JPH10294735A - Line interface facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continue data communication, even on the occurrence of a fault in a line interface section. SOLUTION: This line interface facility(LIF) is constituted of a plurality of physical layer IF sections Ia1 -Ia3 , that execute physical layer termination processing the in response to a line signal received from a connection line, a plurality of host layer IF sections Ib1 -Ib4 that executes a common host layer termination processing and other processings, and a connector 1c that connects a prescribed physical layer IF section and a host layer IF section. On the occurrence of a fault in a host layer IF section, the connection device 1c connects the physical layer IF section connecting to the host layer IF section to other normal host layer IF section having a margin in its frequency band. Furthermore, the connection device 1c connects the physical layer IF section connecting to the host layer IF section only for a prescribed connection to other normal host layer IF section having a margin in its frequency band, only as to the connection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line interface device and a cell switching system, and more particularly to separating a cell from a signal input from a predetermined line, performing predetermined processing on the cell, and transmitting the processed signal to a switch. Also, the present invention relates to a line interface device and a cell switching system for mapping a cell input from a switch to a payload portion of a line signal and transmitting the cell signal to another line.

[0002]

2. Description of the Related Art ATM network technology is the next generation of B-IS.
It has been developed as a technology for constructing a DN (Broadband Integrated Digital Network) and is being put to practical use. FIG. 17 is a configuration diagram of the ATM switching system, and includes 11 _{11 to} 11 _1n ,
11 _{21 to} 11 _2n , 11 _{31 to} 11 _{3 n} , 11 _{41 to} 11 _{4 n} are line interface units (line IF units) connected to the corresponding lines (transmission paths), 12 _{1 to} 12 ₄ are demultiplexing units, 13 Is an ATM switch unit, 14 is a system control unit, and 15 is a maintenance terminal. ATM switch unit 13 is connected to the plurality of demultiplexer 12 ₁ to 12 _4, and outputs the switching input cells from one demultiplexer to a predetermined demultiplexing unit.
Demultiplexer 12 ₁ to 12 ₄ each of the line IF unit 1
₁₁ 1 to 11 _1n , 11 _{21 to} 11 _2n , 11 _{31 to} 11 _3n , 11 ₄₁
To 11 _4n are connected to the outputs of the upstream cell from a plurality of line IF unit to the ATM switch unit 13 and multiplexed. Further, the demultiplexer 12 ₁ to 12 _4, separates outputs downlink cells from the ATM switch unit 13 to a predetermined line IF unit.

Each of the line IF units 11 _{11 to} 11 _4n is connected to a corresponding demultiplexing unit 12 _{1 to} 12 _4, and receives ATM cells (FIG. 18 (FIG. 18)) from a payload portion of a frame signal (for example, SONET FRAME) input from the line. a)), and after that, predetermined processing (charging / NDC processing, UPC processing, OA)
M processing, etc.) and output to the demultiplexing unit. Demultiplexer 12 ₁ to 12 ₄ inputs an ATM cell to the ATM switch by adding a routing tag information TAG to the cell (FIG. 18 (b)) as well as multiple. The ATM switch switches the cell to a predetermined route with reference to the tag information TAG,
Demultiplexer 12 ₁ to 12 ₄ by separating the cells input to the predetermined line IF unit based on the tag information. Each line IF unit 11
_{11 to} 11 _4n are ATs input from the demultiplexing units 12 _{1 to} 12 ₄
M cells are mapped to the payload of SONET FRAME and transmitted to the line side. The system control unit 14 controls the subscriber I
F unit ₁₁ 11 to 11 _4n, the demultiplexer 12 ₁ ~12 _4, ATM
The switch unit 13 is controlled.

In FIG. 18, HD is a header part, and DT is an information field (payload) of 48 bytes. The header part HD includes (1) a virtual channel identifier (VCI) for call identification so that the destination can be recognized even after the data is decomposed into blocks.
(2) a virtual path identifier (VPI) for identifying a route, (3) a generic flow control (GFC) used for flow control between links, and (4) ) Includes a payload type PT (Payload Type), (5) a header error correction code (HEC), (6) tag information TAG, and the like.

FIG. 19 is a configuration diagram of a line interface unit for SONET, and one line interface unit 11 is configured to correspond to one set of upstream / downstream optical lines. 1
2 is a demultiplexing unit (MUX / DMUX), and 13 is an ATM switch. In the line interface unit 11, 1
Reference numeral 1a denotes a photoelectric conversion unit, 11b denotes an electro-optic conversion unit, and 11c denotes a physical layer termination unit (SONET termination unit). (1) A cell mapped to a payload portion of a SONET frame signal is separated and output, and an ATM is output. The cells input from the switch side are mapped to the payload part of the SONET frame signal and transmitted to the corresponding line, and (2) overhead processing,
(3) Execute SONET / SDH termination processing. For example, the physical layer terminating unit 11c is more overhead than the frame signal having the format of SONET STC-3C (156 Mbps) shown in FIG.
(Section overhead SOH, path overhead P
OH) and performs predetermined processing, and extracts and outputs ATM cells from the payload portion PL. Also, the physical layer terminator 11c converts the cell stream input from the switch side into a SONET STS-3C format frame shown in FIG. 20 and transmits the frame to the line.

[0006] Reference numeral 11d denotes an ATM layer terminating unit.
M-ATM conversion, (2) cell length conversion, (4) cell synchronization processing,
(4) Perform cell wrapping processing. Reference numeral 11e denotes a UPC processing unit which monitors whether or not the declared value of the transmission capacity matches the actual cell inflow amount, and performs a process of discarding a cell violating the regulation when a cell exceeding the declared value flows in. NDC
A processing unit for performing charging control and NDC control for generating charging data by counting the number of passing ATM cells;
g denotes an OAM processing unit that realizes a failure management function for identifying and notifying a failure, and a performance management function such as a user information cell error rate and a cell loss rate.

FIG. 21 is a block diagram of the DS3 line interface unit, and the same parts as those in FIG. 19 are denoted by the same reference numerals. The line interface unit 11 for SONET in FIG.
(1) A line interface unit 11 'is provided corresponding to a set of up / down PCM digital lines, and (2) Bipolar signal (bipolar signal) ) To a unipolar sign
al), and a UB converter 11b 'for converting a bipolar signal to a unipolar signal. (3) A DS3 termination unit 11 as a physical layer termination unit.
c 'is provided. Physical layer termination (DS3
Terminating section) 11c 'is used for conversion between DS3 signals and cells, DS
An alarm detection process for three layers is executed.

