JP3029253B2 - ATM communication network - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ATM (Asynchronou).
s Transfer Mode). The present invention is suitable for use in transferring audio signals. The present invention relates to a technique for effectively using network resources of an ATM communication network.

[0002]

2. Description of the Related Art FIG. 4 shows a configuration for voice communication using a conventional ATM communication network. The configuration shown in FIG.
(ATM Adaptation Layer type2) CLAD (Cell As
This is an example of performing voice communication using senblyDisassenbly). PVC (Permanent Virtual Circuit) between CLAD
And a voice signal is transferred on the PVC by a multiplexing technique using AAL2 cells.

ATM for transferring AAL2 cells over ATM
FIG. 5 shows an outline of the cell frame format. A 64K ATM cell (hereinafter simply referred to as a cell) of 53 bytes
b / s voice is compressed (corresponding to about 8 Kb / s) and transmitted.
At this time, if one voice connection is transferred for a full payload of 48 bytes, the quality is deteriorated due to a delay in cell formation. For this reason, when a voice packet is packed into cells up to 16 bytes, a time-out is transmitted. That is, a cell is not packed tightly in one cell, and a transfer process is performed promptly when a certain number of packets are loaded, thereby shortening a cell delay.

For example, even if the 48-byte payload is not fully filled, the rest is CID (cell identification number) = 0.
And padding with empty cells and transferring.
In this way, voice traffic can be transferred in a form that guarantees quality.

In the example shown in FIG. 5, a CPS-PDU (Common Part Su
blayer-Protocol Data Unit) header.
Indicate the L2 cell. Each AAL2 cell is provided with an AAL2 header, and the AAL2 header has CID and A
AL2 cell length information and others are written. Note that CI
As for the value of D, “0” indicates an empty cell, and “8 to 255” indicates a user cell.

[0006]

However, in such a conventional configuration, for example, when the amount of voice traffic is small, only one copy of the AA is effective due to timeout.
Cells without L2 cells are transferred, resulting in inefficient cell transfer. In the configuration shown in FIG. 4, since the PVC is set in a mesh between the CLADs, the VCI (Vir
tual Channel Identifier) resources are wasted. In the example of FIG. 4, VCIs 1, 2, 3, 4, 6, and 7 are used.

For this reason, an AAL2 switch is mounted on each ATM switch, and the AAL2 switch stores AAL2 cells in A
It is conceivable to terminate a call at the AL2 level and set up a call at the AAL2 level in each transit exchange using a common line signal of another network. Requesting, A
The burden on the TM communication network is very large.

The present invention has been made in such a background, and an AT capable of performing highly efficient voice communication.
It is intended to provide an M communication network. An object of the present invention is to provide an ATM communication network that can effectively use network resources. SUMMARY OF THE INVENTION It is an object of the present invention to provide an ATM communication network that can reduce a load for transfer control.

[0009]

According to the present invention, a PVC terminating between a CLAD of an ATM terminal and an ATM exchange or between ATM exchanges is set, each ATM exchange is provided with an AAL2 trunk, AAL2 cell is extracted from the payload of the cell arriving at the ATM switch of
The most important feature is that the cell is reloaded into another cell for each route according to the destination information.

At this time, for example, A
When an AL2 cell is mounted and other cells are padded, the AAL2 cells mounted on a plurality of cells are collectively mounted on one cell, or conversely, a plurality of AAL2 cells are mounted on one cell. The AAL2 cells can be received together and mounted on one cell, and these AAL2 cells can be mounted on different cells for each route according to the destination information and transferred.

As a result, there is no need to set a PVC between CLADs, and no waste of VCI resources occurs. Also, when replacing the AAL2 cell in the cell, a plurality of PAL
Since a plurality of AAL2 cells arriving from the VC can be collectively mounted in one cell, efficient cell transfer can be performed. At this time, by setting in advance which PVC the AAL2 cell arriving via which PVC is transferred to which PVC, it is possible to eliminate the need for complicated call processing in the AAL2 trunk.

Also, a plurality of AAL2 cells receive a cell mounted together in one cell, and these AAL2 cells are received.
When a cell is mounted in a different cell for each route according to the destination information and transferred, this destination information is
D, and by setting a route corresponding to the CID in advance, it is possible to eliminate the need for complicated call processing in the AAL2 trunk.

Further, regarding the VCI resources, since each PVC is independent, the VCI is
What is necessary is just to set suitably among VCs irrespective of other PVCs, and a VCI resource can be operated efficiently.
Therefore, the VCI used in one PVC is
, It is possible to use VCI resources efficiently.

That is, the present invention is an ATM communication network, and the feature of the present invention is that one cell includes one cell.
Means for mounting the above AAL2 cell, terminating the incoming cell, and extracting the AAL2 cell mounted on this cell;
This AAL2 cell according to the destination information of this AAL2 cell
Means for transferring a cell to a cell to be transferred to a desired output path.

The extracting means and the means for rewriting are provided in an ATM exchange, and include an ATM terminal and the AT.
Different PVCs are desirably set between the M exchanges and between the ATM exchanges.

It is preferable that a means for recording a preset output PVC corresponding to the input PVC of the ATM exchange is provided. It is preferable that the destination information is displayed by a CID included in an AAL2 header, and a means for recording a PVC serving as a transfer route set in advance corresponding to the CID value is provided.

[0017]

Embodiments of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention.

