JP3893950B2 - LAN connection system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inter-LAN connection system, and more particularly to an inter-LAN connection system that is suitable for application when connecting LANs through a large-capacity transmission line such as an optical fiber.
[0002]
[Prior art]
In recent years, wide-area LANs based on local area network (LAN) technology have been constructed in each region, and communication networks in which these are connected by a high-speed and broadband backbone network have been developed nationwide. It is being An optical fiber is applied as the transmission path base, and a network service extended to a user connection called FTTO (fiber to the office) or FTTH (fiber to the home) has been provided.
[0003]
Further, as is well known, as an inter-LAN connection device for connecting LANs, a bridge for connection at the data link layer level of an OSI (open systems interconnection) model, a router for connection at the network layer level, and There are known gateways that connect at a higher level than the transport layer. In particular, since the bridge-type LAN connection is made through a common data link layer, the LANs are connected by an inexpensive device regardless of a higher-level protocol such as TCP / IP (transmission control protocol / internet protocol). be able to.
[0004]
[Problems to be solved by the invention]
By the way, when connecting a user LAN to a wide area LAN of a communication carrier as described above via an optical fiber transmission line, a bridge type LAN connecting device is applied to the terminal point on the communication carrier side of the optical fiber transmission line. In this case, it is difficult to make detailed settings according to the bandwidth contract that the user desires when making a contract with the user. For example, two types of 10BASE-T bandwidth and 100BASE-T bandwidth depending on the speed of the user LAN. It was only a thing corresponding to the change of.
[0005]
The present invention has been made in view of the problems as described above, and allows a user LAN to be connected to a wide area LAN of a telecommunications carrier by an inexpensive device, and further, a contract bandwidth from the user LAN is set in detail. An object of the present invention is to provide an inter-LAN connection system that can do this.
[0006]
[Means for Solving the Problems]
An inter-LAN connection system according to the present invention is an inter-LAN connection system that connects a user LAN 10 and a wide area LAN 30 of a communication carrier via a transmission line such as an optical fiber in order to solve the above-described problem. First transfer devices 40 and 60 that are installed on the side and transfer predetermined data frames between the wide area LAN 30 and the transmission line 20, and are installed in the user's home and between the user LAN 10 and the transmission line 20. A second transfer device 50 for transferring a data frame, and at least the first transfer devices 40 and 60 include a first physical layer termination unit 402 for terminating a physical layer between the data line and a wide area LAN side. The data frame is transferred by medium access control between the second physical layer termination means 406 that terminates the physical layer of the first physical layer and the first and second physical layer termination means This is an AC switch, and a plurality of input / output ports are provided for each group so that the port VLAN can be set. The input / output ports grouped on the transmission line side and the wide area LAN side can transfer the data frame between groups. The connected MAC switches 404 and 500, and the transfer frequency of the data frame between them can be freely set at a predetermined interval, and at least from the user LAN transferred from the second transfer device 50 via the transmission path to the wide area Band limiting control means 410, 550, and 560 for limiting the amount of data to the LAN to a desired transmission capacity are included.
[0007]
In this case, the MAC switch 404 in the first transfer device 40 includes at least first to fourth ports (422 to 428), and the first port 422 is connected to the first physical layer termination unit 402, The first port 422 and the second port 424 are set as the first VLAN group 420, and the third port 426 is connected to the second physical layer terminator 406, and the third port 426 and the second port 424 are connected. 4 ports 428 are set as the second VLAN group 430, and the second port 424 and the fourth port 428 further allow the first and second VLAN groups 420 and 430 to transfer data frames between the groups. It should be connected.
[0008]
The MAC switch 500 in the first transfer device 60 includes at least first to eighth ports (502 to 518), and the input of the first port 502 is connected to the first physical layer terminator 402, The first port 502 and the second port 504 are set as the first VLAN group 510, and the third port 506 and the fourth port 508 are set as the second VLAN group 520. The output of the port 504 is connected to the second physical layer terminator 406, and the second port 504 and the third port 506 further transfer the data frame between the groups in the first and second VLAN groups 510 and 520. They may be freely connected to each other.
[0009]
In this case, in the MAC switch 500 in the first transfer device 60, the input of the fifth port 512 is further connected to the second physical layer terminator 406, and the fifth port 512 and the sixth port 514 are connected. The third VLAN group 530 is set, the seventh port 516 and the eighth port 518 are set as the fourth VLAN group 540, and the output of the eighth port 518 is the first physical layer termination unit 402. The sixth port 514 and the seventh port 516 may be connected to each other by the third and fourth VLAN groups 530 and 540 so that they can be transferred between the groups.
[0010]
In these cases, the MAC switches 404 and 500 in the first transfer apparatuses 40 and 60 include input means (432 to 438) for the respective ports, buffer means 440 for temporarily storing data frames from the input means, and buffer means. The output means (444 to 450) of each port for outputting the data frame read from the band in response to the transfer frequency from the band limit control means, and the output of the data frame from the buffer means to the desired port set in VLAN It is preferable to include buffer control means 442 for reading out the means.
[0011]
The band limit control unit 410 includes an oscillation unit 480 that generates a desired oscillation frequency, and a switching unit 482 that freely switches the oscillation frequency from the oscillation unit. It is good to drive.
[0012]
Advantageously, the first transfer device 60 of the LAN connection system according to the present invention includes oscillation means 552 and 562 for generating a desired oscillation frequency, and switching means 554 and 564 for freely switching the oscillation frequency from the oscillation means. Including two or more band limitation control units 550 and 560, and these band limitation control units may drive the buffer control unit with different frequencies of uplink and downlink.
[0013]
The data frame transferred in the LAN connection system according to the present invention includes a tag frame having a VLAN tag to which VLAN control information indicating which VLAN is transferred, or an untagged frame having no VLAN tag. The first transfer device 40, 60 includes a setting unit 452 for setting the MAC switch 404, 500 to process the tag frame and the untagged frame as an untagged frame regardless of the presence or absence of the VLAN tag. Good.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of an inter-LAN connection system according to the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show an embodiment of an inter-LAN connection system according to the present invention. The inter-LAN connection system according to the present embodiment is a subscriber access system interface that connects a user LAN 10 to a carrier network such as a wide area LAN 30 of a communication carrier via an optical fiber transmission line 20 as shown in FIG. In this embodiment, the bridge system includes the optical fiber transmission line 20, the first optical conversion bridge 40 connected to the telecommunications carrier side, and the second optical conversion bridge 50 connected to the inside of the house. This is an inter-LAN connection system. In particular, in the present embodiment, as shown in FIG. 1, for example, the first optical conversion bridge 40 on the station side has a port VLAN (virtual LAN) settable MAC (media access control) having at least four input / output ports. ) Switch 404 is provided, and the input / output ports grouped on the optical fiber transmission line side and the wide area LAN side are connected so as to be able to transfer between the groups, and the transfer frequency between them is set to a desired value and the user LAN 10 The main feature is that the data capacity from the wide area LAN 30 to the wide area LAN 30 and the data capacity from the wide area LAN 30 to the user LAN 10 are limited.
[0015]
The details of each part will be described. In this embodiment, the user LAN 10 is a 10Base-T or 100Base-T Ethernet LAN or an IEEE 802.3 Ethernet LAN to which data terminals such as a plurality of personal computers are connected. For example, an arbitrary transmission band from 10 Mbps to 100 Mbps is selected for each 10 Mbps step unit by a bandwidth contract with a communication carrier, and is connected to the wide area LAN 30 by the LAN connection system of this embodiment. This user LAN 10 is connected to the optical conversion bridge 50 via a hub or router 100. On the other hand, the wide-area LAN 30 is a network based on a high-speed and wide-band LAN technology having a transmission band of several Gbps, for example, and accommodates a plurality of user LANs 10 for each area, and further via each 100 Gbps class backbone network. It is connected to the. This wide area LAN 30 is connected to the optical conversion bridge 40 via the router 300 in this embodiment.
