JP2000069014A - ATM-M bus system maintenance and operation method and ID reassignment method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a maintenance operation method and an ID reassignment method in an ATM-M bus system in which a downstream side is not affected when a failure occurs. SOLUTION: An M bus interface unit 12 accommodated in an ATM exchange 11, an M bus 2 composed of a down bus and an up bus whose both ends are accommodated in the unit 12 and turned back at the farthest end, and serially connected to the M bus 2. In the ATM-M bus system composed of a plurality of branch devices 3 connected to the network, a loopback is formed in a branch device higher than the failure point when a fault occurs, thereby enabling the operation of the higher branch device. Further, at the time of failure recovery, the lower branch device periodically sends an ID assignment request, and the unit 12 sends an ID assignment confirmation request carrying an ID number on the downstream bus in ascending order from the youngest ID number. When the ID assignment confirmation request is received on the bus, the ID assignment request for the ID is sent to the downstream bus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM (Asynchro
nous Transfer Mode: As for the bus system applied to the switching system, in detail, a multimedia bus for exchanging data between terminals accommodated in an ATM exchange
(M bus) system.

[0002]

2. Description of the Related Art In the application of Japanese Patent Application No. 9-10231, the present applicant comprises a main device having an ATM switch and an ATM 155 Mbps interface, and a plurality of branching devices accommodated in series in the main device. The branching device accommodates a terminal device and is connected to an upstream bus and a downstream bus of the ATM 155 Mbps interface, and the terminal of the downstream bus is folded back to be an "AT bus".
A bus system called "MU bus system" has been proposed. The U bus main unit used in this bus system converts all voice / image / data into ATM cells, has a unique ATM bus interface (I / F) at a 155 Mbps port, and accommodates a plurality of standard ATM terminals under its control. In addition, a high-speed ATM terminal is directly accommodated in its port, so that it is an ATM device for small offices that performs exchange processing centrally.

[0003] Fig. 12 shows the configuration of a U bus main unit for a small business employing the U bus system. U bus main unit 1
Has a function as an ATM switching device,
Switch (ATM-SW) 11 and 155 Mbps U-
It has an ATM interface with GFC control 12 ′, and further has a 100 Mbps LAN interface (not shown), an existing WAN interface, a control unit, and a power supply unit having a storage battery. .

[0004] The ATM switch (ATM-SW) 11
This is the same as a normal ATM switch.
It has eight ports of 55 Mbps.

155 of U bus main unit (ATM exchange) 1
The Mbps ATM interface 12 'is an interface package capable of directly accommodating the U bus 2, the ATM 155 Mbps terminal, and the ATM 155 Mbps line.
It has a U-GFC control function using a GFC part provided in the header of the ATM cell. The ATM interface 12 'is a VP / VC conversion means for converting a GFC, a virtual path (VP) and a virtual channel (VC) in an ATM cell and adding a tag for switching, and a user network interface conforming to the ATM 155 Mbps specification. SRA storing a 155 Mbps ATM unit, an optical / electrical conversion interface, and a lookup table (including GFC) for VP / VC conversion
M, and a U-GFC control unit that performs U-GFC control of the transmission / reception cells, and is formed, for example, in a card-shaped package. The U-GFC control unit includes a downstream cell FIFO memory for storing an ATM cell (down cell) ID to be transmitted to the downstream bus, an upstream cell FIFO memory for storing the upstream cell ID received from the upstream bus, and a downstream cell FIFO. There is a comparing means for checking the coincidence between the down cell ID stored in the memory and the up cell ID recorded in the up cell FIFO memory.

[0006] ATM 155 Mbps interface 12 '
Has an ATM bus 2 and an ATM terminal called a U bus,
Other ATM exchanges, ATM-U via TM-PNNI
The ATM-WAN is connected via the NI. An existing LAN network of 100 Mbps is connected to the LAN interface. In addition, existing WAN interfaces include ISDN or analog lines, dedicated lines,
OCN and the like are connected.

[0007] The control unit performs exchange control and package control of the U bus main unit 1 and control of network management.

[0008] The U bus 2 is a bus to which an ATM terminal can be connected, and is an ATM 155 with U-GFC control.
It is accommodated in the Mbps interface 12 '. For example, a 25 Mbps ATM key telephone (A), which is a multi-function key telephone, such as a plurality of multimedia terminals and image terminals, is connected to the U bus 2 via branching devices 3-1, 3-2, and 3-n.
TM-KT) 51, 155 Mbps ATM terminal 52, 3.
1 KHz audio (64 Kbps) analog telephone 53, ISDN terminal 54, 25 Mbps ATM terminal 55
Are connected via the branching device 3, and the analog telephone 53,
The ISDN terminal 54 and the like are connected via the existing terminal branching device 3-3, and further connected to the ATM terminal 52 such as a 155 Mbps server / computer.

For example, a plurality of these terminals are connected in consideration of the traffic capacity of the U bus 2 of 155 Mbps.

An ATM key telephone has a CL inside the telephone.
It has AD, and it is U by ATM 25bps interface.
Connected to bus 2.

As described above, in the ATM-U bus system, an identifier is given to each branching device and the GFC (General Flow Control) field of the header of the ATM cell sent from the main unit is used to specify the branching device of the destination of the ATM cell. And sends it out. In addition, the ATM-U bus system allows the branching device to branch the cell addressed to itself and send it to the terminal device. When there is no transmission data from the terminal device accommodated in the branching device, the branching device receives the cell. Deletes the identifier of the self-addressed cell destined for itself and sends it to the downstream node as an empty cell, and when there is transmission data from the terminal device accommodated in the branch device, the transmission data is transmitted to the self-addressed cell or the empty cell received by the branch device. And send it out.

In the ATM-U bus system, a plurality of transmission buffers for temporarily storing transmission data from a terminal device are provided in a branching device, and when the value of the transmission buffer reaches a predetermined value, the destination of the branching device is designated. Is returned to the main unit as a "SOS" cell, and upon receiving the "SOS" cell, the main unit forcibly transmits a reserved vacant cell in which the identifier of the branching device is assigned to a downstream cell other than the shared channel. I have to.

The branching device used for the ATM-U bus system is as follows:
Connected to an ATM-U bus, and an upstream interface;
A function of having a downstream interface and an input / output interface to the terminal device, extracting an identifier given to the header of the received ATM cell, and branching the cell addressed to itself;
A bus control unit having a cell disassembly / assembly (CLAD) function and a cell insertion function for placing transmission data in a cell addressed to itself or an empty cell is provided.

ATM 155 used for ATM-U bus system
The Mbps interface is connected to an ATM bus, and stores an identifier attached to the GFC of the ATM cell to be transmitted to the downstream bus, a FIFO memory for storing an identifier attached to the GFC of the ATM cell received on the upstream bus, Means for comparing the identifier attached to the GFC of the ATM cell transmitted to the downstream bus with the identifier attached to the GFC of the ATM cell received on the upstream bus; When the identifier assigned to the GFC of the ATM cell received on the upstream bus is stored without storing the identifier, a function of allocating an empty cell designating the terminal device to the downstream bus is provided.

