JP2002094549A - Line trunk unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line trunk unit that contains an existing channel interface board so as to conduct voice exchange by means of packets. SOLUTION: An exchange system 10 includes a call processing unit 1, a LAN switch 2, and the line trunk unit 12, which are designed to be contained in separate enclosures, the enclosure of the line trunk unit 12 contains an extension I/F board 14, an external line I/F board 16 and a miscellaneous I/F board 18 as channel interface boards, a conversion processing circuit 20 interfaces the channel interface boards by means of a PCM(Pulse Code Modulation) highway and interfaces the LAN switch 2 by a LAN-or the like in compliance with the MII(Media Independent Interface) and the IEEE 802.3. The conversion processing circuit 20 applies conversion processing to a PCM frame and a voice packet and conversion processing to a control signal and a control packet in response to an order from the call processing unit 1 and an event from the channel interface boards.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line trunk unit in which a voice circuit board for connecting a voice terminal and connecting to a communication path is accommodated in a housing, and in particular, performs voice communication using voice packets corresponding to voice signals. It relates to a line trunk unit to be performed.

[0002]

2. Description of the Related Art Conventionally, in a digital private branch exchange (PBX),
For example, there has been a system in which a control signal is exchanged between a circuit board having a DPRAM interface and a time-division switch, and a call connection is performed by transmitting and receiving a voice signal through a PCM interface.

[0003] Such a PBX is, for example, a circuit board for accommodating an analog extension or a digital extension, a circuit board for accommodating an analog or digital external line, and a circuit board for other services.
They are connected via the M highway, and these circuit boards and time-division switches are connected to the control unit via a DPRAM interface. The control unit controls the functional units by transmitting / receiving the order / event to / from the call processing unit and other units. Also,
PCM voice exchange is performed by supplying a control signal from the call processing unit to the time division switch via the control unit.

[0004] In recent years, so-called VoIP (Voice over IP) for performing voice communication on a local area network (LAN) constituting an IP network has attracted attention as an integrated environment for communicating data and voice. This integrated environment, for example, allows digital IP phones using the IP protocol,
An integrated communication system that communicates voice and data in a LAN environment by being housed in a switch equipped with a LAN switch.
The packetized voice packet is exchanged for a desired destination.

[0005] As such an exchange system, for example, there is an "audio data integrated exchange system" as disclosed in Japanese Patent Application Laid-Open No. H11-252249. This system includes PBX telephones, trunks of telephone network trunks (TRKs), and data terminals (PKs).
C) and Internet Protocol Telephone (IP-TEL) are connected to the exchange respectively, and the signal processing protocol for voice signal and exchange control and medium access control (MAC) frame format packets are performed by the subscriber's circuit (SLIC) in the exchange. The trunk (TRK) and the Internet protocol telephone (IP-TEL) also transmit information in MAC frame format,
N switches exchange packets.

[0006]

However, in the above-mentioned "voice data integrated switching system", the subscriber circuit (SLI)
It is necessary to newly develop and manufacture line connection interface circuits such as C) and trunk (TRK) for the new switch, and use the 2M highway interface standardized and used in the conventional digital PBX in the switch It was not something.

Further, in this conventional example, since each circuit configuration is housed in the same housing to form one exchange, the installation place of the exchange is limited to one place.
Inability to properly arrange for network connection.

[0008] Further, no consideration is given to a configuration for increasing or decreasing the number of subscriber circuits or trunk circuits. In particular, when an additional circuit is added, there is a physical limit depending on the hardware design of the switching device. Was. For this reason, it has been difficult to configure an exchange having a high degree of freedom that can appropriately cope with an increase or decrease in the number of lines.

The present invention solves the above-mentioned drawbacks of the prior art, makes it possible to divert a line connection interface designed and manufactured for a conventional PBX system, and realizes a conversion function between the line connection interface and a LAN interface. It is an object of the present invention to provide a line trunk unit that can flexibly add or reduce the number of line connection interfaces and that can arrange the entire switching system freely according to the LAN system. .