FIG. 22 is an explanatory diagram of an ATM switch.
Reference numerals 12a to 12c denote VC conversion circuits provided in each demultiplexing unit, 13 denotes an ATM switch unit, and 13 denotes a system control unit (call control unit) 14. VC conversion circuits 12a to 12c
Is provided corresponding to each of the incoming lines # 1 to # 3, adds a tag TAG (FIG. 18B) to a cell input from the corresponding incoming line, and includes a VCI (input VCI) included in the cell.
Is replaced with another VCI (output VCI) and sent to the ATM switch unit 13.

When a call is originated, a system control unit (call control unit) 14 performs a call control, and sets a VPI / VCI value (input VP) of the call.
I / VCI) and a tag T for routing
AG and a replacement VCI value (output VCI) are determined, and the input VCI, tag, and output VCI are stored in a tag table (not shown) of a VC conversion circuit into which a cell corresponding to the call is input.
Write the CI correspondence. After the call control, when a cell is input to a predetermined input line, the VC conversion circuits 12a to 12c connected to the input line determine tag information TAG and output VC according to the input VCI added to the input cell from the tag table.
Read I. Then, the tag information TAG is added to the cell, and the VCI of the cell is replaced with the output VCI, and A
Send it to the TM switch unit 13. ATM switch unit 13
Switches the cell based on the tag TAG and sends it out to a predetermined outgoing line.

In the ATM switch 13, I _{1 to} I ₃
Is a tag information detection circuit, D _{1 to} D ₃ are transmission information delay circuits, D
M _{1 to} DM ₃ are demultiplexers, and DEC _{1 to} DEC ₃ are tag information decoding circuits.
An ELD is configured. FM _{11 to} FM ₃₃ are buffer memories, for example, FIFO (First-In First-Out) memory, SEL
_{1 to} SEL ₃ are selectors, and AOM _{1 to} AOM ₃ are arrival order management FIFOs. Each arrival order management FIFO (AOM ₁
To AOM ₃ ) are tag information decoding circuits DEC ₁ to DEC _1, respectively.
Is connected to the output end of the DEC _3, corresponding three buffer memories FM ₁₁ ~FM _{13 to, FM 21 ~FM 23, FM 31} ~FM
₃₃ stores the order in which cells arrive, and stores a corresponding selector S
By controlling EL _{1 to} SEL ₃ , the cells are read from the three buffer memories in the order of arrival of the cells and transmitted to outgoing lines # 1 to # 3.

The cell input to the ATM switch unit 1 has the configuration shown in FIG. 18B, and has a detection circuit Ii (i = 1).
To 3) extract the tag information contained in this signal and send it to the decoding circuit DECi (i = 1 to 3). Decode circuit DEC
If the input tag information indicates the output terminal #j (j = 1 to 3), the transmission information is sent to the FIFO memory FMji by operating the demultiplexer DMi by the switching signal Si. For example, if the tag TAG indicates an output terminal # 2, the buffer cells from the decoding circuit DEC ₁ is input # 1 by operating a demultiplexer DM ₁ memory included in the cell inputted from the input terminal # 1 input to FM _21.

The arrival order management FIFO (AOM₁~ AO
M_Three) Indicates the control information decode circuit DEC₁~ DEC
_Three3 buffer memories connected to the output terminals of
FM₁₁~ FM₁₃, FM_{twenty one}~ FM_{twenty three}, FM₃₁~ FM₃₃N
The order in which the files arrive is stored. For example, if the cell is a buffer
Memory FM₁₁→ FM₁₂→ FM₁₃→ FM₁₂→ ... order
, The arrival order management FIFO (AOM₁)
Buffer in the order of cell arrival, such as 1 → 2 → 3 → 2 → ...
A memory identification code is stored. After that, arrival order management
FIFO (AOM₁~ AOM_Three) Is the corresponding selector SE
L₁~ SEL_ThreeTo control the three buffer
Mori FM₁₁~ FM₁₃, FM_{twenty one}~ FM_{twenty three}, FM ₃₁~ FM₃₃
And read out the cells from outgoing lines # 1 to # 3.

As described above, each buffer memory FMij
By having a capacity for multiple cells, the buffer
When the function is obtained and transmission data temporarily increases,
In any case, it can respond sufficiently. Also, buffer the order of cell arrival.
Memory FMi₁~ FMi_Three(FM ₁₁~ FM₁₃, FM_{twenty one}~ FM
_{twenty three}, FM₃₁~ FM₃₃Each buffer to read cells from)
Memory FMi₁~ FMi_ThreeAn equal number of cells are
Cell is discarded due to overflow from memory
Disappears.

[0014]

As described above, the conventional line interface section has the configuration shown in FIG. 19 or FIG. 21 corresponding to one set of uplink / downlink. Such a conventional configuration has the following problems. FIG. 23 is a diagram for explaining a problem of the conventional line interface unit.
0 _1, 10 ₂ OC3C optical line, 11 _1, 11 ₂ a line interface unit for 0C3C, are formed on one sheet each print board (card). 12 is a demultiplexing unit (common device), and 13 is an ATM switch. Optical line 1
User terminals A and B are connected to 0 ₁ and 10 ₂ , respectively, and a connection is currently established between the user terminals A and B. (1) The first problem is that if a failure occurs in _one of the line interface units 11 ₁ and 11 ₂ of the user terminals A and B, then data communication between the user terminals A and B stops. (2) The second problem is that the user terminals A and B for some reason
When one of the line interface units 11 ₁ and 11 ₂ is replaced, the data communication between the user terminals A and B stops due to the removal of the card. (3) The third problem is APS (automatic protection s).
Even if the system is duplexed as in the case of (ystem), if both the active system and the standby system fail, data communication stops. For this reason, a duplex configuration is not sufficient. (4) A fourth problem is that only a predetermined virtual path (VP connection or VC connection) accommodated in a certain line interface unit has an abnormality, and when an interface card is replaced, another normal virtual path has a problem. Data communication stops.

