JPH08186573A - VPI conversion method in ATM subscriber line terminal equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] A common VPI conversion circuit is used for each interface in the ATM communication device. [Structure] Utilizing the fact that GFC data is unnecessary in the ATM subscriber terminal device 1, the subscriber line interface 1
1 is connected to the network terminating device 2 on a one-to-one basis, the GFC
By writing a fixed value in the area and simultaneously handling the 8-bit VPI area and the 4-bit GFC area, the VPI data of the subscriber line interface is artificially set to 12 bits.
As a result, in this device, like the VPI conversion circuit used in the ATM relay system device, both input and output VPI data can be converted in 12 bits, and therefore, this device 1 and the ATM relay system device can perform common conversion. Circuits are available.

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
The present invention relates to a VPI conversion method in an ATM subscriber line terminal device that accommodates an ATM subscriber line.

[0002]

2. Description of the Related Art ATM connected to a network terminating device on a one-to-one basis
In the ATM subscriber line terminal equipment that accommodates the subscriber line interface, the UNI (User) of the VPI data that constitutes the header portion of the ATM cell data to be transmitted is used.
8 specified by the Network Interface)
Bit VPI data and NNI (Network N
The conversion is performed with 12-bit VPI data defined by the Ode Interface). On the other hand, AT
In the ATM relay system device that relays ATM cell data from the M subscriber line terminal device, all input / output interfaces are NNI, so input 12-bit VPI data on the input side is converted to output 12-bit data. It is output as the side VPI data.

[0003]

In such a conventional device, a VPI conversion circuit for converting from 12 bits to 12 bits is required on the side of the ATM relay system device and is connected to the network terminating device on a one-to-one basis. Since an ATM subscriber line interface that requires an 8-bit and 12-bit VPI conversion circuit is required, a VPI conversion circuit corresponding to each interface used in an ATM communication device is required, which is not suitable for configuring the device. There was a problem of becoming an economy. Therefore, an object of the present invention is to economically configure a device by making it possible to use a common VPI conversion circuit for each interface in an ATM communication device.

[0004]

In order to solve such a problem, the present invention provides a subscriber interface connected to a subscriber terminal via a network terminating device and an intra-station connected to an ATM relay system device or the like. VPI in ATM cell data to be transmitted, which comprises an interface and an ATM switch for connecting the subscriber interface and the in-station interface.
When converting data, the subscriber interface and the intra-station interface are provided with first and second VPI conversion circuits, respectively, and each VPI conversion circuit has 4 bits for the first VPI data consisting of 8 bits defined by UNI. GF
C data is added and the conversion process is performed as a pseudo 12 bit. In addition, a first conversion table is provided in the first VPI conversion circuit, a second conversion table is provided in the second VPI conversion circuit, and
Data and first VPI data are assigned as search addresses in the first conversion table and defined by NNI 12
The second VPI data composed of bits is output, and the data in which 4-bit GFC data is added to the first VPI data is set in the second conversion table. In addition, the first VPI conversion circuit is a GFC.
A GFC area conversion unit for writing a fixed value as data, and G
A conversion table for inputting FC data and first VPI data and outputting second VPI data defined by NNI, GFC data in ATM cell data, and first VP
The VPI conversion unit rewrites data corresponding to I data into second VPI data.

[0005]

Operation: The first V consisting of 8 bits defined by UNI
The 4-bit GFC data is added to the PI data, and the conversion process is performed in a pseudo 12-bit manner. As a result, ATM
A common VPI conversion circuit can be used in each interface in the communication device. Further, the GFC data and the first VPI data are assigned as the search address of the first conversion table provided in the subscriber interface, and 4 bits are added to the first VPI data for the second conversion table provided in the intra-station interface. The data to which the GFC data of is added is set. Therefore, the subscriber interface can easily convert and output the second VPI data defined by NNI, and if this second VPI data is used as the search address of the second conversion table, It is easy to use GFC with the in-station interface.
It becomes possible to convert and output the data and the first VPI data. Further, the GFC data in which the fixed value is written and the first VPI data are input to output the second VPI data defined by NNI, and the GFC data and the first VPI data in the ATM cell data are output. The corresponding data is rewritten to this second VPI data. As a result, when ATM cell data is received, the first VPI data specified by UNI in this data can be easily NN
It can be converted and output as the second VPI data defined by I.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an ATM subscriber line terminal device to which the present invention is applied. In the figure, 1 is A
The ATM subscriber line terminal equipment is an ATM subscriber line terminal equipment, and the ATM subscriber line terminal equipment 1 is a subscriber line interface 11 ₁ , 11 ₂ , ATM.
It is composed of a switch 12, intra-station interfaces 13 ₁ , 13 _2, and so on. Here, each subscriber line interface 11 ₁ , 1
1 ₂ each network unit 2 _1, 2 ₂ is connected with, the network terminating device 2 _1, 2 ₂ are connected to the subscriber terminal via the subscriber line. On the other hand, in-station interface 13
₁ , 13 ₂ are connected to, for example, an ATM relay system device (not shown).

