JP2002261768A - Media converter having test manger, and fault detection system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fault detection system for easily detecting the fault of a link including a media converter and specifying the faulty position. SOLUTION: In a link including plural media converters for connecting 100 BASE-TX: UTP cable to BASE-FX: optical cable, a test mode is activated, when a test manager detects link disconnection, and a trigger packet is transmitted from the media converter having the test manger to pluralities of media converter. It is decided whether a response packet is received from each media converter within a given time, thus specifying the faulty location, based on the response packet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure detection technique in a network, and more particularly to a failure detection system, a failure detection method, and a medium used for a link via a media converter for connecting different types of transmission media. About converter.

[0002]

2. Description of the Related Art In recent years, FTTH (Fiber To The Home), which can freely exchange music, moving images, medical data, and the like over a high-speed line by extending an optical fiber line to each home, has been attracting attention. When such FTTH is realized,
A media converter for connecting an optical fiber line to a computer in an office or home is indispensable.

Generally, a media converter is provided with a physical layer device at each of a port for connecting an optical cable and a port for connecting a UTP cable, and each physical layer device is defined by the IEEE802.3 standard. MII (Media Independent Interfac
e) support.

Further, due to the nature of the media converter, those having a missing ring function for automatically disconnecting one link when one link is disconnected are generally used. For example, when an optical fiber cable is disconnected due to a failure, the media converter automatically disconnects the link on the other UTP cable side.

[0005] Utilizing such a media converter, U
When the TP cable is connected to the optical cable, it is necessary to test whether the cable is normally connected to the other party. The conventional media converter is provided with a link test changeover switch, and the link test function can be used to check whether or not a link can be established by turning on an LED or the like for each port.

On the other hand, various link test techniques for networks have been proposed. For example, JP-A-8-3
In the link test method disclosed in Japanese Patent No. 31126,
The special control code is transmitted to the link destination switch, and the switch receiving the control code returns a response message. The source switch can determine whether the network link is functioning normally by analyzing the response message or detecting the presence or absence of a response.

However, this conventional link test technique is based on a network switch (exchange), and is basically different from a media converter having a missing link function mainly for conversion of a transmission medium in terms of configuration and functions. Are different.

[0008]

As described above, in the media converter, the test mode is set by operating the link test switch. For this reason, the link test cannot be started from the cable side (UTP cable side or optical cable side), and there has been a problem that the link test cannot be executed quickly and easily. In other words, such a media converter
Due to its nature, it is not designed to be controlled from the network side.

Further, when the missing link function of the media converter is activated, the host computer cannot monitor the status of the media converter at all even if the media converter is normal. For this reason, if the link via the media converter fails, whether the link to the media converter has failed on the host side, the media converter itself has failed, or the link beyond the media converter has failed Can not be specified.

An object of the present invention is to provide a failure detection system and method which can easily detect a failure in a link including a media converter and can specify a failure position.

It is another object of the present invention to provide a media converter suitable for a fault detection system which can easily detect a fault in a link including a media converter and can specify a fault location.

[0012]

A fault detecting method according to the present invention is a fault detecting method for a link via a plurality of media converters connecting different types of transmission media,
a) transmitting, to each of the plurality of media converters, a data block in which identification data of the media converter is written at a predetermined position; And c) a step of specifying a location where a failure has occurred based on the result of the determining step.

When the response data block is not received from the media converter within a predetermined time, it can be determined that a failure has occurred beyond the media converter.

[0014] Each of the media converters includes first physical layer interface means for connecting a first transmission medium, second physical layer interface means for connecting a second transmission medium, and the first and second physical layer interfaces. Memory means connected between the physical layer interface means for temporarily storing data transferred between them, wherein the memory means is provided at a predetermined position of a received data block stored in the memory means. It is determined whether or not the data and its own identification data match. If it is determined that the data existing at a predetermined position of the received data block matches the own identification data, a response data block to the received data block is determined. Is generated, and the response data block is received from the physical layer interface unit that has received the received data block. Tsu to return click to the source, it is characterized in that.

