Multiplex communications – Pathfinding or routing – Through a circuit switch
Reexamination Certificate
1998-07-16
2001-11-13
Ton, Dang (Department: 2732)
Multiplex communications
Pathfinding or routing
Through a circuit switch
Reexamination Certificate
active
06317429
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a communication apparatus such as a node apparatus used for signal transmission and a network system using the apparatus, and a signal control method used in the network system, and more particularly, to a communication apparatus such as a node apparatus which constructs a network in a flexible manner and selects a transmission direction in a flexible manner, and corrects faults occurred in the network.
2. Description of Related Art
In recent years, a signal transmission construction using a plurality of channels has been studied to realize a high-speed and large capacity network connecting terminal devices. For example, Japanese Patent Application Laid-Open Nos. 8-172394, 8-237306 and 9-55758 disclose a transmission construction using a plurality of channels.
Prior to the explanation of the present invention, an example using a part of the construction disclosed in Japanese Patent Application Laid-Open No. 8-237306 will be described below.
FIG. 5
is a block diagram showing the construction of a node apparatus in a network of the example. The node apparatus is connected to terminals
551
to
558
via sub transmission paths. Reference numerals
501
to
508
denote separation inserting units as separation inserting means having a function for detecting an address of a packet inputted from parallel multiplex transmission paths and separating the packet into a packet to be transmitted to a terminal via a subtransmission path and a packet to be inputted into a buffer, and a function for inserting the packet transmitted from a terminal into a packet stream inputted from the parallel multiplex transmission paths. Numerals
511
to
518
denote buffers as buffer means having a function for temporarily storing a packet outputted from the separation inserting unit into a storage area corresponding to an output terminal of a switch
541
. Numerals
521
to
528
and numerals
531
to
538
denote the parallel multiplex transmission paths of a plurality of channels for connecting nodes. The transmission paths are, e.g., a plurality of spatially separated optical fiber transmission paths or a wavelength multiplex transmission path wavelength-divided and multiplexed on one optical fiber. Numeral
541
denotes the switch, controlled by a switch controller
542
, to connect a packet inputted into one of input terminals IN
1
to IN
8
to arbitrary one of output terminals OUT
1
to OUT
8
. The switch
541
performs switching by using spatial switches when the parallel multiplex transmission paths are a plurality of optical fiber transmission paths. Further, when a wavelength multiplex transmission path is used, the switch is constructed between the nodes by connecting a transmission unit, comprising a plurality of variable-wavelength laser diodes and a wave combiner, to the wavelength multiplex transmission path such that a receiving unit of the wavelength multiplex transmission paths separates the respective wavelengths by using a wave separator, and the switching is performed by arbitrarily setting transmission wavelengths of the variable-wavelength laser diodes within a range of &lgr;1 to &lgr;8. The switching in this case is performed by an arrangement a little different from the arrangement as shown in FIG.
5
. Numeral
542
denotes the switch controller which controls the switch in accordance with, for example, a control pattern in FIG.
4
. Numeral
543
denotes a buffer controller. When the input terminals of the switches connected to the respective buffers are connected to desired output terminals, the buffer controller
543
read stored packets from the buffers.
FIG. 4
shows the control pattern indicative of the input-output connection relation of the switch
54
changed by control addresses A
1
to A
8
. The input terminals IN
1
to IN
8
correspond to the buffers
511
to
518
, and the output terminals OUT
1
to OUT
8
(or transmission wavelengths &lgr;1 to &lgr;8), to storage areas
1
to
8
of the respective buffers.
FIG. 6
shows an example of the construction of a network using the node apparatus in FIG.
5
. In the system, four node apparatuses
601
to
604
are connected in a ring type construction with parallel multiplex transmission paths
605
to
608
. The respective node apparatuses are connected to eight terminals
611
to
618
via eight subtransmission paths. The terminals
611
to
618
correspond to the terminals
551
to
558
, and similarly, terminals
621
to
628
, terminals
631
to
638
, and terminals
641
to
648
, to the terminals
551
to
558
.
FIG. 7
is a block diagram for explaining the communication principle of this network. Numeral
701
to
704
denote node apparatuses;
705
to
708
, switches corresponding to the switch
541
;
709
to
712
, buffers corresponding to the buffers
511
to
518
;
721
to
736
, terminals; and A to D, ring-shaped parallel transmission paths.
First, the communication principle of the network will be described with reference to FIG.
7
. This network has the plurality of rings A to D, interconnected by the switches
705
to
709
. The respective terminals are connected to one of ring transmission paths A to D. Upon communication with another terminal connected to another ring transmission path, the ring of the terminal is switched to the other ring by an arbitrary switch at least once. The position of switching is not specified, however, if the transmission path is switched to the destination transmission path at a node prior to the destination node, and at another node, the transmission path is switched to an arbitrary path, the communication control is easily made. In the network, in order to simplify the node apparatus, the switches
705
to
708
change the input-output connection relation in accordance with a specific circular pattern at predetermined periods regardless of input signals. The input signals are temporarily stored at the buffers
709
to
712
. When the input-output connection relation of the switches becomes a desired relation, the packets are read from the buffer.
For example, if the terminal
722
performs communication with the terminal
732
, a packet outputted from the terminal
722
is stored into the buffer
709
of the node
701
, and when the input terminal IN
3
is connected to the output terminal OUT
2
in the switch
705
, the packet is read from the buffer to the transmission path B. The packet is inputted into the buffer
710
of the node
702
, and when the input terminal IN
2
and the output terminal OUT
4
of the switch
706
are connected, the packet is read from the buffer
710
to the transmission path D. Then, the packet is sent to the terminal
732
.
In this manner, communication is performed by switching to an arbitrary ring in the respective node apparatuses.
Next, the details will be described with reference to
FIGS. 5 and 6
. In the explanation, the parallel multiplex transmission paths are a plurality of spatially separated optical fiber transmission paths. The switch is a spatial switch. In use of wavelength multiplex transmission path, as the communication is based on the above principle, substantially the same operation is performed. Next, an operation example where communication is performed between the terminals
612
and
635
will be described Transmission data from the terminal
612
is divided into fixed-length packets. Then, a destination address is written in the header of each packet, and the packet is outputted. The output packet is inputted through the sub transmission path into the node apparatus
601
, and inserted into a gap in a packet stream from the parallel multiplex transmission path
521
by the separation inserting unit
502
, and sent to the buffer
512
. In the buffer
512
, as the destination address of the input packet does not coincide with a pre-stored address of an adjacent downstream node apparatus, the packet is stored into an arbitrary storage area. In this example, the packet is stored in the storage area
1
. The buffer controller
543
con
Nakata Toru
Yamamoto Noboru
Canon Kabushiki Kaisha
Morgan & Finnegan L.L.P.
Ton Dang
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