Accordingly, an object of the present invention is to provide a line interface device and a cell switching system that can continue data communication between users even if a failure occurs in a line interface unit. An object of the present invention is to provide a line interface device and a cell switching system that can guarantee data communication in the event of a failure regardless of a duplex system. An object of the present invention is to change the line interface unit that accommodates an abnormal connection when there is an abnormality only in a specific connection accommodated in a certain line interface unit, and to have any effect on other normal connections. It is to be able to continue the communication of the abnormal connection without any error.

[0016]

SUMMARY OF THE INVENTION According to the present invention, a cell is separated from a signal input from a predetermined line, the cell is subjected to predetermined processing, transmitted to a switch, and then input to the switch. A plurality of physical layer IF units each performing a physical layer termination process according to a signal from a connected line, in a line interface device for mapping the resulting cell to a payload portion of a line signal and transmitting the cell to another line; This is achieved by a line interface device including a plurality of upper layer IF units that execute common upper layer termination processing and other processes, and a connection device that connects a predetermined physical layer IF unit and the upper layer IF unit.
In this case, when a failure occurs in the upper layer IF section, the connection device connects the physical layer IF section connected to the upper layer IF section to another normal upper layer IF section having sufficient bandwidth. . In addition, when a failure occurs in the upper layer IF section only for a predetermined connection, the connection device determines whether the physical layer I connected to the upper layer IF section has a failure.
The F section is connected to another upper layer IF section having a sufficient band for only the connection.

Further, according to the present invention, the above objects are achieved by (1) a cell switch for switching a cell route in a cell unit, and (2) a plurality of physical layers for executing physical layer termination processing according to a line signal. IF unit and a plurality of upper layer IFs each performing a common upper layer termination process and other processes
Unit, a line interface device including a connection device for connecting a predetermined physical layer IF unit and an upper layer IF unit,
(3) When a failure occurs in the upper layer IF unit, the connection device is controlled to change the physical layer IF unit connected to the upper layer IF unit to another upper layer I with a sufficient band in terms of bandwidth.
This is achieved by a cell switching system including a control device that switches to an F unit and switches a route within a switch of a connection accommodated in the physical layer IF unit.

According to the present invention, the above objects are achieved by (1) a cell switch for switching a cell route on a cell-by-cell basis, and (2) a plurality of physical layer IF sections each executing a physical layer termination process according to a line signal. A line interface device including a plurality of upper layer IF units each performing common upper layer termination processing and other processing, and a connection device for connecting a predetermined physical layer IF unit and the upper layer IF unit;
(3) When a failure occurs in the upper layer IF section only for a predetermined connection, the physical layer IF section connected to the upper layer IF section is changed to another upper layer having a normal band allowance only for the connection. The present invention is achieved by a cell switching system connected to a layer IF unit via the connection device and provided with a control device that switches a route of the connection in a switch.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

 (A) Schematic Description (a) Configuration FIG. 1 is a schematic explanatory diagram of a cell switching system of the present invention.
SW is a cell switch that switches the direction of the cell, LIF is
A line interface device, and a predetermined line L ₁₁,
L_{twenty one}, L₃₁Cells from the signal input from the
After performing a predetermined process on the cell switch SW,
The cell input from the cell switch is used as the payload of the line signal.
To another line L₁₂, L_{twenty two}, L₃₂Send to
CNT is cell switch SW and line interface
This is a control device for controlling the source device LIF. Line interface
In the face device LIF, 1a₁~ 1a_ThreeIs connected
Physical layer termination according to the line signal input from the
Physical layer IF unit for executing the₁~ 1b_Four
Performs common upper layer termination processing and other processing.
The upper layer IF section to execute, 1c is a predetermined physical layer IF
This is a connection device that connects between the unit and the upper layer IF unit.

As shown in FIGS. 2 (a) and 2 (b), each line interface section of an optical line and a digital line (electrical line) is divided into two by a dotted line S1. Although the processing is different depending on the electric line, the transmission speed, etc., the right part on the switch side is functionally the same. Therefore, the portion on the left side of the dotted line is the physical layer I
As shown in FIG. 1, an F section is provided for a required line, and a portion on the right side of the dotted line S1 is an ATM layer IF section (upper layer I
F) is provided for the necessary lines, and the connection device 1
c, so that an arbitrary physical layer IF unit can be connected to an arbitrary upper layer IF unit. When the line interface device is configured in this way, the following control is possible.

[0021] (b) when the first schematic initial connecting device 1c, as shown in FIG. 1 (a), the physical layer IF unit 1a ₁ to 1A ₃ and upper layer IF unit 1b ₁ ~
1b ₃ are connected to each other. In this state, when the upper layer IF section 1b ₃ fails, the controller CNT is said upper layer I by controlling the connection unit 1c
The physical layer IF unit 1a ₃ which is connected to the F unit 1b ₃ as shown in FIG. 1 (b), the band to switch on another upper layer IF section 1b ₄ normal margin. Next, the controller CNT switches to indicate a switch in the root of all the connections that are accommodated in the upper layer IF section 1b ₃ in dotted lines. In this way, even if a failure occurs in the upper layer IF unit, another upper layer IF
Communication can be continued via the unit.

(C) Second schematic explanation FIG. 3 is a second schematic illustration. Initially, connection device 1c
Are the physical layer IF units 1a ₁ to 1a, as shown in FIG.
1a ₃ and the upper layer IF sections 1b _{1 to} 1b ₃ are connected respectively. At this time, the physical layer IF unit 1a ₃ and the upper layer IF unit 1b ₃
VCIa, accommodates VPIb / VCIb, ATM switch SW sends the cell VPIa / VCIa to the line L ₁₂ through the upper layer IF unit 1b _1, VPIb / VCIb
The cell through the upper layer IF section 1b ₂ is transmitted to the line L _22. In such a state, the VC connection VPI
When the upper layer IF section 1b ₃ fails only a / VCIa, the controller CNT, as shown in FIG. 3 by controlling the connection unit 1c (b), the physical layer IF section 1a ₃
The connection to another upper layer IF section 1b ₄ with bandwidth to spare only for connection VPIa / VCIa.
Note that the physical layer IF unit 1a ₃ is still connected to the upper layer IF unit 1b ₃ for the connection VPIb / VCIb.
Connect to Next, the control device CNT switches the intra-switch route of the VC connection VPIa / VCIa as shown by a dotted line. By doing so, the upper layer I
Even if a failure occurs only in a specific connection in the F unit, communication can be continued via another upper layer IF unit having a sufficient band.