In each media converter, a response data block can be returned by receiving a data block containing its own identification data, so that a response test can be started from the cable side. Therefore, by receiving the response data block, it is possible to confirm that not only the link to the media converter but also the media converter itself is operating normally.

It is desirable that the reception data block and the response data block are Ethernet packets having a predetermined format. Further, the predetermined position of the received data block is preferably a source address field of the Ethernet packet.

Each of the media converters is an IEEE 8
MII (Media Indepe
first physical layer interface means for supporting a first transmission medium and supporting the IE
Second physical layer interface means for supporting the MII defined by the EE802.3 standard and for connecting a second transmission medium, and connected between the first and second physical layer interface means and between them. Memory means for temporarily storing data to be transferred, and determining whether or not the data present at a predetermined position of the received data block stored in the memory means and its own identification data match. If it is determined that the data existing at a predetermined position of the received data block matches the identification data of itself, a response data block to the received data block is generated, and one of the physical layer interface units is in a link disconnected state. The other physical layer interface unit also releases the missing link state when the Be returned to the sender of the received data blocks Taburokku, characterized in that.

Therefore, the response data block can be returned even in the missing link state. By returning the response data block, it can be determined that at least the media converter and the link up to the media converter are normal.

Each of the media converters further releases the missing link state when the determination means determines in the missing link state that the data existing at the predetermined position of the received data block does not match the identification data of the media converter. Then, the received data block is transferred. As a result, since a data block which is not subjected to the response test through the media converter passes, a link test beyond that is possible.

Further, the fault detection system according to the present invention includes a link via a plurality of media converters connecting different types of transmission media, and a test manager connected to an arbitrary media converter of the plurality of media converters. A failure detection system comprising:
Each of the media converters includes first physical layer interface means for connecting a first transmission medium, second physical layer interface means for connecting a second transmission medium, and the first and second physical layer interfaces. A memory means connected between the means for temporarily storing data transferred between them, data present at a predetermined position of a received data block stored in the memory means, and self-identification data; It is determined whether or not the received data block matches, and when it is determined that the data existing at a predetermined position of the received data block matches the identification data of itself, a response data block for the received data block is generated, and the received data block is generated. Returning the response data block from the physical layer interface unit that has received the block to the transmission source of the received data block Media test control means, the test manager comprising: an interface means for connecting to a network management unit; and the identification data of each media converter in order from the one closest to the media converter to which the test manager is connected. The data block written to the position is transmitted to the link, and it is determined whether or not a response data block corresponding to the data block is received from each media converter within a predetermined time, and a failure location is specified based on the determination result. Test manager control means.

A media converter with a test manager according to the present invention is used for detecting a failure of a link composed of different types of transmission media, and includes first physical layer interface means for connecting a first transmission medium. ,
Second physical layer interface means for connecting a second transmission medium, and a memory connected between the first and second physical layer interface means for temporarily storing data transferred between them; Means for determining whether data present at a predetermined position of the received data block stored in the memory means matches its own identification data, and determining whether the data present at the predetermined position of the received data block is When it is determined that the received data block matches the identification data, a response data block for the received data block is generated, and the response data block is returned from the physical layer interface unit that has received the received data block to the transmission source of the received data block. Media converter control means; interface means for connecting to a network management unit; It is connected to the media converter control means and sends out a data block in which identification data of another media converter is written at a predetermined position, and determines whether a response data block corresponding to the data block is received from the media converter within a predetermined time. And a test manager control means for specifying a fault occurrence location based on the determination result.

[0022]

FIG. 1 is a block diagram showing an example of a media converter used in an embodiment of a fault detection system according to the present invention. Here, for the sake of simplicity, the media converter 10 is 100BASE-
TX: Connected to the host computer or management switch 20 through a UTP cable, and
SE-FX: A system connected to the other host computer or management switch 30 via an optical cable is illustrated.

A pair of ports of the media converter 10 have physical layer devices (PHYs) 101 and 10 respectively.
2, one physical layer device 101 is connected to a UTP cable, and the other physical layer device 102 is connected to an optical cable. As described above, each of the physical layer devices 101 and 102 is an IEEE 80
MII (Media Independent) defined by 2.3
Interface).

