JP2702429B2 - VPI conversion method in ATM subscriber line terminal equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an ATM (Asynch).
VPI (Virtual Path Iden) in a robust Transfer Mode (communication device) communication device
tiffer) conversion method, especially ATM-PDS
ATM connected to one or more network terminating devices using (Passive Double Star) method
V in ATM subscriber line terminal equipment accommodating subscriber lines
It relates to a PI conversion method.

[0002]

2. Description of the Related Art ATM connected one-to-one with a network terminator
In the ATM subscriber line terminal equipment accommodating the subscriber line interface, among the VPI data constituting the header portion of the transmitted ATM cell data, the UNI (User)
Network Interface) 8
Bits of VPI data and NNI (Network N
The conversion is performed between 12-bit VPI data defined by the "mode." Also, AT
In the ATM relay system which relays ATM cell data from the M subscriber line terminal equipment, since the input / output interfaces are all NNI, the input 12-bit input-side VPI data is converted and output to 12-bit. It is output as side VPI data.

[0003] On the other hand, in an ATM subscriber line terminal device which accommodates an ATM subscriber line interface connected to one or a plurality of network terminating devices using an ATM-PDS system, a currently effective VPI conversion method is used. Has not been established.
However, for example, the identification information from the network termination device is transferred to the VPI conversion circuit via a line separate from the signal line for transmitting the main signal, and the transferred identification information is used as a search address of the VPI conversion circuit. It is conceivable that the output of the VPI conversion circuit converts the VPI in the ATM cell data which is the main signal transmitted via the signal line.

[0004]

In such a conventional method, the ATM relay system requires a VPI conversion circuit for converting from 12 bits to 12 bits, and is connected to the network terminating device on a one-to-one basis. An ATM subscriber line interface requires 8-bit and 12-bit VPI conversion circuits. Also, in an ATM subscriber line interface connected to one or a plurality of network terminating devices using the ATM-PDS method, if the number of bits of identification information is different, a VPI conversion circuit corresponding to the different number of bits is required. From that
A VPI conversion circuit corresponding to each interface used in the ATM communication device is required, and there is a problem that it is uneconomical to configure the device. Accordingly, it is an object of the present invention to economically configure a device so that a common VPI conversion circuit can be used for each interface in an ATM communication device.

[0005]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention provides an ATM-P on an upstream line from a network termination device in a subscriber interface to an ATM switch.
ATM transmitted from network terminating equipment based on DS system
An ATM-PDS termination unit for terminating the cell data and detecting network termination device identification information in the received ATM cell data; an identification information conversion unit for converting the detected network termination device identification information into a 4-bit identification number; A GFC area conversion unit for writing the converted identification number into the GFC area in the ATM cell data, a 4-bit GFC area identification number and UNI
NN from the 8-bit first VPI data defined by
A conversion table for converting into 12-bit second VPI data defined by I, a VPI conversion unit for writing the second VPI data in the GFC area and the first VPI data area in the ATM cell data, and An identification number detector for detecting the identification number of the GFC area in the ATM cell data on the down line from the ATM switch in the subscriber interface to the network terminating device side, and the detected identification number as AT
An identification number conversion unit for converting the network termination device identification information defined by the M-PDS system, and an ATM-PDS configuration unit for writing the converted network termination device identification information into ATM cell data and outputting the ATM cell data as a frame of the ATM-PDS system Are provided. In addition, the above-mentioned identification number detection unit and identification number conversion unit are provided in the intra-office interface, and an ATM-PDS configuration unit is provided on the down line from the ATM switch in the subscriber interface to the network terminating device side.

[0006]

