JPH0946365A - Network system and method for connecting additional node to network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a network system capable of easily adding a node without exerting adverse influence upon the network system itself and an additional node connecting method for the network system. SOLUTION: The network system is provided with a main line 133 having plural transmission lines 101 to 108, plural nodes 109 to 132 on the main line 133 connected to the transmission lines 101 to 108 and a branch part 134 arranged on the main line 133 to connect additional nodes 135 to 137. A local closed loop capable of circulating a signal is formed by the branch part 134 and the additional nodes 135 to 137. The branch part 134 is constituted so as to input a signal from each transmission line to the local closed loop and send a signal from the closed loop to each transmission line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network system using a plurality of transmission lines and capable of easily adding nodes.

[0002]

2. Description of the Related Art Conventionally, several network systems have been proposed in order to achieve both an increase in network transmission capacity and simplification of node configuration. In a network system which is an example thereof, d ^k lines (d and k are natural numbers of 2 or more) in which the transmission direction is assigned in the forward direction and the backward direction according to the rule
, And each node is connected and arranged to d transmission lines which are regularly selected (shuffle network). When communication is performed between arbitrary nodes in this configuration, an intermediate node, which is located between the transmitting node and the receiving node and performs a switching operation, selects a transmission path for transmitting a signal and relays and transfers it according to an appropriate routing algorithm. By doing so, communication is possible even when the transmitting node and the receiving node do not share the same transmission path. In addition, the transmission distance is shortened as compared with the case where the transmission lines are all in the same direction.

However, the number of nodes connected to the network is usually not fixed. Therefore, it is necessary for the network side to be able to cope with changes in the number of nodes.In a shuffle network such as the above proposed example, expansion is performed for each group of nodes, or depending on the combination of transmission lines to be connected, I was adding nodes one by one. An example of the latter is given below.

FIG. 9 shows an example of adding nodes when the number of transmission lines is 8 and the number of connection points of each node is 2 (that is, d = 2, k = 3). In FIG. 9, transmission lines 101, 104, 106 and 1
Reference numeral 07 denotes the optical wavelengths of λl, λ4, λ6, and λ7 of the optical wavelength division multiplexing transmission line in which different optical wavelengths are multiplexed and used. As shown by the arrow in FIG. 9, the first transmission path group is composed of transmission paths whose transmission direction is from left to right. In addition, the transmission paths 102, 103, 105, 108 are
The second transmission line group is configured by the transmission lines that use the wavelengths λ2, λ3, λ5, and λ8 and have the transmission direction from the right to the left in FIG. Switching nodes 109 to 132 are shown in FIG.
It is connected to the transmission line indicated by Medium ● and transmits and receives. In this example, each switching node 109-132 is connected to one transmission line in each of the first and second transmission lines. Node 90
Reference numerals 1, 902, and 903 denote additional nodes that are about to be newly connected.

This proposed method has an advantage that the configuration of each node is the same. But on the other hand,
Since each node to be added (additional node) is the same as a conventional node (exchange node), all the additional nodes require a wavelength add / drop unit that drops / adds the wavelength to be passed and the wavelength to be taken in. Further, such an increase in the number of additional nodes may attenuate the optical signal on the main loop, and may also increase the traffic of the main loop regarding the transmission between the additional nodes.

[0006]

As described above, in the above proposed example, since the additional nodes are added on the main loop, respectively, there are the following problems. (1) The additional node requires a device for extracting a desired wavelength from the multiplexed wavelengths in the transmission line and a device for returning the selected wavelength to the transmission line. (2) Since the additional nodes are connected in multiple stages on the main loop, there is a risk that signals of wavelengths that pass through the additional nodes without being transmitted or received are attenuated. (3) Since data transmission between the additional nodes is performed using the transmission path of the main loop, the transmission amount on the main loop may increase.

Therefore, an object of the present invention is to provide a network system or the like which solves these problems.

[0008]

A network system according to the present invention comprises a main line having a plurality of transmission lines, a plurality of nodes on the main line connected to at least one transmission line, and at least one transmission line. A branch for connecting an additional node on the main line connected to the path, said branch forming at least one transmission line forming a locally closed loop capable of circulating a signal with at least the additional node; From the local closed loop and the signal can be transmitted from the local closed loop to at least one transmission line.