Physical layer device 101 and physical layer device 1
In addition, a FIFO (First in First out) memory 103 is provided between the transmission and reception devices 02 and 02 so that a frequency deviation between transmission and reception can be absorbed. Data received by one physical layer device is sequentially written to the FIFO memory 103, read out in the written order, and sent to the other physical layer device.

Further, in the FIFO memory 103, a PLD (Programmable Logic) in which a predetermined logic function is written.
Device 104 is connected. As described later, the PLD 104 is designed to check the contents of the FIFO memory 103 at a predetermined timing after receiving a packet, and to output the enable signal _ELB to the microprocessor 105 only when the content matches the predetermined data. ing.

[0026] Microprocessor 105, as described later, upon receiving the enable signal E _LB from the PLD 104, it generates a predetermined response packet and controls the physical layer device to send it back the received packet to the sender .

Furthermore, the microprocessor 105
In accordance with the physical layer MII of the EEE802.3 standard, a farEF (far En) provided in the physical layer devices 101 and 102 is provided.
Various internal registers such as d Fault) register and Force Link register can be accessed. Thereby, for example, link information indicating whether link establishment is possible or half-duplex / full-duplex can be acquired from the physical layer device. Also, by accessing the forced link register, it is possible to forcibly set the physical layer device in the link disconnected state to the transmission enabled state.

The management switch 20 also has I
Physical layer device (PHY) 201 supporting EEE802.3 standard MII, MAC (Media Access Control)
Layer device 202 and a microprocessor (CP
U) 203 is provided. The physical layer device 20
1 is connected to the physical layer device 101 of the media converter through a UTP cable. The microprocessor 203 complies with the IEEE 802.3 standard MII.
Various internal registers provided in the physical layer device 201 can be accessed. This allows U
It is possible to acquire link information indicating whether or not a link can be established by a TP cable, and to forcefully set the physical layer device 201 in a link disconnected state to a transmission enabled state by accessing a forced link register.

The management switch 30 has the same configuration as that of the management switch 20, and its physical layer device is connected to the physical layer device 102 of the media converter through an optical cable, and also supports the MII defined by IEEE802.3.

When a normal Ethernet packet is transmitted and received, the media converter only performs a normal media conversion operation. That is, management switch 2
The ordinary Ethernet packet transmitted from 0 is converted into optical data by the media converter 10 and transmitted to the destination host computer or management switch 30 through the optical cable. Conversely, normal optical data sent from the management switch 30 is converted into a normal Ethernet packet by the media converter 10 and received by the management switch 20 through the UTP cable.

In response to this, when the response test is started, the management switch 20 transmits an Ethernet packet including predetermined trigger data (hereinafter referred to as a trigger packet P).
_TRG . ) Is generated and sent to the media converter 10.

FIG. 2 is a format diagram showing an example of a trigger packet. The trigger packet also includes an 8-byte preamble, a 6-byte destination address field, a 6-byte source address field, a 48 to 1502 bytes data field, and a 4-byte FCS field, similarly to a normal Ethernet packet. However, in the case of a trigger packet, predetermined trigger data is written in the source address field.

It is desirable that the trigger data be unique identification data as unique as possible. Here, a circuit board number built in the media converter 10 is used. The circuit board number is a unique number given by the vendor. A packet in which this circuit board number is stored in the source address field is transmitted to the media converter as a trigger packet.

When the media converter receives a packet in which its own circuit board number is written in the source address field, it switches to the response test mode and generates and returns a response packet, as described later. If it is data other than its own circuit board number, it is passed as a normal packet.

FIG. 3 is a block diagram showing an embodiment of a media converter with a test manager according to the present invention. Media converter 300 with test manager
Includes a media converter 301 and a test manager 302 connected to the microprocessor 105 of the media converter 301 via a unique bus 303. The media converter 301 is the media converter 10 shown in FIG.
Therefore, each circuit block is given the same reference numeral, and description thereof is omitted.

The test manager 302 controls the microprocessor 105 of the media converter 301 via the bus 303.
Has a microprocessor 304 and a network interface card (NIC) 305. The network interface card 305 is connected to a network management rule (not shown) through a UTP cable.