This ATM-U bus system is a standard system AT
This can be realized by using an M-switch (SW). In each of the 155 Mbps interfaces of the main unit, the above “M-switch” is used.
By ignoring or disabling the “GFC flow control”, it can be used as a standard ATM 155 Mbps port, and the terminal device of each branching device can transmit fairly and efficiently, and the maximum delay of the cell, etc. Symmetric services such as existing terminals such as voice can be guaranteed transmission only by the receiving cell of the terminal.Asymmetric services such as server access and Internet access can be guaranteed. U-GF
The C flow control and the "SOS" cell enable effective use of the cell. Terminal devices on the U bus can perform "multicast" communication. It becomes possible to connect terminal devices to a multipoint under the branch device. CLAD
It is possible to directly accommodate existing terminal equipment by connecting a branch device with a tag. Since almost no software processing of the U bus system is required other than the initial setting, OAM management, and U bus management, the U bus system can be easily realized. The hardware only provides an ATM 155 Mbps interface and only increases the UTOPIA bus control, cell insertion / branching, and buffer processing, so that the U bus system can be easily realized. This is a method that provides an excellent effect.

In the above-mentioned ATM-U bus system, in order to control a branch device connected to the bus, it is necessary to allocate a unique identifier to each branch device. It was set manually using a switch. As described above, the manual assignment of the identifier causes an error in the assignment of the identifier, and it is necessary to individually manage the branching devices connected to the U bus.

[0017]

SUMMARY OF THE INVENTION The present invention relates to the above ATM.
-U bus (hereinafter, referred to as M bus)
In a system, a maintenance operation method for ensuring operation of a higher-order branch device when a failure occurs in an M bus is provided. An object of the present invention is to provide a method of reassigning an ID to a downstream branch device without interrupting the operation of the upstream branch device when the branch device starts up a program.

[0018]

In order to solve the above-mentioned problems, the present invention provides an M bus interface unit housed in an ATM exchange, and both ends are housed in the M bus interface unit and folded at the farthest end. In a maintenance operation method of an ATM-M bus system including an M bus including a down bus and an up bus, and a plurality of branch devices connected in series to the down bus and the up bus of the M bus, respectively, the branch device has a fault. Monitoring is always performed, and a loopback is formed in a branch device higher than the point of occurrence of the failure.

According to the present invention, in the above maintenance and operation method for an ATM-M bus system, an input signal interruption (LO
S) or the branching device that has detected frame loss of synchronization (LOF) clears its own ID to “0”, sends a multicast cell ID reset request to the lower order, and sends a far-end reception failure (FERF) signal to the upper order. The higher order branch device that has transmitted and received the far end reception failure (FERF) signal,
A loopback is set in the own branching device, all cells destined for the lower branching device are discarded at the receiving end, the lower side is separated, and a loopback execution notification (LBA) is transmitted to the M bus interface. .

Further, according to the present invention, in the above-mentioned maintenance and operation method for an ATM-M bus system, the branching device that detects an input signal loss (LOS) or a loss of frame synchronization (LOF) on the upstream bus is provided with a lower alarm display signal. (AIS), sets a loopback in its own branching device, discards all cells addressed to the lower branching device at the receiving end, disconnects the lower side, and notifies the M bus interface of the loopback execution (LBA). ) Is sent.

Further, according to the present invention, in the above-mentioned maintenance and operation method for the ATM-M bus system, the highest-order branching device which detects an input signal loss (LOS) or a loss of frame synchronization (LOF) on the downlink bus may be its own branch device. The ID is cleared to "0", and a lower-order multicast cell ID reset request is sent, and a far-end reception failure (FERF) signal is sent to the M bus interface unit.
The M bus interface unit that has received the ERF signal notifies the central control unit (CCU) of the M bus main unit of information equivalent to loop back using a control cell.

According to the present invention, in the above-mentioned maintenance and operation method for the ATM-M bus system, the input signal disconnection (LO
S) or the M bus interface unit that has detected frame loss of synchronization (LOF) sends an alarm indication signal (AIS) to the downstream bus and loops using the control cell to the central control unit (CCU) of the M bus main unit. Added information equivalent to backing up.

In order to solve the above problems, the present invention provides an A
An M bus interface unit housed in the TM exchange, an M bus consisting of a down bus and an up bus whose both ends are housed in the M bus interface unit and turned back at the farthest end, and a plurality of M buses connected in series to the M bus An ATM-M bus system comprising a branching device of the type described above, wherein when a fault occurs in the M bus, a loopback is formed in the branching device on the higher side of the failure point to secure communication on the upper side. ATM-M for reassigning IDs to lower branching devices at the time of failure recovery in the M bus system
In the bus ID reassignment method, the branching device constantly monitors the upper-side fault, the branching device that detects the upper-side fault sets its own ID to “0”, and sends the ID to the lower-order branching device by the multicast method. The lower branch device that has transmitted the reset request and received the ID reset request resets its own ID to “0” and periodically transmits an ID assignment request to the M bus interface unit.

Further, according to the present invention, in the above ATM-M bus system ID reassignment method, when the M bus interface unit receives an ID request from the branch device,
D, sends an ID assignment confirmation notification requesting a temporary suspension of the assignment request, and then sends an ID assignment confirmation request carrying the ID number on the downstream bus in ascending order from the youngest ID number.
D When the ID assignment confirmation request of the ID number transmitted without receiving an assignment confirmation response is received on the upstream bus, the ID of the ID number is received.
The assignment request is sent to the down bus.

Further, according to the present invention, in the above-described method for reassigning IDs of the ATM-M bus system, the branching device having its own ID of "0" receiving the ID assignment request on the downstream bus fetches the ID and sends it downstream. While transferring an empty cell, M
An ID assignment response is sent to the bus unit.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ATM-M according to the present invention will be described.
An embodiment of a bus type identification number assigning method will be described with reference to the drawings.

[0027] The present invention relates to the ATM-
A system conforming to the U bus system is adopted, and a multimedia bus (hereinafter, referred to as M bus), an M bus interface unit (hereinafter, referred to as MBU), and a terminal interface branching device (hereinafter, simply referred to as branching device). The present invention relates to a configured ATM-M bus system. AT according to the present invention
The branching device used for the MM bus system is an ATM 25 Mbps.
A branching device that can support multimedia such as a terminal device and an ATM 155 Mbps terminal device.
25 Mbps ATM terminal devices such as key telephones and 15
It accommodates a 5 Mbps dedicated ATM terminal device and a general-purpose ATM terminal device. The MBU has an ATM connection with the branching device.
Send and receive cells.

The outline of the ATM-M bus system according to the present invention will be described with reference to FIG. The ATM-M bus system includes an M bus main unit 1, an M bus 2 of 155 Mbps, and a plurality of branching devices 3 connected in series to the M bus. The branching device 3 has a 25 Mbps ATM-KT51. , 155Mb
The ATM terminal device 52 of ps and the ATM terminal device 55 of 25 Mbps are accommodated through the connection line 6.

The M bus main unit 1 has a function as an ATM exchange, and has an ATM switch (ATM-SW) 1
1, an MBU 12 serving as a gateway for accommodating the M bus 2 in an ATM switch, an N-ISDN basic interface unit 15, and a central control unit (hereinafter referred to as a CCU).
19). Further, the M bus main unit 1 has a 25 Mbps terminal interface unit 1.
3, LAN unit 14, 25Mbps interface unit between nodes (25MNU) 16, three-way conference unit (CNFU) 17, voice communication type conversion unit (VT
U) 18 and the like.

