JP3640551B2 - ATM equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ATM (Asynchronous Transfer Mode) device having an alarm indication signal (AIS) generating function.
[0002]
[Prior art]
Generally, an ATM device is provided with an AIS generation function. By providing the AIS generation function, when a failure occurs in the physical layer, it is possible to generate a VP-AIS that is a virtual path (VP) for transmitting this failure state to a lower level device. Further, when a failure occurs in the virtual path, VC-AIS which is a virtual channel (VC) for transmitting this failure state to the lower-level device is generated.
[0003]
3A and 3B are conceptual diagrams for explaining the operation of a conventional ATM device.
[0004]
As shown in FIGS. 3A and 3B, in the ATM device 300, the cell received from the upstream device is transmitted to the downstream device.
[0005]
Here, as shown in FIG. 3A, when the ATM device 300 detects that a failure has occurred in the physical layer 310, a VP-AIS is generated at the VP level 321 of the ATM layer 320, and is downstream. Sent to the device.
[0006]
Further, as shown in FIG. 3B, when the ATM device 300 detects that a failure has occurred at the VP level 321, a VC-AIS is generated at the VC level 322 of the ATM layer 320, Sent to the device.
[0007]
The VP-AIS generated by the ATM device 300 is transmitted only to each VP of another ATM device whose connection is valid when a failure is detected. For this reason, conventionally, a table indicating the connection state of VP-AIS has been provided in the alarm generation unit in the ATM device 300. The alarm generation unit sequentially determines effective transmission destinations of the connection, and generates and transmits VP-AIS for each of the transmission destinations.
[0008]
Similarly, the VC-AIS is transmitted only to each of the VCs of other ATM devices for which a connection is set when a failure is detected. Also in this case, each ATM device was provided with a table indicating the VC-AIS transmission destination.
[0009]
[Problems to be solved by the invention]
As described above, the apparatus shown in FIG. 3 requires connection setting tables for VP-AIS and VC-AIS. This table requires a storage area of 8 or 12 bits for VP-AIS and 16 bits for VC-AIS for each destination that can be set.
[0010]
For this reason, in the conventional ATM device, when an AIS generation function is provided, a large-scale memory is required, and the hardware scale increases.
[0011]
[Means for Solving the Problems]
ATM apparatus according to the present invention, the alarm display cell generated when receiving a failure signal indicating that a failure in the ATM layer or the physical layer is generated, a timer for generating a generation period, given from the timer An address generation counter that sequentially generates address signals by counting up or counting down in a cycle, a cell generation unit that generates an alarm display cell using an address signal input from the address generation counter, and connection setting Connected to a function unit that transmits or discards cells according to invalidity, monitors other types of cells that are input to the function unit from the outside, and displays the alarm display cell in a band where the other types of cells do not exist. An alarm generation means having a cell insertion section that is inserted and sent to the function section is provided.
[0012]
In the apparatus having such a configuration, an alarm display cell is generated according to the generation cycle generated by the timer, and the alarm display cell is transmitted using a band in which no other type of cell exists. That is, according to the present invention, it is possible to control the cycle at which the alarm display cell is transmitted and the band used for transmitting the alarm display cell.
[0013]
Thereby, it can be avoided that the cells communicated in the network are only alarm display cells, and further, the influence of the alarm display cells on the communication of other types of cells can be suppressed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the size, shape, and arrangement relationship of each component are shown only schematically to the extent that the present invention can be understood, and the numerical conditions described below are merely examples. Please understand that.
[0015]
FIG. 1 is a block diagram schematically showing the overall configuration of an ATM apparatus according to this embodiment.
[0016]
In the figure, an interface 101 receives data A from the outside.
[0017]
The alarm generation unit 102 monitors the input of data A as will be described later. When the failure signal B is input, an alarm display cell (VP-AIS cell or VC-AIS cell) is generated and inserted in a band without a user cell.
[0018]
The route distribution unit 103 is a functional unit for transmitting user cells. The route distribution unit 103 inputs a user cell from the outside via the alarm generation unit 102. Then, the connection setting table 104 is used to determine whether the connection between the input user cell and the transmission destination is valid or invalid. If the connection is invalid, the cell is discarded. On the other hand, when the connection is valid, the header of the user cell is rewritten according to the transmission destination. In this embodiment, a warning display cell is also input to the route distribution unit 103. Therefore, the route distribution unit 103 also determines the validity / invalidity of the connection using the connection setting table 104 for the alarm display cell, and discards the cell if invalid, and cell header if valid. Will be rewritten.
[0019]
The interface 105 transmits the user cell and alarm display cell whose header has been rewritten by the route distribution unit 103 to the outside.
[0020]
FIG. 2 is a block diagram schematically showing the internal configuration of the alarm generation unit 102.