Further, a method for connecting an additional node to a network system according to the present invention is a network system having a main line having a plurality of transmission lines and a plurality of nodes on the main line connected to at least one transmission line. In, the additional node is connected at a branch portion on the main line connected to at least one transmission line,
The branch may form a local closed loop capable of circulating a signal with at least an additional node, may introduce a signal into the local closed loop from at least one transmission line, and the local closed loop to at least one transmission line. It is characterized in that it is configured to be able to send a signal from the.

Further, a branching device for connecting an additional node to the network system according to the present invention comprises a main line having a plurality of transmission lines and a plurality of nodes on the main line connected to at least one transmission line. A branching device for connecting an additional node to a network system having, which can be connected to at least one transmission line on a main line and can form at least a local closed loop capable of circulating a signal together with the additional node. It is characterized in that a signal can be introduced into the locally closed loop from one transmission line and a signal can be sent from at least one transmission line from the locally closed loop.

The above network system, connection method, and branching device may have the following modes. The main line has a plurality of transmission lines consisting of first and second transmission line groups whose transmission directions are opposite to each other, and the node has at least one transmission line in the first transmission line group and the transmission line. It is connected to at least one transmission line in the second transmission line group, and the branching unit is connected to at least one transmission line in the first transmission line group and at least one transmission line in the second transmission line group. Connected. The branching unit is arranged adjacent to the node and connected to the same transmission line as the node.
The branching unit forms a local closed loop together with the additional node and the adjacent node. Two branching units are arranged at positions adjacent to each other on both sides of the node, connected to the same transmission line as the node. The two branches are
A local closed loop is formed with an additional node connected to the two branches with the adjacent node sandwiched therebetween. The plurality of nodes have a function of selecting a transmission path for transmitting a signal, and the branching unit does not have a function of selecting a transmission path for transmitting a signal. The plurality of nodes and the branching unit have a function of selecting a transmission path for transmitting a signal. The plurality of transmission lines are annular transmission lines. The plurality of transmission lines are optical wavelength division multiplexing transmission lines. At least one additional node is connected to the branch in a daisy chain. At least one additional node is annularly connected to the branch. At least one additional node is connected to the branch by a single-core optical fiber, a two-core optical fiber, or an electrical conductor. The additional node does not have a function of selecting a transmission path for transmitting a signal.

According to the present invention, for example, a branching unit for transmitting and receiving the same channel as this switching node is provided at a position adjacent to an arbitrary switching node on the main line, and an additional node having no wavelength branching / merging function is provided. By connecting the branching portion in a daisy chain or in a ring shape, it is possible to configure a network system in which an additional node having a simple configuration can be added without attenuating the signal on the main line.

[0013]

Embodiment 1 FIG. 1 shows a first embodiment of the present invention. The present embodiment is a configuration example in which the total number of transmission lines is 8, of which the number of transmission lines of the first and second transmission line groups is 4 and the number of transmission lines connected to each switching node is 2.

In the figure, reference numerals 101 to 108 are annular transmission lines, and eight transmission lines are formed by wavelength multiplexing of eight wavelengths (λ1 to λ8). Here, the case where they are multiplexed in one annular optical fiber 133 is shown, but they may be distributed to a plurality of optical fibers. Of these, the transmission lines 101, 104, 106, 107
Is a transmission line that uses wavelengths of λ1, λ4, λ6, and λ7, and has a first transmission line group in which the transmission direction is from left to right as indicated by the arrow in FIG. In addition, the transmission path 102,
Reference numerals 103, 105, and 108 are transmission lines that use the wavelengths of λ2, λ3, λ5, and λ8, respectively, and the transmission direction is from right to left in FIG. 109 to 13
Reference numeral 2 denotes an exchange node, which is connected to the transmission path indicated by ● in FIG. 1 and transmits / receives signals. In this embodiment, each switching node is connected to one transmission line in each of the first and second transmission line groups.

The relationship between each switching node and the transmission line adopts a network configuration known as a shuffle network, as in the network system described in the above-mentioned proposed example. That is, when the transmission line numbers from 000 to 111 are sequentially given to the transmission lines 101 to 108 in binary notation, a group of two transmission lines which differ only in one digit of each of the transmission line numbers is selected. , Set up a switching node to connect to it. In this embodiment, the switching nodes 109 to 112 are in the first digit and the switching nodes 113 to 116 are in the lower two digits.
The third digit and the exchange nodes 117 to 120 are connected to different transmission lines only in the last digit of the third digit. The exchange nodes 121 to 132 are set by repeating the same procedure. Although the number of basic switching nodes is 24 in this embodiment, the number of switching nodes can be increased by repeating the same procedure as this any number of times. The transmission directions of the respective transmission lines are set so that the transmission lines having the different numbers of different digits in the transmission line number are in the same direction and the odd transmission lines are in the opposite direction.

