JPH11220480A - Method and device for exchanging atm cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of circuits required for providing the cell exchange of VP/VC connection by handling the VP connection as the assembly of pseudo VC connections. SOLUTION: The distinguishment of VP/VC is eliminated inside an ATM cell exchange, and the VP connection is handled as the assembly of pseudo VC connections. Therefore, the number of bits to be used for a virtual path identifier(VPI) field 48 and virtual channel identifier(VCI) field 49 is limited and by using the plural low-order bits of the VPI field 48 and the plural high- order bits of the VCI field 49, a pseudo VCI field 53 is constituted on a VPI/VCI field 55. By performing only the VC connection exchange while using this pseudo VCI field 53, the ATM cell exchange of VP/VC connection is enabled only by a single cell exchange function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM (Asynchronous Transfer Mode) cell switching method and an ATM cell switching apparatus used in a public network or a private network.

[0002]

2. Description of the Related Art FIG. 4 is a functional block diagram showing a configuration of a conventional ATM cell switching system, and FIG. 5 is a diagram showing ATM cell switching on a VC (virtual channel) and VP (virtual path) in the conventional ATM cell switching system. It is explanatory drawing which shows operation | movement of the above ATM cell exchange.

In FIG. 4, an ATM cell switching device 12
Is provided with a VC switch 1 for exchanging ATM cells on a VC and a VP switch 2 for exchanging ATM cells on a VP.
Cell interface (input / output port) 3, VC / VP connection multiplexing / demultiplexing unit 4, VC header conversion / routing unit 5, which performs header conversion and self-routing for VCI (virtual channel identifier) of ATM cells, A
A VP header conversion / routing unit 6 that performs header conversion and self-routing for a VPI (virtual path identifier) of a TM cell is provided.

Reference numeral 7 denotes an input / output ATM cell path between the input / output ATM cell interface 3 and the multiplexing / demultiplexing unit 4;
And 10, VCs set between the VC switch 1 and the multiplexing / demultiplexing unit 4 by the PC header conversion / routing unit 5.
Connection paths 9 and 11 are VP header conversion /
3 shows a path of a VP connection set between the VP switch 2 and the multiplexing / demultiplexing unit 4 by the routing unit 6.

Next, the operation of the conventional example configured as described above will be described with reference to FIG. First, it is assumed that the cell switching path in the case of ATM cell switching in the VP is indicated by reference numeral 13 in FIG. 5, and the function of each part related to the cell switching path 13 is different along the cell switching path 13 from FIG. The description is given with reference numerals.

First, an input / output ATM cell interface 1
5, an ATM cell is input, and the multiplexing / demultiplexing unit 16 separates the VP / VC connection based on the registration information. The ATM cell of the separated VP connection is
In the VP header conversion / routing unit 17, the VP
The VPI value of the input cell is converted into an address indicating the destination by referring to a header conversion table set in advance at the time of connection setting, and the port to be output is routed according to this address. The output is output to the VP header conversion / routing section 18 by switching. The output ATM cell is converted to a VP header conversion / routing unit 1.
8, a new VPI value is assigned and the multiplexing / demultiplexing unit 1
At 9 multiplexed as a VP / VC connection and output via input / output ATM cell interface 20.

Next, it is assumed that the cell exchange path in the case of ATM cell exchange in the VC is indicated by reference numeral 14 in FIG. 5, and the function of each part related to the cell exchange path 14 is shown along the cell exchange path 14. A description will be given by attaching a continuous code different from 4.

First, an input / output ATM cell interface 2
At 1, an ATM cell is input, and a multiplexing / demultiplexing unit 22 separates a VP / VC connection based on registration information. The separated VC connection ATM cell is
The C header conversion / routing unit 23 converts the VCI value of the input cell into an address indicating the destination by referring to a header conversion table set in advance when setting the VC connection, and to which port is output according to this address. Is routed, and is switched by the VC switch 27 to be output to the VC header conversion / routing unit 24. The output ATM cell is transferred to the VC header conversion / routing unit 24.
A new VCI value is assigned to the multiplexing / demultiplexing unit 25.
Are multiplexed as VP / VC connections and output through the input / output ATM cell interface 26.
Operations for other VP / VC connections and ports are performed in the same manner as described above.

As described above, the ATM cell exchange in the VP / VC connection can be performed.
When dealing with both VC connections, a similar exchange
You need a pair.