As will be described later, the test manager 302
Monitors a link disconnection, issues a test start instruction, sorts and determines collected information, and the like. The media converter 301 basically operates in the same manner as the above-described media converter 10, except that control signals and data are exchanged with the microprocessor 304 of the test manager 302 via the unique bus 303.

Hereinafter, the test operation of the system using the media converter 300 with the test manager will be described in detail.

(Test Sequence) FIG. 4 is a block diagram showing a schematic configuration of a network system for explaining an embodiment of a failure detection method according to the present invention. Here, for simplicity of explanation, the media converter 300 with a test manager is connected to the management switch 2.
0 through the UTP cable UTP1, the other media converter 40 through the optical fiber cable FO, and the media converter 40 connected to the UTP cable UTP2.

Here, the UTP cable UTP2
Assume that a failure has occurred. In this case, in the media converter 40 and the media converter 301 of the media converter 300 with the test manager, the missing link function operates, and all the links are disconnected.

FIG. 5 is a sequence diagram showing a test operation according to the present embodiment. , The test manager 302 monitors the link function through the media converter 301, and detects that the link is disconnected (step S50).
1), a link disconnection is notified to the network management tool (step S502). Upon receiving the link disconnection notification,
The network management tool instructs the test manager 302 to start a test (Step S503).

When receiving the test start instruction, the test manager 302 activates the test mode (step S50).
4) The media converter 301 is shifted to the test mode (step S505). As a result, the media converter 301 releases the missing link function (step S506), and sets the physical layer device 102 to a forced transmission enabled state (ForceLink Enable) (step S506).
507), a trigger packet addressed to the media converter 40 is transmitted to the media converter 40. After the trigger packet is transmitted, the forcible transmission enabled state is released (ForceLink Disa
ble) (step S508), and returns to the normal mode after notifying the link information to the test manager 302 (step S509), and waits for reception of a response packet corresponding to the trigger packet.

On the other hand, the media converter 40 receiving the trigger packet shifts to the test mode (step S5).
10) Release the missing link function (step S)
511), a response packet is returned to the media converter 301. Thereafter, the mode returns to the normal mode (step S51)
2). Upon receiving the response packet from the media converter 40, the media converter 301 reads the link information and notifies the link information to the test manager 302.

The test manager 302 sorts out the link information received from the media converters 301 and 40 and determines the location of the failure (step S51).
3) Notify the network management tool of the test result.

FIG. 6 is a flowchart showing a test operation of the media converter 301 in this embodiment.

When the test mode is started by the test manager 302 (YES in step S601), the microprocessor 105 of the media converter 301 releases the missing link function (step S602), and the physical layer device 102 can be forcibly transmitted. Status (ForceLink
Enable) (step S603). Then, after transmitting the trigger packet addressed to the adjacent media converter 40 (step S604), the forcible transmission enabled state is canceled (ForceLink Disable) (step S60).
5). Subsequently, the microprocessor 105 acquires link information of each physical layer device (step S606), and notifies the test manager 302 via the unique bus 303 (step S607).

Thereafter, the microprocessor 105 returns to the normal mode (step S608), and waits for reception of a packet that is a response to the transmitted trigger packet (step S608).
609). Upon receiving the response packet (step S60)
9), the microprocessor 105 reads out the written link information and transmits it to the test manager 30.
2 is notified (step S610). When a packet other than the response packet is received (N in step S609)
O), transfer as it is (step S611).

If the test mode is not activated (NO in step S601), the microprocessor 105 determines whether a trigger packet has been received (step S601).
612), if no trigger packet has been received (NO in step S612), the control proceeds to step S608. Specifically, the physical layer device 101 or 102
, The PLD 104 determines whether or not the data written to the FIFO memory 103 at a predetermined timing is predetermined trigger data (its own identification number). Here, the contents of the FIFO memory 103 are checked at the timing of the source address field as shown in FIG. If trigger data addressed to itself exists in the source address field, it is determined that a trigger packet has been received.

When the trigger packet is received (YES in step S612), the microprocessor 105 of the media converter 301 releases the missing link function (step S613), and acquires link information of each physical layer device (step S614). . As described above, the microprocessor 105 generates a response packet in which the acquired link information is written at a predetermined position, and transmits the response packet to the transmission source of the trigger packet (Step S615). After transmitting the response packet, the control moves to step S608.