[0016]
The routers 100 and 300 are switches at the network layer level, and are inter-LAN connection devices that distribute routes according to IP (Internet protocol) addresses in data frames transmitted in the present embodiment. The data frame transferred in the present embodiment includes an untagged frame such as an Ethernet frame or an IEEE802.3 Ethernet frame, and a tag frame conforming to IEEE802.1Q with a VLAN tag added thereto. As shown in FIG. 6A, the Ethernet frame includes a preamble PA representing a synchronization signal, a destination MAC address DA representing the next next destination, a source MAC address SA representing a source address, and a data type. Ethernet type ET representing the IP, 46 to 1500 octet variable length transmission data DT including the IP header, and so-called CRC (cyclic redundancy check) code for error detection from the destination MAC address DA to the data DT are inserted. Frame check sequence FCS. As shown in FIG. 2B, the IEEE 802.3 Ethernet frame includes a preamble PA representing a synchronization signal, an 8-bit frame start delimiter SFD, a destination MAC address DA representing an adjacent next destination, and a source address. A source MAC address SA representing the data length, a data length DL representing the length of the data, a logical link LLC providing a common service to the network layer for various medium access control layers, and a data type representing the data type It includes SNAP, variable-length transmission data DT including 38 to 1492 octets including an IP address, and a frame check sequence FCS in which a CRC code for error detection is inserted.
[0017]
On the other hand, the tag frame is a frame in which VLAN is set. As shown in FIG. 5C, the tag protocol identifier TPID indicating that the frame has a VLAN tag and the VLAN to which the frame belongs. Tag control information TCI having information such as a VLAN identifier indicating whether or not these are applied to an Ethernet frame, for example, and inserted between the transmission source MAC address SA and the data type ET, respectively. When applied to an IEEE 802.3 Ethernet frame, it is inserted between the source MAC address SA and the data length DL. VLAN is a technology capable of constructing a logical network independent of physical network wiring, and is a port VLAN grouped in units of physical ports of a bridge and a layer 2 VLAN grouped in units of layer 2 addresses such as MAC addresses. And a policy-based VLAN that is grouped according to a layer 3 address unit such as an IP address or IPX, or a protocol ID in a MAC header in layer 2 or contents arbitrarily set by a user. In the inter-LAN connection system of the present embodiment, the bridge 40 capable of setting the port VLAN is applied, and based on the destination MAC address DA and the transmission source MAC address SA regardless of the presence or absence of the VLAN tag by the settings specific to the present application. This is a bridge-type inter-LAN connection system for transferring data frames.
[0018]
Specifically, the first optical conversion bridge 40 according to the present embodiment is installed on the telecommunications carrier side and is transferred from the data LAN from the router 300 of the wide area LAN 30 and transferred from the user LAN 10 via the optical fiber transmission line 20. This is a first transfer device that transfers data frames to each other. In this embodiment, the data frame between the electrical transmission line such as a twisted pair from the router 300 and the optical fiber transmission line 20 is subjected to electro-optical conversion. This is an optical conversion device that transfers data. More specifically, as shown in FIG. 1, the first optical conversion bridge 40 according to the present embodiment includes an optical physical layer termination unit 402, a MAC switch 404, an electrophysical layer termination unit 406, and a VLAN setting unit 408. And a bandwidth limitation control unit 410.
[0019]
The optical physical layer termination unit 402 is a layer 1 termination circuit that terminates an Ethernet frame transmitted to and received from the optical fiber transmission line 20, and in this embodiment, a line interface 412, a physical layer device PHY 414, and a fixed clock And an oscillator 416. The line interface 412 includes an electro-optical conversion circuit, and is a serial interface that performs electro-optical conversion and serially transfers a data frame between the optical fiber transmission line 20 and the physical layer device PHY 414. The physical layer device PHY 414 is a processing circuit that performs processing such as waveform shaping of a frame converted into an electric signal from the line interface 412. In the present embodiment, the physical layer device PHY 414 uses, for example, a 25 MHz fixed clock supplied from the fixed clock oscillator 416. It includes a serial-parallel conversion circuit that is driven and converts a serially input frame of 100 Mbps via the line interface 412 into a 4-bit parallel and supplies it to the MAC switch 404. The fixed clock oscillator 416 is a clock generation circuit that supplies a fixed clock to the physical layer device PHY 414. In the present embodiment, the physical layer device PHY 414 converts a 100 Mbps serial data frame into 4-bit parallel and transfers it at 25 MHz. This is an oscillation circuit that oscillates the operating frequency of.
[0020]
The MAC switch 404 has a port VLAN function in this embodiment, and is a transfer processing unit that transfers an Ethernet frame including a tag frame conforming to IEEE802.3Q or an IEEE802.3 Ethernet frame according to the VLAN tag and the MAC address. In particular, the present embodiment includes first to fourth ports 422 to 428 that are grouped into a transmission line side and a wide area LAN side by a port VLAN function, and a data frame is connected between them so as to be transferred between groups. . More specifically, the first port 422 is connected to the physical layer device PHY 414 of the optical physical layer termination unit 402, and the first port 422 and the second port 424 are set as the VLAN group 420. . The third port 426 is connected to the physical layer device PHY 472 of the electrophysical layer termination unit 406, and the third port 426 and the fourth port 428 are set as the VLAN group 430. Furthermore, in the present embodiment, the second port 424 and the fourth port 428 are externally connected so that data frames can be transferred between groups. More specifically, as shown in FIG. 3, for example, the MAC switch 404 according to the present embodiment includes reception FIFOs (first in first out memory) 432 to 438 of the first to fourth ports 422 to 428, and buffers. Section 440, buffer control section 442, and transmission FIFOs 444 to 450 of the first to fourth ports 422 to 428, respectively. The reception FIFO 432 of the first port 422 receives the reception frame from the physical layer device PHY 414 of the optical physical layer termination unit 402 in synchronization with the 25 MHz speed, and supplies the received frame to the buffer unit 440 in the order of input. 422 is an input circuit. The reception FIFO 434 of the second port 424 is externally connected to the transmission FIFO 450 of the fourth port 428 and buffers frames received in synchronization with the transfer rate, that is, the transfer frequency from the band limit control unit 410 in the order of input. 4 is an input circuit of the second port 424 supplied to the unit 440. The reception FIFO 436 of the third port 426 is an input circuit of the third port 426 that receives the reception frame from the electrophysical layer termination unit 406 in synchronization with the 25 MHz speed and supplies the received frame to the buffer unit 440 in the order of input. is there. The reception FIFO 438 of the fourth port 428 is externally connected to the transmission FIFO 446 of the second port 424 and supplies frames received at a speed synchronized with the transfer frequency from the band limitation control unit 410 to the buffer unit 440 in the order of input. The input circuit of the fourth port 428.
[0021]
The buffer unit 440 is a storage circuit in which received frames from the respective reception FIFOs 432 to 438 are temporarily stored under the control of the buffer control unit 442. In the present embodiment, for example, an SDRAM (synchronous dynamic random access memory) or the like is used. Volatile memory circuits are advantageously applied. For example, in this embodiment, a storage area is provided for each of the ports 422 to 428, and a plurality of data areas for storing each frame are formed in each storage area for each 1536 bytes that is the maximum packet length of the Ethernet frame. ing. In this embodiment, when the number of input frames stored in these data areas exceeds the number of output frames, these frames are discarded and the data capacity is limited. The buffer control unit 442 is a VLAN control circuit that controls writing and reading of data frames in the buffer unit 440 according to the setting of the VLAN setting unit 408. In this embodiment, as shown in FIG. The address search unit 454 includes a write pointer 456, a read pointer 458, a descriptor 460, an address table 462, and a VLAN table 464.