[0010]

According to the present invention, in order to solve the above-mentioned problems, a communication path interface is formed by a PCM highway, and a voice circuit board for performing voice communication between lines is accommodated in a housing. A line trunk unit for converting and controlling a voice signal of a voice circuit board and a voice packet on a network, and connecting a voice circuit board for transmitting / receiving a voice frame by time division multiplex communication. 1 connection means, second connection means for connecting the audio circuit board, conversion processing means for performing a conversion process between an audio signal and an audio packet, and third connection means connected to the conversion processing means for inputting and outputting the audio packet. Conversion means, wherein the conversion processing means is connected via the first connection means and performs conversion processing between voice frames and voice packets. And a second conversion unit connected via the second connection unit and configured to perform a conversion process between the control signal and the control packet on the audio circuit board side, and transmit and receive the audio packet and the control packet to and from the network side. It is characterized by.

In this case, the conversion processing means may be connected to the first LAN switch in a separate housing from the line trunk unit via the third connection means by the medium independent interface.

In this case, a call processing device for performing call control on the voice circuit board is connected to the first LAN switch, and the second conversion means controls the call according to an event addressed to the call processing device from the voice circuit board. A packet is formed, the control packet is output via the third connection means, and the control packet corresponding to the order addressed to the voice circuit board is transmitted from the call processing device to the third connection means.
And a control signal may be formed from the control packet and output to the audio circuit board.

The conversion processing means includes a second LAN switch for connecting the first conversion means and the second conversion means with a medium independent interface, and the third connection means is connected to the second LAN switch. Should be connected.

The first conversion means includes a frame processing means for inputting / outputting a PCM frame signal corresponding to a voice circuit board, a voice packet processing means for disassembling and assembling voice packets, and a MAC for voice packets. A first MAC processing means for processing a frame; a second conversion means for processing a control packet for disassembling and assembling a control packet; and a second processing means for processing a MAC frame of the control packet.
It is preferable that the first and second MAC means are respectively connected to the second LAN switch.

In this case, the control packet processing means generates a clock signal for controlling the synchronization of the frame processing means and the audio packet processing means corresponding to the audio circuit board,
It may be supplied to the frame processing means and the voice packet processing means.

In this case, when the synchronization packet is further received by the second MAC processing means, the control packet processing means
It is preferable to generate a clock signal synchronized with the synchronization packet.

Further, the frame processing means compresses the PCM frame signal output from the audio circuit board, outputs the compressed signal to the audio packet processing means, expands the PCM frame signal output from the audio packet processing means, and outputs It is good to output to a substrate.

Preferably, the frame processing means includes a removing means for removing an echo component contained in the PCM frame signal output from the audio circuit board.

The control packet processing means may generate a synchronization packet synchronized with the clock signal, and output the synchronization packet to the second MAC processing means to control the synchronization with another line trunk unit. .

In this case, the second MAC processing means may add a header indicating multicast to the synchronization packet.

Further, the control packet processing means may add a header indicating multicast to the synchronization packet.

The first converting means includes a frame processing means for inputting / outputting a PCM frame signal, a voice packet processing means for disassembling and assembling a voice packet, and a priority control means for controlling a transmission timing of a voice packet. , A set of first MAC processing means connected to the priority control means for processing the MAC frame of the voice packet, respectively, corresponding to the voice circuit board, and the second conversion processing means is provided for disassembling and assembling the control packet. A control packet processing means for performing processing; and a set of second MAC processing means connected to the control packet processing means for processing a MAC frame of the control packet, wherein the set of first MAC processing means includes a plurality of first MAC processing means. Cascade-connected to one of the other sets of first MAC processing means provided respectively corresponding to the audio circuit boards of the first and second sets, and one set of the second MAC processing means comprises one of the first MAC processing means. It is connected to one of the means, the other, may be connected to the network side.

