to use as a protocol for bandwidth reservation in a public network or carrier network.
Reserved bandwidths can be managed on the network side by a method that uses ATM, but the number of virtual channels to be processed increases at higher-ranking trunk nodes such as trunk nodes
70
and
80
in
FIG. 1
where multiple virtual channels are concentrated. This gives rise to the problem of higher costs of the system because intelligent, high-performance trunk nodes are required at higher-ranking trunk nodes where the number of virtual channels increases for the purpose of setting, managing and bandwidth-guaranteeing processes of guaranteed bandwidths. Furthermore, the number of subscriber nodes becomes limited as the number of virtual channels increases. A concrete explanation of this limitation on the number of subscriber nodes follows herein below.
FIG. 2
is a block diagram showing an interface of the prior art that includes a peak-rate bandwidth control capability. Data in which the virtual channel number and reserved bandwidth value are placed in correspondence are multiple-recorded in bandwidth control data memory
94
. Bandwidth control circuit
92
, which has a scheduler capability, accesses bandwidth control data memory
94
and transmission cell buffer
91
in which cells to be transmitted are stored, and transmits by way of transmission interface circuit
93
at the peak rate (maximum bandwidth) set at cells to be transmitted (Refer to section 3.7 of the Users Manual of “&mgr;PD98401 Local ATM SAR Chip” published by Nippon Electric Corporation).
If the number of virtual channels that can be controlled by bandwidth control circuit
92
is, for example, 32,000, this type of interface can handle communications on the order of 30,000 partner subscriber nodes at subscriber node
10
, but at higher-ranking trunk nodes such as trunk nodes
70
and
80
, communication can be handled for only about 180 subscriber node pairs, i.e., a number equal to the square root of 32,000, (in the case of a logical mesh). Thus, a significant limit exists for the bandwidth reservation channels on the subscriber nodes.
In addition to the above-described point in methods using ATM, a bandwidth control data memory of large volume becomes necessary as the number of virtual channels increases, and this leads to the problems of both greater size and greater cost of the device.
SUMMARY OF THE INVENTION
The first object of the present invention is to provide a bandwidth control method and bandwidth control system that allows the management of bandwidths to be reserved to be performed on the network administration side.
The second object of the present invention is to provide a bandwidth control method and bandwidth control system that allow simple management and setting of guaranteed bandwidths regardless of increases in the number of channels for which bandwidths are to be reserved.
To achieve the above-described objects, the bandwidth control method of the present invention is a bandwidth control method that is carried out in a network in which a plurality of subscriber nodes accommodating a plurality of subscribers are each connected to each other by trunk nodes; and that includes: for the data transfer from subscriber nodes to trunk nodes, setting virtual channels to each of destination subscriber nodes that are relayed by way of the trunk nodes and reserving bandwidths based on the virtual channels; and for the data transfer from trunk nodes to other trunk nodes or to destination subscriber nodes, establishing virtual channel groups according to route by organizing virtual channels that are relayed by the transfer nodes and reserving bandwidths based on the virtual channel groups.
In the above-described cases, the bandwidth control method of the present invention may further include:
between each of the subscriber nodes, setting a maximum bandwidth for each node pair in which one subscriber node is taken as the source and the other is taken as the destination; and
for the data transfer from the source subscriber node to the destination subscriber node, for each of the links from the source subscriber node to a trunk node, between trunk nodes, and from a trunk node the destination subscriber node, setting bandwidths corresponding to the sum of maximum bandwidths of subscriber node pairs through which data transfer is carried out.
In addition, the bandwidth control method o
Luther William
McGinn & Gibb PLLC
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