[0022]
The TPID setting unit 452 is a part in which a tag protocol identifier TPID for identifying whether or not the received frame is a tag frame is set. In this embodiment, the VLAN setting unit 408 sets a tag protocol identifier TPID unique to the present application. For example, a value of 0xffff is set, and with this value, all frames are processed as untagged frames regardless of whether or not there is a frame tag. The address search unit 454 is a circuit that determines which port the frame is to be transferred to based on the header of each frame including the MAC address and VLAN tag extracted from each reception FIFO 432 to 438. In this embodiment, the MAC address is searched from the address table 462, the VLAN group is further searched from the VLAN table 464, and the result is supplied to the corresponding write pointer 456 and read pointer 458, respectively. For example, in the present embodiment, each reception FIFO 432 to be transferred from the reception FIFO 432 of the first port 422 to the transmission FIFO 446 of the second port 424 set in the same VLAN group 420 via the buffer unit 440. The address search result is supplied to the write pointer 456 and the read pointer 458 so that the frame from 438 is transferred to the transmission FIFOs 444 to 450 of the same VLAN group via the buffer unit 440.
[0023]
The write pointer 456 is provided for each of the ports 422 to 428, and sequentially instructs the location where the read address from the reception buffer 440 is stored in the descriptor 460 when there is a frame reception instruction from the address search unit 454. This is an instruction circuit. Similar to the write pointer 456, the read pointer 458 is an instruction circuit that is provided for each of the ports 422 to 428 and sequentially instructs the descriptor 460 to read a frame in the buffer unit 440. Read instructions are sequentially supplied in response to output timings of the transmission FIFOs 444 to 450. In other words, in the present embodiment, a read instruction to the buffer unit 440 for the transmission FIFOs 444 and 448 of the first and third ports 422 and 426 is supplied at a fixed operating frequency of 25 MHz, and the second and fourth ports 424 and 428 are supplied. Read instructions to the buffer unit 440 for the transmission FIFOs 446 and 450 are supplied at an operating frequency set to any of 2.5 MHz to 25 MHz. The descriptor 460 is an address generation circuit that supplies a read address to the buffer unit 440 according to instructions from the write pointer 456 and the read pointer 458. The address table 462 is a MAC table in which, for example, the source address SA assigned to the Ethernet frame is stored in a rewritable manner. The VLAN table 464 is a table in which grouping in units of ports, that is, a correspondence table between VLAN identifiers and each port is stored in a rewritable manner. In this embodiment, the VLANs of the first port 422 and the second port 424 are stored. The VLAN setting circuit 408 writes in advance that the identifier is in the same group 420 and that the VLAN identifiers of the third port 426 and the fourth port 428 are in the same group 430.
[0024]
In FIG. 3 again, the transmission FIFO 444 of the first port 422 is connected to the physical layer device PHY 414 of the optical physical layer termination unit 402. In this embodiment, the transmission FIFO 444 of the second port 424 read from the buffer unit 440 is used. It is an output circuit of the first port 422 that outputs a frame from the reception FIFO 434 in synchronization with a transmission frame transfer rate of 25 MHz in the physical layer device PHY414. The transmission FIFO 446 of the second port 424 is externally connected to the reception FIFO 438 of the fourth port 428, and in this embodiment, the frame from the reception FIFO 432 of the first port 422 read from the buffer unit 440 is band-passed. This is an output circuit of the second port 424 that outputs in synchronization with the transfer frequency from the restriction control unit 410. That is, in the present embodiment, the transmission FIFO 446 is driven at an operating frequency set to any of 2.5 MHz to 25 MHz. The transmission FIFO 448 of the third port 426 is connected to the physical layer device PHY 472 of the electrical physical layer termination unit 406, and in this embodiment, the frame from the reception FIFO 438 of the fourth port 428 read from the buffer unit 440. Is output from the third port 426 in synchronization with the 25 MHz speed of the transmission frame in the physical layer device PHY472. The transmission FIFO 450 of the fourth port 428 is externally connected to the reception FIFO 434 of the second port 424. In this embodiment, the frame from the reception FIFO 436 of the third port 426 read from the buffer unit 440 is band-passed. It is an output circuit of the fourth port 428 that outputs in synchronization with the transfer frequency from the restriction control unit 410. In other words, in the present embodiment, the transmission FIFO 450 is driven by the operating frequency set to any one of 2.5 MHz to 25 MHz that is the same as the transmission FIFO 446 of the second port 424.
[0025]
Returning to FIG. 1, the electrophysical layer termination unit 406 is a layer 1 termination circuit that terminates a data frame transmitted to and received from the router 300. In this embodiment, the line interface 470, the physical layer device PHY 472, , A fixed clock oscillator 474. The line interface 470 is a serial interface that is connected to an electrical cable such as a twisted pair laid between the router 300 of the wide area LAN and serially transfers a data frame to and from the physical layer device PHY 472. The physical layer device PHY 472 is a circuit that performs processing such as waveform shaping of the frame received from the line interface 470. In this embodiment, the physical layer device PHY 472 is driven by the fixed clock oscillator 474, for example, at a fixed operating frequency of 25 MHz, and A parallel-serial conversion circuit for converting the 4-bit parallel frame from the serial frame into serial data. The fixed clock oscillator 474 is a clock generation circuit that supplies a fixed clock to the physical layer device PHY 472. In this embodiment, the physical layer device PHY 472 converts a 100 Mbps serial data frame to 4-bit parallel and transfers it at 25 MHz. This is an oscillation circuit that oscillates the operating frequency of.
[0026]
On the other hand, the VLAN setting unit 408 is a setting circuit that sets the tag protocol identifier TPID in the TPID setting unit 452 of the MAC switch 404 and the VLAN identifier in the VLAN table 464. In this embodiment, as described above, the TPID setting is performed. The value of 0xffff is set in the unit 452, and the first and second ports 422 and 424 are in the same VLAN group 420 in the VLAN table 464, and the third and fourth ports 426 and 428 are in the same VLAN group 430. A VLAN identifier representing a certain thing is set. On the other hand, the bandwidth limit control unit 410 is a control unit that freely sets the oscillation frequency to the second and fourth ports 424 and 428 interconnected in the MAC switch 404 and limits the data transfer amount. In the embodiment, a variable clock oscillator 480 and a switching circuit 482 are included. The variable clock oscillator 480 is a variable oscillator that supplies a common operating frequency when transferring frames in the second and fourth ports 424 and 428 of the MAC switch 404. In the present embodiment, the variable clock oscillator 480 is connected via the switching circuit 482. The oscillation frequency can be freely set from the set 2.5 MHz to 25 MHz, for example, in units of 2.5 MHz. More specifically, for example, FIG. 5 shows an example of the variable clock oscillator 480 of this embodiment including the switching circuit 482. In this figure, a selector 490 is a selection circuit that selects a setting value from, for example, a 4-bit DIP switch and supplies it to the variable oscillator 492. In this embodiment, a contract for each 10 Mbps step unit from a bandwidth speed of 10 Mbps to 100 MHz. A transfer frequency setting value is selected for each 2.5 MHz step unit from 2.5 MHz to 25 MHz according to the band. The selection value of the selector 490 is supplied to the variable oscillator 492. As the variable oscillator 492, for example, an oscillator capable of oscillating a desired frequency from 10 MHz to 100 MHz is advantageously applied. In this embodiment, an oscillation frequency for each 10 MHz step is selected from 20 MHz to 100 MHz, and the frequency dividing circuit 494 is selected. Supplied. The frequency dividing circuit 494 divides the oscillation frequency from the variable oscillator 492, and includes a 1/8 frequency dividing circuit and a 1/4 frequency dividing circuit in the present embodiment. The 1/8 frequency divider circuit is selected in the case of 2.5 MHz clock output, and divides the 20 MHz oscillation frequency from the variable oscillator 492 by 1/8 and outputs a 2.5 MHz clock. The 1/4 frequency divider circuit is selected in the case of 5.0 MHz to 25 MHz clock output, and divides the oscillation frequency of 20 MHz to 100 MHz from the variable oscillator 492 by 1/4 and outputs the result. The output from the frequency dividing circuit 494 is switched to the 1/8 frequency division and 1/4 frequency division by the 2-input 1-output selector 496, and is sent to the second and fourth ports 424 and 428 of the MAC switch 404. Commonly supplied. FIG. 7 shows the relationship among the band speed, the oscillation frequency, and the operating frequency supplied in common to the second and fourth ports 424 and 428 of the MAC switch 404 according to the present embodiment. Yes. For example, when the band speed is set to 10 MHz, the dip switches D0 to D3 are set to “0000”. As a result, the oscillation clock having a frequency of 20 MHz is divided by 1/8 and a clock having an operation frequency of 2.5 MHz is output. In the following, the operating frequency can be set in steps of 2.5 MHz up to 25 MHz by setting the dip switches D0 to D3.