A first LAN switch connected to the conversion processing means via a third connection means; and a call processing apparatus connected to the first LAN switch and performing call control on the line trunk unit. Is connected to the packet switching system.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a switching system to which the present invention is applied will be described in detail with reference to the accompanying drawings. Referring to FIG. 1, a switching system 10 according to the present embodiment is shown. The switching system 10 includes a call processing unit 1, a LAN switch 2, and a line trunk unit 12.
3 IP switching system configured with standard LAN or Ethernet.

The line trunk unit 12 (hereinafter, referred to as a trunk unit 12) is a single device in which a plurality of line interface boards are accommodated in its housing and each line is connected to the LAN switch 2 via a LAN cable. As shown, each line interface board in the present embodiment includes an extension I / F board 14, an outside line I / F board 16, and a miscellaneous I / F board 18, which are converted in the trunk unit 12. It is connected to the processing circuit 20 via a connector or the like. In addition,
In the following description, parts not directly related to the present invention are not shown and described, and reference numerals of signals are represented by reference numerals of connection lines in which the signals appear.

As the extension I / F board 14, a subscriber circuit (SLIC) used in a conventional PBX or the like can be used.
Specifically, the extension I / F board 14 is an extension circuit having a so-called BORSCHT function and transmitting and receiving a voice signal through a PCM highway. A plurality of extensions 22 to which various types of terminals are connected are connected to the extension I / F board 14, and convert audio signals from each terminal into, for example, PCM audio signals of 64 kPCM (G.711), and convert the audio signals. The data is output to the PCM / PACKET conversion unit 26 in the conversion processing circuit 20 via the connection line 24 interfaced with the 2Mbit / s PCM highway (2MHW) and a connector (not shown). Also, the PCM audio signal input from the connection line 24 to the extension I / F board 14 is inversely converted, and the processed audio signal is output to each terminal via the extension 22. The terminal may be either an analog terminal or a digital terminal, and the extension I / F board 14 employs a circuit configuration suitable for various terminals.

Further, the extension I / F board 14 generates a control signal indicating an event related to an outgoing / incoming call addressed to the call processing unit 1 and transmits the control signal to a DPRAM of a dual port RAM provided in the extension I / F board 14. 28, a control signal in the conversion processing circuit 20 connected via the bus 30 and a connector (not shown) to the / PACKET conversion unit 32. The extension I / F board 14 transmits a control signal including an order from the call processing unit 1 to a control signal / PACKE.
The terminal receives from the T conversion unit 32 via the bus 30 and controls and monitors the terminal connected to the extension 22 according to the control content.

The external line I / F board 16 is a station line interface circuit board on which a trunk (TRK) similarly used in a conventional PBX or the like is mounted. Specifically, external I / F board 16
Is connected to an external line 34 of various communication lines, converts an audio signal from the external line 34 into a PCM audio signal, and connects the conversion processing circuit 20 via a connection line 36 interfaced by a PCM highway and a connector (not shown). To the PCM / PACKET conversion unit 26 in the. The external line I / F board 16 is input from the connection line 36.
Inverts the PCM audio signal and converts the processed audio signal to external
Send to 34 side. The external line 34 may be either an analog line or a digital line, and the external line I / F board 16 has a circuit configuration suitable for the line type. External line I / F board 16 is also an internal line
As with the I / F board 14, a DPRAM 28 is provided and the external I / F board 16
And a control signal / PACKET conversion unit 32 in the conversion processing circuit 20 via a DPRAM 28, a bus 30, and a connector (not shown) provided in the extension I / F board 14, Is transmitted and received.

The miscellaneous I / F board 18 is a service circuit for performing various services. The miscellaneous I / F substrate 18 is, for example, P
It is a board for implementing additional functions such as a B / DT receiver, voice guidance, and a conference trunk. Miscellaneous
An external computer device can be connected to the I / F board 18 as needed for providing services such as a charge service and operation management. The miscellaneous I / F board 18 is also connected to the PCM / PACK in the conversion processing circuit 20 through the connection line 38 interfaced with the PCM highway, like the other interface boards.
It is connected to the ET conversion unit 26 to transmit and receive audio signals. Also,
The miscellaneous I / F board 18 similarly has a DPRAM 28, is connected to the bus 30 via the DPRAM 28, and controls signals in the conversion processing circuit 20.
/ PACKET Transmits and receives control signals to and from the converter 32.

