Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1999-08-31
2004-06-01
Pham, Chi (Department: 2667)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S395300, C370S400000, C370S424000
Reexamination Certificate
active
06744762
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a node device, communication network system having a plurality of node devices, and control method therefor.
2. Description of the Related Art
In recent years, networks having node devices connected by multiplex transmission paths have been so examined as to cope with high-speed, large-capacity networks for connecting terminal devices along with an increase in information amount.
Some of these networks transmit packets while changing the communication channel in a node device.
An example of this network will be described.
FIG. 11
is a block diagram showing the arrangement of a node device in this network that is connected to terminals
1151
to
1158
via sub-transmission paths.
Reference numerals
1101
to
1108
denote separation/insertion units having a function of detecting the addresses of packets input via parallel multiplex transmission paths, separating the packets into packets to be transmitted to terminals via sub-transmission paths and packets to be input to buffers, and inserting packets transmitted from terminals into packet flows input via the parallel multiplex transmission paths.
Reference numerals
1111
to
1118
denote buffers having a function of temporarily storing packets output from the separation/insertion units in storage areas corresponding to the output terminals of a switch
1141
.
Reference numerals
1121
to
1128
and
1131
to
1138
denote parallel multiplex transmission paths for connecting nodes on which a plurality of transmission paths (communication channels) are multiplexed. For example, the parallel multiplex transmission paths
1121
to
1128
and
1131
to
1138
are a plurality of spatially separated optical fiber transmission paths, or wavelength multiplex transmission paths wavelength-divided and multiplexed on one optical fiber.
Reference numeral
1141
denotes a switch controlled by a switch controller
1142
to connect packets input to input terminals IN
1
to IN
8
to arbitrary output terminals OUT
1
to OUT
8
. The switch
1141
is switched using a space switch or the like when a plurality of optical fiber transmission paths are used for the parallel multiplex transmission paths. When the wavelength multiplex transmission paths are used, transmitters made up of a plurality of tunable laser diodes and multiplexer are connected to the wavelength multiplex transmission paths, and respective wavelengths are demultiplexed by a demultiplexer at the receivers of the wavelength multiplex transmission paths, thereby constituting the switch between nodes, although not shown in FIG.
11
. The switch is switched by setting the transmission wavelength of the tunable laser diode to an arbitrary one of wavelengths &lgr;
1
to &lgr;
8
.
The switch controller
1142
controls the switch in accordance with, e.g., a control pattern in FIG.
5
.
Reference numeral
1143
denotes a buffer controller for controlling to read out a packet stored in the buffer when the input terminal of the switch connected to each buffer is connected to a desired output terminal.
FIG. 5
shows a control pattern representing the connection relationship between the input and output of the switch
1141
. The input/output connection relationship of the switch is changed by control addresses A
1
to A
8
. The input terminals IN
1
to IN
8
correspond to the buffers
1111
to
1118
, and the output terminals OUT
1
to OUT
8
(or transmission wavelengths &lgr;
1
to &lgr;
8
) correspond to storage areas
1
to
8
of the buffers.
The communication principle of the network will be explained with reference to FIG.
13
. For illustrative convenience,
FIG. 13
shows node devices each having four terminals connected to parallel multiplex transmission paths made up of four transmission paths.
This network has a plurality of rings A, B, C, and D, and these rings are connected to each other by switches
1305
to
1308
.
Each terminal is connected to one ring transmission path of the parallel transmission paths A, B, C, and D, and when communicating with a terminal connected to another ring, switched at least once to that ring by an arbitrary switch. The switching position is not specified. To facilitate communication control, the terminal is switched to a transmission path connected to a destination terminal at a node immediately preceding the destination node, and switched to an arbitrary transmission path at another node.
To simplify the node device in this network, the switches
1305
to
1308
change the input/output connection relationship in accordance with a specific cyclic pattern every predetermined period regardless of an input signal. Input signals are temporarily stored in buffers
1309
to
1312
. When the input/output connection relationship of the switch attains a desired one, packets are read out from the buffers and switched.
For example, when a terminal
1322
communicates with a terminal
1332
, a packet output from the terminal
1322
is stored in the buffer
1309
of a node
1301
. When the input terminal IN
2
of the switch
1305
is connected to, e.g., the output terminal OUT
2
, the packet is read out from the buffer and output to the transmission path B. When IN
2
and OUT
4
of the switch
1306
are connected, the packet input to the buffer
1310
of anode
1302
is readout from the buffer, output to the transmission path D, and transmitted to the terminal
1332
.
In this way, communication is done by switching to an arbitrary ring transmission path at each node device.
In this network, when a plurality of packets transmitted by a given terminal reach a destination terminal, the packet transmission order of the transmitting terminal may be different from the packet reception order.
This will be described with reference to
FIGS. 5
,
6
,
7
,
11
, and
12
.
In the following description, the parallel multiplex transmission paths are a plurality of spatially separated optical fiber transmission paths, and the switch is a space switch. When the wavelength multiplex transmission paths are used, almost the same operation is done based on the above principle. An example of operation when a terminal
1213
communicates with a terminal
1232
will be explained.
Data transmitted from the terminal
1213
is segmented into fixed-length packets
1
,
2
,
3
, and
4
, and each packet is output with a destination address described at its header. Output packets
1
,
2
,
3
, and
4
are input to a node device
1201
via a sub-transmission path, inserted in a packet flow from the parallel multiplex transmission path by the separation/insertion unit
1103
, and transmitted to the buffer
1113
. Since the destination address of the input packet does not coincide with the address of an adjacent downstream node device, the buffer
1113
stores the packet in an arbitrary storage area. In this case, packets
1
,
2
,
3
, and
4
are respectively stored in storage areas
1
,
2
,
3
, and
4
.
The buffer controller
1143
waits for reading out packet
1
until the input terminal IN
3
of the switch
1141
is connected to the output terminal OUT
1
. When the input terminal IN
3
is connected to the output terminal OUT
1
, buffer controller
1143
reads out packet
1
. The buffer controller
1143
similarly reads out packets
2
,
3
, and
4
. The switch controller
1142
sequentially supplies control addresses A
1
, A
2
, A
3
, A
4
, A
5
, A
6
, A
7
, and A
8
in accordance with a table shown in
FIG. 5
to change the connection relationship of the switch
1141
. Further, the switch controller
1142
supplies the control addresses every 1-packet period to control to repeat the same pattern every 8-packet period. The switch controller
1142
informs the buffer controller
1143
of this information, thereby controlling the buffer read timing.
In this example, when the input terminal IN
3
of the switch
1141
is connected to the output terminal OUT
1
, packet
1
is read out from storage area
1
of the buffer
1113
, and output to the transmission path
1131
via the output terminal OUT
1
o
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hoang Thai
Pham Chi
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