JP3214473B2 - VP switching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a VP switching system for switching a duplicated VP pair in ATM communication.

[0002]

2. Description of the Related Art In ATM communication, in order to improve communication reliability, a transmission line or a VP (Virtual Path) has a duplex configuration including an active system and a standby system, and a process of switching at high speed is performed. VP is a VPI (Virtual Path Ide) given in a header area of a cell which is an information transfer unit.
ntifier), and a redundant configuration (duplex configuration) is provided for each VP by selecting a VP pair from a plurality of VPs having different VPIs. Conventionally, ATM
In the VP switching method in the transmission device, switching on a cell-by-cell basis has been realized by updating path information referred to by a switch (ATM switch) that switches VPs. FIG. 7 is a block diagram showing a main part of an ATM transmission apparatus to which an example of a conventional VP switching method is applied. As shown in FIG. 7, the ATM transmission device 10
It comprises a first upstream interface unit 1 and a second upstream interface unit 2 in which P pairs are set, a downstream interface unit 3, and a switch 4 for switching VP.

An input signal 11 to the first upstream interface unit 1 and an input signal 21 to the second upstream interface unit 2 are terminated at each of the interface units 1 and 2 and connected to the switch 4. . Output signal 12 from first upstream interface 1 and second upstream interface 2
Are output from the switch 4. Also, the input signal 3 of the downstream interface 3
1 is terminated at the downstream interface unit 3 and connected to the switch 4, and the output signal 32 is output from the switch 4. Note that VP is applied to each of the input signals 11, 21, 31.
A plurality of cells having different I are accommodated. Here, VP of API = A0 in the first upstream interface unit 1
And VPI = A in the second upstream interface unit 2
The VP of No. 1 is set as a VP pair, and the VP of VPI = B0 in the downstream interface unit 3 is connected to the end of the VP pair. In the following, for example, a VP of VPI = A0 is simply described as VPI = A0.

[0004] The switch 4 refers to the route information and, for VPI = B0 in the downstream interface section 3, VPI = A0 in the first upstream interface section 1 or VPI = A0 in the second upstream interface section. VPI at 2 = A1
Is set as the active system. For example,
As shown by the solid line in FIG. 7, when VPI = A0 in the first upstream interface unit 1 is set as the active system, VPI = B in the downstream interface unit 3 is used.
0 is connected. Here, the path information referred to by the switch 4 is described, for example, in a path table 4A shown in FIG. 8, and is changed from VPI = A0 to VPI = B0 and VPI = B0.
A route is set from PI = B0 to VPI = A0,
= A1 indicates that no route is set. On the other hand, FIG.
In the case where VPI = A1 in the second upstream interface unit 2 is set as the active system as shown by the dotted line in FIG. 7, for example, the route information is changed from the route table 4A shown in FIG. 8 to the route table 4B shown in FIG. VPI =
From A1 to VPI = B0 and from VPI = B0 to VP
The path is routed to I = A1, and VPI = A0 is left unrouted.

[0005]

However, in the VP switching method as described above, it is necessary to update the route information as an operation for performing VP switching control.
When rewriting a huge amount of route information in the M communication network,
There is a possibility that the time of the update control becomes longer and the communication is disconnected. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a VP switching method capable of performing VP switching control by selection processing based on VPI without rewriting path information.

[0006]

In order to solve the above-mentioned problems and achieve the above object, a VP according to the present invention according to claim 1 is provided.
In the switching method, a VP pair that is duplexed upstream is set via an ATM switch, and a VP switch in which a downstream VP is routed to one of the upstream VP pairs based on route information. In the VP switching system, the VP switching system extracts a target cell for VP switching based on a VPI from an upstream signal input to the ATM switch, and creates two identical cells by duplicating the target cell. Means, means for creating two different cells by converting the same VPI of the two same cells to different VPIs, and system information for designating one of the different VPIs as an active system and the other as a standby system by, and outputting the ATM switch to select either one of said two different cell as the active system, a fixed route information
One of the two different cells based on the VP pair
Route one of the two different cells to the other
The ATM switch for routing to the other side of the VP pair;
Without changing the route information,
Switching VP by selection processing based on VPI
It is characterized by:

In the VP switching method as described above, when switching VPs, it is not necessary to rewrite route information such as a routing table referred to by an ATM switch, and control of VP switching is performed only by selection processing based on VPI. As a result, the processing time for VP switching can be reduced,
It is possible to improve communication reliability.