[0021]
In the figure, a timer 201 generates an AIS generation cycle.
[0022]
The address generation counter 202 generates a VPI (Virtual Path Identifier) or VCI (Virtual Channel Identifier) as an address signal based on the period given by the timer 201.
[0023]
When the failure signal B is input from the lower layer, the AIS cell generation circuit 203 generates an alarm display cell using the above address signal.
[0024]
The AIS cell insertion circuit 204 monitors the input of data A. Then, the alarm display cell received from the AIS cell generation circuit 203 is inserted into a band without a user cell and sent to the route distribution unit 103.
[0025]
Next, the operation of the ATM device according to this embodiment will be described taking as an example the case where a failure has occurred in the physical layer.
[0026]
When a failure occurs in the physical layer, a failure signal B is transmitted from the failure location to the AIS cell generation circuit 203. When receiving the failure signal B, the AIS cell generation circuit 203 sends a command for generating a VPI to the address generation counter 202.
[0027]
When receiving this command, the address generation counter 202 starts counting up (or counting down) based on the period given by the timer 201, and sequentially generates VPIs having respective count values as addresses. These VPIs are sequentially sent to the AIS cell generation circuit 203. Here, it is assumed that VPIs at addresses 0 to 4095 are generated by the address generation counter 202 and transmitted to the AIS cell generation circuit 203.
[0028]
The AIS cell generation circuit 203 sequentially generates VP-AIS cells using each VPI received from the address generation counter 202.
[0029]
Then, as described above, the AIS cell insertion circuit 204 inserts the VP-AIS cell into a band without a user cell and transmits it to the route distribution unit 103.
[0030]
The route distribution unit 103 uses the connection setting table 104 to determine the transmission destination of each cell, rewrites the header of each cell according to this transmission destination, and sends it to the interface 105. Here, the route distribution unit 103 determines that a cell for which no connection is set is an invalid cell and discards it. Therefore, only the VP-AIS cell with a valid connection is sent from the interface 105 to the transmission destination. For example, if the VPIs corresponding to valid connections are only the 10th address, the 20th address, and the 30th address, only the VP-AIS cell storing the VPIs of these addresses is transmitted from the interface 105, and the other VP-AISs are transmitted. All cells (that is, cells into which VPIs at addresses 0-9, 11-19, 21-29, and 31-4095 are inserted) are all discarded.
[0031]
Thereafter, a VP-AIS cell with a valid connection is transmitted from the interface 105 to a downstream device.
[0032]
Even when a failure occurs at the VP level of the ATM layer, only the VC-AIS cell for which the connection is determined to be valid by the route distribution unit 103 is transmitted in the same manner as in the physical layer.
[0033]
Thus, in this embodiment, at the time of failure, the alarm generation unit 102 generates alarm display cells for all addresses and transmits them to the route distribution unit 103 which is a functional unit for user cells. did. As a result, alarm display cells that do not need to be transmitted are discarded by the route distribution unit 103, so that the alarm generation unit 102 does not need to determine whether the connection is valid or invalid. Therefore, in this embodiment, since it is not necessary to provide a connection setting table, the scale of hardware can be reduced as compared with the prior art.
[0034]
In this embodiment, the connection setting table 104 of the user cell route distribution unit 103 is used, but it goes without saying that the connection setting table of another functional unit may be used.
[0035]
【The invention's effect】
As described above in detail, according to the ATM device of the present invention, the connection setting table for the alarm display signal can be eliminated, and therefore the hardware scale can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing an overall configuration of an ATM apparatus according to an embodiment.
FIG. 2 is a block diagram schematically showing an internal configuration of an alarm generation unit shown in FIG.
FIGS. 3A and 3B are conceptual diagrams for explaining the operation of a conventional ATM device.
[Explanation of symbols]
101, 105 Interface 102 Alarm generation unit 103 Route distribution unit 104 Connection setting table 201 Timer 202 Address generation counter 203 AIS cell generation circuit 204 AIS cell insertion circuit

Claims (3)

A timer for generating an occurrence period of an alarm display cell generated when a failure signal indicating that a failure has occurred in an ATM layer or a physical layer is received ;
An address generation counter that sequentially generates address signals by counting up or counting down at a period given by the timer; and
A cell generator for generating the alarm display cell using the address signal input from the address generating counter,
Connected to a function unit that transmits or discards cells according to the validity / invalidity of connection settings, monitors other types of cells that are input from the outside to the function unit, and sets the band so that no other type of cells exist A cell insertion unit that inserts the alarm display cell and sends it to the functional unit ;
An ATM device comprising an alarm generating means having The ATM apparatus according to claim 1, wherein the address signal is a virtual path identifier or a virtual channel identifier. The ATM device according to claim 1, wherein the functional unit is a route distribution unit for user cells.

Images