The conversion processing circuit 20 to which the interface boards 14, 16, 18 are connected is connected to the connection lines 24, 3 of the PCM highway.
6 and 38, and a control signal / PACKET converter 32 connected to the bus 30. The converters 26 and 32 further include a medium defined by IEEE standard 802.3u. Media Independent Interface (MII)
PHY circuit (PHY) 44, 46 via connection lines 40, 42
Connected to each other.

The PCM / PACKET conversion unit 26 is a PCM highway 2
Frames transmitted to 4, 36, and 38 are detected, and packets from the MII connection line 40 are detected, and a conversion process between a PCM frame signal and a MAC frame format voice packet is performed. The MAC address is registered in the PCM / PACKET conversion unit 26, and when assembling a voice packet addressed to the LAN switch 2, the destination MAC address addressed to the LAN switch 2 is added to the packet header. The PCM / PACKET conversion unit 26 converts the upstream PC from each line interface 14, 16, 18 to the LAN switch 2.
The M highway audio signal is packetized at regular intervals and transmitted to the connection line 40. In this case, the PCM / PACKET conversion unit 26
A voice packet is assembled by adding a network layer IP address including a destination address and a source address and a data link layer MAC address to a header.

When the PCM / PACKET conversion unit 26 receives a downstream packet from the LAN switch 2 to the line interface boards 14, 16, and 18 via the connection line 40, the PCM / PACKET conversion unit 26 converts an audio signal from the packet at regular intervals. Isolated on, isolated
The PCM voice frame signal is transmitted to the line interface boards 14, 16, 18 via the PCM highways 24, 36, 38. At this time, the PCM / PACKET conversion unit 26
Destination line interface boards 14, 16, 18 and terminals,
In other words, the destination is recognized and the corresponding line interface board is
Transmit PCM frame signal to 14,16,18. Like this PC
The M / PACKET conversion unit 26 is connected to each of the line interface boards 14, 16,
18 and PCM interface to convert audio system.

The control signal / PACKET converter 32 is connected to each of the line interface boards 14, 16, and 18 via the bus 30, and decomposes a packet including an order sent from the call processing unit 1 via the LAN switch 2. Then, the control signal is extracted, and the control signal is transmitted to the line interface board via the bus 30. When the control signal / PACKET conversion unit 32 receives a control signal indicating an event transmitted from each line interface board, it assembles it into a packet including the destination and source MAC addresses in the header. The control signal / PACKET converter 32 sends the assembled packet to a PHY circuit (PHY) 46 via the MII connection line 42. The control signal / PACKET converter 32 mutually converts a control signal indicating a signal processing protocol between the LAN switch 2 and each line interface and a packet, and transfers an order and an event. As described above, the control signal / PACKET converter 32 is interfaced with each of the line interface boards 14, 16, and 18 by the bus 30, and performs conversion of the control system.

A phi circuit (P) connected to each connection line 40, 42
HY) 44 and 46 are physical layer circuits for terminating packets to be transferred, and shape and output the electrical waveform of the input signal. Each of the PHY circuits (PHY) 40, 46 is interfaced with the PCM / PACKET conversion unit 26 and the control signal / PACKET conversion unit 32 by MII. The inputs and outputs 50 and 52 of the PHY circuits 40 and 42 form input and output ports of the trunk unit 12 and are connected to the LAN switch 2 via connection lines 50 and 52 of a network cable, respectively.