[0010]

As described above, the conventional AT
In the M-cell switching system, the VP connection and the VC connection are treated as independent ones, and therefore, one set of switching functions is required for each connection, and there is a problem that the amount of circuits increases. Further, since the switching functions of the VP / VC connections are independent of each other, there is a problem that control between the switching functions is required.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and provides an ATM cell switching method and an ATM cell switching apparatus capable of greatly reducing the amount of circuits required to realize VP / VC connection cell switching. The purpose is to provide.

[0012]

In order to solve the above-mentioned problems, the present invention divides user information into fixed-length transfer units called cells and stores them in a header of the cell. Cell switching method and apparatus for performing a cell switching operation by routing a virtual path and a virtual channel of an input cell and switching an ATM switch based on a virtual path identifier and a virtual channel identifier for establishing And eliminating the virtual path and the virtual channel so that the virtual path is simulated as a set of virtual channels,
Based on this, a pseudo-virtual channel identifier is constituted by a plurality of lower-order bits of bits assigned to the virtual path identifier of the header and an upper-order plurality of bits of bits assigned to the virtual channel identifier, and a virtual It is characterized in that cell exchange of a path connection is performed.

According to the present invention, it is possible to greatly reduce the amount of circuit necessary for realizing the cell exchange of the VP / VC connection.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention divides user information into fixed-length transfer units called cells and stores the virtual path connection and virtual channel connection stored in the header of the cell. Based on the virtual path identifier and virtual channel identifier to establish, route the virtual path and virtual channel of the input cell,
And an ATM cell switching method for performing a cell switching operation by switching an ATM switch, wherein the virtual path is pseudo-aggregated as a set of virtual channels without discriminating between the virtual path and the virtual channel. A pseudo virtual channel identifier is constituted by a plurality of lower bits of bits allocated to the virtual path identifier of the header and a plurality of upper bits of bits allocated to the virtual channel identifier, and a virtual path connection is established using the pseudo virtual channel identifier. The cell switching is performed, and only the virtual channel connection switching is performed using the pseudo virtual channel identifier, whereby the ATM cell switching of the virtual path connection / virtual channel connection can be performed by a single cell switching function. Having.

According to a second aspect of the present invention, the ATM switch comprises a switch for a virtual channel, and routes a virtual path of an input cell and switches the ATM switch using a pseudo virtual channel identifier. Thus, the cell exchange of the virtual path connection is performed, and the virtual path connection exchange and the virtual channel connection exchange can be realized by a single VC switch.

According to a third aspect of the present invention, the ATM switch comprises a switch for a virtual channel, and routes the virtual channel of the input cell using the virtual channel identifier stored in the header of the input cell. In addition, by switching the virtual channel switch, the cell exchange of the virtual channel connection is performed, and the virtual path connection exchange and the virtual channel connection exchange can be realized by a single VC switch.

According to a fourth aspect of the present invention, a virtual path identifier for establishing a virtual path connection and a virtual channel connection stored in the header of the cell by dividing user information into fixed-length transfer units called cells. A that performs a cell exchange operation by routing the virtual path and virtual channel of the input cell based on the virtual channel identifier and the ATM switch.
A TM cell switching apparatus, wherein the virtual path is simulated as a set of virtual channels without discriminating between the virtual path and the virtual channel, and based on this, a lower order of bits assigned to a virtual path identifier of the header is determined. A pseudo-virtual channel identifier is constituted by a plurality of bits and higher-order bits of bits assigned to the virtual channel identifier, and the virtual path of the input cell is routed using the pseudo virtual channel identifier, and the ATM switch is switched. Thus, the cell exchange of the virtual path connection is performed, and only the virtual channel connection exchange is performed using the pseudo virtual channel identifier, so that the ATM cell of the virtual path connection / virtual channel connection can be performed by a single cell exchange function. It has the effect that replacement is possible.

According to a fifth aspect of the present invention, the ATM switch comprises a switch for a virtual channel, and routes a virtual path of an input cell and switches the ATM switch using a pseudo virtual channel identifier. Thus, the cell exchange of the virtual path connection is performed, and the virtual path connection exchange and the virtual channel connection exchange can be realized by a single VC switch.