Reference numerals 135, 136 and 137 denote additional nodes, which respectively receive the signals of wavelength λ8 branched by the branching section 134 and transmit them at wavelength λ7. 138 is a branching unit 1
34 is an optical fiber that connects the 34 and the additional nodes 135, 136, and 137.

FIG. 2 shows an example of the configuration of each switching node in the embodiment shown in FIG. 1, and reference numeral 133 in FIG.
Corresponds to the optical fiber shown in FIG. The optical coupler 201 demultiplexes and outputs the optical signal from the left side to the two-wavelength cut filter 203 and the optical coupler 204.
Optical signal from wavelength cut filter 203 and optical coupler 20
The optical signals from 4 are multiplexed and output to the left. Similarly, the optical coupler 202 demultiplexes the optical signal from the right direction to the two-wavelength cut filter 203 and the optical coupler 205, and also combines the optical signal from the two-wavelength cut filter 203 and the optical signal from the optical coupler 205. Wave and output to the right. The two-wavelength cut filter 203 blocks λr and λl (lambda), which are wavelengths at which the switching node transmits and receives, of the optical signals from the left and right directions, and transmits the other wavelengths. The optical coupler 204 is the optical coupler 2
01 output to the fixed wavelength filter 206, and output light from the EO conversion unit 210 to the optical coupler 2
Output to 01. Similarly, the optical coupler 205 is the optical coupler 2
02 to the fixed wavelength filter 207 and output light from the EO converter 211 to the optical coupler 2.
Output to 02. The fixed wavelength filter 206 has a wavelength λ transmitted to the right of the transmission / reception wavelengths of the exchange node.
Only r is transmitted and other wavelengths are blocked. Similarly, the fixed wavelength filter 207 transmits only the wavelength λl transmitted to the left and blocks the other wavelengths.

The OE converters 208 and 209 respectively receive the optical signals from the fixed wavelength filters 206 and 207, convert the optical signals into electrical signals, and output the electrical signals. EO converter 210, 2
Reference numeral 11 converts the electric signals output from the switch units (SW) 212 and 213 into optical signals having predetermined wavelengths λl and λr, respectively, and outputs the optical signals. The switch unit 212 includes the OE conversion unit 2
09 and the electric signal from the switch 213, the control unit 2
According to the instruction of No. 15, the EO conversion unit 210, the switch 21
3 or terminal 214. The switch unit 213 outputs an electric signal from the OE conversion unit 208, the switch 212, and the terminal 214 to either the EO conversion unit 211 or the switch 212 according to an instruction from the control unit 215. The control unit 215 includes an OE conversion unit 208,
Of the electric signals from the terminal 209 and the terminal 214, the data indicating the destination is referenced to refer to the terminal 214 and the EO, respectively.
The switch 21 is used to select the conversion units 210 and 211.
2 and 213 are controlled.

FIG. 3 shows a structural example of the branching section 134 in the embodiment shown in FIG. 1, and 133 in the figure corresponds to the single-core optical fiber shown in FIG. 301 to 31
The elements up to 1 have the same functions as the elements 201 to 211 shown in FIG. Switch 31
Reference numeral 2 denotes an electric signal from the OE converter 309,
According to the instruction of No. 4, it is output to one of the EO conversion units 310 and 315. The switch 313 includes an OE conversion unit 308,
One of the electrical signals 316 is output to the EO conversion unit 311 according to the instruction of the control unit 314. The control unit 314
The switch 3 is selected so as to select one of the two outgoing lines (EO conversion unit 310 and EO conversion unit 315) by referring to the data indicating the destination of the electric signal from the OE conversion unit 309.
12 is controlled. In addition, the switch 31 is configured to refer to the data indicating the destination from the OE conversion units 308 and 316, select any one of the data, and output the EO conversion unit 311.
3 is controlled.