Further, in the VP switching system according to the present invention, the VP switching system extracts two cells corresponding to a VP pair from a downlink signal output from the ATM switch based on a VPI. And means for selecting one of the two cells as the active system based on the system information, and means for converting the VPI of the selected cell to the same VPI.

In the VP switching method as described above, the VPI rewritten corresponding to the VP pair is rewritten so as to correspond to the VP on the downstream side. In the case where the reception is performed by the same terminal device or the like, it is possible to simplify the correspondence between the cells accommodated in the respective signals.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a VP switching system according to the present invention will be described with reference to the accompanying drawings. Note that the same reference numerals are assigned to the same parts as those of the above-described conventional technology, and the description is omitted or simplified. FIG. 1 is a block diagram showing a main part of an ATM transmission device to which a VP switching system according to an embodiment of the present invention is applied, and FIG. 2 is a diagram showing a duplex VP-0.
FIG. 3 is a diagram illustrating a conversion table referred to by a system cell header conversion circuit, FIG. 3 is a diagram illustrating a conversion table referred to by a duplicated VP-1 system cell header conversion circuit, and FIG. 4 is a routing table referred to by a switch; FIG. 5 is a diagram showing a conversion table referred to by the duplicated VP cell header conversion circuit.

As shown in FIG. 1, the downstream interface unit 3 includes a first duplicated VP cell extraction circuit 101, a cell copy unit 102, a duplicated VP-0 cell header conversion circuit 103, Dual VP-1 cell header conversion circuit 104
, A first selector unit 105, a second duplicated VP cell extraction circuit 201, a 0/1 cell division circuit 202, a second selector unit 203, and a duplicated VP cell header conversion circuit 20
And 4. The first duplicated VP cell extraction circuit 101 includes, among the cells accommodated in the input signal 31,
The target cell for VP switching is output to the cell copy unit 102, and the other cells are output to the switch 4. The cell copy unit 102 copies the target cell for VP switching, and outputs it to the duplicated VP-0 cell header conversion circuit 103 and the duplicated VP-1 cell header conversion circuit 104 by broadcast. Duplex VP-0
Each of the system cell header conversion circuit 103 and the duplex VP-1 system cell header conversion circuit 104 adds information for distinguishing the VP-0 system or the VP-1 system to, for example, a header area of a VP switching target cell. To convert the header. The first selector unit 105 is a VP-0 system or a VP-
For example, NMC (Network Management Center) of the ATM network
er: network management device), and based on this system information,
A cell corresponding to the active system is selected from the cells whose headers have been converted into the VP-0 system and the VP-1 system, and output to the switch 4.

The second duplicated VP cell extracting circuit 201 extracts V from the cell contained in the signal received from the switch 4.
A target cell for P switching is selected and output to the 0/1 system dividing circuit 202, and the other cells are output as output signals 32. 0 /
The 1-system cell sorting circuit 202 sets the target cell for VP switching to VP
The output is divided into -0 system and VP-1 system. The second selector 203 determines whether the VP-0 system or the V
One of the cells of the P-1 system is selected as the active system and output to the duplicated VP cell header conversion circuit 204. The duplicated VP cell header conversion circuit 204 includes a second selector unit 2
The header of the cell selected at 03 and contained in the output signal 32 is converted.