The LAN switch 2 has a plurality of input / output ports, extracts a header from a packet input to the port, and extracts a source MAC address and a destination MA included in the header.
Recognizes the C address, refers to the address table, finds an outgoing port according to the destination MAC address, and switches between the two ports. The LAN switch 2 is housed in a separate housing from the trunk unit 12, and has a plurality of ports connected to an existing network, another trunk unit, and the call processing unit 1 by a network cable. Although not shown, the LAN switch 2 includes a PHY circuit (PHY) for each port, a plurality of media access control (MAC) circuits for recognizing and forming a MAC frame for each port, and a A frame buffer for each MAC circuit for temporarily storing and holding,
It has a switch circuit that switches between each MAC circuit. As described above, the LAN switch 2 is a switching network device that performs switching between ports and has a connection function according to a MAC address. Although not shown, a computer device is connected to the other ports of the LAN switch, so that not only voice packet exchange but also data packet transfer between the computer devices can be performed via the LAN switch 2.

The call processing unit 1 includes a trunk unit 12
And LAN switch 2 in a separate housing,
This is a call processing device that executes a signal processing protocol for each of the line interface boards 14, 16, 18. The call processing unit 1 sends a packet for performing call processing such as call connection and call disconnection to a port to which the connection line 54 of the LAN cable is connected. Upon receiving a packet representing an event transmitted from each line interface, the call processing unit 1 generates an order for call processing control according to the content of the event, packetizes a control signal corresponding to the order, and generates a target trunk unit. A control packet addressed to 12 is sent to the LAN switch 2. As described above, the call processing unit 1 includes a MAC address, a packet and a frame disassembly / assembly circuit, transmits a signal processing protocol indicating various types of call processing and exchange processing via a network including the LAN switch 2 and transmits the trunk unit 12 Control. The call processing unit 1 performs such processing as control of transmission / reception of an extension / external line, confirmation and release of connection, transmission / reception of switching information, and the like by program processing. Further, the call processing unit 1 has a function of performing an update process of the MAC table and the like.

The operation of the switching system 10 in this embodiment will be described with reference to the flow of various signals. The event addressed to the call processing unit 1 from each of the line interfaces 14, 16, and 18 is transmitted to the DPRAM 28 and the bus. The signal is transferred to a control signal / PACKET converter 32 via 30 and is converted into a packet by the converter 32. The converted packet is sent to the phi circuit.
It is transmitted over the network via 46. LAN switch 2
Are switched and transferred to the call processing unit 1.

On the other hand, a packet including an order to each of the line interfaces 14, 16 and 18 generated in the call processing unit 1 is switched by the LAN switch 2 and
The signal is transferred to the control signal / PACKET conversion unit 32 via 44 and processed, and its order is set to the desired line interface 14, 16, 18
Sent to As a result, processing according to a signal processing protocol such as a call connection is performed. For example, when the call connection is completed, the upstream PCM audio signal is transmitted from the line interface board to the PCM / PACKET conversion unit via the PCM highway.
When input to 26, the PCM audio signal is packetized at regular intervals. The converted voice packet is transmitted from the PCM / PACKET converter 26 to the LAN switch 2 by MII. When a voice packet is input to the LAN switch 2, the voice packet
The MAC frame is temporarily stored in the frame buffer, and the output port corresponding to the destination MAC address is determined according to the address table. The MAC frame stored in the frame buffer is forwarded to the determined output port.

Here, for example, when a call is made from the extension line 22 to the external line 34, the packet is converted into a voice packet addressed to the external line interface board 28 and transmitted from the LAN switch 2 to the trunk unit 12 via the connection line 50. You. PCM / PACKET converter
When the voice packet is input, 26 extracts the PCM voice signal and sends out the extracted PCM voice signal to the external interface board 16. On the external interface board 16,
The frame of the transferred PCM audio signal is decoded into an audio signal, and the audio signal is transmitted to the outside line 34.