The M bus 2 comprises a down bus and an up bus connected to the MBU 12, and a plurality of branching devices 3 are connected in series. The down bus is the turn-back part 2 provided at the end.
It is turned up at 1 and becomes an up bus. M bus 2
It is configured as a 155 Mbps ATM bus using a multimode optical fiber (hereinafter, referred to as MMF) or a 100Ω copper cable (hereinafter, referred to as UTP). MBU
In the branching device 3-n at the farthest end from 12, the down bus and the up bus of the M bus 2 are connected in a U-shape by the turnback unit 21. Cells transmitted from the MBU 12 to the down bus are:
It is turned back at the turn-back part 21 and rides on the up bus.
Come back to.

The branching device 3 is connected to the down bus and the up bus of the M bus 2 composed of the MMF, and receives the A received by the down bus.
The function of relaying TM cells downstream, the function of relaying ATM cells received on the upstream bus upstream, the function of capturing ATM cells received on the downstream bus addressed to itself, and the function of loading data from terminal devices into empty cells. It has a function to send out. Further, the branching device 3 has a function of acquiring and managing the VPI / VCI of the corresponding user cell by signaling, a GFC control function of the corresponding user cell, and a failure monitoring function of the M bus and the terminal interface port. Further, the branching device 3 has a 155 Mbps terminal interface port or a plurality of 25 Mbps terminal interface ports. Each branch device 3 has a 25 Mbps ATM key telephone (ATM-KT) 51 and a 25 Mbps ATM
The standard terminal device 55 accommodates an ATM standard terminal device 52 of 155 Mbps, a general-purpose ATM terminal device supporting the Q2931 and the like. A maximum of 14 branching devices 3 are connected in series.

The branching device 3 includes a branching device 155M having a terminal interface port of 155 Mbps and a branching device 155M having a terminal interface port of 25 Mbps.
There is a branching device 25M having a terminal interface port of No. The branching device 155M is an M provided by the MBU 12.
This is a branching device for connecting a 155 Mbps ATM terminal device to the bus 2 by one port. The branching device 25M is an MBU1
2 is a branching device for connecting a 25 Mbps ATM button telephone or an ATM standard terminal device to the M bus 2 provided by 1 port. The branching device 155M and the branching device 25M can be accommodated on a single M bus and accommodate up to 14 devices.

The block configuration of the branching device 155M will be described with reference to FIG. The branching device 3 includes the M buses 2 and 155
Three optical / electrical conversion interfaces 30 connected to the Mbps ATM terminal and three 155 Mbps ATM UN
I LSIs 31-1, 31-2, 31-3 and a programmable gate array (Pr
ogramable Logic Device (hereinafter referred to as PLD) 32
ROM 33 for PLD control, F-ROM 34, R
AM 35, CPU 36, LED display unit 37, AC
And a reset circuit 39. The optical / electrical conversion interface 30 is M
When the bus 2 is composed of UTP, it is composed of a pulse transformer.

The block configuration of the branching device 25M will be described with reference to FIG. The branching device 3 is connected to the M bus 2
Two optical / electrical conversion interfaces 30 and two 15
5Mbps ATM UNI LSI 31-1, 31-2
And one 25Mbps ATM UNI LSI 31-3
, PLD 32, PLD control ROM 33, F-R
It includes an OM 34, a RAM 35, a CPU 36, an LED display 37, an AC / DC converter 38, a reset circuit 39, and a pulse transformer 30PT connected to a 25 Mbps ATM terminal. The optical / electrical conversion interface 30 is configured by a pulse transformer when the M bus 2 is configured by UTP.

M bus interface unit (MBU)
12 will be described with reference to the block diagram of FIG. M
The BU 12 has two GFC / VP / VC conversion units (AT
C) 120, PLD121, 155 Mbps ATM
UNI LSI 122, optical / electrical conversion interface 123, F-ROM 124, S-RAM 125
, A CPU 126, an LED display section 127, and a PLL circuit 128.

The PLD 121 includes a tag deleting unit 1211,
Two M-GFC controllers 1212 and two AAL5
It is configured to include a processing unit 1213, a reset circuit 1214, an OAM circuit 1215, and a tag insertion unit 1216.

The GFC (4 bits) of the ATM cell is NNI
(Network Node Interface) is not specified and is not used as an end-to-end function.
This field is used only for the part. M of the present invention
In the bus 2, a plurality of branching devices 3 are connected in series, and only between the branching devices (M bus section), the ATM cell header G
The identification number (hereinafter, referred to as ID) of each branch device is mounted on 4 bits of FC, and routing is performed by the ID mounted on GFC.

The GFC control protocol in the ATM-M bus system is defined as an M-GFC control protocol in this specification. The M-GFC control protocol is a bus control protocol realized by hardware of the MBU 12 and the branching device 3 (partially through software). Preconditions for realizing the M-GFC flow control are shown below. A bus transmitted from the MBU 12 is referred to as a down bus, and a bus returned to the MBU 12 by the furthest branching device 3-n is referred to as an up bus.
The identifier ID of each branch device 3 is determined by an identifier automatic assignment process from the MBU 12 described later. In the transmission and reception of ATM cells on the bus by the branching device 3, the reception cells can be fetched only from the downstream bus, and the transmission cells can be set to either empty cells on the downstream bus or the upstream bus. However, transmission has priority on transmission to the upstream bus.

The cell type managed by the M bus is GFC /
Defined by VP / VC. Table 1 shows the contents of the definition.

[0040]

[Table 1]

As shown in Table 1, ATM cells whose GFC / VP / VC are set to "0/0/0" are empty cells, and all payloads are repeated "6Ah". GF
The cell whose C / VP / VC is set to “0 / VPI / VCI” is the SOS cell from the branching device, and the data cell G
It is made with FC set to "0". A cell whose GFC / VP / VC is set to “ID / 0/0” is a reserved vacant cell whose branching device is specified by the ID, and is transmitted from the MBU to the downstream bus. GFC / VP / VC is "ID / VPI
/ VCI "is a transmission or reception data cell in which the branching device is specified by the ID. GFC / V
A cell whose P / VC is set to “ID / VPI / VCI”
It is a control cell between the multi-bus interface unit MBU and the branch device, and uses a VPI / VCI value dedicated to control. GFC / VP / VC is "15 / VPI / VC
The cells designated as I "are transmission and reception data cells for multicast from the branching device. GFC / VP / VC
Are "ID / 0/5" are transmission and reception point-point signaling cells in which the branching device is specified by the ID. GFC / VP / VC is "ID /
The cell designated as VPI / 3 "is a dedicated cell at the time of failure,
This is a transmission or reception point-point correspondence VP OAM cell in which the branching device is designated by D, and corresponds to a segment. GFC / VP / VC is "ID / VPI
The cell designated as / 4 "is a dedicated cell at the time of failure, and is a transmission or reception point-to-point VP OAM cell in which a branching device is designated by an ID, and corresponds to end-to-end.