According to a sixth aspect of the present invention, the ATM switch comprises a switch for a virtual channel, and routes the virtual channel of the input cell using the virtual channel identifier stored in the header of the input cell. In addition, by switching the virtual channel switch, the cell exchange of the virtual channel connection is performed, and the virtual path connection exchange and the virtual channel connection exchange can be realized by a single VC switch.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an ATM according to an embodiment of the present invention.
FIG. 2 is a functional block diagram showing a configuration of a cell switching method and apparatus, FIG. 2 is an explanatory diagram showing an ATM cell switching operation of a VP / VC connection according to an embodiment of the present invention, and FIG.
TM cell format and VPI / VC in the present invention
FIG. 4 is an explanatory diagram showing a configuration of an I field (pseudo VCI field).

In FIG. 1, the ATM cell switching device is
A switch 29 for VC which exchanges ATM cells on C is provided. Further, an input / output ATM cell interface (input / output port) 30 to the ATM cell switching device, and a VP shown in FIG.
A header conversion / routing section 31 for performing header conversion and self-routing on an I / VCI field (pseudo VCI field) 53 is provided. Numeral 32 denotes an ATM cell path which is input / output to / from the header conversion / routing unit 31, and 33 denotes a header conversion / routing unit 31.
3 shows a VP connection (pseudo VC connection) and a path of the VC connection set between the switch 29 and the switch 29.

In FIG. 3A, the ATM cell 60 is
It is composed of a 5-octet header 45 storing an identifier indicating a cell destination and the like, and a 48-octet information field 46.

As shown in FIG. 3A, the header 45 includes a 4-bit generative flow control (GFC) field 47, an 8-bit virtual path identifier (VPI) field 48, and a 16-bit virtual channel identifier. (VCI) field 49, a 3-bit payload type (PT) field 50 for indicating whether the content included in the information field is user information or network information, a 1-bit cell loss priority (CLP) field 51, and an 8-bit It comprises a header error control (HEC) field 52.

In FIG. 3B, reference numeral 53 denotes a pseudo VCI field, reference numeral 54 denotes a combined VPI / VCI field, and reference numeral 55 denotes the position of the pseudo VCI field 53 in the VPI / VCI field. .

As described above, the VP / VC is not distinguished inside the ATM cell switching apparatus, and the VP is treated as a pseudo VC aggregate. For this purpose, as shown in FIG. 3B, the bits used in the virtual path identifier (VPI) field 48 and the virtual channel identifier (VCI) field 49 are limited, and the lower plural bits of the virtual path identifier (VPI) field 48 are limited. And a plurality of upper bits of the virtual channel identifier (VCI) field 49,
The pseudo VCI field 53 on the / VCI field 55
And use this pseudo VCI field 53 to generate VC
By performing only the connection exchange, the ATM cell exchange of the VP / VC connection can be performed by a single cell exchange function.

Next, the operation of the embodiment of the present invention configured as described above will be described with reference to FIG. First, it is assumed that a cell exchange path in the case of ATM cell exchange in a VP connection is indicated by reference numeral 34 in FIG.
The code of each unit related to the cell switching path 34 is set to a continuous code different from that in FIG.

First, the input / output ATM cell interface 3
6, the ATM cell is input, and the header conversion / routing section 37 outputs the virtual path identifier (V) shown in FIG.
Instead of routing with reference to only the PI) field 48, as shown in FIG. 3B, a pseudo VCI field 5 obtained by using a plurality of lower bits of the VPI field 48 and a plurality of upper bits of the VCI field 49.
3 based on the information registered in advance using the switch 38
Route to which port is output at
The switching is performed by the switch 38 as a set of pseudo VCs, and output to the header conversion / routing unit 39. The output ATM cell is provided with a new VPI / VCI value in the header conversion / routing section 39 based on the information registered in advance, and is output through the input / output ATM cell interface 40.

Next, it is assumed that the cell exchange path in the case of ATM cell exchange in the VC connection is indicated by reference numeral 35 in FIG. It will be described in the order of cell switching paths.

First, the input / output ATM cell interface 4
1, an ATM cell is input, and the header conversion / routing section 37 determines which port the switch 38 outputs to the switch 38 based on information registered in advance using a virtual channel identifier (VPC) field 49 shown in FIG. The data is routed and switched by the switch 38, and is output to the header conversion / routing unit 43. The output ATM cell is provided with a new VPI / VCI value in the header conversion / routing section 43 based on the information registered in advance, and is output through the input / output ATM cell interface 44. In addition, other V
Operations on the P / VC connection and port are performed in the same manner as described above.