The ATM transmission apparatus to which the VP switching system according to the present embodiment is applied has the above-described configuration. Next, the operation of the VP switching system in the ATM transmission apparatus will be described with reference to FIGS. explain. In a state where VPI = A0 of the first upstream interface unit 1 and VPI = B0 of the downstream interface unit 3 are bidirectionally cross-connected in advance, for example, the first upstream interface unit is controlled by the NMC. 1 and VPI = A1 of the second upstream interface unit 2 are set in the VP pair. First, the first duplicated VP cell extraction circuit 101 sets the target cell of the VP switching to the cell of VPI = B0, and, from the cell accommodated in the input signal 31 which is the uplink signal, VPI = The cell B0 is extracted and the cell copy unit 102 is extracted.
Output to Cells other than VPI = B0 are output to the switch 4 as they are. The cell copy unit 102 copies only the same cell as the received cell and duplicates the duplicated VP-0.
The same cell is output to the system cell header conversion circuit 103 and the duplicated VP-1 system cell header conversion circuit 104 by broadcasting.

Double VP-0 cell header conversion circuit 10
3 converts a cell of VPI = B0 into a VP-0 system, that is, a cell of VPI = B0-0 as shown in a conversion table 5A shown in FIG. Output to the unit 105. Similarly, the duplicated VP-1 cell header conversion circuit 104 converts a cell of VPI = B0 into a VP-1 cell, that is, a cell of VPI = B0-1, as shown in a conversion table 5B shown in FIG. Output to the first selector unit 105. The first selector 105 selects NM
From the system information received from C, it is determined which of the VP-0 system and the VP-1 system is the active system, and VPI = B0-
A cell corresponding to the active system is selected from the cell of 0 and the cell of VPI = B0-1 and output to the switch 4. In the switch 4, path information is set in advance as shown in a path table 4C shown in FIG. 4, and cells with VPI = B0-0 have VPI =
In the cell of A0, the cell of VPI = B0-1 is VPI = A1.
, The cell with VPI = A0 is converted into the cell with VPI = B0-0, and the cell with VPI = A1 is converted into the cell with VPI = B0-1. That is, the first selector unit 105
If the cell received from is VPI = B0-0, VPI =
API is converted to VPI = A1 when VPI = B0-1.

On the other hand, the input signal 11 which is a down direction signal
And when the input signal 21 is received by the switch 4, the cell of VPI = A0 is set to VPI = B0−0 based on the path information.
Then, the cell of VPI = A1 is routed to VPI = B0-1 and output to the downstream interface unit 3. The second duplicated VP cell extraction circuit 20 of the downstream interface unit 3
No. 1 sets the target cell for VP switching to the cell of VPI = B0-0 and the cell of VPI = B0-1, and the cell received from the switch 4 is the cell of VPI = B0-0 or V
If the cell is PI = B0-1, the 0 / 1-system cell division circuit 2
02, and outputs the output signal 32 as it is for cells other than these cells. 0/1 system cell division circuit 202
Represents a cell received from the second duplicated VP cell extraction circuit 201 as a VP-0 system, that is, a cell of VPI = B0-0,
The data is divided into cells of VP-1 type, that is, cells of VPI = B0-1 and output to the second selector unit 203. Second selector unit 2
Reference numeral 03 selects a cell corresponding to the active system from the cells of VPI = B0-0 and the cell of VPI = B0-1 based on the system information and outputs the selected cell to the duplicated VP cell header conversion circuit 204. In the duplicated VP cell header conversion circuit 204, as shown in a conversion table 5C shown in FIG.
The cell of I = B0-1 is converted to VPI = B0 and output to the output signal 32.

According to the VP switching method according to the present embodiment, it is not necessary to rewrite the routing table 4C referred to by the switch 4 when switching the VP, and the control of the VP switching is performed by the VP switching.
Since the first and second selectors 105 and 203 select one of the corresponding cells as the active system by using either the -0 system or the VP-1 system as the active system, the processing time for VP switching is reduced. AT can be shortened
It is possible to improve the reliability of the M communication.