[0027]
On the other hand, in FIG. 2, the second optical conversion bridge 50 on the inside of the house is installed in the user's house and the data from the router 100 of the user LAN 10 and the data from the wide area LAN 30 transferred via the optical fiber transmission line 20. This is a second transfer device that transfers frames to each other according to their MAC addresses. In this embodiment, the data frame between the electrical transmission line such as a twisted pair from the router 100 and the optical fiber transmission line 20- It is an optical conversion device that performs optical conversion and transfers it by medium access control. More specifically, an optical physical layer termination unit that is formed with substantially the same configuration as the optical conversion bridge 40 shown in FIG. 1 and that is connected to the optical fiber transmission line 20 and terminates its layer 1; It includes a MAC switch for transferring according to an address, and an electrophysical layer termination unit that is connected to the router 100 of the user LAN 10 and terminates its layer 1. In this case, the difference from the optical conversion bridge 40 is that the electrophysical layer termination unit and the MAC switch are switched to the operating frequency of only 2.5 MHz or 25 MHz according to 10BASE-T or 100BASE-T of the user LAN 10. Is a point. The optical physical layer termination portion has an operating frequency fixed at 25 MHz in response to the transmission speed of the optical fiber transmission line 20. When a contract bandwidth is set, for example, when a contract bandwidth exceeding 10 Mbps is required depending on the number of terminals connected to the user LAN 10 or the performance of each terminal, a transmission rate of 100BASE-T is used.
[0028]
Next, the operation of the inter-LAN connection system having the above configuration will be described. First, the VLAN setting circuit 408 is activated, and the VLAN setting specific to the present application is set in the MAC switch 404 in advance. That is, a value “0xffff” for processing a tag frame as an untagged frame is set in the TPID setting circuit 452 in the buffer control unit 442 of the MAC switch 404, and a port VLAN setting in which the frame transfer destination is fixed in the VLAN table 464 is set. The representing VLAN identifier is written in advance. In other words, in this embodiment, the first port 422 and the second port 424 are the same VLAN group 420, and the third port 426 and the fourth port 428 are the same VLAN group 430. The identifier is written in the VLAN table 464 in advance.
[0029]
Next, based on the contract with the user, the optical conversion bridge 40 is set to a contract bandwidth required by the communication carrier. For example, when the upstream and downstream data capacities are set to 50 MHz contract bandwidths, the dip switches D0 to D3 in the switching circuit 482 of the bandwidth limitation control unit 410 are set to the bandwidth setting value “0100” as shown in FIG. 7, for example. When the power switch is turned on, a clock with an oscillation frequency of 50 MHz is supplied from the variable clock oscillator 480, for example, the oscillator 492 to the frequency dividing circuit 494. Next, the frequency dividing circuit 494 divides the oscillation frequency of 50 MHz by the 1/4 frequency dividing circuit and supplies the 12.5 MHz clock to the selector 496. As a result, the selector 496 selects the 12.5 MHz clock output from the 1/4 frequency divider circuit of the frequency divider circuit 494 and supplies it to the second and fourth ports 424 and 428 of the MAC switch 404, respectively. .
[0030]
On the other hand, in the optical physical layer termination unit 402, an oscillation clock fixed at 25 MHz is supplied to the physical layer device PHY 414 by the fixed clock oscillator 416, and a data frame can be transferred at a frame rate of 100 Mbps. Similarly, the electrophysical layer termination unit 406 is supplied with a fixed oscillation clock of 25 MHz from the fixed clock oscillator 474 to the physical layer device PHY 472 and can transfer the frame at 100 Mbps. On the other hand, in the second optical conversion bridge 50, an oscillation frequency set in advance to 25 MHz is supplied to the electrophysical layer termination unit, the MAC switch, and the optical physical layer termination unit, so that frames up to 100 Mbps can be transferred. It has become.
[0031]
Next, when a data frame such as an Ethernet frame including a tag frame or an IEEE 802.3 Ethernet frame is transmitted from the user LAN 10 via the router 100 in the communication state, the second frame received from the router 100 is received. In the optical conversion bridge 50, the frame is subjected to processing such as waveform shaping and parallel conversion at the end portion of the electrophysical layer, and transferred to the MAC switch. Next, the MAC switch checks whether it is a frame to be transferred to the network side according to the MAC address of the frame, and transfers it to the optical physical layer termination unit. Next, in the optical physical layer termination unit, the data frame is subjected to electro-optical conversion and transferred to the network side via the optical fiber transmission line 20. In this case, in the second optical conversion bridge 50, even if the electrophysical layer termination unit, the MAC switch, and the optical physical layer termination unit each operate at a fixed operating frequency of 25 MHz and exceed the contracted bandwidth. Are transferred to the first optical conversion bridge 40 via the optical fiber transmission line 20.
[0032]
Next, in the second optical conversion bridge 40 that has received the data frame from the user LAN 10 via the optical fiber transmission line 20, the frame is photoelectrically converted by the line interface 412 of the optical physical layer termination unit 402 to perform physical conversion. Supplied to the layer device PHY414. At this time, the frame is serially input to the physical layer device PHY 414 at a transmission rate of 100 Mbps. Next, the physical layer device PHY 414 performs processing such as frame waveform processing and parallel conversion, and supplies a frame of 25 MHz × 4 bits to the MAC switch 404. Next, in the MAC switch 404, the reception FIFO 432 operates in accordance with the speed of the reception frame at the first port 422, and supplies the frame to the address search unit 454 of the buffer unit 440 and the buffer control unit 442. Next, the address search unit 454 determines that the received frame is an untagged frame based on the value of “0xffff” set in the TPID setting unit 452 in advance, and the frame transfer destination is the second port from the VLAN table 464. 424 is determined. Next, the address search unit 454 searches the address table 462 for the MAC address of the frame, and determines whether the frame is a frame to be transferred to the network side. If it is a frame to be transferred, the corresponding write pointer 456 is driven to accumulate the control address supplied from the descriptor 460 to the buffer unit 440.
[0033]
Next, when a read instruction is supplied from the read pointer 458 to the descriptor 460, the frames accumulated in the buffer unit 440 are sequentially read out from the buffer unit 440 by the control address from the descriptor 460, and the second port 424. Are transmitted to the reception FIFO 446 of the fourth port 428 via the external connection line. At this time, the transmission FIFO 446 of the second port 424 operates at the operating frequency of 12.5 MHz from the band limitation control unit 410 and outputs the frame in 4-bit parallel. When the frame is output, the read pointer 458 instructs the buffer control unit 442 to read the next frame. As a result, a frame received at the first port 422 at 100 Mbps is output from the transmission FIFO 446 of the second port 424 at a speed of 50 Mbps, and a frame transmitted from the user LAN 10 exceeding the amount of data is The buffer unit 440 overflows and is discarded.