As described above, the call processing unit 1
It is not built in the trunk unit 12, and the call processing unit 1 and the trunk unit 12 are connected via the LAN switch 2 in a separate housing. Also, the phi circuits 44 and 46
PCM / PACKET converter 26 and control signal / PACKET converter 32
Interface between the LAN switch 2 and MII / Et
Performs hernet conversion. Thus, a configuration in which the number of trunk units 12 is flexibly increased or decreased is realized. Also, the call processing unit 1 and the trunk unit 12
Because they are connected by LAN interface, call processing unit 1, LAN switch and trunk unit 12
Need not be installed at the same location, and the system can be operated in any arrangement. Also, since each line interface board can use a conventional one, the voice signal and the control signal can be interfaced with the LAN without newly developing a line system board. Also, the call processing unit 1 and the trunk unit
By connecting to the LAN switch 2 in combination with 12, the same exchange processing as the conventional PBX can be performed. Therefore, the switching system 10 can be freely installed in a place satisfying the accommodation conditions of the LAN.

Next, another embodiment of the switching system will be described with reference to FIG. In this switching system 60, an external LAN
The trunk unit 200 is connected to the switch 2 via the connection line 202 of the LAN cable. The trunk unit 200 in the present embodiment has a built-in LAN switch 204 in the conversion processing circuit 62 in its housing. Built-in LAN switch
204 connects the MII connection lines 40 and 42 from the PCM / PACKET conversion unit 26 and the control signal / PACKET conversion unit 32 in the conversion processing circuit 62 to the respective ports and terminates the connection. A phi circuit (P
HY) 206 differs from the embodiment shown in FIG. The other configuration may be the same as the configuration indicated by the same reference numeral shown in FIG. The phi circuit 206 is connected to the external LAN switch 2 via a connection line 202.

As with the external LAN switch 2, the built-in LAN switch 204 converts a packet input to each port into an MA.
It has the function of extracting C frames, recognizing the source MAC address and destination MAC address contained in the header, referring to the address table, finding the outgoing port according to the destination MAC address, and switching between both ports. ing.
The built-in LAN switch 204 includes three media access control (MAC) circuits for recognizing and forming a MAC frame for each port, three frame buffers for temporarily storing and holding the recognized MAC frame, and each MAC circuit It has a switch circuit for switching between them. Built-in LA
The N switch 204 performs switching between ports,
PCM / PACKET converter 26 according to MAC address, control signal / P
The MAC frame is exchanged between the ACKET conversion unit 32 and the call processing unit 1 to transfer the packet.

As described above, the built-in LAN switch 204 is connected to the PCM /
Packet transfer processing between PACKET conversion units 26, PCM / PACKET
Packet transfer processing between the conversion unit 26 and the control signal / PACKET conversion unit 32, the call processing unit 1 and the PCM / PACKET conversion unit 26
A packet transfer process between the call processing unit 1 and the control signal / PACKET conversion unit 32 is performed.

With this configuration, in this embodiment, in addition to the effects of the embodiment shown in FIG. 1, a port for connecting the line unit 200 and the call processing unit 1 via the LAN switch 2 is set to a trunk. Only one unit 200 is required. That is, if the number of ports of the external LAN switch 2 that interfaces the call processing unit 1 and the trunk unit 200 is equal to the total number of the trunk units 200 plus one of the call processing units, the switching system 60 is constructed. be able to. Therefore, external LA
N The number of ports required in the switch 2 can be reduced. This is the case, for example, when connecting a plurality of line units 200 to the LAN switch 2.
This is particularly effective in reducing the equipment burden on the network side.

Next, in the conversion processing circuit 62 shown in FIG.
An example of the internal configuration of the PCM / PACKET converter 26 and the control signal / PACKET converter 32 will be described with reference to FIG. As shown
The PCM / PACKET conversion unit 26 has a number of DSPs 300a, 3a corresponding to the line interface boards accommodated in the trunk unit 60.
00b, 300c, voice CPU 302a, 302b, 302c and MAC circuit 304
a, 304b, and 304c are provided for each line interface board.

More specifically, the connection lines 24, 36, and 38 of the PCM highway to which each interface board is connected
P 300a, 300b, 300c are connected. These DSP 300
Performs transmission and reception of 64 kbps (G.711) PCM audio signals between the PCM highways 24, 36, and 38 and the audio CPU 302.
For example, the DSP 300a converts the PCM audio signal input from one of the audio CPU 302a or the connection line 24 at a constant interval synchronized with the clock signal supplied from the control signal / PACKET conversion unit 32 via the connection line 306, Other connection line 24 or voice CP
Send to U 302a. Similarly, for the DSPs 300b and 300c, the PCMs of the connection lines 36 and 38 and the audio CPUs 302b and 302c, respectively.
Transfers audio signals.