The GFC of the cell flowing between the MBU-ATM switch and between the branching device and the terminal device is constituted by "0".

Next, the MBU protocol will be described. In the MBU 12, a conversion table including an upstream routing table and a downstream routing table is formed. The upstream routing table is a table for mutually converting GFC (ID) / VP / VC of a call in communication on the bus into GFC / VP / VC for ATM switch management. The downstream routing table stores the GFC / VP / VC for ATM switch management in the GFC of the call being communicated on the bus.
It is a table for mutual conversion into (ID) / VP / VC.
These routing tables are managed based on the data determined by the CCU with the maximum number of connections on the M bus. These routing tables are ATM
It also inserts and removes switching tags for switch replacement.

A basic conversion rule and a conversion method using a routing table in the ATC 120 will be described with reference to Table 2 and FIG. Table 2 (A) shows the conversion on the shared channel for signaling cells and OAM cells, Table 2 (B) shows the conversion on the user channel for user cells, and Table 2 (C) shows the conversion on the multicast cell. Conversion on the user channel.

[0045]

[Table 2]

In the shared channel for signaling cells and OAM cells, GFC / VP
/ VC, the "ID number / 0 (fixed) / VCI" of the cell on the M bus is replaced with "0 (fixed) / VPI (for CCU management) / VCI (CC) of the cell between the MBU and the ATM switch.
U management) ”. On the other hand, GFC
/ VP / VC, "0 (fixed) / VPI (for CCU management) / VCI of cell between ATM switch and MBU"
(For CCU management) ”is changed to“ ID number / 0 ”of the cell on the M bus.
(Fixed) / VCI ".

In a user channel intended for a user cell, in the uplink direction, the GFC / VP / VC is provided with the “ID number / VPI / VCI” of the cell on the M bus and the MBU.
"0 (fixed) / VPI (C
CU management) / VCI (for CCU management) ".
On the other hand, in the downlink cell, GFC / VP / VC
"0 (fixed) / VPI of cell between TM switch and MBU"
(For CCU management) / VCI (for CCU management) "to the" ID number / VPI / VCI "of the cell on the M bus.

In the user channel intended for the multicast cell, no conversion is performed in the uplink direction, and in the downlink cell, the GFC / VP / VC is not subjected to the AT conversion.
"0 (fixed) / VPI of cell between M switch and MBU"
(For CCU management) / VCI (for CCU management) "to" 15 / VPI / VCI "of the cell on the M bus.

The operation of the GFC / VP / VC conversion means (ATC) 120 provided in the MBU 12 will be described with reference to FIG. Here, the 53-byte A input from the upstream bus
The ATC 120-2 converts a TM cell into a 56-byte ATM cell to be transmitted to the ATM switch 11 as an example. The ATC 120-2 reads the GFC / VP / VC from the 53-byte ATM cell input from the M bus, inserts a switching tag space, and obtains a GFC / VP for the output cell obtained by referring to the conversion table # 2 1202. The VP / VC / switching tag is set in the input cell and the ATM switch 1 is set as a 56-byte output cell.
Send it out to 1. AT in ATC120-1
The operation of converting a 56-byte ATM cell from the M switch 11 into an ATM cell to be transmitted to the M bus 2 as a 53-byte ATM cell is performed in substantially the same manner as described above.

Hereinafter, the MBU protocol will be described with reference to FIG. The MBU 12 has a downstream routing table (ATC # 1) 1201, an upstream routing table (ATC # 2) 1202, a tag space deletion function 1211, a GFC control function 1212, and a tag space insertion function 1216.

In the MBU 12, the 56-byte ATM cell received from the ATM switch 11 refers to the downlink routing table (ATC # 1) 1201, and the GF
The C / VP / VC is converted, and then the switching tag space is deleted by the tag space deletion function 1211 and transmitted to the downstream bus as a 53-byte ATM cell.

In the MBU 12, a 53-byte ATM cell received on the upstream bus from the branching device 3 is provided with a switching tag space by the tag space insertion function 1216, and the upstream routing table (ATC # 2).
GFC / VP for ATM switch replacement with reference to 1202
/ VC, a switching tag is added, and the packet is sent to the ATM switch 11 as a 56-byte exchange ATM cell.

In the MBU 12, the SOS from the branching device 3
When a cell (GFC = 0) is received on the up bus, V
The ID of the branching device, that is, the GFC, is retrieved from the P / VC value, the ID of the branching device 3 is set in the GFC of an empty cell to the downstream bus, and the GFC is transmitted as a "reserved cell" specifying the branching device. This SOS cell is used for the purpose of receiving buffer size from the terminal device, guaranteeing the maximum delay, suppressing burstiness, and the like. The description of the processing for the SOS cell is as follows:
This will be described in detail in the description of the protocol of the branching device 3 described later.

The MBU 12 stores a plurality of, for example, 42 cells of transmission IDs of ATM cells transmitted to the down bus in the FIFO memory in order to cope with traffic having burst characteristics. At the same time, a configuration is provided in which the reception ID of one ATM cell received from the upstream bus is stored for one cell, and the reception ID is compared with the transmission ID of the FIFO. This configuration constitutes the following hardware logic.

Correspondence to constant-speed traffic If the reception ID and the transmission ID match, traffic at the same speed is transmitted in both transmission and reception. Therefore, communication is continued without any particular operation, and the transmission ID / reception ID is cleared. Only.

Correspondence to Downlink Burst Asymmetric Traffic When the transmission ID to the downlink bus is recorded but the reception ID of the uplink bus is not recorded, download data to the terminal device accommodated in the branching device, that is, downlink data, Since it is a burst, communication is continued as it is, and no particular operation is performed.

Correspondence to Uplink Burst Asymmetric Traffic When the reception ID of the upstream bus is recorded, but the transmission ID of the downstream bus is not recorded, burst traffic has occurred from the terminal device accommodated in the branching device. Therefore, a “reserved vacant cell” designating the branching device is newly assigned to the downstream bus.

As described above, it is possible to dynamically cope with either symmetric traffic or asymmetric traffic of the terminal device.

(Branch Device Protocol) Hereinafter, the branch device protocol will be described. The branching device 3 has a relay function of regenerating an ATM cell received from the upstream node and transmitting the ATM cell to the downstream node, and monitors the ID of the ATM cell flowing through the down bus and / or the up bus, that is, the GFC, and transmits the ATM cell addressed to itself. A transmission buffer and a reception buffer for transmitting and receiving data to and from a terminal device accommodated therein are provided.

The operation of the hardware of the branching device 3 will be described with reference to FIG. When an ATM cell is received in the reception buffer of the upstream node downstream bus (S1), it is determined whether the reception cell is an empty cell (S2). If the cell is not an empty cell, it is determined whether or not the cell is a multicast cell by referring to the GFC (S3). If the cell is not a multicast cell, it is determined whether or not the cell is an ID cell assigned to itself (S3).
4). If the ID cell is a self-assigned ID cell, the GFC is cleared to "0" (S5), converted to the UNI format and stored in the transmission buffer addressed to the terminal device (S6), and the received ATM cell is converted into an empty cell (GFC = 0, V
P = 0, VC = 0) (S7) and send it to the downstream node.