The EO converter 315 converts the electric signal output from the switch 312 into an optical signal of wavelength λ1 (this wavelength may be arbitrary) and outputs it to the optical coupler 318. O
The E conversion unit 316 receives the optical signal of the wavelength λ2 (this wavelength may be arbitrary) from the fixed wavelength filter 317, converts the optical signal into an electric signal, and outputs the electric signal to the switch 313.
The fixed wavelength filter 317 receives the wavelength λ from the optical coupler 318.
The optical signal of 1 is selected and output to the OE converter 316. The optical coupler 318 outputs the optical signal of the wavelength λ1 from the EO conversion unit 315 to the single core optical fiber 138. Further, the optical coupler 318 branches the optical signal from the single core optical fiber 138 to the fixed wavelength filter 317. Single-core optical fiber 13
8 is a branch unit 134 and each additional node 135, 136, 1
It is a daisy chain connection between 37.

FIG. 4 shows a configuration example of the additional nodes 135, 136, 137 in the embodiment shown in FIG.
In FIG. 4, reference numeral 138 corresponds to the optical fiber extended from the branch portion 134 shown in FIG. 402, 404, 4
06 and 408 are elements 318 and 3 shown in FIG. 3, respectively.
The elements 401, 403, 405, and 407 have the same functions as those of the numerals 17, 316, and 315. The switch 409 sends the signal from the OE converter 405 to the controller 41.
According to the instruction No. 1, the data is sent to any of the EO conversion unit 408, the terminal 412, and the switch 410. The control unit 411
Control the switch 409 so as to select any one of the three outgoing lines (EO conversion unit 408, terminal 412, switch 410) by referring to the data indicating the destination among the electric signals from the OE conversion unit 405. To do. In addition, the control unit 411
Refers to the data from the OE conversion unit 406, the terminal 412, and the switch 410, and acquires necessary data from the EO conversion unit 40.
The switch 410 is controlled so as to send the data to the No. 7 switch.

An operation example of this embodiment will be described below with reference to the drawings. The transmitting node is the switching node 11 in FIG.
9 and the receiving node is the additional node 136,
The operation is as follows. The transmitting node 119 has the configuration shown in FIG. 2, and when the data to be transmitted is input from the terminal 214, the control unit 215 determines the transmission route from the addresses of the own node and the destination node, and the transmitting node 119 transmits the data. The wavelength to be emitted is determined (λ7 in this case), and the destination address and routing information are added to the beginning of the packet. In this case, the destination address is a unique address in the network representing the receiving node 136. The routing information is information for instructing which transmission path is selected and transmitting the packet at the time of regenerative relay at each switching node. In this example, the switching node selects the right transmission path. This is information for instructing to do. As the routing algorithm for determining the transmission path, a relatively simple one can be applied because the connection form of each switching node is regular as described above. Control unit 215
Of the EO conversion unit 21 via the switch unit 213
The electrical signal input to 1 is converted into an optical signal of wavelength λ7, and sequentially output to the right direction to the optical fiber 133 via the optical couplers 205 and 202. In this way, the exchange node 1
The optical signal of wavelength λ7 output from 19 reaches the adjacent switching node 120 together with the optical signals of other wavelengths, but since this switching node is not connected to the transmission line using wavelength λ7, it passes therethrough (this Such a node will be referred to as a through node hereinafter). That is, the optical signal of wavelength λ7 is sequentially transmitted through the optical coupler 201, the wavelength cut filter 203, and the optical coupler 202 in the switching node 120 and is sent to the next switching node.

The next switching nodes 121, 122 and 123 are also through nodes. In FIG. 1, reference numeral 134 denotes the branching unit shown in FIG. 3, which is the additional node 136 of the wavelength λ7.
Separate the packet data addressed to it. The optical signal reaching the branching unit 134 from the left direction is branched and output by the optical coupler 301 to the two-wavelength cut filter 303 and the optical coupler 304. The optical signal is blocked here. On the other hand, in the optical signal input to the optical coupler 304, only λ7 is transmitted through the fixed wavelength filter 306, and the OE conversion unit 30
Enter in 8. The destination address and routing information of the packet converted into the electric signal by the OE unit 308 are analyzed by the control unit 314, the competition with the packet from the OE unit 316 is adjusted, and the packet is sent to any transmission path on the right side. Therefore, after being sent to the EO conversion unit 311 via the switch unit 313 and converted into an optical signal of the wavelength λ7 here, the switching node 124 adjacent to the right via the optical couplers 305 and 302.
Is output. The next switching node 124 is the transmission line 107.
And functions as an intermediate node that performs regenerative relay. The optical signal that reaches the node 124 from the left is
The optical coupler 201 branches and outputs the two-wavelength cut filter 203 and the optical coupler 204, but among the optical signals input to the two-wavelength cut filter 203, the optical signal of wavelength λ7 is cut off here. On the other hand, the optical signal input to the optical coupler 204 is λ7 in the fixed wavelength filter 206.
Only the light is transmitted and input to the OE conversion unit 208. OE part 2
The destination address and routing information of the packet converted into the electric signal in 08 are analyzed by the control unit 215,
It is determined to be sent to the transmission path to the left. Therefore, the EO conversion unit 210 is switched through the switch units 213 and 212.
To the node adjacent to the left via the optical coupler 204 and the optical coupler 201 after being converted into an optical signal of wavelength λ8.