FIG. 7 is a flowchart showing a test operation of the test manager 302 in this embodiment.

The microprocessor 304 of the test manager 302 monitors the link status through the microprocessor 105 of the media converter 301 (step S702) unless there is a test instruction from the network management tool (NO in step S701), and determines whether the link is disconnected. Is determined (step S703). If the link is normal (NO in step S703), steps S701 and S702 are repeated.

When a link disconnection is detected (step S7)
03 (YES), a link disconnection is notified to the network management tool (step S704), and a test start instruction from the network management tool is waited. When a test start instruction is received from the network management tool (step S701)
YES), the microprocessor 304 activates the test mode of the media converter 301 (step S70).
5) The media converter (here, MC301 and MC40) until the timer of the predetermined time has timed out.
Wait for the notification from (steps S706 to S708).

When there is a notification from the media converter (YES in step S706), the information is organized (step S707), and a determination is made based on the information obtained after a lapse of a predetermined time (step S709). For example, when information is obtained from the media converter 301 but is not obtained from the media converter 40 within a predetermined time, it is determined that a failure has occurred in the media converter 40 or the optical fiber cable therebetween. be able to. Alternatively, even when both the media converter 301 and the media converter 40 notify within a predetermined time, the presence or absence of a failure can be determined based on the link information from the media converter 40 (see FIG. 4). The determination result is notified to the network management tool (step S710).

As described above, in a network including a plurality of media converters, a trigger packet can be sequentially transmitted to a plurality of media converters, and a failure can be detected based on the response packets. Also,
It is not necessary to provide a special function in the management switch 20, and the media converter 300 with the test manager
The failure detection described above can be performed simply by using
The system configuration is simplified.

FIG. 8 is a flowchart showing a test operation of the media converter 40. The microprocessor 403 determines whether or not a trigger packet has been received (step S801). When the trigger packet has been received (YES in step S801), the microprocessor 403
Releases the missing link function (step S80).
2), link information of each physical layer device is obtained (step S803). As described above, the microprocessor 403 generates a response packet in which the acquired link information is written at a predetermined position, transmits the response packet to the transmission source of the trigger packet (step S804), and shifts to the normal mode (step S805). When the trigger packet is not received (NO in step S801), the mode shifts to the normal mode.

FIG. 9 is a block diagram showing another embodiment of a media converter with a test manager according to the present invention. The test manager with media converter 300 of this embodiment includes a port P ₀ to be connected to the network management roots, N pieces of media converters MC ₁ ~
N pairs of ports P _i1 and P corresponding to each of the MC _N
i2 (i = 1, 2, 3,..., N). The network manager 302 manages the _N media converters MC _{1 to} MC _N as described above.

[0057]

As described above in detail, according to the fault detection system and method according to the present invention, a trigger packet is sequentially transmitted to a plurality of media converters, and fault detection is performed based on those response packets. it can. In particular, when a response packet is not received from a certain media converter within a predetermined time, it can be determined that a failure has occurred beyond the media converter. Therefore, it is easy to detect a failure in a link including a media converter, and it is also possible to identify a failure position to some extent.

In each media converter, a test mode is started by receiving a trigger packet including its own identification data, and a response packet is returned. Therefore, the test can be started from the cable side, and by receiving the response packet, it can be confirmed that not only the link to the media converter but also the media converter itself is operating normally.

Further, when each of the media converters receives a trigger packet other than the trigger packet addressed to itself in the missing link state, the media converter shifts to the normal mode and transfers the received packet. As a result, a packet that is not subjected to a response test through the media converter passes, and a link test beyond that can be performed.

The media converter with a test manager according to the present invention can execute a failure detection test by activating a test mode when a link disconnection is detected, transmitting a trigger packet, and receiving a response packet in response to the trigger packet. it can. Since it is not necessary to provide a special function for the management switch, the system configuration can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a media converter according to the present invention.

FIG. 2 is a format diagram showing an example of a trigger packet.

FIG. 3 is a block diagram showing one embodiment of a media converter with a test manager according to the present invention.

