Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-07-08
2001-07-03
Chin, Wellington (Department: 2664)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S410000, C370S422000, C370S398000
Reexamination Certificate
active
06256316
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to methods for communications between terminals in a centralized supervisory system, and more particularly to a method for a communication between terminals in a centralized supervisory system equipped with a centralized supervisory device which collects supervisory information included in control signal cells sent from individual supervisory devices and sends main signal cells to a network.
Recently, communications in an asynchronous transfer mode (ATM) have been in the spotlight as a communication method due to diversification of communication services. When an ATM communication takes place, an ATM terminal assembles a cell of a setup message including a sender number and a receiver number and sends the cell to an ATM network. Upon receiving the cell for setup, the ATM network establishes a VCC (Virtual Channel Connection) between the sender terminal and the receiver terminal, and notifies the sender and receiver terminals of respective connection identifiers VPI and VCI (Virtual Path Identifier and Virtual Channel Identifier) used in the communication. Then, the sender terminal segments data into cells and adds the notified connection identifiers to the header of each cell. Then, the cells are sent via the line. Each switch in the ATM network performs switching while changing the values of the connection identifiers of the input cells. The receiver terminal accepts the cells each having the specified connection identifiers, and disassembles the cells into data.
A plurality of ATM terminals can be accommodated in the ATM network as follows. The ATM terminals are connected to first transmission devices which implement an UNI (User Network Interface). The first transmission devices are connected to a second transmission device, which is connected to the ATM network. In such a structure, an individual supervisory device provided in each of the first transmission devices supervises the line quality (performance) and a fault state (alarm), and sends the supervisory information thereon to a centralized supervisory device provided in the second transmission device. The centralized supervisory device collects and manages the supervisory information sent from the supervisory devices, and outputs it to an external device such as a personal computer.
FIG. 15
is a block diagram of a conventional centralized supervisory system in which the supervisory function of the system is mainly illustrated. Referring to
FIG. 15
, there are illustrated individual supervisory devices (first transmission devices)
1
1
-
1
n
, a centralized supervisory device (second transmission device)
2
, an ATM network
3
, and an MMI (Man Machine Interface) unit
4
. A large number of ATM terminals are connected to each of the individual supervisory devices
1
1
-
1
n
, which are connected to the centralized supervisory device. The MMI unit
4
is a personal computer, a workstation or the like.
FIG. 16
schematically shows a communication part of each of the individual supervisory devices
1
1
-
1
n
. The communication part is made up of a supervisory information memory
1
a
, a processor (CPU)
1
b
, a frame assemble/cell separate part
1
c
, and a cell assemble/disassemble part
1
d
. The supervisory information memory
1
a
stores the collected supervisory information. The supervisory items of the individual supervisory devices include the fault state (alarm) and the line quality (performance). The frame assemble/cell separate part lc assembles the cells (the main signal cells and control signal cells) into a frame which conforms with, for example, the SONET OC
3
level, and sends the OC
3
frame to a transmission line (optical fiber) TL. Further, the frame assemble/cell separate part
1
c
separates the received OC
3
frame into the main signal cells and control signal cells. The cell assemble/disassemble part
1
d
assembles a control signal from the CPU
1
b
into control signal cells, and disassembles control signal cells supplied from the frame assemble/cell separate part
1
c
into the control signal, which is input to the CPU
1
b
. The control signal cells are cells which are used to transfer the supervisory information between the individual supervisory devices
1
1
-
1
n
and the centralized supervisory device
2
, and is equipped with a particular connection identifier (VPI/VCI) directed to discriminating the control signal cell from the main signal cells. The main signal cells are cells which are received from the ATM terminals and are sent thereto.
FIG. 17
is a diagram of a frame format of the SONET OC
3
signal. One frame consists of 9×270 bytes. The first 9×9 bytes form the section overhead SOH, and the remaining bytes form the path overhead POH and the payload PL. The section overhead SOH is used to transmit information indicating the beginning of the frame (framing signal), information inherent in the transmission line (information concerning error on the transmission line and information for maintenance of the network), and a pointer indicating the position of the path overhead POH. The path overhead POH is used to transmit end-to-end supervisory information in the network. The payload PL is used to transmit information at a bit rate of 150 Mbps so that a large number of cells (main signal cells and control signal cells) CL
1
-CLn are mapped therein.
FIG. 18
schematically shows a communication part of the centralized supervisory device
2
. The communication part shown in
FIG. 18
is made up of a supervisory information memory
2
a
, a processor (CPU)
2
b
, a frame assemble/cell separate part
2
c
, and a cell assemble/disassemble part
2
d
. The supervisory information memory
2
a
stores the supervisory information collected from the individual supervisory devices
1
1
-
1
n
. The frame assemble/cell separate part
2
c
assembles the cells (the main signal cells and control signal cells) into a frame which conforms with, for example, the SONET OC
3
level, and sends the OC
3
frame to a transmission line (optical fiber) TL. Further, the frame assemble/cell separate part
2
c
separates the OC
3
frame received over the transmission line TL into the main and control signal cells. The cell assemble/disassemble part
2
d
assembles a control signal from the CPU
2
b
into control signal cells, and disassembles control signal cells supplied from the frame assemble/cell separate part
2
c
into a control signal, which is then input to the CPU
2
b.
FIG. 19
is a diagram of a supervisory sequence in which the centralized supervisory device
2
collects the supervisory information from the individual supervisory devices
1
1
-
1
n
. The CPU
2
b
of the centralized supervisory device
2
sends a polling cell to the individual supervisory device
1
1
via the cell assemble/disassemble part
2
d
and the frame assemble/cell separate part
2
c
. The frame assemble/cell separate part
1
c
of the individual supervisory device
1
1
supplies the received polling cell to the CPU
1
b
via the cell assemble/disassemble part
1
d
. The CPU
1
b
checks whether there is a change in the supervisory information between the previous polling and the current polling. If it is judged that there is no change, the CPU
1
b
sends an ACK cell to the centralized supervisory device
2
via the cell assemble/disassemble part
1
d
and the frame assemble/cell separate part
1
c.
The CPU
2
b
of the centralized supervisory device
2
receives the ACK signal via the frame assemble/cell separate part
2
c
and the cell assemble/disassemble part
2
d
, and thus recognizes that there is no change in the supervisory information on the individual supervisory device
1
1
. Then, the CPU
2
b
sends the polling cell to the next individual supervisory device
1
2
. If there is a change in the supervisory information on the individual supervisory device
1
2
, the CPU
1
b
thereof assembles changed supervisory information (change data) into the cell, which is then sent to the centralized supervisory device
2
. Then, the centralized supervisory devic
Chin Wellington
Fujitsu Limited
Helfgott & Karas P.C.
Pham Brenda
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