(B) Embodiment (a) Overall Configuration FIG. 4 is a configuration diagram of an ATM switching system according to the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals. SW is the ATM switch, MUX / DMUX for switching the route of the cell multiplexing cells from the line side, demultiplexer for separating the cells from the switch side, LIF is line interface device, a predetermined line L _11, L _21, separates the ATM cells from the input signal from the L _31, performs predetermined processing to the cell, and transmitted to the demultiplexer MUX / DMUX, the payload portion of the line signal the cell inputted from the demultiplexing unit And sends it to another line L ₁₂ , L ₂₂ , L ₃₂ . CNT is an ATM switch SW, a demultiplexing unit MUX / DMUX, a control device for controlling the line interface device LIF, MT
R is a maintenance terminal.

In the line interface device LIF,
1a₁~ 1a_ThreeIs the connected line L ₁₁, L₁₂L_{twenty one}, L
_{twenty two}L₃₁, L₃₂Physical layer termination processing according to
Physical layer IF section to be executed, 1b₁~ 1b_FourAre each
Processing (ATM layer termination processing, UPC processing, charging /
ATM layer I that performs NDC processing, OAM processing, etc.)
F section (upper layer IF section), 1c is a predetermined physical layer I
A connection device for connecting between the F section and the ATM layer IF section.
You.

(B) Demultiplexing unit FIG. 5 is a block diagram of the demultiplexing unit MUX / DMUX. 2
a ₁ to 2A region ₄ is VC conversion unit provided corresponding to each ATM layer IF unit 1b ₁ ~1b _4, the input VCI along with adding a tag TAG for routing header of an input cell, included in the header With the output VCI, 2
b _{1 to} 2b ₄ are a tag TAG for routing and an output VC
VC conversion table, 2c are multi-section to be input to the ATM switch SW multiplexes the cells output from the plurality of ATM layer IF unit 1b ₁ ~1b ₄ for storing the I, 2d was switched by the ATM switch SW cell And a predetermined ATM layer IF unit 1 is referred to the tag TAG.
a separating unit for inputting the b ₁ ~1b _4.

(C) Physical Layer IF Units The physical layer IF units 1a _{1 to} 1a ₃ include an ATM layer IF identifier adding unit 21, a VPI / VCI, and a basic configuration unit 11a to 11c as shown in FIG. ATM to send cell to
An ATM layer IF storage unit 22 for storing the correspondence of the layer IF unit is provided. The physical layer termination unit 11c of the basic configuration unit separates the cell (FIG. 7A) mapped to the line signal, and the ATM layer IF identifier adding unit 21 stores the ATM layer IF based on the VPI / VCI of the cell. Part 22
The cell destination ATM layer IF section is obtained from FIG.
As shown in (1), an identifier ID1 for specifying the destination ATM layer IF unit and its own identifier ID2 are added to the header portion, and the header ID is input to the connection device 1c.

(D) ATM Layer IF Unit The ATM layer IF units 1b _{1 to} 1b ₄ are provided with a physical layer IF identifier adding unit 23, a VPI / VCI, and a basic configuration unit 11d to 11g as shown in FIG. Physical layer IF storage unit 24 for storing the correspondence of the cell destination physical layer IF unit
And a failure detection unit 25. The physical layer IF identifier adding unit 24 is an ATM layer terminating unit 11d of the basic configuration unit.
A cell destination physical layer IF section is obtained from the physical layer IF storage section 24 based on the VPI / VCI of the cell output from the cell, and an identifier for specifying the destination physical layer IF section and its own identifier are added to the header section of the cell. And input to the connection device 1c. The failure detection unit 25 compares the number of cells input to the ATM layer IF unit with the number of cells output from the ATM layer IF unit for each of the uplink and downlink paths, detects a cell loss based on a difference in the number of input / output cells, and generates a failure. Is detected. Also, VPI / VC
By similarly comparing the number of input cells and the number of output cells for each I, the occurrence of a failure in a cell having a specific VPI / VCI value is detected.

[0028] (e) when the control normal normal, the connection device 1c, as shown in solid line in FIG. 4, the physical layer IF unit 1a ₁ to 1A ₃ and upper layer IF unit 1b ₁ ~
1b ₃ are connected to each other. That is, the physical layer IF unit 1a ₁ of the ATM layer IF storage unit 22 (FIG. 6) Identifier of the ATM layer IF portion 1b ₁ in response to all input VPI / VCI is stored, likewise, the physical layer IF section 1a _2, 1a ₃ ATM layer IF in the storage unit 22 ATM layer IF unit 1 in response to all input VPI / VCI
The identifiers b ₂ and 1b ₃ are stored. Also, ATM layer IF portion 1b ₁ of the physical layer IF memory section 24 the physical layer IF unit 1 in response to all input VPI / VCI in (Figure 8)
identifier of a ₁ is stored, likewise, the physical layer IF storage unit 24 of the ATM layer IF section 1b _2, 1b ₃ all inputs V
Physical layer IF units 1a ₂ and 1a ₃ corresponding to PI / VCI
Is stored.

The physical layer IF unit 1a ₁ obtains a cell sending destination ATM layer IF portion 1b ₁ in accordance with the VPI / VCI of the cell along with the separation of cell from the line signal from the storage unit 22, thereafter, of the cell the identifier ID1 of the cell transmission destination ATM layer IF portion 1b ₁ adds its own identifier ID2 (see FIG. 7 (b)) is output to the header. Connection device 1c inputs the cell to the ATM layer IF portion 1b ₁ with reference to the identifier. Similarly, the isolated cells in other physical layer IF unit 1a ₂ ~1a _{3 2} corresponding ATM layer IF section 1b ~
Input to 1b _3. ATM layer IF unit 1b ₁ ~1b ₃ is subjected to predetermined processing to an input cell demultiplexer MUX / DM
Output to UX. The demultiplexing unit MUX / DMUX adds a routing tag TAG to an input cell and inputs VC.
I is replaced by the output VCI, after which the cells are multiplexed and input to the ATM switch SW. The ATM switch SW switches cells based on the tag TAG added by the demultiplexing unit and inputs the cells to a predetermined demultiplexing unit MUX / DMUX. Demultiplexing unit while separating the cell inputted from the ATM switch SW, and outputs based on the tag attached to the cell in a predetermined ATM layer IF unit 1b ₁ ~1b _3. As described above, for the physical layer IF unit 1a ₃ and the ATM layer IF unit 1b ₃ , cells are routed as shown by dotted lines A and B in FIG. 4, for example.