FIG. 4 is a block diagram showing a schematic configuration of a network system for explaining an embodiment of a failure detection method according to the present invention.

FIG. 5 is a sequence diagram illustrating a response test operation according to the embodiment.

FIG. 6 is a flowchart showing test control in a media converter with a test manager.

FIG. 7 is a flowchart showing test control of a test manager.

FIG. 8 is a flowchart showing test control in the media converter.

FIG. 9 is a block diagram showing another embodiment of a media converter with a test manager according to the present invention.

[Explanation of symbols]

 10 Media Converter 20 Management Switch 30 Management Switch 40 Media Converter 101 Physical Layer Device 102 Physical Layer Device 103 FIFO Memory 104 PLD Device 105 Microprocessor 300 Media Converter with Test Manager 301 Media Converter 302 Test Manager 303 Own Bus 304 Microprocessor 305 Network Interface Phase card 401 Physical layer device 402 Physical layer device 403 Microprocessor

Claims (18)

[Claims] 1. A method for detecting a failure of a link via a plurality of media converters connecting different types of transmission media, comprising the steps of: a) for each of the plurality of media converters, identifying data of the media converter in a predetermined position; Transmitting the data block written to the media converter; b) determining whether a response data block corresponding to the data block is received from the media converter within a predetermined time; c) based on a result of the determination step Identifying a location where a failure has occurred. 2. In the step (c), when a response data block to the data block is not received from the media converter within a predetermined time, it is determined that a failure has occurred beyond the media converter. The method for detecting a failure according to claim 1. 3. Each of the media converters comprises: first physical layer interface means for connecting a first transmission medium; second physical layer interface means for connecting a second transmission medium; And a memory means for temporarily storing data transferred between the second physical layer interface means, and a memory means for temporarily storing data transferred therebetween. It is determined whether or not the existing data matches its own identification data. If it is determined that the data existing at a predetermined position of the received data block matches the own identification data, a response to the received data block is determined. A data block is generated, and the response data block is transmitted from the physical layer interface unit that has received the received data block. The failure detection method according to claim 1, wherein the failure is returned to the transmission source of the block. 4. The fault detecting method according to claim 3, wherein said first and second physical layer interface means respectively support MII (Media Independent Interface) defined by IEEE802.3 standard. 5. When each of the media converters determines that the data present at a predetermined position of the received data block matches the identification data of its own, the respective media converters transmit the signals to the first and second physical layer interface means. 5. The failure detection method according to claim 4, further comprising: accessing and acquiring link information of each physical layer interface unit; and generating the response data block according to the link information. 6. Each of the media converters may be a MII (Me) defined by the IEEE 802.3 standard.
dia Independent Interface) and a first physical layer interface means for connecting a first transmission medium, and MII defined by the IEEE 802.3 standard
And a second physical layer interface means for connecting a second transmission medium, and is connected between the first and second physical layer interface means and temporarily stores data transferred between them. And determining whether data present at a predetermined position of the received data block stored in the memory means matches its own identification data, and When it is determined that the data existing at the position matches the identification data of the own, a response data block for the received data block is generated, and when one of the physical layer interface units is in the link disconnected state, the other physical layer interface is generated. The means also cancels the missing link state to set the link disconnected state, and sets the response data block to the received data block. Be returned to the sender, failure detection method according to claim 1, wherein a. 7. Each of the media converters further includes a missing link when the determination means determines in the missing link state that data present at a predetermined position of the received data block does not match the identification data of the own device. The failure detection method according to claim 6, wherein the state is released and the received data block is transferred. 8. The failure detection method according to claim 1, wherein said reception data block and said response data block are Ethernet packets having a predetermined format. 9. A fault detection system comprising: a link via a plurality of media converters connecting different types of transmission media; and a test manager connected to an arbitrary media converter of the plurality of media converters. Each of the media converters comprises: first physical layer interface means for connecting a first transmission medium; second physical layer interface means for connecting a second transmission medium; and the first and second physical layer interfaces. A memory means connected between the means for temporarily storing data transferred between them, data present at a predetermined position of a received data block stored in the memory means, and self identification data; Is determined as to whether the data is present at a predetermined position in the received data block. A medium that generates a response data block to the received data block when it is determined that the received data block matches the data, and returns the response data block from the physical layer interface unit that has received the received data block to the transmission source of the received data block And a converter control unit. The test manager comprises: an interface unit for connecting to a network management unit; and the identification data of each media converter in a predetermined position in order from a media converter connected to the test manager. A test manager that sends out the written data block to the link, determines whether a response data block corresponding to the data block is received from each media converter within a predetermined time, and specifies a failure location based on the determination result. Control means Failure detection system characterized to have it. 10. The test manager control means, when a response data block corresponding to the data block is not received from a media converter within a predetermined time, determines that a fault has occurred beyond the media converter. The fault detection system according to claim 9. 11. The first and second physical layer interface means of each media converter are respectively IEEE8