The network termination unit identification information obtained by terminating the frame or overhead information as ATM cell data from the network termination unit based on the ATM-PDS system is converted into a 4-bit identification number and written into the GFC area. At the same time, the identification number in the GFC
It is converted into network termination device identification information defined by TM-PDS and transmitted. As a result, at the ATM subscriber line interface connected to one or more network terminating devices by using the ATM-PDS method, even if the number of bits of the identification information is different, it is converted into a 4-bit identification number. Therefore, a common VPI conversion circuit can be used. Also, U
4-bit GF in the first VPI data defined by the NI
Since the conversion process is performed as pseudo 12 bits by adding C data, a common VPI conversion circuit can be used in each interface in the ATM communication device.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ATM subscriber line terminal to which the present invention is applied. In the figure, 1 is A
A TM Line Termination, ATM Line Termination 1, subscriber line interface 11 _1, 11 _2, ATM
It comprises a switch 12, an intra-station interface 13 ₁ , 13 _{2 and the} like. Here, each subscriber line interface 11 ₁ , 1
1 ₂ is connected to the optical passive elements 2 ₁ and 2 ₂ , respectively. Optical passive element 2 ₁ The network terminating device 3 ₁₁ to 3 ₁₃ ATM-
Star connection is performed based on the PDS system, and the star-connected network terminating devices 3 _{11 to} 3 ₁₃ are connected to respective subscriber terminals via respective subscriber lines. Also, optical passive element 2 ₂ is star-connected in the same manner as the network terminating device 3 _21, 3 _22, each network terminating device 3 ₂₁ are star connected, 3 ₂₂ connected to the subscriber terminals via a respective subscriber line Have been. On the other hand, the intra-office interfaces 13 ₁ and 13 ₂ are connected to, for example, an ATM relay system not shown.

[0008] Each subscriber line interface 11 ₁ , 11 ₂
The, VPI conversion circuit described below for converting a VPI data in the ATM cell data is provided to be transmitted to each optical passive element 2 _1, 2 ₂ ATM switch 12 side from the network terminating device side through the. FIG. 5 shows the subscriber line interface 11.
₁ is a diagram showing a format of a header portion of the ATM cell data received by the 11 _2. In FIG.
As an area of the TM cell header, a 4-bit GFC (Generic Flow C) is sequentially arranged from the first byte.
control area, an 8-bit (1 byte) VPI area, and a 16-bit (2 byte) VCI (Virtual) area.
Channel Identifier area, 3-bit PT (Payload Type) area, 1-bit CLP (Cell Loss Priority)
Area, 8-bit HEC (Header Error)
Control area is allocated. Subsequent to the ATM cell header, a subscriber voice or data area called a 48-byte payload is added to form a series of ATM cell data.

FIG. 4 shows an intra-station interface 13 ₁ ,
13 ₂ and AT are transmitted in ATM relay units to be connected
It is a figure showing the format of an M cell header. here,
The difference from the format shown in FIG. 5 is that the format shown in FIG. 4 has a 12-bit VPI area from the first byte, whereas the format shown in FIG. , An 8-bit VPI area. For this reason, when converting data having VPI areas of different numbers of bits, two types of VPIs of 8 bits and 12 bits are stored in the device.
Since a conversion circuit is required, the present invention sets an identification number in the GFC area shown in the format of FIG.
Is converted into a format as shown in FIG.
To support VPI data in the format specified by

That is, in the ATM subscriber terminal 1, the GF
Paying attention to the fact that data in the C area is unnecessary, by setting an identification number in the GFC area and making the VPI data pseudo 12 bits, the ATM cell header to the intra-office interface 13 side in the subscriber line interface 11 can be obtained. VPI conversion circuit for converting the
And a common VPI conversion circuit for converting the ATM cell header to the subscriber interface 11 side.

FIG. 2 is a block diagram of a VPI conversion circuit showing a main part of the present invention, which is provided in the subscriber line interface 11. In this figure, the VPI conversion circuit 11A is connected to an upstream line extending from the transmission line side to the inside of the device.
1, GFC area conversion section 112, identification information conversion section 113,
A VPI conversion table 114 and a VPI conversion unit 115 are provided. In addition, an identification number detection unit 116, an identification number conversion unit 117, and an ATM-PDS configuration unit 118 are provided on the downstream line extending from the inside of the device to the transmission line side.

Next, the operation of the VPI conversion circuit 11A configured as described above will be described. First, the conversion operation of the ATM cell data transmitted from the transmission line side (that is, the network terminating device 3 side) to the inside of the device (that is, the ATM switch 12 side) on the up line will be described. The ATM cell data a, which is the main signal transmitted from the transmission path side, is terminated by the ATM-PDS terminating unit 111 and identification information for identifying the network terminating device 3 defined in the frame of the ATM-PDS system. b is extracted for each ATM cell. And A
Identification information b extracted by TM-PDS termination section 111
Is converted by the identification information conversion unit 113 into a coded identification number c represented by 4 bits, and the GFC area conversion unit 1
It is sent to 12. In the GFC area conversion unit 112, the ATM
-Write the identification number c in the GFC area in the ATM cell data d sent by extracting the identification information a by the PDS terminating unit 111 and send it out as the ATM cell data e.