If it is determined in step S3 that the received cell is a multicast cell (GFC = 15), the received cell is copied (S8), the process proceeds to step S5, and the received cell is relayed as it is (S9). ), And sends it out to the downstream bus (S10) and relays it to the downstream node.

If it is determined in step S2 that the received ATM cell is an empty cell, it is determined whether or not there is data to be transmitted from the branching device (S11). Cell (GFC =
0, VP = 0, and VC = 0) and send them to the downstream node (S10).

On the other hand, when the transmission data is transmitted from the terminal device accommodated in the branching device 3 to the terminal reception buffer (S12), the number of transmission data stored in the reception buffer is smaller than, for example, "3". It is determined whether it is larger (S1
3) If larger, GFC is set to "0" (S1).
4) The GFC (= 0) and VPI / VCI are put on an empty cell and transmitted to the MBU 12 as an SOS cell.

The branching device 3 is provided with a reception buffer capable of receiving transmission data for 10 cells from the terminal device, and the transmission data (ATM) received in the reception buffer is provided.
Only when the count number of the cell reaches a certain value “3”, the SOS cell is transmitted once and the reception buffer count value is decremented to “2”. By transmitting the SOS cell, a "reserved empty cell" in which the branch unit is forcibly specified by the MBU 12 is generated, and the zone of the terminal reception buffer of the branch unit is eliminated. When the SOS cell system is not used, it is necessary to provide a buffer for storing data of 18 cells or more.

The branching device 3 monitors whether or not there is transmission data from the terminal device (S15). When there is transmission data, first, it determines whether or not there is an uplink free cell (S15).
16). If there is no uplink free cell, it is monitored whether there is a downlink empty cell (S17). If there is a downlink empty cell, the transmission data is stored in this empty cell and the IFC is stored in the GFC.
D is set (S18), and an ATM cell is transmitted to the down bus (S10). If there is an upstream empty cell in the monitoring of step S16, the transmission data and GF
Set own ID to C (S25), and set A to the up bus
A TM cell is transmitted (S26).

The transmission data is configured to be transmitted to an empty cell on the upstream bus so that the data can be transmitted to the empty cell generated by the downstream node. When an ATM cell is received by the upstream bus reception buffer (S19), it is determined whether or not the cell is an empty cell (S2).
0), when the cell is not an empty cell, it is determined whether or not the GFC is “15”, that is, whether or not the cell is a multicast cell (S2).
1) If it is not a multicast cell, the received A
The TM cell is relayed as it is (S22), and the ATM cell is transmitted to the upstream bus (S26). As a result of the determination in step S21, the A received from the upstream bus,
When the TM cell is a multicast cell, since the self is the branching device located farthest from the MBU 12, an empty cell is immediately created and the multicast cell is deleted (S23). If this process is selected, when there is a vacancy in both the up bus and the down bus, the up vacant cell is used preferentially.

(Multicast) The multicast will be described below. As a control unique to the key telephone system, there is a broadcast communication mode (multicast) for notifying a plurality of terminal devices of the same information. To enable multicasting on the M bus, "15" is assigned to the GFC of the multicast cell which is a dedicated cell for multicasting, and the branching device and the ATM button telephone are operated as follows. The branching device receives the ATM cell GFC received on the down bus.
, And a multicast cell with a GFC of “15” is unconditionally fetched and relayed downstream without being converted to an empty cell. The CPU 36 of the branching device clears the GFC of the fetched multicast cell to “0” and copies and transmits the multicast cell to all terminal devices under the branching device. In the case of a configuration in which a terminal device that sends out a multicast cell is selected, the branch device 3 needs all signaling information of each terminal device, and the hardware configuration increases. The ATM key telephone is configured so that only the terminal device specified by signaling separately takes in and discards the others. Since the branching device that has received the multicast cell on the upstream bus does not need to relay this cell to the upstream node,
The cell is discarded to prevent circulation of the multicast cell.

(Maintenance operation of M bus) Next, operation, administration and maintenance of the M bus:
Hereinafter, the OAM function will be described. The OAM function is defined to be classified into the following five as failure and performance management means in the network management function. Performance monitoring function: Function to monitor performance by means of continuous or periodic measurement in time Defect and failure detection function: Function to detect deterioration in performance by means of continuous or periodic measurement in time System protection function: Failed Function to perform recovery by closing or disconnecting the transmission part or switching to spare, etc. Failure information or report information transfer function: Function to notify performance and failure information to other management parts as display parameters or signals Failure point identification function: Failure Function to specify the site by special test method etc.

The M bus has a form in which a plurality of branch devices are connected in series to a reciprocating bus that is turned back at the furthest branch device. Therefore, if the bus is disconnected on the way, a failure occurs in the entire M bus. It may spread. In order to make the M bus as effective as possible, the present invention introduces the following OAM processing flow so as to achieve the above-described defect and failure detection function and system protection function.

This OAM processing flow is executed under the following preconditions. The connection order of the branching devices from the MBU is from the youngest ID (near end) to the old ID (far end) of the ID. When a failure occurs, an internal loopback (U connection) circuit is created in the branching device that recognizes the failure. CC
U has a table (table describing the connection order of the branching devices from the MBU) that manages the connection ladder of the branching devices on the M bus, and the downstream branching device separated by the loopback notification from the branching device. The management of "calls" (such as disconnection and notification) is performed. The OAM flow of the M bus is applied only on the M bus (terminated at the MBU), and only the F5-OAM cell transmitted from the terminal device is transparently delivered to the partner terminal device.

FIG. 8 shows the structure of the OAM cell. OAM cells include GFC field, VPI field, VCI field, PT field, CLP field, HEC
A field, an OAM type field, an OAM function type field, a function specific field, a reserved field for future use, and an error detection code field are provided. The ID number of the branching device is described in the GFC field. The VPI field, which is a routing field, is set arbitrarily, and “0003H” or “0004H” is set in the VCI field. In the PT field,
“000” is set, and “0” is set in the CLP field.
However, in the OAM type field, "000" indicating failure management is set.
In the OAM function type field, “0000” is set in the case of the alarm indication signal (AIS), “0001” is set in the case of the far-end reception failure (FERF), and the loopback notification (LBA) is set. In the case of ()), “1000” is set.

The maintenance signal described in the OAM function type field will be described. The following segment OAM cells are used as maintenance signals on the M bus. FERF (Far
The End Receive Failure signal is a signal for notifying the transmitting end point that a failure or AIS has been detected on the receiving side of the main signal. AIS (Alarm Indication Sig
nal) is a signal for notifying downstream that a failure has occurred when a failure occurs in the transmission path. LBA (Loop B
ack Active) is M from the branching device that performed the loopback.
This is a signal for notifying the BU (CCU).

Hereinafter, the MBU 12, the branching device 3- (n-1),
The OAM processing for each fault that occurs in the M bus system including the branching device 3- (n) and the branching device 3- (n + 1) will be described with reference to FIG. When a failure occurs at the point a When the LOS (input signal loss) or LOF (out of frame synchronization) is detected at the down-bus receiving end of the branching device 3- (n), the branching device 3- (n) sets the upper level. F3-FERF is transmitted to the node transmitting end (branching device 3- (n-1)), the own ID is cleared to "0", a multicast cell ID reset request is transmitted downstream, and F3 is transmitted downstream simultaneously. -Send AIS, and at the same time, clear the VP / VC managed by the branching device 3- (n).