[0034]
Next, the frame transferred from the transmission FIFO 446 of the second port 424 is input at the transfer speed of the reception FIFO 438 of the fourth port 428, that is, at a speed of 50 Mbps, and is sequentially stored in the buffer unit 440. The frame stored in the buffer unit 440 is determined to be an untagged frame by collating the tag protocol identifier as in the case where the frame is transferred from the first port 422 to the second port 424. It is read out to the third port 426 by the MAC address and transferred to the electrophysical termination unit 406 via the transmission FIFO 448. At this time, the transmission FIFO 448 of the third port 426 operates at an operating frequency of 25 MHz and outputs the frame at a rate of 25 Mbps × 4 bits and 100 Mbps. The electrical physical layer termination unit 406 that has received the transfer frame from the transmission FIFO 448 of the third port 426 performs the waveform processing and serial conversion in the physical layer device PHY 472 in the same manner as the optical physical layer termination unit 402, and sets the line interface 470. To the wide area LAN 30 at a transfer rate of 100 Mbps serial.
[0035]
On the other hand, a data frame transmitted from the wide area LAN 30 to the user LAN 10 is transferred to the user LAN 10 through a path opposite to the data frame transferred from the user LAN 10 to the wide area LAN 30. That is, the data frame from the wide area LAN 30 is supplied to the first optical conversion bridge 40 via the router 300, and the termination of layer 1 is executed by the electrophysical layer termination unit 406, so that the third of the MAC switch 404 Supplied to port 426. The data frame supplied to the third port 426 is transferred to the fourth port 428 by the port VLAN function, and is input to the second port 424 by external connection. At that time, the data rate of 100 Mbps is band-limited to the data rate of 50 Mbps. When the frame includes a VLAN tag, the VLAN tag frame is determined as an untagged frame and is effectively transferred by the MAC address. The data frame transferred to the second port 424 is transferred to the first port 422 by the port VLAN function and supplied again to the optical physical layer termination unit 402 at a data rate of 100 Mbps. The data frame supplied to the optical physical layer termination unit 402 is converted into an optical signal and supplied to the second optical conversion bridge 50 via the optical fiber transmission line 20, and the optical physical layer termination unit again converts it into an electrical signal. Converted. The data frame converted into the electrical signal is further transferred from the MAC switch to the router 100 via the electrical physical layer termination unit, and reaches the user LAN 10.
[0036]
Similarly, with respect to the transfer of the upstream data frame from the user LAN 10 to the wide area LAN 30, when a frame exceeding the contracted bandwidth is generated in the data amount supplied from the user LAN 10, the MAC switch 404 of the first optical conversion bridge 40 The buffer unit 440 between the first port 422 and the second port 424 is supplied beyond the contracted band by a transfer frequency corresponding to the contracted band between the second port 424 and the fourth port 428. The data frame overflows and is discarded. Similarly, regarding the transfer of the downlink data frame from the wide area LAN 30 to the user LAN 10, when a frame exceeding the contracted bandwidth is generated in the transmission frame from the wide area LAN 30, the third switch in the MAC switch 404 of the first optical conversion bridge 40 In the buffer unit 440 between the port 426 and the fourth port 428, the data frame supplied beyond the contracted bandwidth overflows and is discarded, and the bandwidth limitation is effectively executed with the same bandwidth frequency as that of the uplink.
[0037]
As described above, according to the inter-LAN connection system of the present embodiment, the user LAN 10 is effectively used as the wide-area LAN 30 of the communication carrier by using the first optical conversion bridge 40 and the second optical conversion bridge 50 of the inexpensive bridge method. Can be connected to. In this case, the first and second ports 422 and 424 and the third and fourth ports 426 and 428 are set as the same VLAN group 420 and 430 by the VLAN function in the MAC switch 404 of the first optical conversion bridge 40, respectively. The groups 420 and 430 are externally connected by the second port 424 and the fourth port 428, and the group is driven by the operating frequency set in the band limitation control unit 410 according to the contract band. Therefore, the upstream data frame from the user LAN 10 exceeding the set bandwidth and the downstream data frame from the wide area LAN 30 are effectively discarded, and the bandwidth limitation is effectively realized to a desired data amount within the contract bandwidth. Can do. At that time, since the oscillation frequency of the band limitation control unit 410 is set in, for example, 2.5 MHz steps, the contract band can be set finely for every 10 Mbps steps, and the charge setting is finely set according to the contract band. It can be set. Further, in the MAC switch 404 of the first optical conversion bridge 40, the value “0xffff” for processing the tag frame as an untagged frame is set as the tag protocol identifier TPID in the TPID setting unit 452, so that the data frame including the tag frame Can be transferred effectively without destroying. Therefore, not only a user LAN that handles only untagged frames such as ordinary Ethernet frames or IEEE802.3 Ethernet frames, but also a user LAN that handles data frames including tag frames with a VLAN tag or a mixture of these. However, each user LAN 10 can be effectively connected to the wide area LAN 30 between the LANs.
[0038]
Next, FIGS. 8 and 9 show another embodiment of an inter-LAN connection system according to the present invention. In these figures, the difference from the above embodiment is that a VLAN switchable MAC switch 500 including eight ports 502 to 518 is applied as the first optical conversion bridge 60 installed on the station side. The ports 502 to 518 are VLAN-configured in the four VLAN groups 510 to 540, respectively, and the groups are externally connected so that the upstream and downstream data frames pass through different routes, and the different routes are different. The first and second band limitation control units 550 and 560 for supplying a clock having an operating frequency are provided, and are configured so as to be set to contract bands different from each other in uplink and downlink. 8 and 9, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted.
[0039]
That is, the first optical conversion bridge 60 applied to this embodiment includes an optical physical layer termination unit 402, a MAC switch 500, an electrophysical layer termination unit 406, and a VLAN setting circuit 408 as shown in FIG. A first band limitation control unit 550 and a second band limitation control unit 560. The MAC switch 500 includes first to eighth ports 502 to 518, and the input of the first port 502 is connected to the physical layer device PHY 414 of the optical physical layer termination unit 402. The second port 504 is set as the same first VLAN group 510 as the first port 502 and is externally connected to the third port 506. The third port 506 and the fourth port 508 are set as the second VLAN group 520, and the output of the fourth port 508 is connected to the physical layer device PHY 472 of the electrophysical layer termination unit 406. The input of the fifth port 512 is connected to the physical layer device PHY 472 of the electrophysical layer termination unit 406. The sixth port 514 is set as the same third VLAN group 530 as the fifth port 512 and is externally connected to the seventh port 516. The seventh port 516 and the eighth port 518 are set as a fourth VLAN group 540, and the output of the eighth port 518 is connected to the physical layer device PHY 414 of the optical physical layer termination unit 402.
[0040]
On the other hand, the first band limitation control unit 550 includes a variable clock oscillator 552 and a switching circuit 554, similar to the band limitation control unit 410 in the embodiment of FIG. 1, for example, as shown in FIG. And a variable oscillator 492, a frequency dividing circuit 494, and a selector 496. The outputs are respectively connected to the second port 504 and the third port 506 of the MAC switch 500. Similar to the first band limitation control unit 550, the second band limitation control unit 560 includes a variable clock oscillator 562 and a switching circuit 564, and is configured in substantially the same manner as the circuit shown in FIG. The output of the second band limitation control unit 560 is connected to the sixth port 514 and the seventh port 516, respectively.