Then, each subscriber line interface 11
₁ and 11 ₂ are connected to the ATM from the side of each network terminating device 2 ₁ and 2 _2.
VP in ATM cell data transmitted to the switch 12 side
A VPI conversion circuit, which will be described later, for converting I data is provided, and each intra-station interface 13 ₁ , 13 ₂ is provided with a VPI conversion circuit for converting VPI data transmitted from the ATM relay system side to the ATM switch side. Has been.

FIG. 5 is a diagram showing the format of the header portion of the ATM cell data transmitted by the ATM subscriber line terminal device 1. In the figure, as the area of the ATM cell header, 4-bit G is sequentially arranged from the first byte.
FC (Generic Flow Control) area, 8-bit (1 byte) VPI area, 16-bit (2 bytes) VCI (Virtual Channel)
l Identifier area, 3-bit PT (P
ayload type area, 1-bit CLP (C
ell Loss Priority area, 8-bit HEC (Header Error Control)
l) Area is allocated. Then, following this ATM cell header, a payload of 48 bytes (Payloa
A voice or data area on the subscriber side, called d), is added to form a series of ATM cell data.

Further, FIG. 4 shows the intra-station interface 13 ₁ ,
AT transmitted by an ATM relay system device connected to 13 ₂
It is a figure which shows the format of an M cell header. here,
5 differs from the format of the ATM subscriber line terminal device 1 shown in FIG. 5 in that the format shown in FIG. 4 has a VPI area of 12 bits from the first byte at the beginning, whereas the format of FIG. 4-bit GFC from the beginning
The area has an 8-bit VPI area. For this reason, when converting data having VPI areas of different numbers of bits, two types of VPI conversion circuits are required in the apparatus, so a fixed value is set in the GFC area shown in the format of FIG. As shown in FIG. 3, it is handled as pseudo 12-bit VPI data.

That is, in the ATM subscriber terminal device 1, the GF
Paying attention to the fact that the data in the C area is unnecessary, a fixed value is set in the GFC area and converted into pseudo 12-bit VPI data. A VPI conversion circuit for converting a cell header and an ATM for the subscriber interface 11 side in the intra-office interface 13
A VPI conversion circuit for converting a cell header can be shared.

FIG. 2A is a VPI showing the essential part of the present invention.
It is a block diagram of a conversion circuit, showing an example applied to a subscriber line interface 11. In the figure, this VPI conversion circuit 11A (first VPI conversion circuit) includes a GFC area conversion unit 111, a VPI conversion table 112 (first conversion table), and a VPI conversion unit 113. GFC
When receiving the ATM cell data a, which is the main signal from the transmission line side, that is, the network terminating device 2 side, the area conversion unit 111 receives the 4-bit GFC for all of the data a.
Predetermined fixed value for the area (for example, "0000")
Write. And ATM in which only GFC area is converted
While outputting the cell data b to the VPI conversion unit 113,
The converted GFC area data in the ATM cell data a and the unconverted subsequent 8-bit VPI area data (first VPI data) are sent to the conversion table 112 as 12-bit pseudo VPI data c, and the conversion table 11
Search for 2.

In the conversion table 112 which inputs the pseudo VPI data c as an address, the data at the corresponding address is output to the VPI conversion unit 113 as the converted VPI data d (second VPI data). As a result, the VPI conversion unit 113 replaces 12 bits from the upper bits of the ATM cell data b output from the GFC area conversion unit 111 with the converted VPI data d, and the ATM cell data e as ATM cell data e, that is, ATM side. It is sent to the switch 12 side. Note that the ATM cell data f in the downstream direction (that is, the direction from the inside of the device to the transmission path side) is not converted and is directly transmitted to the network terminating device 2 side. FIG. 6A shows the relationship between the input information (that is, the search address) and the output data (that is, the output VPI value) when accessing the conversion table 112.

By the way, such a VPI conversion circuit is
It is also provided on the internal interface 13 side. Figure 2 (b)
Is an example of a VPI conversion circuit provided in the intra-station interface 13, and this VPI conversion circuit 13A (second VP
In the I conversion circuit), the GFC area conversion unit is removed, and
PI conversion table 132 (second conversion table) and V
It is configured by only the PI conversion unit 133. And this V
The PI conversion circuit 13A does not convert the VPI data in the upstream direction (that is, the direction toward the ATM relay system device outside the device), but does not convert the VPI data in the downstream direction (that is, the direction toward the ATM switch 12 side). Convert the data. This conversion operation is almost the same as the VPI conversion circuit 11A provided in the subscriber line interface 11.

That is, in this case, the ATM cell data g in the downward direction is directly input to the VPI conversion section, and only the 12-bit VPI data of this ATM cell data is used as a search address in the VPI conversion table 132. Is entered. Then, the data in the conversion table 132 is searched by this search address, and the searched 1
The 2-bit converted VPI data h is output to the VPI conversion unit 133. In the VPI converter 133, the input ATM
Conversion table 1 for 12 bits from the beginning of cell data g
Replaced with the converted VPI data h input from 32, AT
It is output to the ATM switch 12 side as M cell data j.

