JPH04310033A - Atm cross connector - Google Patents

Abstract

PURPOSE:To simplify the transfer control of an OAM cell in the ATM cross connector in which a VPI of an input cell is rewritten by a VPI conversion section and them relevant input cell is outputted from an output port of a switching section corresponding to the rewritten VPI. CONSTITUTION:An OAM cell generated in the inside of the ATM cross connector is not inserted from an insert section different from a conventional system but inserted from an input port 21 for exclusive use of insertion of a switch section 2 and outputted by being switched to any of output ports #1-#N corresponding to the VPI representing by header information of the OAM cell. Moreover, when the OAM cell is sent from other ATM cross connector or terminal equipment, VPI conversion is implemented by VPI conversion sections 11-1N corresponding to any of them similarly to the case with a usual cell with respect to the OAM cell and inputted to the switch section 2, then the switch section 2 realizes it that the cell is an OAM cell based on the header information, then the cell is outputted from an exclusive use output port 22 of the OAM cell.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an ATM cross-connect device, and in particular to an OAM (operator) for monitoring whether or not the functions of an ATM network are operating correctly.
ion Administration Management
ent) This relates to an ATM cross-connect device that transfers cells.

[0002] Recently, ATM (Asynchronous Trans
(fer Mode: asynchronous transfer technology) Network research is being actively conducted, and this ATM network has a header part (5 bytes) and a payload part (48 bytes), as shown in the NNI (inter-network) example in Figure 4. STM (Synchronous Transport) is a system that unifies all information in a cell format composed of
nsfer Mode: Synchronous Transfer Technology) Compared to networks, time slot allocation processing is unnecessary, so it is suitable for distributed processing control and allows for highly flexible multiplex transmission.

[0003] FIG. 5 shows an example of the configuration of such an ATM network. In the figure, the parts marked with ○ represent cross-connect devices (nodes), and the parts marked with △ are connected to the cross-connect devices. indicates a terminal equipment (CPE),
Each cross-connect device indicates a link (high-speed transmission path), and a path set between any set of terminal devices indicated by the same number is a VP (Virtual Pat
h). Therefore, for example, regarding the VP between the terminal devices CPE1, cross-connect device 1-link 1-cross-connect device 2-link 4-cross-connect device 4-link 7 will be set as an example.

[0004] In order for a cell to flow through a desired VP in such a network, 12 characters for identifying the VP are added to the header of the cell as shown in FIG.
Bit VPI (Virtual Path Iden)
tifier) and VC (Virtual Channel)
VCI (Virtual Channel) for identifying
Annel Identifier) is provided, and each link has a different VPI value (
In the example of Fig. 5, the VPs do not overlap for each link, but when the VPs overlap, the VPIs differ for each link.
value) within each cross-connect device.
A map representing the correspondence between cross-connect information and VPI for setting the VP is prepared, and each cross-connect device looks at this VPI to allocate cells.

[0005] Furthermore, in order to periodically monitor whether or not cells are normally transferring VPs between cross-connect devices in an ATM network, the 2-bit PT ( An OAM cell has already been proposed that uses a payload type (payload type) section to indicate that the cell is a monitoring cell rather than a user information cell, but it is possible to make the transfer of this OAM cell more efficient in each ATM cross-connect device. The ability to do this is required.

[0006]

[Prior Art] Figure 6 shows a conventionally known ATM.
A cross-connect device is shown, and to begin with, we will explain a case in which OAM cells are not handled.Input cells from other terminal devices or cross-connect devices are multiplexed into N cells by a multiplexer (MUX) 3, and each VPI converter 11 ~
1N, the VPI of each cell is rewritten to the VPI for the next link, and the VPI is sent to the input port of the switch unit 2 corresponding to the rewritten VPI. The switch section 2 outputs cells from the corresponding output ports based on the header information of each cell, and the cells from these output ports are sent to the separation section (DM
UX) 4 and sent to a link to an adjacent cross-connect device or to a terminal device.

FIG. 7 shows each of the above-mentioned VPI converters 11 to
1N configuration example is shown, and when the header information (12 bits) of the input cell is sent to the VPI table 11, this table 11 converts it to a new VPI and sends it to the selector along with other data passed through the delay section 12. (SEL) 13 to synthesize and output.

FIG. 8 shows an example of the configuration of the switch unit 2, in which N input ports and N output ports are connected to N2 buffer memories (for example, FIFO memories) BM11 to BMNN. Construct a matrix using
Each cross point has a VPI judgment unit JD11 in the cell.
~JDNN is provided. And this judgment department JD
11 ~ In JDNN, VP of cell from input port
The corresponding output port is detected based on I, the cell is temporarily written to the buffer memory of the cross point corresponding to the VPI under write control from a control unit (not shown), and further read control is performed from the control unit. Accordingly, written cells are read out in a predetermined order and outputted from the corresponding output port.