[0041]
In the configuration as described above, first, the VLAN setting circuit 408 is activated, and the VLAN setting specific to the present application is previously set in the MAC switch 500. That is, a value “0xffff” for processing a tag frame as an untagged frame is set in the TPID setting circuit of the buffer controller in the MAC switch 500, and a VLAN identifier representing a port VLAN setting in which the frame transfer destination is fixed in the VLAN table. Is written in advance. That is, in the present embodiment, the first and second ports 502 and 504 are set as the first VLAN group 510, the third and fourth ports 506 and 508 are set as the second VLAN group 520, and the first VLAN identifiers indicating that the fifth and sixth ports 512 and 514 are set as the third VLAN group 530 and the seventh and eighth ports 516 and 518 are set as the fourth VLAN group 540 are stored in the VLAN table. Write in advance.
[0042]
Next, based on the contract with the user, the optical conversion bridge 60 is set to a contract bandwidth required by the communication carrier. When the uplink data capacity is set to, for example, a 20 MHz contract band, the dip switches D0 to D3 in the switching circuit 554 of the first band limitation control unit 550 are set to the band setting value “0001” as shown in FIG. On the other hand, when the downlink data capacity is set to 50 MHz, the dip switches D0 to D3 in the switching circuit 564 of the second band limitation control unit 560 are set to “0100”. When the power switch is turned on in such a state, in the first band limitation control unit 550, a clock having an oscillation frequency of 20 MHz is supplied from the variable clock oscillator 552, for example, the oscillator 492 to the frequency dividing circuit 494. Next, the frequency dividing circuit 494 divides the 20 MHz oscillation frequency by the 1/4 frequency dividing circuit and supplies the 5.0 MHz clock to the selector 496. Thus, the selector 496 selects the 5.0 MHz clock output from the 1/4 frequency divider of the frequency divider 494 and supplies it to the second and third ports 504 and 506 of the MAC switch 500, respectively. In the second band limitation control unit 560, a clock having an oscillation frequency of 50 MHz is supplied from the oscillator 492 of the variable clock oscillator 562 to the frequency dividing circuit 494. Next, the frequency dividing circuit 494 divides the 50 MHz oscillation frequency by the 1/4 frequency dividing circuit and supplies the 12.5 MHz clock to the selector 496. As a result, the selector 496 selects the 12.5 MHz clock output from the 1/4 frequency divider circuit of the frequency divider circuit 494 and supplies it to the sixth and seventh ports 514 and 516 of the MAC switch 500, respectively. .
[0043]
On the other hand, in the optical physical layer termination unit 402, similarly to the above embodiment, the fixed clock oscillator 416 supplies an oscillation clock fixed at 25 MHz to the physical layer device PHY 414 so that a data frame can be transferred at a frame rate of 100 Mbps. Yes. Similarly, the electrophysical layer termination unit 406 is supplied with a fixed oscillation clock of 25 MHz from the fixed clock oscillator 474 to the physical layer device PHY 472 and can transfer the frame at 100 Mbps. On the other hand, in the second optical conversion bridge 50, the oscillation frequency set in advance to 25 MHz is supplied to the electrophysical layer termination unit, the MAC switch, and the optical physical layer termination unit in the same manner as in the above-described embodiment, and up to 100 Mbps. The frame can be transferred.
[0044]
Next, when a data frame such as an Ethernet frame including a tag frame or an IEEE 802.3 Ethernet frame is transmitted from the user LAN 10 via the router 100 in the communication state, the second frame received from the router 100 is received. In the optical conversion bridge 50, similarly to the above-described embodiment, the frame is subjected to processing such as waveform shaping and parallel conversion at the terminal end of the electrophysical layer, and transferred to the MAC switch. Next, the MAC switch checks whether it is a frame to be transferred to the network side according to the MAC address of the frame, and transfers it to the optical physical layer termination unit. Next, in the optical physical layer termination unit, the data frame is subjected to electro-optical conversion and transferred to the network side via the optical fiber transmission line 20. In this case, in the second optical conversion bridge 50, as in the above-described embodiment, the electrophysical layer termination unit, the MAC switch, and the optical physical layer termination unit operate at a fixed operating frequency of 25 MHz, respectively. Even if it is, all data frames are transferred to the first optical conversion bridge 60 via the optical fiber transmission line 20.
[0045]
Next, in the first optical conversion bridge 60 that has received the data frame from the user LAN 10 via the optical fiber transmission line 20, the frame is received at the line interface 412 of the optical physical layer termination unit 402 as in the above embodiment. Photo-electrically converted and supplied to the physical layer device PHY 414. At this time, the frame is serially input to the physical layer device PHY 414 at a transmission rate of 100 Mbps. Next, the physical layer device PHY 414 performs processing such as frame waveform processing and parallel conversion, and supplies a frame of 25 MHz × 4 bits to the MAC switch 500. Next, in the MAC switch 500, the reception FIFO operates in accordance with the speed of the reception frame at the first port 502, and supplies the frame to the address search unit of the buffer unit and the buffer control unit. Next, the address search unit determines that the received frame is an untagged frame based on the value of “0xffff” set in advance in the TPID setting unit, and the frame transfer destination is the second port 504 from the VLAN table. Judge that. Next, the address search unit searches the MAC address of the frame from the address table and determines whether or not the frame is a frame to be transferred to the network side. If it is a frame to be transferred, the corresponding write pointer is driven to accumulate the control address supplied from the descriptor to the buffer unit.
[0046]
Next, when a read instruction is supplied from the read pointer to the descriptor, the frames accumulated in the buffer unit are sequentially read from the buffer unit by the control address from the descriptor and supplied to the transmission FIFO of the second port 504. Then, the data is sequentially transferred to the reception FIFO of the third port 506 via the external connection line. At this time, the transmission FIFO of the second port 504 operates at the operating frequency of 5.0 MHz from the first band limitation control unit 550 and outputs the frame in 4-bit parallel. When the frame is output, the read pointer instructs the buffer control unit to read the next frame. Thus, a frame received at the first port 502 at 100 Mbps is output from the transmission FIFO of the second port 504 at a speed of 20 Mbps, and a frame transmitted from the user LAN 10 exceeding the data amount is Overflow is discarded in the buffer unit.
[0047]
Next, the frame transferred from the transmission FIFO of the second port 504 is input at the transfer speed of the reception FIFO of the third port 506, that is, the speed of 20 Mbps, and is sequentially stored in the buffer unit. The frame stored in the buffer unit is determined to be an untagged frame by collating the tag protocol identifier as in the case where the frame is transferred from the first port 502 to the second port 504. Further, the VLAN table setting and the MAC address are determined. Is read out to the fourth port 508 and transferred to the electrophysical layer termination unit 406 via the transmission FIFO. At this time, the transmission FIFO of the fourth port 508 operates at an operating frequency of 25 MHz, and outputs the frame at a rate of 100 Mbps of 25 MHz × 4 bits. When receiving the transfer frame from the transmission FIFO of the fourth port 508, the electrophysical layer termination unit 406 performs waveform processing and serial conversion in the physical layer device PHY 472 to perform the line interface 470 in the same manner as the optical physical layer termination unit 402. To the wide area LAN 30 at a transfer rate of 100 Mbps serial.
[0048]
On the other hand, a data frame transmitted from the wide area LAN 30 to the user LAN 10 is first supplied from the wide area LAN 30 to the first optical conversion bridge 60 via the router 300, and the termination of layer 1 is executed by the electrophysical layer termination unit 406. And supplied to the fifth port 512 of the MAC switch 500. The data frame supplied to the fifth port 512 is transferred to the sixth port 514 by the port VLAN function and input to the seventh port 516 by external connection. At that time, the data rate of 100 Mbps is band-limited to the data rate of 50 Mbps. When a tag frame is included, the tag frame is determined as an untagged frame and is effectively transferred by its MAC address. The data frame transferred to the seventh port 516 is transferred to the eighth port 518 by the port VLAN function and supplied again to the optical physical layer termination unit 402 at a data rate of 100 Mbps. The data frame supplied to the optical physical layer termination unit 402 is converted into an optical signal and supplied to the second optical conversion bridge 50 via the optical fiber transmission line 20 as in the above embodiment, and the optical physical layer It is again converted into an electric signal by the terminal portion. The data frame converted into the electrical signal is further transferred from the MAC switch to the router 100 via the electrical physical layer termination unit, and reaches the user LAN 10.