Here, the 4-bit identification number c and the 8-bit VPI data (first VPI data) of the header portion in the ATM cell data e are extracted as 12-bit data f and input to the VPI conversion table 114. Is done. V
The PI conversion table 114 uses the input 12-bit data f as a search address and outputs a 12-bit VPI value g (second VPI data) on the intra-office interface 13 side to the VPI conversion unit 115. VPI converter 1
15 writes the VPI value g converted by the VPI conversion table 114 into the upper 12-bit area of the ATM cell data e sent from the GFC area conversion unit 112;
It is transmitted to the ATM switch 12 as TM cell data h.

Next, ATM cell data j transmitted from the inside of the device via the down line to the transmission line side is ATM-P
While being directly input to the DS composing unit 118,
The header k in the TM cell data j is the identification number detector 116.
Is input to The identification number detector 116 extracts a 4-bit identification number m from the input header k and sends it to the identification number converter 117. Upon input of the 4-bit identification number m, the identification number conversion unit 117 converts it into identification information n for identifying the network terminating device 3 defined in the frame of the ATM-PDS system, and converts it into the ATM-PDS configuration unit 118. Send to
The ATM-PDS forming unit 118 forms an ATM-PDS frame based on the input ATM cell data j and identification information n, and outputs the ATM-PDS frame to the transmission line side as ATM cell data p. In this way, the VPI data located in the header portion of each of the upstream and downstream ATM cell data is converted in the subscriber line interface 11.

FIG. 6A shows the relationship between input information (ie, a search address) and output information (ie, an output VPI value) when accessing the VPI conversion table 114 described above. In FIG. 6A, the input information and the output information are both 12 bits, and the upper four bits of the input information, G,
An identification number for identifying the network terminating device corresponds to the FC area.

FIG. 6B shows an intra-office interface 1.
3 shows the relationship between input information (retrieval address) when accessing a VPI conversion table (not shown) and output information output from this table. In this table as well, both input and output information are 12 bits. ing. Here, the GFC area of the output information outputted from the table, network terminating device 3 ₁₁ connected via an optical passive element 2 ₁ and 2 ₂ and the subscriber line interface 11 ₁ and 11 ₂
To 3 ₁₃ and 3 _21, 3 ₂₂ identification number for identifying it is written, via the ATM switch 12, and output as ATM cell data j shown in FIG. 2 described above.

As described above, since the GFC data is unnecessary in the ATM subscriber terminal device 1, the ATM-
In a subscriber line interface connected to a plurality of network terminating devices to which the PDS method is applied, a 4-bit coded identification number for identifying each network terminating device is written in the GFC area, and an 8-bit VPI area and The VPI data of the subscriber line interface 11 is simulated to be 12 bits by simultaneously handling the 4-bit GFC area. As a result, the VPI conversion circuit of the device
Similarly to the VPI conversion circuit used in the M relay system, both input and output VPI data can be converted as 12-bit data.
And a common VPI conversion circuit can be used for the ATM relay system device.

In this embodiment, the subscriber line interface 11 is provided with the identification number detecting unit 116 and the identification number converting unit 1.
17 for detecting the identification number m output from the intra-office interface 13 and converting it into identification information n.
The S-configuration unit 118 outputs the ATM-PDS frame as an ATM-PDS frame. However, an identification number detection unit and an identification number conversion unit are provided on the intra-office interface 13 side. It may be configured to transmit the data to the ATM-PDS composing unit 118 in the subscriber interface 11 through the communication interface 12.

[0019]

As described above, according to the present invention, A
The network termination unit identification information obtained by terminating the frame or overhead information, which is the ATM cell data from the network termination unit based on the TM-PDS system, is converted into a 4-bit identification number and written into the GFC area. For the termination device, the identification number in the GFC area is assigned to the ATM-PDS.
The ATM subscriber line interface connected to one or a plurality of network terminating devices using the ATM-PDS method is converted to the network terminating device identification information defined in the above. Even if the number of bits is different, it is converted into a 4-bit identification number, so that a common VPI conversion circuit can be used. Further, since 4-bit GFC data is added to the first VPI data defined by the UNI and the conversion processing is performed as pseudo 12-bit data, a common VPI conversion circuit is used in each interface in the ATM communication device. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ATM subscriber line terminal equipment.