The 3-branch device (n−1) that has received the F3-FERF performs a loopback to disconnect the downstream,
The BU 12 is notified (loopback point “n−1”) that the loopback has been performed with the segment OAM cell F4-LBA (function type “1000”). F4-LBA
Is transmitted once / second. It should be noted that all cells destined for the downstream branch device (GFC is larger than the self ID) are discarded at the receiving end that has looped back. MBU12
Sends to the CCU 19 the unusable information (layer 1 inactivity) of the terminal device downstream of the branching device 3- (n-1) in the control cell. Also, the VP / VC table of the unusable branch device managed by the MBU 12 is cleared.

The CCU 19 clears all VP / VCs being used in the branching device downstream from the branching device 3- (n-1), and sends an end-to-end OAM cell F4- to the VP / VC-compatible communication partner terminal device. FERF (Function type "000
1)).

The downstream branch device that has received the ID reset request clears its own ID, and manages the managed VP / VC.
Also clear. In addition, IDs are periodically sent to MBUs.
Keep sending requests.

The loopback release is performed by the branching device 3- (n)
LOS / LOF recovery causes F3- in branching device 3- (n-1)
When the FERF reception is released, the loopback is released, and the segment OAM cell F4-
Stop transmission of LBA (once / second). MBU12 is
When F4-LBA has not been received for 2.5 ± 0.5 seconds, the CCU is notified of the M bus failure recovery by the control cell.

When a failure occurs at point b When the LOS (input signal loss) or LOF (out of frame synchronization) is detected at the upstream bus receiving end of the branching device 3- (n), the branching device 3- (n + In 1), F3-AIS is transmitted. The branching device 3- (n) performs a loopback to disconnect the downstream, and sends a segment OAM cell F4-L to the MBU12.
Notify that a loopback has been made with BA (function type “1000”). F4-LBA is transmitted at an interval of once / second. Thereafter, the same operation as that at the time of the occurrence of the failure at point a is performed.

When faults occur simultaneously at points a and c The branching device 3- (n) performs the same operation as when a fault occurs at the point a, and the branching device 3- (n-1) operates at the point b. The operation is the same as when the failure occurs.

When a failure occurs at the point d when the branching device 3- (n-1) is at the highest level, the LOS / LO at the downstream bus receiving end of the branching device 3- (n-1)
F is detected, and F3-F
An ERF is sent. The branching device 3- (n) clears its own ID to "0" and sends a multicast cell ID reset request downstream, and at the same time, the VP / VC managed by the branching device 3- (n-1). To clear. The MBU 12 that has received the F3-FERF does not perform loopback, but notifies the CCU 19 of information equivalent to loopback in the control cell. (Loop-back point "0") Thereafter, the same operation as that described in 1 when a failure occurs at point a is performed.

When a failure occurs at point e LOS / LOF is detected at the upstream bus receiving end of the MBU 12, and the branching device 3- (n-1) is notified by F3-AIS.
The CCU is notified of information equivalent to loopback in the control cell. (Loop-back point "0") Thereafter, the same operation as that at the time of occurrence of a failure at point a is performed.

When a fault occurs simultaneously at point d and point e The branching device 3- (n-1) performs the same operation as when a fault occurs at point d, and when the MBU 12 fails at point e. The operation is the same as.

When a fault occurs at the point f When an error is detected at the terminal-side receiving end of the branching device 3- (n), the terminal device is notified by F4-FERF (F3-A
IS not used), segment OAM cell F4-FE
The MBU 12 is notified by RF (function type “0001”). F4-FERF is transmitted once / second.
The MBU 12 uses the control cell to branch to the CCU 19 for the branching device 3- (n).
Raise the unusability of the terminal device. The CCU 19 controls all Vs used in the branching device 3- (n).
The P / VC is cleared and the VP / VC compatible communication partner terminal device is notified by an end-to-end OAM cell F5-FERF (function type "0001"). When the error state is recovered, F4- of the branching device 3- (n)
The periodic transmission of the FERF is stopped, and the CCU 19
-Automatically release when LBA is not received for 2.5 ± 0.5 seconds.

When a Failure Occurs at Point g When a failure occurs at point g, the terminal device sends F4-FERF
Is transmitted once / one second, and the CC is transmitted via the MBU 12.
U19 is notified and the operation is the same as that when a failure occurs at point f.

(Prevention of Circulation of ATM Cells in M Bus) Hereinafter, prevention of circulation of ATM cells in the M bus will be described. Processing of Multicast Cell A branching device that detects a multicast cell which is a dedicated cell using a dedicated channel (VP / VC) having a fixed value of GFC (GFC = 15) on the upstream bus is configured to discard the multicast cell. To prevent multicast cell circulation. Operation of the branching device during loopback The branching device during loopback has an ID larger than its own ID.
If the cells of (GFC) are received on the uplink bus, all the cells are discarded, thereby preventing unnecessary cells from circulating downstream from the loopback point.

(Commands Used on M Bus)
The commands and GFC values used in the present invention and their functions will be described with reference to Table 3.

[0087]

[Table 3]

The ID assignment confirmation notice is a command sent from the MBU 12 to the branching unit, with the GFC set to “15”. The ID assignment confirmation notification is a command for notifying the start of ID assignment.
Stop sending the D request.

The ID reset request is a command in which the GFC is set to “15” sent from the upper branch device to the lower branch device. The ID reset request has a function of deleting an ID owned by the branching device and giving an instruction to deactivate the terminal-side layer 1 in order to cope with the ID automatic assignment procedure.

The ID assignment confirmation request has a function of confirming the ID assignment status of the branching device by a command sent from the MBU 12 to the branching device, in which “ID” is set in the GFC. The branch device that has received the ID assignment confirmation request compares the ID set in the received command with its own ID, and outputs an ID assignment confirmation response when they match.

The ID assignment confirmation response is sent from the branch unit to the MBU.
12 has a function of notifying that the ID of the branching device has been set by a command in which “ID” has been set in the GFC sent to the device 12.

The ID allocation request is a command sent from the MBU 12 to the branching unit with the GFC set to “0”, and has a function of designating the ID to be set by a parameter.
The branching device whose ID has already been set relays this command directly to the lower side. Upon receiving this command, the branching device in which the ID is not set (ID = 0) sets the ID specified by the parameter to its own ID, and transmits the cell carrying this command to the lower side as an empty cell. The branching device that has set the ID sends the ID assignment response to the MB.
Send to U12.

The ID assignment response is sent from the branch unit to the MBU 12
Command with "ID" on GFC sent to
It has a function of notifying the completion of the setting of D.

The ID assignment completion notification is a command sent from the MBU 12 to the branching device with “15” added to the GFC, and has a function of terminating the automatic ID assignment and instructing all the branching devices to activate the layer 1. Have.

The ID assignment end response is sent from the branch unit to the MBU.
12 is a command in which “ID” is mounted on the GFC and is a response command to the ID assignment completion notification.

The ID request has a function of requesting the execution of an automatic ID assignment procedure by a command sent from the branching unit to the MBU 12 with “0” added to the GFC.