On the other hand, when using OAM cells, OAM cell insertion sections 51 to 5N are provided between the multiplexing section 3 and the VPI conversion sections 11 to 1N, respectively, and
OAM cell branching units 61 to 6N are provided between the conversion units 11 to 1N and the switch unit 2, and during network monitoring, OAM cells generated inside the cross-connect device are transferred to one of the corresponding insertion units 51 to 5N. The OAM cells inserted and sent again are sent to branch sections 61 to 6N.
The data is extracted using one of the following methods and processed within the cross-connect device.

0010

[Problem to be solved by the invention] Such a conventional AT
In the M cross-connect device, an insertion section and a branch section for OAM cells are provided, one before and one after the VPI conversion section, so the same number of these insertion/branch sections as the number of VPI conversion sections are required. As a result, OAM cell transfer control becomes complicated, and this becomes a factor that prevents miniaturization of cross-connect devices.

Therefore, the present invention sets the VPI of the input cell to V
The purpose of this invention is to realize a configuration that simplifies OAM cell transfer control in an ATM cross-connect device that rewrites the input cell in a PI conversion unit and outputs the input cell from the output port of the switch unit corresponding to the rewritten VPI. shall be.

0012

[Means for Solving the Problems] FIG. 1 shows A according to the present invention.
This conceptually shows the configuration of a TM cross-connect device. In the present invention, a dedicated insertion port 21 and a branch port 22 are added to the input port and output port of the switch unit 2 for inserting and branching OAM cells, respectively. It is characterized by what it did.

[0013]

[Operation] Fig. 2 is for explaining the operation of the ATM cross-connect device shown in Fig. 1. In Fig. 2 (a), OAM generated inside the ATM cross-connect device
Cells are not inserted from the insertion section as in the past, but are inserted from the insertion-only input port 21 of the switch section 2, and are inserted into the output ports #1 to #N corresponding to the VPI indicated by the header information of the OAM cell. It is output by switching to either one.

Furthermore, when an OAM cell is sent from another ATM cross-connect device or terminal device, one of the corresponding VPI converters 11 to 1N converts the OAM cell into a VPI in the same way as a normal cell. After the conversion, when the cell is input to the switch unit 2, the switch unit 2 recognizes that this cell is an OAM cell from its header information, so as shown in FIG. It can be output from the output port 22.

[0015] In this way, OAM cell insertion and branching can be performed without using any special circuit.

[0016]

[Embodiment] FIG. 3 shows an embodiment of a switch section used in the ATM cross-connect device shown in FIG. and buffer memories BM11 to BM
In addition to the NN, N determination units JD1Na to JDNNa and buffer memories BM1Na to BMNNa are provided for the input port 21 dedicated to the OAM cell, and N output ports #1 to #N are connected to each. Judgment unit JDN for each input port #1 to #N
1b ~JKDNNb and buffer memory BMN1b
~BMNNb are provided and both are connected to the output port 22 dedicated to the OAM cell.

Therefore, in operation, an OAM cell input from the input port 21 of the OAM cell is stored in the buffer memories BM1Na to BMNNa corresponding to any of the output ports specified by the VPI indicated by the header.
Then, as in the case of FIG. 8, the determination units JD1Na to JDNN
The VPI is detected based on the determination in step a, and the cells are temporarily stored under write control from the control unit (not shown), read out in a predetermined order under read control from the control unit, and sent out as output cells from the output port. be done. Further, the OAM cells sent from the VPI converters 11 to 1N are
The OAM specification bit in the VPI area indicated by the cell header (see Figure 4) also allows the control unit to specify the OAM
Any applicable buffer memory BM that controls the cell
After being temporarily stored in N1b to BMNNb, it is read out from the output port 22 dedicated to the OAM cell.

[0018]

As described above, according to the ATM cross-connect device according to the present invention, a dedicated insertion port and a branch port for inserting and branching OAM cells are added to the input port and output port of the switch section, respectively. So,
It is only necessary to add a switching function for inserting and dropping OAM cells to the switch section, which simplifies OAM cell transfer control and allows the cross-connect device itself to be downsized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the principle of an ATM cross-connect device according to the present invention.

FIG. 2 is a diagram for explaining the operation of the ATM cross-connect device according to the present invention.

FIG. 3 is a diagram showing an embodiment of a switch section used in an ATM cross-connect device according to the present invention.

FIG. 4 is a frame format diagram showing the basic structure of an ATM cell.

FIG. 5 is a diagram showing an example of a general ATM network.

FIG. 6 is a block diagram showing a conventional ATM cross-connect device.

FIG. 7 is a block diagram showing a configuration example of a VPI conversion block used in an ATM cross-connect device according to the present invention and a conventional example.

FIG. 8 is a block diagram showing an example of the configuration of a switch section used in a conventional ATM cross-connect device.

[Explanation of symbols]

11 ~ 1N VPI conversion section 2 Switch part 21 OAM cell dedicated input port 22 OAM cell dedicated output port In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] [Claim 1] The VPI of the input cell is converted into a VPI converter (1
1 to 1N), and the rewritten VPI
In an ATM cross-connect device that outputs the input cell from the output port of the switch section (2) corresponding to the switch section (2), a dedicated insertion device is used for inserting and branching OAM cells into the input port and the output port of the switch section (2), respectively. An ATM cross-connect device characterized by adding a port (21) and a branch port (22).