The present invention is an ATM communication network, and the feature of the present invention is that, as shown in FIG. 5, one cell includes one or more AAL2 cells and terminates an incoming cell. An AAL2 trunk 10 which is a means for extracting an AAL2 cell mounted on the cell and replacing the AAL2 cell with a cell to be transferred to a desired output route in accordance with the destination information of the AAL2 cell is provided.

As shown in FIG. 1, AAL2 trunk 10
Is provided in the ATM switch 20, and the ATM terminal 30 and A
Between the TM exchanges 20 and between the ATM exchanges 20,
Different PVC-1 to PVC-5 are set respectively.

The destination information is, as shown in FIG.
Indicated by CID included in L2 header, AAL2
The trunk 10 has a PVC serving as a transfer route set in advance corresponding to the CID value, and an ATM switch 20.
Output PVC corresponding to the input PVC of
And a memory 40 as means for recording the information.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention. FIG. 2 is a diagram showing an AAL2 trunk as a line concentrator according to the embodiment of the present invention. FIG. 3 is a diagram showing an AAL2 trunk as a separating device according to the embodiment of the present invention.

In the embodiment of the present invention, as shown in FIG.
Between the TM terminal 30 and the ATM exchange 20 and between the ATM exchanges 20, different PVC-1 to PVC-
5 is set. This makes it possible to effectively use the VCI resources as compared with a state in which mesh PVC is formed between CLAD and CLAD as in the conventional example shown in FIG.

Since the traffic density from the ATM terminal 30 is low, it is unlikely that the cell payload is completely filled with AAL2 cells, and in many cases, empty cells are padded due to timeout.

FIG. 2 shows the operation of multiplexing AAL2 cells by the AAL2 trunk 10 as a concentrator.
All AAL2 cells to which PVC-1 and PVC-2 are transferred from the ATM terminal 30 are multiplexed to PVC-3 by the AAL2 trunk 10. Of course, when going to another route, it is transferred to the ATM switch using another PVC. At this time, PVC-1 and PVC
The mapping from -2 to PVC-3 is already set when setting the PVC. This setting is AAL
It is recorded in the memory 40 of the second trunk 10. PVC
-1 and C of AAL2 cell transferred from PVC-2
For example, P
VC-1 divides the area fixedly with the identification numbers "8 to 125", and PVC-2 divides the area fixedly with the identification numbers "126 to 255".

FIG. 3 shows the operation of separating AAL2 cells by the AAL2 trunk 10 as a separating device.
The AAL2 cell to which the PVC-3 has been transferred is distributed to the PVC-4 and the PVC-5 by the AAL2 trunk 10. Also at this time, the PVC of the transfer route corresponding to the value of CID
Is set in advance. This setting is recorded in the memory 40 of the AAL2 trunk 10. For example, an odd number is assigned as PVC-4, and an even number is assigned as PVC-5. As a result, the odd and even numbers are CID
The value is selected and transferred to the CLAD of the desired destination ATM terminal 30 simply by transferring using PVC-1 or PVC-2.

As described above, complicated call setup and the like are not performed in the ATM communication network, and the AAL2
Cells can be transferred. At this time, the AAL2 trunk 10 provided in the ATM switch 20 is
AAL2 cells can be mapped and multiplexed or demultiplexed on a desired PVC according to the header information of the AL2 cells.

[0027]

As described above, according to the present invention,
Highly efficient voice communication can be performed. In addition, network resources can be used effectively. Further, the load for transfer control can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing an AAL2 trunk as a concentrator according to the embodiment of the present invention.

FIG. 3 is a diagram showing an AAL2 trunk as a separation device according to the embodiment of the present invention.

FIG. 4 is a diagram showing a configuration for voice communication using a conventional ATM communication network.

FIG. 5 is a diagram showing an outline of an ATM cell frame format for transferring AAL2 cells over ATM.

[Description of Signs] 10 AAL2 trunk 20 ATM exchange 30 ATM terminal 40 Memory

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-186576 (JP, A) WO 97/33406 (WO, A1) IEICE Technical Report IN97-62 IEICE Technical Report IN97-4 IEICE Technical Report IN96-37 IEICE Technical Report IN96-36 NTT R & D Vol. 46 No. 11 pp. 1181-1188 (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/56 H04L 12/28

Claims (4)

(57) [Claims] 1. One ATM (Asynchronous Transfer M)
ode) cell contains one or more AAL2 (ATM Adaptation Layer
r type 2) A cell is mounted, a means for terminating an incoming ATM cell and extracting an AAL2 cell mounted on the ATM cell, and the extracted ALL
Characterized by comprising a means for changing carrying the AAL2 cell from pre Symbol excised ATM cell transferred to the output route of the cell identification number is preset shown on the basis of the cell identification number included in the 2 cell header ATM communication network. 2. The method according to claim 1, wherein said extracting means and said replacing means are provided in an ATM exchange, and different PVCs (Permanent Virtues) are provided between an ATM terminal and said ATM exchange and between said ATM exchanges.
al circuit) is set. 3. An ATM communication network according to claim 2, further comprising means for recording a preset output PVC corresponding to the input PVC of said ATM exchange. 4. The ATM switching system according to claim 1, wherein said ATM exchange is a PV which is a transfer route set in advance corresponding to the value of said cell identification number.
3. The ATM communication network according to claim 2, further comprising means for recording C.