Voice CPU 3 connected to each DSP 300
02 is a circuit for performing voice packet processing. Voice CPU 30
2 has a function of buffering a PCM audio signal input to one side and outputting the buffered signal to the other side. For example, voice
The CPU 302a buffers the audio signal transmitted from the DSP 300a at regular intervals synchronized with the clock signal 306, assembles an IP packet, and outputs the packet to the MAC circuit 304a. Further, the voice CPU 302a transmits the IP transmitted from the MAC circuit 304a at regular intervals synchronized with the clock signal 306.
Disassemble the packet and DSP the audio signal according to the packet
Output to 300a. Similarly, the audio CPUs 302b and 302c exchange signals between the DSPs 300b and 300c and the MAC circuits 304b and 304c, respectively, by disassembling and assembling audio signals and packets at regular intervals.

MAC connected to each audio CPU 302
The circuit 304 performs data conversion between the voice CPU 302 and the built-in LAN switch 204. For example, the MAC circuit 304a
Is a built-in LAN switch that stores voice packets output from the voice CPU 302a in a frame buffer, converts them into MAC frame format packets, and connects to the MII connection line 40a.
The packet temporarily stored in the frame buffer is transmitted to port 204. The MAC circuit 304a receives a packet in the MAC frame format input from the built-in LAN switch 204 via the connection line 40a according to the MAC address, and outputs the received packet to the voice CPU 302a. MAC circuit 304b, 304c
Similarly, the built-in LAN switch 204 and the audio CPUs 302b and 302 connected by MII connection lines 40b and 40c respectively
Perform MAC frame conversion processing between c and c.

Control signal / P for supplying a clock signal to each part
One ACKET conversion unit 32 is provided in the line trunk 62, and is connected to the control CPU 310 to which the connection lines 30 and 306 of the PCM highway are connected, and to the control CPU 310 and to the built-in LAN switch 204. And a MAC circuit 312 for interfacing.

The control CPU 310 transmits and receives control signals between the DPRAM 28 provided on each line interface board and the MAC circuit. The control CPU 310 receives a control signal indicating an event from each interface board, generates a packet, and sends the packet to the MAC circuit 312. The control signal is extracted from the packet transferred via the built-in LAN switch 204 and the MAC circuit 312, and the extracted control signal is output to the bus 30. Thus, the control CPU 310 has a function of disassembling and assembling an IP packet related to a control signal. Control CP
U 310 generates a clock signal for synchronization on the PCM highway and outputs it to output 306. Control CPU 310
For example, upon receiving a synchronization packet from another trunk unit connected via the external LAN switch 2 and becoming a clock slave, a clock signal synchronized with the synchronization packet may be generated. As a result, the entire switching system can be synchronized.

The MAC circuit 312 includes a control CPU 310 and a built-in LAN.
Data conversion is performed with the switch 204. MAC circuit 31
2 converts the control signal output from the control CPU 310 into a packet in the MAC frame format, and sends the packet to the built-in LAN switch 204 via the MII connection line 42. Also, MA
The C circuit 312 receives a packet input from the built-in LAN switch 204 via the connection line 42 according to the MAC address, extracts a control signal from the received packet, and outputs the extracted control signal to the control CPU 310. . Thus, the MAC circuit 31
2 performs MAC frame conversion processing between the built-in LAN switch 204 and the control CPU 310.