MII (Media Indepe
10. The failure detection system according to claim 9, wherein the failure detection system supports ndent interface. 12. The media converter control means of each of the media converters accesses each physical layer interface means when it is determined that the data existing at a predetermined position of the received data block matches the identification data of itself. 12. The failure detection system according to claim 11, wherein the link information is obtained by using the link information, and the response data block is generated according to the link information. 13. The test manager control means releases the missing link state at the time of test activation, and sends the data block to the link by forcibly setting the physical layer interface means to a transmittable state. The fault detection system according to claim 11, wherein 14. A media converter control unit of each of the media converters determines whether or not data present at a predetermined position of a reception data block stored in the memory unit matches its own identification data, When it is determined that the data existing at the predetermined position of the received data block matches the identification data of itself, a response data block to the received data block is generated, and one of the physical layer interface units is in the link disconnected state. 14. The fault detection according to claim 11, wherein the other physical layer interface unit sometimes releases the missing link state in which the link state is also changed to the link disconnected state, and returns the response data block to the transmission source of the reception data block. system. 15. The media converter control means of each of the media converters further determines in the missing link state that the data present at a predetermined position of the received data block does not match the identification data of itself. 15. The failure detection system according to claim 14, wherein when the error occurs, the missing link state is released and the received data block is transferred. 16. The fault detection system according to claim 9, wherein said host computer is a management switch. 17. A media converter with a test manager used for detecting a failure of a link composed of different types of transmission media, wherein the first physical layer interface means for connecting the first transmission medium and the second transmission medium are connected to each other. A second physical layer interface means for connecting; a memory means connected between the first and second physical layer interface means for temporarily storing data transferred between them; and the memory It is determined whether or not the data present at a predetermined position of the received data block stored in the means matches the own identification data, and the data present at the predetermined position of the received data block matches the own identification data. If it is determined that the response data block corresponding to the received data block is generated, the received data block is received. Media converter control means for returning the response data block from the physical layer interface means to the source of the received data block; interface means for connecting to a network management unit; and other media connected to the media converter control means. A data block in which the identification data of the converter is written at a predetermined position is transmitted, and it is determined whether or not a response data block corresponding to the data block is received within a predetermined time from the media converter, and a failure occurrence location is determined based on the determination result. A media converter with a test manager, comprising: 18. A media converter with a test manager used for detecting a failure of a link composed of different types of transmission media, comprising: a plurality of media converters; a test manager for managing each of the plurality of media converters; And wherein each of the plurality of media converters comprises: first physical layer interface means for connecting a first transmission medium; second physical layer interface means for connecting a second transmission medium; And a memory means for temporarily storing data transferred between them, and data existing at a predetermined position of a received data block stored in the memory means. And whether or not the self-identification data coincides with the self-identification data. When it is determined that the received data block matches the identification data of itself, a response data block for the received data block is generated, and the response data block is received from the physical layer interface unit that has received the received data block. Media converter control means for returning to the transmission source, the test manager comprising: an interface means for connecting to a network management unit; and another medium connected to the media converter control means and linked to the media converter. A data block in which the identification data of the converter is written in a predetermined position is transmitted, and it is determined whether or not a response data block corresponding to the data block is received from the other media converter within a predetermined time. Identify location That has a test manager controller means, the test manager with media converter, characterized in that.