[0030] After the ATM layer IF unit 1b ₁ is executing the predetermined process, VPI / VC added to the cell header
The cell sending destination physical layer IF unit 1a ₁ corresponding to I obtained from the storage unit 24. Thereafter, and outputs the added and cell transmission destination physical ID ID1 Layer IF unit 1a ₁ found the header of the cell self-identifier ID2 (see FIG. 7 (b)). Connection device 1c inputs the cell to the physical layer IF section 1a ₁ by referring to the identifier. Similarly, other ATM layer IF units 1
The cells output from b _{2 to} 1b ₃ correspond to the corresponding physical layer I
Input to the F unit 1a ₂ ~1a _3.

(F) First Control at the Time of Failure Occurrence FIG. 9 is a processing flow when a failure occurs in the ATM layer IF unit. When a failure occurs in a predetermined ATM layer IF unit, the occurrence of the failure is detected by the failure detection unit 25 (FIG. 8) and notified to the control device CNT (step 10).
1). The control device CNT confirms the number of connections accommodated in the faulty ATM layer IF section (step 102). Next, the control unit CNT sets 1 → i, and obtains the bandwidth u of the i-th connection accommodated in the faulty ATM layer IF unit with reference to the declared bandwidth value of each call declared at the time of call processing (step 104). Thereafter, a new A having an allocatable band larger than the band u
Check whether a TM layer IF section exists (step 10).
5). The control device CNT is connected to each ATM layer IF unit 1b ₁
１1b _{4 Since} the physical band a, the actual used band b, and the available band c (= ab) are managed in the memory, the available band is larger than the band u by referring to the memory. Check whether there is an ATM layer IF unit having c. If it does not exist, it is displayed on the maintenance terminal MTR that the repair is impossible (step 106).

On the other hand, if there is another ATM layer IF unit having an allocatable band c larger than the band u, the AT
The route in the M switch is switched to the ATM layer IF unit (step 107). The route replacement is performed as follows. (1) When the i-th connection is in the upstream direction: Failure A
VC conversion information corresponding to the i-th connection is obtained from the VC conversion table 2b ₁ (FIG. 5) corresponding to the TM layer IF section, and the VC conversion information is converted to the VC conversion table 2b corresponding to the another ATM layer IF section. to move to _1. (2) When the i-th connection is in the downstream direction: In the VC conversion table, VC conversion information having the VCI value of the i-th connection as the output VCI and having the tag value for the faulty ATM layer IF section as the tag. Searching the tag of the VC conversion information to the another ATM layer IF
Change to the tag value for the department.

Thereafter, the control device CNT starts the connection device 1
c, for the i-th connection, the physical layer IF
The change of the connection between the unit and the ATM layer IF unit is instructed (step 108). In response to the connection instruction, when the i-th connection is an uplink connection, the connection device 1c notifies the specified physical layer IF unit of the VPI / VCI and the new connection destination ATM layer IF unit. The physical layer IF unit stores the identifier of the connection destination ATM layer IF unit in association with the VPI / VCI notified to the storage unit 22 (FIG. 6). On the other hand, when the i-th connection is a downlink connection, the connection device 1c transmits the VPI to the designated ATM layer IF unit.
/ VCI and a new connection destination physical layer IF unit.
The ATM layer IF unit stores the identifier of the connection destination physical layer IF unit in association with the VPI / VCI notified to the storage unit 24 (FIG. 8).

As described above, the i-th connection (V
If the processing for the C connection or the VP connection is completed, it is determined whether or not the above processing has been completed for all connections (step 109). If not completed, i is incremented (step 110).
The process after 04 is repeated. Accordingly, in the state of FIG. 4, when a failure occurs in the ATM layer IF unit 1b ₃ 9
According to the processing flow of (1), switching of the ATM layer IF unit and switching of the switch-side path are performed, and communication continues. That is, when a failure occurs in the ATM layer IF section 1b _3, the failure is reported to the controller CNT is detected by the failure detecting unit 25 (FIG. 8). Control device CNT
The physical band a of the ATM layer IF unit 1b ₁ ~1b _4,
The actual used bandwidth b, because managing the assignable bandwidth c, the bandwidth to determine the different ATM layer IF section 1b ₄ normal can afford a failure notification.

Next, the control unit CNT sets the fault occurrence AT
The contents of the VC conversion table 2b ₁ (see FIG. 5) corresponding to the M layer IF unit 1b ₃ and the another ATM layer IF unit 1b ₄ are changed. For example, the switch-side path of all the connections that are accommodated in the ATM layer IF unit 1 ₃ failed (root of FIG 4 A, B) is the root A of FIG. 10 ',
Switch to B '. This switching is performed as follows. (1) change of the uplink connection (A → A change of '): failure ATM layer IF section VC conversion table 2b that the contents of the VC conversion table 2b ₁ corresponding to 1b ₃ corresponding to the new ATM layer IF section 1b ₄ to move to _1. (2) Downlink change (change from B to B '): all V
To change the tag value of the failed ATM layer IF section 1b ₃ friendly held in C conversion table tag value of a new ATM layer IF section 1b for _4.

Thereafter, the control device CNT connects to the connection device 1c.
And instructs the connection between the physical layer IF unit 1a ₃ and the ATM layer IF section 1b ₄ in. By this connection instruction, the connection device 1c
And notifies the destination ATM layer IF section 1b ₄ The physical layer IF unit 1a _3. Physical layer IF unit 1a ₃ storage unit 22
Storing an identifier of the ATM layer IF section 1b ₄ notified (FIG. 6). The connection device 1c notifies the destination physical layer IF unit 1a ₃ to the ATM layer IF section 1b _4. AT
M layer IF section 1b ₄ stores the identifier of the storage unit 24 the physical layer IF unit 1a ₃ is notified (FIG. 8).