At this time, in the branch section 134, the optical coupler 30
The signal of wavelength λ8 input from 2 is branched, and one is cut by the two-wavelength cut filter 303. Optical coupler 3
The signal input to 05 is the filter 3 that selects only λ8.
After passing 07, it is converted to an electric signal by the OE conversion unit 309, and it is determined that the packet is addressed to the additional node by solving the destination address. Therefore, the switch unit 312
Is transmitted to the optical fiber 138 at the wavelength λ1 via the EO unit 315 and the optical coupler 318. The next additional node 135 connected by the optical fiber 138 is the one shown in FIG. 4, and receives the optical signal of the wavelength λl from the right of the additional node 135. The signal of wavelength λl is transmitted through the optical coupler 401, the fixed wavelength filter 403, and the OE unit 405 to the switch 40.
9 is input. The control unit 411 determines that the packet is not addressed to itself, and the switch 409 sets the data to EO.
It is sent to the unit 408. Next, the data is transferred from the EO unit 408 to the next additional node 136 via the optical coupler 402 as a signal of wavelength λl.

The next additional node 136 is the additional node 13
5 has the same configuration as that of FIG.
It is determined that the packet is data addressed to itself. Therefore,
It is sent to the terminal 412 by the switch 409, and a series of communication processing is completed.

As described above, the branching unit 134 does not differ much in complexity from the configuration of the exchange node, but the additional node does not require the elements 201, 202, 203, etc. in FIG. 2, and the node configuration is simple. Becomes Further, since only the branch unit 134 exists on the main loop and the additional node does not exist on the main loop, it is possible to reduce the attenuation of the optical signal on the main loop.

Next, when the transmitting node is the additional node 136 in FIG. 1 and the receiving node is the additional node 135, the following operation example is performed. The transmission node 136 has the configuration shown in FIG. 4, and the number of wavelengths and directions to be transmitted is determined to be one (here, wavelength λ2 to the right). Terminal 412
When the data to be transmitted is input from the control unit 411, the control unit 411 determines the transmission route from the addresses of the own node and the destination node, and adds the destination address and the routing information to the head portion of the packet. In this case, the destination address is a unique address in the network representing the receiving node 135. The routing information is information for instructing which transmission path should be selected and which packet should be transmitted at the time of regenerative relay in each intermediate node. In this example, the routing information is closest to the switching node (in this case, switching node). This is information that instructs the node 124) to select the transmission path in the left direction. In the additional node 136 that performs transmission, the EO conversion unit 407 passes through the switch unit 410 according to an instruction from the control unit 411.
The electrical signal input to is converted into an optical signal of wavelength λ2, passes through the optical coupler 401, and is sequentially output to the right.
Next, the packet that reaches the additional node 135 is sent to the optical coupler 402, the fixed wavelength filter 404, and the OE unit 40 of FIG.
6, the switch 410 adjusts the competition with the packet from the terminal 412 and the packet from the switch 409, and sends the packet to the EO unit 407. And optical coupler 401
Is sent to the branching unit 134 via.

In the branching section 134, the optical signal reaching the optical coupler 318 is sent to the fixed wavelength filter 31 as shown in FIG.
The wavelength λ2 is transmitted at 7 and converted to an electric signal at the OE unit 316. The electric signal reaching the switch 313 is adjusted for contention with the packet coming from the OE unit 308 by the control unit 314, and is sent to the EO unit 311. In the EO section, it is converted into an optical signal of wavelength λ7. This optical signal is sent to the optical fiber 133 on the main loop via the optical couplers 305 and 302.