[0049]
Similarly, with respect to the transfer of the upstream data frame from the user LAN 10 to the wide area LAN 30, when a frame exceeding the contracted bandwidth is generated in the data amount supplied from the user LAN 10, the MAC switch 500 of the first optical conversion bridge 60 Data supplied beyond the contracted bandwidth in the buffer unit between the first port 502 and the second port 504 by the transfer frequency corresponding to the contracted bandwidth between the second port 504 and the third port 506 The frame overflows and is discarded. Similarly, regarding the transfer of the downlink data frame from the wide area LAN 30 to the user LAN 10, when a frame exceeding the contracted bandwidth is generated in the transmission frame from the wide area LAN 30, the fifth switch in the MAC switch 500 of the first optical conversion bridge 60 is used. In the buffer unit between the port 512 and the sixth port 514, the data frame supplied beyond the contracted bandwidth overflows and is discarded, and the bandwidth limitation is effectively executed by the bandwidth frequency different from the upstream.
[0050]
As described above, according to the inter-LAN connection system of the present embodiment, the user LAN 10 is communicated using the first optical conversion bridge 60 and the second optical conversion bridge 50 of an inexpensive bridge system, as in the above-described embodiment. It is possible to connect effectively to the wide area LAN 30 of the business operator. In this case, in the MAC switch 500 of the first optical conversion bridge 60, eight ports 502 to 518 are set as four VLAN groups 510 to 540 by the port VLAN function, and an upstream data frame and a wide area from the user LAN 10 are set. The first and second VLAN groups 510 and 520 and the third and fourth VLAN groups 530 and 540 are externally connected so as to forward the downlink data frame from the LAN 30 via different ports, respectively. Since the transfer rates between the externally connected ports are set to different contract bandwidths according to the operating frequencies set in the first or second bandwidth limitation control units 550 and 560 in different paths, the user LAN 10 exceeding the respective set bandwidths. Or frame from wide area LAN 30 The effectively destroyed respectively, it is possible to realize the band-limited to a desired amount of data in the contract bandwidth. At this time, since the oscillation frequencies of the first and second band limit control units 550 and 560 are set, for example, in 2.5 MHz steps, the contract band can be set finely for each 10 Mbps steps. Can be set in detail according to the contracted bandwidth. Therefore, it is possible to set a contract bandwidth according to the user's request for each of the upstream and downstream, and to provide an excellent service that meets the user's request. Moreover, since the tag protocol identifier TPID for processing the tag frame as an untagged frame is set as in the above embodiment, the data frame including the tag frame can be effectively transferred without being discarded.
[0051]
In each of the above embodiments, “0xffff” is set as the value of the tag protocol identifier TPID in the TPID setting unit of the MAC switch. However, in the present invention, a value applied to a frame flowing in a general LAN environment. Any value other than the above may be used. In each of the above embodiments, the case where the received frame is processed as 4-bit parallel in the MAC switch has been described as an example. However, in the present invention, the present invention is not limited to this. It may be a thing. In this case, of course, an operating frequency corresponding to the number of conversion bits is supplied to the physical layer termination unit, and an operating frequency obtained by dividing the frequency according to the contract band is supplied from the variable clock oscillator to the MAC switch. . Further, in each of the above embodiments, the case where the band limiting frequency is set from 10 Mbps to 100 Mbps in 10 Mbps steps has been described as an example. However, in the present invention, the band limiting range and the setting step are of course arbitrary. Things can be used. In each of the above embodiments, the band limit control unit is manually set by a dip switch as the switching circuit of the band limit control unit. However, in the present invention, the band limit value is set by remote control using a remote device of the station. Also good. In each of the above-described embodiments, the second optical conversion bridge 50 is described as an example in which the same MAC switch as that of the first optical conversion bridges 40 and 60 is applied to fix the transfer frequency. In the present invention, an optical conversion repeater configured without using a MAC switch may be used. Furthermore, in each of the above embodiments, the case where the optical fiber transmission line 20 has a transmission band of 100 Mbps has been described as an example. However, in the present invention, a transmission band having an arbitrary transmission band may be applied. In each of the above embodiments, the case where the first optical conversion bridge and the second optical conversion bridge are connected via an optical fiber transmission line has been described as an example. Any medium such as an electric transmission line such as a cable may be applied. Similarly, another medium such as an optical fiber transmission line may be used between the wide area LAN and the first optical conversion bridge or between the user LAN and the second optical conversion bridge. In these cases, it is preferable to apply a termination unit corresponding to the medium to the physical layer termination unit of each bridge or repeater.
[0052]
【The invention's effect】
As described above, according to the LAN connection system of the present invention, it is a LAN connection system that connects a user LAN and a wide area LAN of a communication carrier via a transmission line such as an optical fiber. A first transfer device that is installed in the network and transfers a predetermined data frame between the wide area LAN and the transmission line, and a first transfer device that is installed in the user's house and transfers the predetermined data frame between the user LAN and the transmission line. 2, and at least the first transfer device includes a first physical layer termination unit that terminates the physical layer between the transmission line and a second physical layer that terminates the physical layer on the wide area LAN side. A MAC switch for transferring a data frame by medium access control between a termination means and first and second physical layer termination means, wherein a plurality of input / output ports are provided for each predetermined group. A MAC switch that is provided so as to be LAN-configurable and is grouped on the transmission line side and the wide-area LAN side so that the data frame can be transferred between groups, and the transfer frequency of the data frame between them is predetermined. And a bandwidth restriction control means for restricting the amount of data from the user LAN transferred from the second transfer device via the transmission path to the wide area LAN to a desired transmission capacity. With an inexpensive bridge system, at least the amount of data from the user LAN to the wide area LAN can be set to a fine contract bandwidth according to the user's request.
[0053]
According to the LAN connection system according to claim 2 of the present invention, the MAC switch in the first transfer device includes at least first to fourth ports, and the first port is the first physical layer termination means. The first port and the second port are set as the first VLAN group, the third port is connected to the second physical layer termination means, the third port and the fourth port Since the port is set as the second VLAN group, and the second port and the fourth port are connected so that data frames can be transferred between the groups in the first and second VLAN groups, the second By setting the data transfer rate between the port and the fourth port as the contract bandwidth, the data capacity can be effectively limited.
[0054]
According to the LAN connection system according to claim 3 of the present invention, the MAC switch in the first transfer apparatus includes at least first to eighth ports, and the input of the first port is the first physical layer termination. The first port and the second port are set as a first VLAN group, and the third port and the fourth port are set as a second VLAN group, and the fourth port Are connected to the second physical layer termination means, and the second port and the third port are connected to each other so that the data frame can be transferred between the groups in the first and second VLAN groups. Therefore, when the data capacity input from the first physical layer termination means to the first port is transferred from the second port to the third port, the data transfer rate is effectively limited to the fourth port. From The data frame frequency limit can be effectively output to the second physical layer terminating unit. Therefore, it is possible to effectively limit the upstream data capacity transferred from the first physical layer termination unit to the second physical layer termination unit to a desired contract bandwidth.
[0055]
According to the inter-LAN connection system according to claim 4 of the present invention, the MAC switch in the first transfer device further includes an input of the fifth port connected to the second physical layer termination means, The port and the sixth port are set as the third VLAN group, the seventh port and the eighth port are set as the fourth VLAN group, and the output of the eighth port is the first physical layer termination. Since the sixth port and the seventh port are connected to each other so that the data frame can be transferred between the groups in the third and fourth VLAN groups, the second physical layer termination means to the fifth port. When the data frame input to the first port is transferred from the sixth port to the seventh port, the bandwidth is effectively limited, and the data frame whose bandwidth is limited from the eighth port is effectively used as the first physical layer termination means. It is possible to force. Therefore, it is possible to effectively limit the downstream data capacity transferred from the second physical layer termination means to the first physical layer termination means to a desired contract bandwidth.