FIG. 6B shows the relationship between the input information (search address) when accessing the VPI conversion table 132 in the VPI conversion circuit 13A and the output information output from the table 132. Here, an arbitrary fixed value such as "0000" is written in the GFC area in the output information output from the table. That is, as described above, the GF set by the subscriber line interface 11 is set.
The fixed value of the C area is a value defined in the device, so that the information required on the transmission side of the subscriber line interface 11 is 8
Since the transmission side of the subscriber line interface 11 ignores the GFC area because it is only VPI data of bits, the data of the GFC area output from the VPI conversion table 132 of the in-office interface 13 is arbitrarily set. be able to. The data in the GFC area is meaningful data between the network terminating device 2 of the connection destination and the subscriber terminal, and is actually written as official data in the network terminating device 2.

As described above, by utilizing the fact that GFC data is not required in the ATM subscriber terminal device 1, when the subscriber line interface 11 is connected to the network terminating device 2 in a one-to-one correspondence, By writing a fixed value in the area and simultaneously handling an 8-bit VPI area and a 4-bit GFC area, the VPI data of the subscriber line interface 11 is artificially made to be 12 bits. As a result,
The VPI conversion circuit of this device can convert both input and output VPI data into 12-bit data, like the VPI conversion circuit used in the ATM relay system device. Therefore, the ATM subscriber line terminal device 1 and The VPI conversion circuit common to the ATM relay system device can be used.

[0017]

As described above, according to the present invention, the subscriber interface and the intra-station interface are respectively provided with VPI conversion circuits, and each conversion circuit converts the first VPI data consisting of 8 bits defined by UNI. Since 4-bit GFC data is added and the conversion process is performed as 12 bits in a pseudo manner, a common VPI conversion circuit can be used in each interface in the ATM communication device. Further, the GFC data and the first VPI data are assigned as search addresses of the first conversion table provided in the subscriber interface, and the first VPI is assigned to the second conversion table provided in the intra-station interface.
Since the 4-bit GFC data is added to the data, it is set to N in the subscriber interface.
It becomes possible to easily convert and output the 12-bit second VPI data defined by NI, and
When this second VPI data is used as the search address of the second conversion table, it becomes possible to easily convert and output the GFC data and the first VPI data in the intra-station interface. Also, GF in which a fixed value is written
The C data and the first VPI data are input to output the second VPI data defined by NNI, and the AT
Since the data corresponding to the GFC data and the first VPI data in the M cell data is rewritten to the second VPI data, when the ATM cell data is received, the first stipulated by the UNI in this data is specified. VPI data can be easily converted and output as the second VPI data specified by NNI.

[Brief description of drawings]

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

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 an ATM cell header format 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 defined by UNI.

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

[Description of Codes] 1 ... Subscriber line terminal device, 2 ₁ , 2 ₂ ... Network terminating device, 11
₁ , 11 ₂ ... Subscriber line interface, 11A, 13A
... VPI conversion circuit, 12 ... ATM switch, 13 ₁ , 1
3 ₂ ... Intra-station interface, 111 ... GFC area conversion unit, 112, 132 ... VPI conversion table, 113, 1
33 ... VPI converter.

Claims (3)

[Claims] 1. A subscriber interface connected to a subscriber terminal via a network terminating device, an intra-station interface connected to an ATM relay device, etc., and an ATM switch connecting the subscriber interface to the intra-station interface. In an ATM subscriber line terminal station device for converting VPI data in ATM cell data to be transmitted, the subscriber interface and the intra-station interface are provided with first and second VPI conversion circuits, respectively.
The conversion circuit includes a first 8-bit unit defined by UNI.
VP in an ATM subscriber line terminal device, characterized in that 4-bit GFC data is added to the VPI data of the
I conversion method. 2. The VPI conversion system in the ATM subscriber line terminal device according to claim 1, wherein a first conversion table is provided in the first VPI conversion circuit and in the second VPI conversion circuit. A second conversion table is provided, and the GFC data and the first VPI are set.
Data and data are assigned as a search address of the first conversion table, and a second bit of 12 bits defined by NNI is assigned.
ATM VPI data is output, and data in which the 4-bit GFC data is added to the first VPI data is set in the second conversion table.
VPI conversion method in subscriber line terminal equipment. 3. The VPI conversion method in an ATM subscriber line terminal device according to claim 1, wherein the first VPI conversion circuit writes a fixed value as the GFC data, and the GFC data. The conversion table for inputting the first VPI data and outputting the second VPI data consisting of 12 bits defined by NNI, and the GFC data in the ATM cell data and the data corresponding to the first VPI data Second VP
A VPI conversion system in an ATM subscriber line terminal equipment, which comprises a VPI conversion unit for rewriting to I data.