FIG. 2 is a block diagram showing a configuration of a VPI conversion circuit in the device.

FIG. 3 is a diagram showing a conversion example of the format of an ATM cell header when the present invention is applied.

FIG. 4 is a diagram showing a format of an ATM cell header defined by NNI.

FIG. 5 is a diagram showing a format of an ATM cell header specified by UNI.

FIG. 6 is a diagram showing the input / output status of a VPI conversion table in a VPI conversion circuit.

[Explanation of symbols]

1 ... subscriber line terminal equipment, 2 ₁ , 2 ₂ ... optical passive element, 3 ₁₁
... 3 ₁₃ , 3 ₂₁ , 3 ₂₂ ... Network terminator, 11 ₁ , 11 ₂ ... Subscriber line interface, 11 A.
... ATM switches, 13 ₁ , 13 ₂ ... Inter-office interfaces, 111 ... ATM-PDS terminators, 112 ... GFC area converters, 113 ... Identification information converters, 1114 ... VPI
Conversion table, 115: VPI conversion unit, 116: identification number detection unit, 117: identification number conversion unit, 118: ATM-
PDS component.

Claims (2)

(57) [Claims] 1. A subscriber line interface connected to at least one or more network terminating devices to which the ATM-PDS system is applied, an intra-station interface connected to an ATM relay system, etc., a subscriber interface and an intra-station interface. And an ATM switch for converting VPI data in the transmitted ATM cell data.
In the subscriber line terminal device, the ATM cell data transmitted from the network terminating device side based on the ATM-PDS system is terminated and received on the up line from the network terminating device in the subscriber interface to the ATM switch side. An ATM-PDS termination unit for detecting the network termination device identification information in the ATM cell data, an identification information conversion unit for converting the detected network termination device identification information into a 4-bit identification number, and transmitting the converted identification number to an ATM. A 12-bit second VPI defined by the NNI from a GFC area conversion unit that writes to the GFC area in the cell data, and the 8-bit first VPI data defined by the UNI and the 4-bit GFC area identification number A conversion table for converting to data,
A VPI conversion unit for writing the second VPI data in the GFC area and the first VPI data area in the ATM cell data, and an ATM line in the subscriber interface to the downstream line from the ATM switch to the network terminator. An identification number detection unit for detecting an identification number of a GFC area in cell data, an identification number conversion unit for converting the detected identification number into network termination device identification information defined by the ATM-PDS method, and a converted network An ATM-PDS component for writing termination device identification information to ATM cell data and outputting it as an ATM-PDS frame, and adding a 4-bit identification number to the first VPI data defined by the UNI to generate pseudo Conversion processing of VPI data as 12 bits to the ATM subscriber line terminal equipment.
I conversion method. 2. A subscriber line interface connected to at least one or more network terminating devices to which the ATM-PDS method is applied, an intra-office interface connected to an ATM relay system or the like, a subscriber interface and an intra-office interface. And an ATM switch for converting VPI data in the transmitted ATM cell data.
In the subscriber line terminal device, the ATM cell data transmitted from the network terminating device side based on the ATM-PDS system is terminated and received on the up line from the network terminating device in the subscriber interface to the ATM switch side. An ATM-PDS termination unit for detecting the network termination device identification information in the ATM cell data, an identification information conversion unit for converting the detected network termination device identification information into a 4-bit identification number, and transmitting the converted identification number to an ATM. A 12-bit second VPI defined by the NNI from a GFC area conversion unit that writes to the GFC area in the cell data, and the 8-bit first VPI data defined by the UNI and the 4-bit GFC area identification number A conversion table for converting to data,
An identification number for detecting an identification number of the GFC area in the ATM cell data in the intra-office interface, comprising: a GPI area in the ATM cell data; and a VPI conversion unit for writing the second VPI data in the area of the first VPI data. A detection unit, and an identification number conversion unit for converting the detected identification number into network termination unit identification information defined by the ATM-PDS system, and a downlink from the ATM switch in the subscriber interface to the network termination unit side. An ATM, comprising: an ATM-PDS component for writing, on a line, the network termination device identification information converted by the identification number conversion unit into ATM cell data and outputting it as an ATM-PDS frame.
VPI conversion method in the subscriber line terminal equipment.