In this embodiment, the input signal 11 and the input signal 21, which are the down-going signals, are transmitted via the switch 4 to the second duplex V of the downstream interface unit 3.
When received by the P cell extraction circuit 201, VPI = B0−
The cell of 0 or the cell of VPI = B0-1 is extracted to 0
/ 1 system cell dividing circuit 202, and other cells are output as output signal 32 as they are.
The signal from the switch 4 is output as it is, as shown in FIG. 6, which is a block diagram showing a main part of an ATM transmission apparatus to which the VP switching method according to the modification of the embodiment of the present invention is applied. It may be output as the signal 32. That is, normally, there is no flow of cells from the standby system for the downlink signal, so that the processing for the downlink signal can be omitted as shown in FIG. In this case, AT
It is possible to reduce the circuit scale of the M transmission device. Further, since all of the downstream signals are made conductive, the first selector unit 10
By performing the VP switching in 5 in synchronization with the cell transmission time, it is possible to prevent the communication from being disconnected due to the VP switching.

[0018]

As described above, according to the VP switching method according to the first aspect of the present invention, when the VP is switched,
For example, there is no need to rewrite route information such as a routing table referred to by the ATM switch, and VP switching control is realized only by selection processing based on VPI, so that VP switching processing time can be reduced, It is possible to improve the reliability of ATM communication. Furthermore, V according to claim 2
In the P switching method, the V rewritten corresponding to the VP pair
Since the PI is written back so as to correspond to the VP on the downstream side, for example, when transmission of an uplink signal and reception of a downlink signal are processed by the same terminal device or the like, the PI is stored in each signal. It is possible to simplify the correspondence relationship of each cell.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of an ATM transmission device to which a VP switching method according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a conversion table referred to by a duplicated VP-0 cell header conversion circuit.

FIG. 3 is a diagram showing a conversion table referred to by a duplicated VP-1 cell header conversion circuit.

FIG. 4 is a diagram showing a routing table referred to by the switch shown in FIG. 1;

FIG. 5 is a diagram showing a conversion table referred to by a duplicated VP cell header conversion circuit.

FIG. 6 is a block diagram showing a main part of an ATM transmission device to which a VP switching method according to a modification of the embodiment of the present invention is applied.

FIG. 7 is a block diagram showing a main part of an ATM transmission device to which an example of a conventional VP switching method is applied.

8 is a diagram illustrating a route table referred to by a switch when a route is set by a solid line illustrated in FIG. 7;

9 is a diagram illustrating a route table referred to by a switch when a route is set by a dotted line illustrated in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 First upstream interface unit 2 Second upstream interface unit 3 Downstream interface unit 4 Switch 101 First duplicated VP cell extraction circuit 102 Cell copy unit 103 Duplexed VP-0 system cell header Conversion circuit 104 Duplex VP-1 cell header conversion circuit 105 First selector unit 201 Second duplicate VP cell extraction circuit 202 0/1 system cell division circuit 203 Second selector unit 204 Duplex VP cell header conversion circuit

Claims (2)

(57) [Claims] 1. A VP pair that is duplexed upstream is set via an ATM switch, and a VP in which a downstream VP is routed to one of the upstream VP pairs based on route information. In the switching method, the VP switching method extracts a target cell for VP switching based on a VPI from an upstream signal input to the ATM switch, and creates two identical cells by duplicating the target cell. And the same V of the two same cells.
Means for creating two different cells by converting the PI to different VPIs, and
Means for selecting one of the two different cells as the active system and outputting it to the ATM switch according to system information designating one of the I as the active system and the other as the standby system ;
One of the two different cells based on the route information
To one of the VP pairs and the two different
The A that routes the other cell to the other of the VP pair
A TM switch, and based on the VPI without changing the route information.
VP is switched by selective selection processing
VP switching method. 2. The system according to claim 1, wherein said VP switching method comprises: means for extracting two cells corresponding to a VP pair based on a VPI from a downstream signal output from said ATM switch; Means for selecting one of the two as an active system, and the VPI of the selected cell.
2. The VP switching method according to claim 1, further comprising means for converting the same into the same VPI.