Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-05-08
2001-09-04
Chin, Wellington (Department: 2737)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
Reexamination Certificate
active
06285676
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an asynchronous transfer mode (ATM) network, particularly, relates to a method of controlling bandwidth of virtual path between two ATM subscriber switches connected to each other through at least one ATM transit switch.
An ATM network must guarantee bandwidth of a call which is established by negotiation with the terminal (i.e. a source) to guarantee quality of the call. This is because traffic of data transmitted by the terminal is changed with time and the ATM network can neither determine nor estimate the data traffic.
The ATM network negotiates with the terminal to decide a maximum data transfer rate when the call is established. The ATM network guarantees the maximum data transfer rate to guarantee perfect quality of service (QoS) for the call.
In the ATM network, each node which relates to the call must process some tasks when the call is established and released. For example, the node calculates free bandwidth and renews a management table.
There is a case that an ATM transit switch is connected to many terminals through a plurality of ATM subscriber switch. In this case, the ATM transit switch relates to the many calls and spends a long time for processing the tasks. Accordingly, the ATM transit switch will become bottleneck for the conventional ATM network.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a method capable of reducing processing load of a transit switch in an asynchronous transfer mode network.
It is another object of this invention to provide a subscriber switch capable of reducing processing load of a transit switch in an asynchronous transfer mode network.
It is still another object of this invention to provide the highly performance ATM network including a subscriber switch which can reduce processing load of a transit switch.
Other object of this invention will become clear as the description proceeds.
On describing the gist of this invention, it is possible to understand that a method of controlling bandwidth of a virtual path accommodates a virtual channel in an asynchronous transfer mode network. The virtual path is established between two subscriber switches through a transit switch. The virtual channel is established between two terminals which are connected to the subscriber switches, respectively.
According to the gist of this invention, the method comprises the steps of detecting a command signal sent from an source which is one of the terminals for establishing/releasing the virtual channel at a specific subscriber switch which is one of the subscriber switches and which is connected to the source, judging at the specific subscriber switch whether or not it is necessary to change bandwidth of the virtual path on the basis of the command signal, producing a direction signal for directing the transit switch to extend/reduce the bandwidth of the virtual path at the specific subscriber switch when the specific subscriber judges that it is necessary to change the bandwidth of the virtual path, and extending/reducing the bandwidth of the virtual path at the transit switch by a predetermined step in response to the direction signal.
According to another gist of this invention, a subscriber switch is for use in an asynchronous transfer mode network which has terminals and a transit switch and which establishes a virtual path to accommodate a virtual channel. The subscriber switch comprises a detecting section to detect a command signal sent from an source which is one of the terminals for establishing/releasing the virtual channel. A judging section is connected to the detecting section to judge whether or not it is necessary to change bandwidth of the virtual path in the basis of the command signal. A routing section is connected to the judging section to produce a direction signal for directing the transit switch and to extend/reduce the bandwidth of the virtual path when the specific subscriber judges that it is necessary to change the bandwidth of the virtual path.
According to still another gist of this invention, a transit switch is for use in an asynchronous transfer mode network which has subscriber switches connected to the transit switch for establishing a virtual path to accommodate a virtual channel. The transit switch comprises a receiving section to receive a transmission signal sent from one of the subscriber switches. A judging section is connected to the receiving section to judge that the transmission signal is a direction signal or a passage signal. A changing section is connected to the judging section to change the bandwidth of the virtual path in response to the transmission signal when the transmission signal is the direction signal. A passing section is connected to the judging section to pass the transmission signal to another subscriber indicated by the transmission signal when the transmission signal is the passage signal.
According to further still another gist of this invention, an asynchronous transfer mode network uses a virtual path to accommodate a virtual channel. The virtual path is established between two subscriber switches connected to terminals through a transit switch. The asynchronous transfer mode network comprises a detecting section which is arranged in each subscriber switch to detect a command signal sent from an source which is one of the terminals for establishing/releasing the virtual channel. A judging section is arranged in each subscriber switch and is connected to the detecting means to judge whether or not it is necessary to change bandwidth of the virtual path on the basis of the command signal. A producing section is arranged in each subscriber switch and connected to the judging section to produce a direction signal for directing said transit switch and to extend/reduce the bandwidth of the virtual path when the specific subscriber judges that it is necessary to change the bandwidth of the virtual path. An extending/reducing section is arranged in the transit switch to extend/reduce the bandwidth of the virtual path by a predetermined step in response to the direction signal.
REFERENCES:
patent: 5200952 (1993-04-01), Bernstein et al.
patent: 5878029 (1999-03-01), Hasegawa et al.
patent: 9-51341 (1999-02-01), None
Chin Wellington
Jones Premell
McGinn & Gibb PLLC
NEC Corporation
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