According to the present embodiment, the VPI / VCI field 55 is obtained by using the lower bits of the virtual path identifier (VPI) field 48 and the upper bits of the virtual channel identifier (VCI) field 49. A pseudo VCI field 53 is formed above, and only the VC connection exchange is performed by using the pseudo VCI field 53.
/ VC connection ATM cell exchange can be performed, and the circuit amount required for ATM cell exchange can be greatly reduced.

[0032]

As described above, according to the present invention, a VP connection exchange and a VC connection exchange can be realized by a single VC switch by treating a VP connection as a set of pseudo VC connections. ,
This has the effect that the circuit amount required for ATM cell switching can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of an ATM cell switching method and apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an ATM cell exchange operation of a VP / VC connection according to the embodiment of the present invention;

FIG. 3 shows a standard ATM cell format and a VPI / VCI field (pseudo VCI field) in the present invention.
FIG. 3 is a diagram illustrating a configuration of a frame used in an optical communication system according to Embodiment 1 of the present invention.

FIG. 4 is a functional block diagram showing a configuration of a conventional ATM cell switching system.

FIG. 5 is an explanatory diagram showing operations of ATM cell exchange on a VC (virtual channel) and ATM cell exchange on a VP (virtual path) in the conventional ATM cell exchange system.

[Explanation of symbols]

29, 38 VC switch 30, 36, 40, 41, 44 Input / output ATM cell interface 31, 37, 39, 42, 43 Header conversion / routing unit 60 Cell 45 Header 46 Information field 48 VPI field 49 VCI field 53 Pseudo VCI field

Claims (6)

[Claims] 1. A method according to claim 1, wherein user information is divided into fixed-length transfer units called cells, and a virtual path identifier and a virtual channel identifier for establishing a virtual path connection and a virtual channel connection stored in a header of the cell.
An ATM cell switching method for performing a cell switching operation by routing a virtual path and a virtual channel of an input cell and switching an ATM switch, wherein the virtual path and the virtual channel are distinguished from each other. The path is simulated as a set of virtual channels, and based on this, a pseudo-virtual channel identifier is formed by a plurality of lower bits of bits assigned to the virtual path identifier of the header and a plurality of upper bits of bits assigned to the virtual channel identifier. An ATM cell exchange method comprising: configuring a virtual path connection using the pseudo virtual channel identifier. 2. The ATM switch comprises a switch for a virtual channel, and uses a pseudo virtual channel identifier.
Route the virtual path of the input cell, and
The cell switching of the virtual path connection is performed by switching the M switch.
The ATM cell exchange method according to the above. 3. The ATM switch comprises a switch for a virtual channel, routes a virtual channel of an input cell using a virtual channel identifier stored in a header of an input cell, and switches the virtual channel. 2. The ATM cell switching method according to claim 1, wherein the cell switching of the virtual channel connection is performed by switching the ATM cell switching. 4. Dividing user information into fixed-length transfer units called cells, and based on a virtual path identifier and a virtual channel identifier for establishing a virtual path connection and a virtual channel connection stored in a header of the cell.
An ATM cell switching apparatus for performing a cell switching operation by routing a virtual path and a virtual channel of an input cell and switching an ATM switch, wherein the virtual path and the virtual channel are distinguished from each other by eliminating the distinction between the virtual path and the virtual channel. The path is simulated as a set of virtual channels, and based on this, a pseudo-virtual channel identifier is formed by a plurality of lower bits of bits assigned to the virtual path identifier of the header and a plurality of upper bits of bits assigned to the virtual channel identifier. And using this pseudo-virtual channel identifier,
Route the virtual path of the input cell, and
An ATM cell switching apparatus for performing cell switching of a virtual path connection by switching an M switch. 5. The ATM switch includes a switch for a virtual channel, and uses a pseudo virtual channel identifier.
Route the virtual path of the input cell, and
The cell switching of the virtual path connection is performed by switching the M switch.
An ATM cell switching device as described in any of the preceding claims. 6. The ATM switch comprises a switch for a virtual channel, routes a virtual channel of an input cell using a virtual channel identifier stored in a header of an input cell, and switches the virtual channel. 5. The ATM cell switching device according to claim 4, wherein cell switching of the virtual channel connection is performed by switching the ATM cell switching.