In these commands, commands having the same GFC are distinguished by the data of the cell payload.

(Automatic Assignment of Branch Device ID) Next, automatic assignment of branch device IDs will be described with reference to Table 3 and FIG. In order to enable automatic assignment of the ID (GFC) of the branching device 3, the configuration (software control) is performed under the following preconditions. To enable automatic ID assignment, a command shown in Table 3, that is, a cell unique to the system is newly provided on the M bus 2. When its own ID is “0”, the branching device continues to transmit the ID request until receiving the ID assignment. The branching device starts up with its own ID set to “0” at the time of power-on initial.

FIG. 10 shows an example of an M bus system in which two branching devices 3-1 and 3-2 are connected in series to the MBU 12 via the M bus 2. When the power of the branching device 3-1 is turned on, the branching device 3-1 sends the IBU to the MBU 12.
Send a D request. Similarly, when the power of the branch device 3-2 is turned on, the branch device 3-2 sends an ID request to the MBU 12. This ID request is relayed to the branching device 3-1 and notified to the MBU 12. After the power-on initial, the MBU 12 transmits an ID automatic assignment confirmation notice as a multicast cell to all the branching devices. Each branch device receives the ID automatic assignment confirmation notification and stops the periodic transmission of the ID request.

To check the ID setting status, the MBU 12 first transmits an ID assignment confirmation request (GFC = 1) as to whether or not there is a branching device with ID = 1. Since the IDs of all the branching devices are “0”, the ID assignment confirmation request (GFC =
1) turns back on the M bus 2 and returns to the MBU 12. Since the MBU 12 has confirmed that ID = 1 is unassigned, the MBU 12 starts assignment from ID = 1.

The MBU 12 sends a GFC =
An ID assignment request indicating an ID (= 1) with a parameter of 0 is transmitted. Upon receiving the ID assignment request, the highest-ranked branching device 3-1 whose ID has not been set sets its own ID to “1”, sends the cell carrying the command as an empty cell to the lower order, and sends its own to the GFC. The MBU 12 is notified of an ID assignment response in which an ID has been set.

When the MBU 12 confirms that the ID setting of the branching device 3-1 has been completed, the MBU 12 shifts to the next ID setting.
Similarly, an ID assignment request in which ID (= 2) is set in the parameter of GFC = 0 is transmitted. The highest-order branching device 3-1 that has already set ID = 1 ignores the ID assignment request and sends this command to the downstream node. Second branching device 3-2
Captures this command, sets its own ID to “2”, and sends an ID assignment response in which its own ID has been set to the GFC to the MB.
Notify U12.

When the MBU 12 confirms that the ID setting of the branching device 3-2 has been completed, the MBU 12 shifts to the next ID setting.
Similarly, an ID assignment request instructing ID (= 3) with the parameter of GFC = 0 is transmitted.

When the ID assignment for all the branching devices on the M bus has been completed, the ID assignment request (ID = 3) is returned at the downstream side of the branching device 3-2, and the MBU 1
2 is received. Upon receiving the ID assignment request (ID = 3) on the uplink bus, the MBU 12 recognizes the end of the ID automatic assignment and transmits an ID assignment end notification of the multicast cell GFC = 15.

Branching device 3 that has received the ID assignment end notification
-1 and 3-2 activate the terminal-side layer 1 and transmit the layer 1 state (active / inactive) of the terminal port to the MBU 12 as an ID assignment end response. The MBU 12 notifies the CCU 19 of the layer 1 status of all terminal devices on the M bus,
The ID automatic assignment procedure ends.

As described above, the ID assignment request in which the number (ID) of the branching device is sequentially updated is sent out to the M bus, and the ID of the branching device connected in series on the M bus is changed to the highest branching device. Are assigned sequentially.

(ID Reassignment) When there is a time difference in the start of the branching device or when a failure occurs in the branching device, the upper branching device loops back the M bus to communicate with the upstream branching device. An ID reassignment method for reallocating an ID to a lower order branch device without interrupting communication of an upper order branch device when a lower order branch device is restarted or a fault is recovered in an ATM-M bus system that is secured. Will be described with reference to FIG.

The branching device 3-2 monitors an abnormality on the upstream side, and when detecting a failure on the upstream side, sets its own ID to “0” and sets the GFC to “1” for the lower order branching device.
The lower branch device that has received the ID reset request resets its own ID to “0” and deactivates the terminal-side layer 1. When the failure is recovered or the program of the branch device is restarted, the GFC is set to “0” from the branch device with ID “0” and the ID assignment procedure is executed. ID to request
The request is sent to the MBU 12 periodically and repeatedly. In order to perform such an operation, each branch device is configured such that each branch device of ID = 0 issues an ID request when the failed branch device starts up a program (when the failure is recovered). It is necessary to put. The MBU 12 that has received the ID request uses the multicast cell in which the GFC is set to “15” for all the branching devices, and starts the ID assignment, which means that the ID allocation is started.
Send a D assignment confirmation notice. The branch device that has received the ID assignment confirmation notification stops repeatedly sending the ID request. Next, the MBU 12 sends an ID assignment confirmation request for confirming the ID assignment status in which ID = 1 is set in the GFC. The branching device (ID = 1) for which the own ID has been set is
When receiving the ID assignment confirmation request addressed to itself, it sends an ID assignment confirmation response to the GFC, indicating that the ID has been set with its own ID = 1. MBU1 which received ID assignment confirmation response (ID = 1)
2 confirms the assignment of ID = 1 and then sends the GFC an I
An ID assignment confirmation request for confirming the ID assignment status with D = 2 is transmitted. If there is no branch device having ID = 2, the ID assignment confirmation request returns to the M bus and returns to the M bus.
Return to BU12. MBU1 that has received the ID assignment confirmation request (ID = 2)
2 confirms that ID = 2 has not been assigned, and uses the cell in which GFC is set to “0” and uses ID = 2
Is transmitted on the downstream bus. Branch device that has deleted the ID that received the ID assignment request on the down bus ((is immediately below the branch device with ID = 1)
Means that GFC = 0 matches its own ID = 0.
Take in the allocation request cell and set its own ID to “2”,
An ID assignment response for notifying the completion of the ID setting in which the own ID = 2 is set in the GFC is transmitted to the MBU 12. MBU 12 receiving ID assignment response (ID = 2)
Sends an ID assignment confirmation request for confirming the ID assignment status in which ID = 3 is set to the GFC, and executes the ID assignment of the next branch device. Thereafter, in the same procedure, the lower-ranked branch device is sequentially set with the oldest ID, and the ID numbers are assigned to all the branch devices.

According to this ID reassignment method, the branching device higher than the branching device that loops back the M bus can execute communication even when a failure occurs in the lower order. Further, even when the lower-level fault is recovered or the program of the lower-level branch device is started, it is not necessary to newly assign an ID to the higher-level branch device, and thus the operation of the higher-level branch device such as communication is hindered. Without this, IDs can be reassigned to all lower branching devices.

[0110]

According to the present invention, when a failure occurs on the M bus in the ATM-M bus system in which the end of the downstream bus is turned back and the upstream bus is turned over, the upper branch device receives the failure. The operation can be continued without any change.