As described above, the physical layer 1a ₃ adds the identifier of the ATM layer IF section 1b _{4 to} the cell header and inputs the cell header to the connection device 1c. Connection device 1c enter the cell by referring to the identifier in the ATM layer IF section 1b _4, ATM layer IF section 1b ₄ is input to the demultiplexing unit MUX / DMUX performs a predetermined process on the cell demultiplexing Department and ATM
The switch routes the cell according to route A '. Further, the demultiplexer MUX / DMUX and ATM switch SW to route the cells of the physical layer 1a ₃ for the ATM layer IF section 1b ₄ according to the route B '. AT
M layer IF section 1b ₄ is input to the connection device 1c by adding an identifier of a physical layer IF unit 1a ₃ in the header of the cell input from the switch side. Connection device 1c inputs the cell to the physical layer IF section 1a ₃ with reference to the identifier.

(G) Second Control at the Time of Failure Occurrence FIG. 11 is a cell switching system for explaining control when a failure occurs in the ATM layer IF section only for a connection having a specific VPI / VCI. Is the processing flow. When a failure occurs in the ATM layer IF unit for a connection having a specific VPI / VCI, the failure is detected by the failure detection unit 25 (FIG. 8) and notified to the control device CNT (step 201).
The control unit CNT obtains the bandwidth u of the failed connection from the declared bandwidth value of each call declared and stored at the time of call processing (step 202), and there is an ATM layer IF unit having an assignable bandwidth larger than the bandwidth u. A check is made as to whether or not to perform (step 203). If it does not exist, it is displayed on the maintenance terminal MTR that it cannot be repaired (step 204).

If there is, the route in the ATM switch is switched to the ATM layer IF section (step 20).
5). The replacement of the path is performed as follows. (1) When the failed connection is in the upstream direction: Failure A
VC conversion information corresponding to the faulty connection is obtained from the VC conversion table 2b ₁ (FIG. 5) corresponding to the TM layer IF unit, and the VC conversion information is converted to a new VC conversion table 2b ₁ corresponding to another ATM layer IF unit. Moving. (2) When the failed connection is in the downstream direction: Search the VC conversion table for VC conversion information having the VCI value of the failed connection as the output VCI and the tag value for the failed ATM layer IF section as a tag. And the tag of the VC conversion information,
Change to the tag value for the department.

Thereafter, the control device CNT starts the connection device 1
Instruct c to change the connection between the physical layer IF unit and the ATM layer IF unit for the faulty connection (step 206). In response to the connection instruction, when the failure connection is an uplink connection, the connection device 1c transmits the VPI / VCI and the new connection destination ATM to the specified physical layer IF unit.
Notify the layer IF section. The physical layer IF unit is the storage unit 2
2 (FIG. 6), the identifier of the connection destination ATM layer IF unit is stored in correspondence with the VPI / VCI notified. On the other hand, if the failed connection is a downlink connection, the connection device 1
“c” notifies the instructed ATM layer IF unit of the VPI / VCI and the new connection destination physical layer IF unit. The ATM layer IF unit outputs the VPI / V notified to the storage unit 24 (FIG. 8).
The identifier of the connection destination physical layer IF unit is stored in association with the CI.

As described above, the predetermined VPI / VCI connector
A failure has occurred in the ATM layer IF
The connection device 1c changes the cell only for the connection.
Input to another ATM layer IF unit with sufficient bandwidth
You. For example, in a normal state, the connection device 1c is as shown in FIG.
The physical layer IF unit 1a ₁~ 1a_ThreeAnd upper layer IF section
1b₁~ 1b_ThreeAre connected to each other. In addition, physical
Ear IF section 1a_ThreeAnd ATM layer IF unit 1b_ThreeIs VC
Connection VPIa / VCIa, VPIb / VCIb
Multiplexing / demultiplexing unit MUX / DMUX and ATM switch
Switch SW is the ATM layer IF unit 1b_ThreeThrough these connectors
Cell of VPIa / VCIa
Is the line L₁₂And transmit VPIb / VCIb cells to the line
L_{twenty two}To send to.

In this state, the connection VPI
when a failure occurs in the ATM layer IF section 1b ₃ for a / VCIa, the controller CNT is the connection VPI
Request ATM layer IF section 1b ₄ having a band u greater than the available bandwidth of a / VCIa. Next, the control device CNT switches the intra-switch route of the VC connection VPIa / VCIa as shown by a dotted line A in FIG. 13, and then controls the connection device 1c to control the physical layer IF unit 1a.
₃ to connect the upper layer IF section 1b ₄ with bandwidth to spare only for connection VPIa / VCIa.
Note that the physical layer IF unit 1a ₃ is still connected to the upper layer IF unit 1b ₃ for the connection VPIb / VCIb.
Connect to By doing so, the cells of the VC connection VPIa / VCIa are thereafter stored in the physical layer IF unit 1a.
₃ → connection device 1c → ATM layer IF section 1b ₄ → demultiplexer, is transmitted to the line L ₁₂ through the ATM switch → ATM layer IF unit 1b _1. That is, the ATM layer IF
Even if a failure occurs only in a specific connection in the unit, communication can be continued via the upper layer IF unit having sufficient bandwidth.

(C) Specific Example (a) When a Failure Occurs in the ATM Layer FIGS. 14 and 15 show specific examples in which a failure occurs in the ATM layer.
F means an ATM layer IF unit. As shown in FIG. 15, a path α is formed between users A and B, and a path β is formed between users B and C. User A is connected to the physical layer IF unit PHIF # 0 and ATM layer IF unit ATIF # 5 by the connection device 1c, and user B is connected to the physical layer IF unit
The user C is connected to the physical layer IF unit PHIF # 7 and the ATM by the connection device 1c.
It is connected to the layer IF unit ATIF # 10 by the connection device 1c.