Next, the switching node 124 selects a leftward route from the header information of the packet as described above. That is, in FIG. 2, the optical coupler 201 and the optical coupler 2
04, fixed wavelength filter 206, OE unit 208, switch 213, switch 212, EO unit 210 (which becomes an optical signal of wavelength λ8 here), optical coupler 204, optical coupler 20.
Optical fiber 1 to the left at wavelength λ8 via the route 1
33. Then, in the branch unit 134, the packet addressed to the additional node 135 is sent to the additional node 135 at the wavelength λ1 according to the information of the header through the above-mentioned process. In the additional node 135, the repacket is taken into the terminal 412 in the additional node 135 according to the header information.

As described above, in the transmission from the additional node 136 to the additional node 135, the switching around the additional node is simplified, and the transmission between the additional nodes is a main loop for creating a local subloop. Does not significantly increase the above traffic.

In the present embodiment, the case where there is one branching part has been described, but branching parts are arranged on both sides of the switching node, and two local branching parts adjacent to the switching node form one local loop. By arranging as described above, it is possible to add a node to each. Therefore, the maximum number of connections at the branch is twice the number of switching nodes.

Further, in the present embodiment, the branching unit does not have a function of selecting a transmission path for transmitting a signal, that is, a switching function. However, if this branching function is provided, the branching unit is adjacent to the switching node. There is no need to provide it. However, in that case, add an extension for each branch unit, or
It is necessary to add one by one according to the combination of transmission lines to be connected. Therefore, although the advantages of this embodiment are diminished, when connecting a large number of additional nodes, the number of branching units connected to the main loop is smaller than when individually connecting the additional nodes to the main loop. There are advantages. .

[0033]

[Embodiment 2] FIGS. 5 and 6 show the configuration of a second embodiment of the present invention. This embodiment is an example in which the single-core optical fiber 138 is replaced with a two-core optical fiber in the first embodiment. According to this embodiment, both the branching unit and the additional node can have a simpler configuration. That is, since the transmission wavelength channel and the reception wavelength channel are physically separated, the fixed wavelength filter 317 and the optical coupler 31 are separated at the branching portion, as can be seen by comparing FIGS.
8 is unnecessary. At the additional node, as can be seen by comparing FIG. 6 and FIG. 4, fixed wavelength filters 403, 40
4. The optical couplers 401 and 402 are unnecessary.

Further, if the two-core optical fiber is replaced with an electric conductor, the OE portion, E, connected to the two-core optical fiber.
The O section is not necessary, and the branch section configuration and the node configuration can be further simplified.

[0035]

Third Embodiment FIG. 7 shows the configuration of the third embodiment of the present invention. In the present embodiment, the additional node 70 following the branch unit 134.
In this example, 1, 702, 703, and 704 are connected in a loop. The branching unit 134 can have the configuration shown in FIG. The configuration of the additional node is shown in FIG. In FIG. 8, reference numeral 70
Reference numeral 5 corresponds to the optical fiber extending from the branch portion 134 shown in FIG. Elements designated by the same reference numerals as those in FIGS. 4 and 6 are elements having the same function. The switch 801 is an OE
The signal from the conversion unit 405 is sent to either the EO conversion unit 408 or the terminal 412 according to the instruction of the control unit 802. The control unit 802 refers to the data indicating the destination among the electric signals from the OE conversion unit 405, and selects the two outgoing lines (the EO conversion unit 408 and the terminal 412) to select the switch 801. To control. The control unit 411 also refers to the data from the OE conversion unit 405 and the terminal 412, and controls the switch 801 to send necessary data to the EO conversion unit 408. The wavelength used between the additional nodes can be arbitrary.

As can be seen from FIG. 8, the additional node has a very simple structure, and the communication between the additional nodes includes the branch part 134 and the switching node 124 to form a local loop. Does not significantly increase the above traffic. Of course, if the optical fiber 705 is replaced with an electrical conductor, the OEs connected before and after the optical fiber are connected.
Section and EO section are unnecessary, and the node configuration and the branching unit configuration can be simpler. Others are the same as those described in the first embodiment.

[0037]

[Other Embodiments] In the above-mentioned embodiments, the shuffle network is adopted for the arrangement of the transmission lines and the nodes. However, in addition to this, various network forms in a so-called switching network such as a Manhattan street network, a Benesi network, etc. It goes without saying that the present invention can be applied to.