[0056]
According to the inter-LAN connection system according to claim 5 of the present invention, the MAC switch in the first transfer device includes input means for each port, buffer means for temporarily storing data frames from the input means, and buffer means Output means of each port for outputting the data frame read from the band limiting control means in response to the transfer frequency from the band limiting control means, and a buffer for reading the data frame from the buffer means to the output means of the desired port set in the VLAN Control means, so that the data frame is effectively transferred from the VLAN-set input means to the output means, and the frame exceeding the contracted bandwidth is discarded by the buffer means at the time of transfer, and the data capacity is made effective. Bandwidth can be limited.
[0057]
According to the LAN connection system according to claim 6 of the present invention, the band limitation control means includes an oscillation means for generating a desired oscillation frequency and a switching means for freely switching the oscillation frequency from the oscillation means. Thus, since the buffer control means is driven by the same frequency for uplink and downlink, the bandwidth can be effectively limited by the same contract bandwidth for uplink and downlink.
[0058]
According to the inter-LAN connection system according to claim 7 of the present invention, the inter-LAN connection system according to the present invention comprises an oscillating means for generating a desired oscillation frequency and a switching means for freely switching the oscillation frequency from the oscillating means. Including two or more band limiting control means, and these band limiting control means drive the buffer control means with different uplink and downlink frequencies, so that the band is effectively limited with different contract bands according to the user's request. Can do.
[0059]
According to the inter-LAN connection system according to claim 8 of the present invention, the transferred data frame includes a tag frame having a VLAN tag to which VLAN control information indicating which VLAN is to be transferred, or a VLAN tag. Since the first transfer apparatus includes setting means for setting the MAC switch to identify the tag frame and the untagged frame as an untagged frame regardless of the presence or absence of the VLAN tag. The data frame including the tag frame can be effectively transferred without being discarded. Therefore, not only a user LAN that handles only an untagged frame such as a normal Ethernet frame or an IEEE 802.3 Ethernet frame, but also a user LAN that handles a data frame including a tag frame to which a VLAN tag is added or a mixture of these. However, each user LAN can be effectively connected to a wide area LAN.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of an optical conversion bridge applied to an inter-LAN connection system according to the present invention.
FIG. 2 is a block diagram showing an embodiment of an inter-LAN connection system to which the optical conversion bridge according to the embodiment of FIG. 1 is applied.
FIG. 3 is a functional block diagram showing a configuration example of a MAC switch applied to the optical conversion bridge according to the embodiment of FIG. 1;
4 is a functional block diagram illustrating a configuration example of a further main part of the MAC switch according to the embodiment of FIG. 3;
FIG. 5 is a functional block diagram illustrating a configuration example of a band limitation control unit applied to the optical conversion bridge according to the embodiment of FIG. 1;
6 is a diagram showing a format example of a data frame applied to the inter-LAN connection system according to the embodiment of FIG.
FIG. 7 is a table showing an example of band speeds and setting values of operating frequencies applied to the embodiment of FIG. 1;
FIG. 8 is a block diagram showing another embodiment of an optical conversion bridge applied to an inter-LAN connection system according to the present invention.
9 is a block diagram showing an embodiment of an inter-LAN connection system to which the optical conversion bridge according to the embodiment of FIG. 8 is applied.
[Explanation of symbols]
10 User LAN
20 Optical fiber transmission line
30 Wide area LAN
40, 60 First optical conversion bridge (first transfer device)
50 Second optical conversion bridge (second transfer device)
402 Photophysical layer termination
404, 500 MAC switch
406 Electrophysical layer termination
408 VLAN setting circuit
410, 550, 560 Bandwidth limit control unit
422-428, 502-518 ports
480, 552, 562 Variable clock oscillator
482,554,564 switching circuit

Claims (8)

An inter-LAN connection system for connecting a user LAN and a wide area LAN of a communication carrier via a transmission line such as an optical fiber,
The system includes a first transfer device that is installed on a telecommunications carrier side and transfers a predetermined data frame between a wide-area LAN and the transmission line, and is installed in a user's home and includes a user LAN and the transmission line. A second transfer device for transferring a predetermined data frame between them,
At least the first transfer device includes a first physical layer termination unit that terminates a physical layer between the transmission line, a second physical layer termination unit that terminates a physical layer on a wide area LAN side, A MAC switch for transferring a data frame between the first and second physical layer termination means by medium access control, wherein a plurality of input / output ports are provided so that a port VLAN can be set for each predetermined group, A MAC switch in which the input / output ports grouped on the LAN side are connected so that the data frame can be transferred between the groups, and the transfer frequency of the data frame between them is freely set at a predetermined interval, and at least the above-mentioned Band limiting system that limits the amount of data transferred from the second LAN to the wide area LAN via the transmission path to a desired transmission capacity. LAN connecting system which comprises a means. 2. The LAN connection system according to claim 1, wherein the MAC switch in the first transfer apparatus includes at least first to fourth ports, and the first port is connected to the first physical layer termination unit. The first port and the second port are set as a first VLAN group, and the third port is connected to the second physical layer terminator, and the third port and the fourth port Is set as the second VLAN group, and the second port and the fourth port are connected so that the data frame can be transferred between the groups in the first and second VLAN groups. Inter-connection system. 2. The LAN connection system according to claim 1, wherein the MAC switch in the first transfer device includes at least first to eighth ports, and an input of the first port is input to the first physical layer termination unit. Connected, the first port and the second port are set as a first VLAN group, and the third port and the fourth port are set as a second VLAN group, and the output of the fourth port Are connected to the second physical layer termination means, and the second port and the third port are connected to each other so that data frames can be transferred between the groups in the first and second VLAN groups. LAN connection system characterized by the above. 4. The LAN connection system according to claim 3, wherein the MAC switch in the first transfer device further has an input of the fifth port connected to the second physical layer termination means, 6 ports are set as the third VLAN group, the seventh port and the eighth port are set as the fourth VLAN group, and the output of the eighth port is sent to the first physical layer termination means. A connection system between LANs, wherein the sixth port and the seventh port are connected so that a data frame can be transferred between the third and fourth VLAN groups in a group-free manner. 5. The LAN connection system according to claim 2, wherein the MAC switch in the first transfer device includes an input unit of each port and a buffer for temporarily storing a data frame from the input unit. Means for outputting the data frame read from the buffer means in response to the transfer frequency from the band limit control means, and the data frame from the buffer means is set in a VLAN-desired manner. And a buffer control means for reading out to the output means of the port. 6. The LAN connection system according to claim 5, wherein the band limitation control unit includes an oscillation unit that generates a desired oscillation frequency, and a switching unit that freely switches an oscillation frequency from the oscillation unit. The inter-LAN connection system, wherein the control means drives the buffer control means with the same upstream and downstream frequencies. 6. The LAN connection system according to claim 5, wherein the system includes two or more band limitation control means including an oscillation means for generating a desired oscillation frequency and a switching means for freely switching the oscillation frequency from the oscillation means. And the band limitation control means drives the buffer control means with different frequencies for uplink and downlink. 8. The LAN connection system according to claim 1, wherein a data frame transferred by the system has a VLAN tag to which VLAN control information indicating which VLAN is transferred is added. The first transfer device processes the tag frame and the untagged frame as an untagged frame regardless of the presence or absence of the VLAN tag, including a tag frame or an untagged frame having no VLAN tag. An inter-LAN connection system comprising setting means for setting as described above.

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