The path α is a 45 Mbps path, and the user A → the physical layer IF unit PHIF # 0 → the connection device 1c → the ATM
Layer IF unit ATIF # 5 → demultiplexing unit, ATM switch → AT
M layer IF unit ATIF # 8 → connection device 1c → physical layer IF
The section PHIF # 4 has a route of user B. Although 16/32 is added to the input cell as the VPI / VCI value,
The multiplexing / demultiplexing unit replaces the data with 48/128 and sends it. Path β is a 32 Mbps path, and the user C → the physical layer IF unit PHIF # 7 → the connection device 1c → the ATM layer I
F unit ATIF # 10 → demultiplexing unit, ATM switch → ATM layer IF unit ATIF # 8 → connection device 1c → physical layer IF unit PHIF # 4
→ It has the route of user B. VPI in input cell
Although 64/84 is added as the / VCI value, it is changed to 32/64 by the demultiplexing unit and transmitted.

When a failure occurs in the ATM layer IF unit ATIF # 8, as shown in FIG.
The physical layer IF unit PHIF # 4 and the ATM layer IF unit ATIF # 12 are connected instead of the connection between the TM layer IF units ATIF # 8, and the paths α and β change to paths α ′ and β ′, respectively. I do. That is, the path α 'is defined as follows: user A → physical layer IF unit PHIF # 0 → connection device 1c → ATM layer IF unit ATIF
# 5 → Demultiplexing unit, ATM switch → ATM layer IF unit ATI
The route changes from F # 12 → connection device 1c → physical layer IF unit PHIF # 4 → user B route. The path α ′ connects the users A and B similarly to the path α, so that communication between the users A and B can be continued. Also, the path β ′ is user C → physical layer IF unit PHIF
# 7 → connection device 1c → ATM layer IF unit ATIF # 10 → multiplexing / demultiplexing unit, ATM switch → ATM layer IF unit ATIF # 12 → connection device 1c → physical layer IF unit PHIF # 4 → user B route. The path β ′ is the same as the path β,
Since the connection between B and B is established, the communication between them can be continued.

(B) When a Failure Occurs for a Specific Connection FIG. 16 shows an ATM layer IF for a specific connection.
This is a specific example in the case where a failure occurs in a unit, where PHIF means a physical layer IF unit and ATIF means an ATM layer IF unit. In the state shown in FIG.
Assume that a failure has occurred in the connection of VPI / VCI = 32/64 in the unit ATIF # 10. In such a case, FIG.
As shown in the figure, for the connection of VPI / VCI = 32/64, the physical layer IF unit PHIF # 4 and the ATM layer IF
Instead of the connection between the units ATIF # 8, the physical layer IF unit PHIF # 4 and the ATM layer IF unit ATIF # 12 are connected, and the path β changes to a path β ′. That is, the path β ′ is determined by the user C →
Physical layer IF unit PHIF # 7 → Connection device 1c → ATM layer IF unit ATIF # 10 → Demultiplexer / ATM switch → ATM layer IF unit ATIF # 12 → Connection device 1c → Physical layer IF unit PHI
F # 4 → changes to the route of user B. The path β 'holds the path between the users C and B, and the communication can be continued.

(D) Modified Example The case where the connection between the physical layer IF unit and the ATM layer IF unit is automatically switched under the control of the control device CRT when a failure occurs has been described. Instructs the connection between the physical layer IF section and the normal ATM layer IF section by a command, and in accordance with the instruction, the control device controls the connection device to connect the specified physical layer IF section to the normal upper layer IF section. It can also be configured to do so. In the above, three physical layer IF units, A
Although the case where four TM layer IF units are illustrated has been described, the physical layer IF unit and the ATM layer IF
The number of parts may be the same, and the number is arbitrary. As described above, the present invention has been described with reference to the embodiments. However, the present invention can be variously modified in accordance with the gist of the present invention described in the claims, and the present invention does not exclude these.

[0048]

As described above, according to the present invention, the line interface section is divided into a physical layer IF section and an upper layer IF section, and a connection device connects an arbitrary physical layer IF section to an arbitrary upper layer IF section. With this configuration, even if a failure occurs in the ATM layer IF unit, another physical A
By connecting to the TM layer IF unit, data communication between users can be continued.

According to the present invention, when only a specific connection accommodated in a certain ATM layer IF unit has an abnormality, only the abnormal layer connection of the ATM layer IF
Since the unit is changed, communication of an abnormal connection can be continued without affecting communication of another normal connection. According to the invention, the upper layer I
Even if a failure occurs in the F section or a specific VPI / VCI
Even if a failure occurs in the upper layer IF section for the connection, another ATM layer IF section having a sufficient band can be used. Therefore, even if a failure occurs without using the operation / spare duplication method. Can guarantee data communication.

[Brief description of the drawings]

FIG. 1 is a first schematic explanatory diagram of the present invention.

FIG. 2 is an explanatory diagram of a physical layer IF unit and an upper layer IF unit.

FIG. 3 is a second schematic explanatory diagram of the present invention.

FIG. 4 is a configuration diagram of an ATM switching system of the present invention.

FIG. 5 is a configuration diagram of a demultiplexing unit.

FIG. 6 is a configuration diagram of a physical layer IF unit.

FIG. 7 is an explanatory diagram of a configuration of an ATM cell.

FIG. 8 is a configuration diagram of an ATM layer IF unit.

FIG. 9 is a processing flow when a failure occurs in an ATM layer IF unit.

FIG. 10 is a diagram illustrating the operation of the present invention.

FIG. 11 is an explanatory diagram of control when a failure occurs in a specific connection.

FIG. 12 is a processing flow when a failure occurs in a specific connection.

FIG. 13 is an explanatory diagram of control when a failure occurs in a specific connection.

FIG. 14 is a specific example (part 1) when a failure occurs in the ATM layer IF unit.

FIG. 15 is a specific example (part 2) when a failure occurs in the ATM layer IF unit.

FIG. 16 is a specific example when a failure occurs in a specific connection.

FIG. 17 is a configuration diagram of an ATM switching system.

FIG. 18 is a configuration diagram of an ATM cell.

FIG. 19 is a configuration diagram of a line interface.

FIG. 20 is an explanatory diagram of a SONET STS-3C frame format.

FIG. 21 is another configuration diagram of a line interface.

FIG. 22 is a configuration diagram of an ATM switch.

FIG. 23 is an explanatory diagram of a problem of a conventional line interface.