[0038]

As described above, a branch section for transmitting and receiving an appropriate channel on the main loop is provided at an appropriate location, and an additional node is connected from this branch section.
This has the effect of making it easier to add nodes to the existing network.

In particular, a branching unit for transmitting / receiving the same channel as an arbitrary node on the main loop is provided adjacent to this node, and an additional node is connected from this branching unit in a daisy chain or loop shape, so that the existing You can easily add nodes to your network.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of an exchange node according to the present invention.

FIG. 3 is a diagram showing an example of the configuration of a branch unit according to the present invention.

FIG. 4 is a diagram showing a configuration example of an additional node according to the present invention.

FIG. 5 is a diagram showing a configuration example of a branching unit according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a configuration example of an additional node according to a second embodiment of the present invention.

FIG. 7 is a configuration diagram of a third embodiment of the present invention.

FIG. 8 is a diagram showing a configuration example of an additional node in the third exemplary embodiment of the present invention.

FIG. 9 is a configuration diagram of a conventional example.

[Explanation of symbols]

 101-108 Transmission line 109-132 Switching node 134 Branching part 135-137, 701-704 Additional node 133, 705 Optical fiber

Claims (16)

[Claims] 1. A main line having a plurality of transmission lines, a plurality of nodes on a main line connected to at least one transmission line, and an additional node on a main line connected to at least one transmission line. A branch for connection is provided, the branch forming a local closed loop capable of circulating a signal with at least an additional node, and the signal can be introduced into the local closed loop from at least one transmission line. And a network system capable of sending a signal from the locally closed loop to at least one transmission path. 2. The main line has a plurality of transmission lines consisting of first and second transmission line groups whose transmission directions are opposite to each other, and the node is at least one of the first transmission line groups. One transmission line and at least one transmission line in the second transmission line group, and the branching unit includes at least one transmission line in the first transmission line group and at least one in the second transmission line group. The network system according to claim 1, wherein the network system is connected to one transmission path. 3. The network system according to claim 2, wherein the branching unit is arranged adjacent to the node and connected to the same transmission line as the node. 4. The network system according to claim 3, wherein the branching unit forms a local closed loop together with the additional node and the adjacent node. 5. The network system according to claim 2, wherein the branching unit is arranged at two positions adjacent to each other on both sides of the node and connected to the same transmission line as the node. 6. The network system according to claim 5, wherein the two branch parts form a local closed loop together with an additional node connected to the two branch parts with the adjacent node sandwiched therebetween. 7. The plurality of nodes have a function of selecting a transmission path for transmitting a signal, and the branching unit does not have a function of selecting a transmission path for transmitting a signal. Alternatively, the network system according to item 2. 8. The network system according to claim 1, wherein the plurality of nodes and the branching unit have a function of selecting a transmission path for transmitting a signal. 9. The network system according to claim 1, wherein the plurality of transmission lines are circular transmission lines. 10. The network system according to claim 1, wherein the plurality of transmission lines are optical wavelength division multiplexing transmission lines. 11. The network system according to claim 1, wherein at least one additional node is connected to the branch unit in a daisy chain. 12. The at least one additional node is connected to the branch portion in a ring shape.
The described network system. 13. The network system according to claim 1, wherein at least one additional node is connected to the branch portion by a single-core optical fiber, a two-core optical fiber, or an electrical conductor. 14. The additional node does not have a function of selecting a transmission path for transmitting a signal.
Alternatively, the network system according to item 2. 15. A main line having a plurality of transmission lines,
A method of connecting an additional node to a network system having at least one transmission line and a plurality of nodes connected to the mainline, the additional node being on a mainline connected to at least one transmission line. Connecting at a branch, the branch being capable of forming a local closed loop capable of circulating a signal with at least an additional node, introducing a signal from the at least one transmission line into the local closed loop and at least one transmission A method for connecting additional nodes, characterized in that it is arranged to be able to send a signal out of the locally closed loop on a path. 16. A main line having a plurality of transmission lines,
A branching device for connecting an additional node to a network system having at least one transmission line and a plurality of nodes on the main line, the branching device being connectable to at least one transmission line on the main line, and at least adding A local closed loop capable of circulating a signal with a node can be formed, a signal can be introduced into the local closed loop from at least one transmission line, and a signal can be sent from the local closed loop to at least one transmission line A branching device characterized by being configured.