Further, according to the present invention, when the above-mentioned fault is recovered, the ID can be automatically reassigned to the lower branch device without obstructing the operation of the upper branch device.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a configuration concept of an ATM-M bus system according to the present invention.

FIG. 2 is a block diagram showing a configuration of a branching device 155M used in the ATM-M bus system according to the present invention.

FIG. 3 is a block diagram showing a configuration of a branching device 25M used in the ATM-M bus system according to the present invention.

FIG. 4 shows M used in the ATM-M bus system according to the present invention.
FIG. 2 is a block diagram showing a configuration of a BU.

FIG. 5 shows M used in the ATM-M bus system according to the present invention.
FIG. 9 is an explanatory diagram illustrating a GFC / VP / VC conversion process in the BU ATC.

FIG. 6 is a diagram showing M used in the ATM-M bus system according to the present invention.
FIG. 3 is a functional block diagram showing a functional configuration of a BU.

FIG. 7 shows an M used in the ATM-M bus system according to the present invention.
FIG. 4 is a flowchart illustrating the operation of a BU.

FIG. 8 shows an O-type bus used in the ATM-M bus system according to the present invention.
The figure which shows the structure of an AM cell.

FIG. 9 is a diagram showing a location where a failure occurs in the ATM-M bus system according to the present invention.

FIG. 10 is a flowchart for explaining an ID automatic assignment sequence in the ATM-M bus system according to the present invention.

FIG. 11 is a flowchart illustrating an ID reassignment sequence in the ATM-M bus system according to the present invention.

FIG. 12 is a conceptual diagram showing a configuration concept of an ATM-U bus system according to the prior application.

[Explanation of symbols]

Reference Signs List 1 M bus main unit (ATM switching device) 11 ATM switch 12 ATM-M bus 155 Mbps interface unit (MBU) 120 GFC / VP / VC conversion unit (ATC) 121 Cell add / drop control unit (PLD) 122 ATM unit LSI 123 Optical / Electrical conversion interface 124 F-ROM 125 S-RAM 126 CPU 127 LED display unit 128 PLL circuit 13 25 Mbps terminal interface unit 14 LAN interface 15 N-ISDN basic interface unit 16 25 Mbps interface between nodes 17 Three-way conference unit 18 Voice Communication type conversion unit 19 Central control unit (CCU) 2 M bus 21 Turnback device 3 Branch device 30 Optical / electrical conversion interface 31 ATM unit SI 32 cell branching insertion controller (PLD) 33 PLD control ROM 34 F-ROM 35 RAM 36 CPU 37 LED display 38 AC / DC converter 39 reset circuit 6 100 [Omega copper cables (UTP)

Continuing on the front page (72) Inventor Shinji Sugawara 24-4 Sakuragaoka-cho, Shibuya-ku, Tokyo Inside the Nakayo Communication Machinery Co., Ltd. (72) Inventor Junji Asakura 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Stocks In-company (72) Inventor Hitoshi Maeda 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation F-term (reference) 5K030 GA12 HA10 KA00 KX30 MB01 MC02 5K032 AA06 CD01 DA04 DA11 DB01 DB28 EA04 9A001 BB06 CC07 JJ19 KK63 LL09

Claims (9)

[Claims] 1. An M-bus interface unit accommodated in an ATM exchange, an M-bus composed of a down bus and an up bus whose both ends are accommodated in the M-bus interface unit and turned back at the farthest end, and a down-link of the M bus In a maintenance and operation method for an ATM-M bus system including a plurality of branch devices connected in series to a bus and an upstream bus, the branch device constantly monitors for a failure, and loops back to a branch device higher than the failure point. AT to form
Maintenance operation method of MM bus system. 2. A branching device that detects an input signal loss (LOS) or loss of frame synchronization (LOF) on a downstream bus clears its own ID to "0" and sends a multicast cell ID reset request to a lower order. In addition, the higher-order branch device that has transmitted the far-end reception failure (FERF) signal to the higher order and received the far-end reception failure (FERF) signal sets loopback in its own branch device, and transmits the cell addressed to the lower-order branch device. At the receiving end, all are discarded and the lower side is separated.
Loopback execution notification (L
A) according to claim 1, characterized in that A) is transmitted.
Maintenance operation method of TM-M bus system. 3. A branching device that detects an input signal loss (LOS) or loss of frame synchronization (LOF) on an upstream bus sends an alarm indication signal (AIS) to a lower order, and loops back in its own branching device. Is set, the cells destined for the lower branch device are discarded at the receiving end, and the lower side is separated.
Loopback execution notification (L
A) according to claim 1, characterized in that A) is transmitted.
Maintenance operation method of TM-M bus system. 4. The highest-order branching device that has detected an input signal loss (LOS) or a loss of frame synchronization (LOF) on the downstream bus clears its own ID to "0" and requests a lower order for a multicast cell ID reset. And the M-bus interface unit sends a far-end reception failure (FER
F) The M bus interface unit that has transmitted the signal and received the far end reception failure (FERF) signal transmits information equivalent to loop back using the control cell to the central control unit (CCU) of the M bus main unit. 2. The maintenance and operation method for an ATM-M bus system according to claim 1, wherein the notification is made. 5. An M bus interface unit that detects an input signal loss (LOS) or a loss of frame synchronization (LOF) on an upstream bus, generates an alarm display signal (A) on a downstream bus.
2. The ATM-based communication system according to claim 1, wherein said control signal is transmitted to a central control unit (CCU) of said M bus main unit using a control cell. Maintenance operation method of M bus system. 6. An M-bus interface unit housed in an ATM exchange, an M-bus consisting of a down bus and an up bus whose both ends are housed in the M-bus interface unit and turned back at the farthest end, and a down-link of the M bus An ATM-M bus system comprising a plurality of branch devices connected in series to a bus and an upstream bus, respectively, wherein when a failure occurs in the M bus, a loopback is formed in a branch device higher than the failure point. In an ATM-M bus ID reassignment method for re-assigning an ID to a lower branch device at the time of recovery from a failure in an ATM-M bus system that secures communication on the upper side, the branch device detects the upper failure. The branching device that constantly monitors and detects a higher-level fault is its own ID.
Is set to “0” and an ID reset request is sent to the lower branch device by a multicast method,
Upon receiving the D reset request, the lower order branch device has its own ID.
Is reset to “0”, and an ID assignment request is
An ATM-M bus system ID reassignment method, wherein transmission is performed to a bus interface unit. 7. Upon receiving the ID request from the branching device, the M bus interface unit sends an ID assignment confirmation notification requesting a temporary suspension of the ID assignment request.
The ID assignment confirmation request carrying the D number is sequentially transmitted to the downstream bus in ascending order from the youngest ID number. When the ID assignment confirmation request of the transmitted ID number without the ID assignment confirmation response is received on the upstream bus, 7. The method according to claim 6, wherein the ID assignment request of the ID number is transmitted to the down bus. 8. A branching device having its own ID of “0” receiving an ID assignment request on a downstream bus takes in the ID, transfers an empty cell downstream, and sends an ID assignment response to the M bus unit. 8. The method according to claim 7, wherein the ID is re-transmitted. 9. The ID reassignment of the ATM-M bus system according to claim 6, wherein the failure on the M bus is a start of a program of a lower branch device. Method.