[Explanation of symbols]

SW · · cell switch LIF · · line interface unit CNT · · controller 1a ₁ ~1a ₃ ·· physical layer IF unit 1b ₁ ~1b ₄ ·· upper layer IF section 1c · · connecting device

Claims (13)

[Claims] A cell is separated from a signal input from a predetermined line, and after performing predetermined processing on the cell, the cell is transmitted to a switch, and the cell input from the switch is mapped to a payload portion of a line signal to be separated. A plurality of physical layer IF units each performing a physical layer termination process according to a line signal, a plurality of upper layer IF units each performing a common upper layer termination process and the like, A line interface device comprising a connection device for connecting a predetermined physical layer IF unit and an upper layer IF unit. 2. A physical layer IF unit for executing a physical layer termination process according to an optical signal, and a physical layer IF unit for executing a physical layer termination process according to an electric signal.
A line interface device as described. 3. The physical layer IF unit adds an identifier for specifying an upper layer IF unit of a connection destination to a header of a cell separated from a line signal, and the connection device refers to the identifier to determine a cell in a predetermined upper layer layer. Input to the IF section, the upper layer IF section adds an identifier for specifying the physical layer IF section to be connected to the header of the cell input from the switch, and the connection device refers to the identifier to refer to the cell to a predetermined physical layer. 2. The line interface device according to claim 1, wherein the signal is input to an IF unit. 4. When a failure occurs in the upper layer IF section, the connection device connects the physical layer IF section connected to the upper layer IF section to another normal upper layer IF section having sufficient bandwidth. The line interface device according to claim 1, wherein 5. When a failure occurs in an upper layer IF section only for a predetermined connection, the connection device has a spare band in the physical layer IF section connected to the upper layer IF section only for the connection. 2. The line interface device according to claim 1, wherein the line interface device is connected to another upper layer IF unit. 6. A cell switching system, comprising: a cell switch for switching a cell route on a cell basis; a cell separating from a signal input from a predetermined line, performing a predetermined process on the cell, and A line interface device for transmitting and mapping the cells input from the cell switch to the payload portion of the line signal and transmitting to another line; and a control device for controlling the cell switch and the line interface device. (1) a plurality of physical layer IF units that execute physical layer termination processing according to the line signal;
(2) a plurality of upper layer IF sections for executing common upper layer termination processing and other processing, and (3) a connection device for connecting a predetermined physical layer IF section and the upper layer IF section, , When a failure occurs in the upper layer IF unit,
The connection device is controlled to switch the physical layer IF unit connected to the upper layer IF unit to another upper layer IF unit having a sufficient bandwidth, and to execute the connection of the connection accommodated in the physical layer IF unit. A cell switching system for switching a route in a switch. 7. A table storing, on the switch side, a correspondence between a VCI value of a cell input from the upper layer IF unit and a tag for determining a cell output route, corresponding to the upper layer IF unit, and the table. And a tag adding means for adding a tag to the input cell, the control device moves the contents of the table corresponding to the upper layer IF unit in which the failure has occurred to a table corresponding to the another upper layer IF unit, 7. The cell exchange according to claim 6, wherein in all the tables, a route in the switch is switched by changing a tag value for the upper layer IF unit in which the failure has occurred to a tag value for the another upper layer IF unit. system. 8. The control device manages an available bandwidth of an upper layer IF unit, and has, for each connection accommodated in the failed upper layer IF unit, an assignable bandwidth wider than the bandwidth of the connection. 7. The cell switching system according to claim 6, wherein another upper layer IF section is obtained, and for each connection, the physical layer IF section is connected to the obtained upper layer IF section. 9. A cell switching system, comprising: a cell switch for switching a cell route on a cell basis; a cell separated from a signal input from a predetermined line, and a predetermined process performed on the cell; A line interface device for transmitting and mapping cells input from the cell switch to a payload portion of a line signal and transmitting to another line, a control device for controlling the cell switch and the line interface device, and a maintenance terminal. The interface device includes: (1) a plurality of physical layer IF units each performing a physical layer termination process according to a line signal; and (2) a plurality of upper layer IF units each performing a common upper layer termination process and other processes. And (3) a connection device for connecting a predetermined physical layer IF section and an upper layer IF section, and a physical The control unit instructs connection between the IF unit and the normal upper layer IF unit, and controls the connection device to connect the physical layer IF unit and the normal upper layer IF unit specified by the maintenance terminal. Cell switching system. 10. A cell switching system, comprising: a cell switch for switching a cell route on a cell-by-cell basis; separating a cell from a signal input from a predetermined line, performing predetermined processing on the cell, and A line interface device for transmitting and mapping the cells input from the cell switch to the payload portion of the line signal and transmitting to another line; and a control device for controlling the cell switch and the line interface device. (1) A plurality of physical layers I each executing a physical layer termination process according to a line signal
F section; (2) a plurality of upper layer IF sections each performing common upper layer termination processing and other processing; and (3) a connection device for connecting a predetermined physical layer IF section and the upper layer IF section. When a failure occurs in the upper layer IF section only for a predetermined connection, the control device changes the physical layer IF section connected to the upper layer IF section to another upper layer having a sufficient bandwidth in connection with the connection. A cell switching system connected to a layer IF unit via the connection device, and switching a route of the connection in a switch. 11. The control device manages an available bandwidth of an upper layer IF unit, obtains another normal upper layer IF unit having an available bandwidth wider than the bandwidth of the connection, and obtains a physical layer IF for the connection. 11. The cell switching system according to claim 10, wherein a unit is connected to said another upper layer IF unit. 12. A table for storing, on the switch side, a correspondence between a VCI value of a cell input from the upper layer IF unit and a tag for determining a cell output route, corresponding to the upper layer IF unit, and the table. And a tag adding means for adding a tag to the input cell, and the control device moves the correspondence between the VCI value of the faulty connection and the tag to a table corresponding to the another upper layer IF unit, and switches the route in the switch. The cell switching system according to claim 10, wherein the cell switching system is switched. 13. The physical layer IF unit includes a VPI / V
A table for storing a correspondence between the CI and an identifier for specifying the upper layer IF unit, and adding an identifier for specifying the cell destination upper layer IF unit to the cell header with reference to the table; 11. The cell switching system according to claim 10, wherein an identifier corresponding to a VPI / VCI value of a connection in which a failure has occurred is changed to an identifier of said another upper layer IF unit.