With the above configuration, the operation of the conversion processing circuit 62 in this configuration example will be described according to the flow of various signals. The control signals indicating the events addressed to the call processing unit 1 from each of the line interfaces 14, 16, and 18 will be described. DPRAM 28 and bus 30
When a packet is input to the control CPU 310 in the control signal / PACKET conversion unit 32 via the, a packet corresponding to the event content is assembled, and the MAC circuit 312 adds the MAC address to the packet. The generated packet is transferred to the built-in LAN switch 204, switched to the call processing unit 1, and sent to the external LAN switch 2 via the phi circuit 206. Thus, when the control packet is input to the call processing unit 1, a packet representing an order corresponding to the input is generated. The generated packet is transmitted to the call processing unit 1
Is transferred to the phi circuit 206 of the conversion processing circuit 62 via the external LAN switch 2. The built-in LAN switch 204 switches the control packet to the control signal / PACKET conversion unit 32 and transfers the packet to the MAC circuit 312.
When the MAC circuit 312 receives a packet addressed to itself, the control CPU 310 generates a control signal corresponding to the order of the received packet, and the generated control signal is output to the bus 30. When the order is input to the desired line interface in this way, a process according to a signal processing protocol such as a call connection is performed.

By the event / order transfer processing, for example, when the call connection is completed, the upstream PCM voice signal output from the extension interface board 14 becomes the PCM audio signal.
Signals are input and output by the DSP 300 of the PCM / PACKET conversion unit 26 via the highway 24, and a PCM audio signal is output to the audio CPU 302 at regular intervals synchronized with the clock signal 306. The voice CPU 302 sends the voice CPU 30
In response to the packet instructed to address 2, the voice signal exchange process starts. The PCM audio signal input to the audio CPU 302 is buffered at regular intervals and packetized, and the assembled audio packet is output to the MAC circuit 304. The input packet to the MAC circuit 304
The address is added and output to the built-in LAN switch 204. The built-in LAN switch 204 sends the packet to a port to which one of the MAC circuits 304a and 304b on the extension interface board 14 and the external interface board 16 or the external LAN switch 2 is connected, according to the destination of the packet. Forward.

Here, for example, if a call connection is made from the extension 22 to the outside line 34, the voice packet output from the built-in LAN switch 204 is transmitted to the outside line interface board.
It is received by the 16-side MAC circuit 304b. The processing of the downstream voice packet is performed by the voice CPU 302b from the packet.
The conversion process to the PCM audio signal is performed, and the converted audio signal is transferred to the DSP 300b while being buffered at regular intervals. These audio signals are DSP 300b
Is transferred via the PCM highway to the external line interface board 16 to which is connected. When voice exchange is performed between the voice CPUs in this manner, the voice exchange is performed via the built-in LAN switch 204.

When a packet addressed to a destination accommodated in another trunk unit is input to the built-in LAN switch 204, the built-in LAN switch 204 converts the packet based on the IP header and address table of the packet. The data is transferred to another trunk unit via the external LAN switch 2. As described above, when voice exchange is performed between the trunk units, the voice exchange is performed via the external LAN switch 2.

In the process of exchanging audio signals between extension interface boards under the control of the DSP 300, the audio signal is looped back by the audio CPU 300a and the audio signal is input to the same extension interface board. When a plurality of extension interface boards are accommodated in the trunk unit, the audio signal is transferred to the extension interface board corresponding to the connection destination.

Note that the DSP 300 shown in FIG.
Although the configuration has been described in which the PCM audio signal is processed, the configuration is not limited to this, and a configuration in which another type of audio signal is processed may be employed.
For example, as shown in FIG.
Each of P 300a, 300b, and 300c includes a companding circuit that compresses and expands an audio signal. As for the audio compression method,
For example, the 32 kADPCM system specified by the ITU-T audio coding standard G.728, the 16 kLD-CELP specified by the G.728
System, 8kCS-ACELP system specified in G.729, G.729
Various standardized methods such as the 8kCS-ACELP method specified in a and the 6.3kMP-MLQ / 5.3kACELP specified in G.723.1 are adopted.

Each DSP 300 is connected to each line interface
64 transferred via PCM highway connection lines 24, 36, 38
The kPCM audio signal is compressed using any of the compression methods described above, and the compressed audio signal is connected to the corresponding connected audio CP.
Output to U 302. Conversely, when each DSP 300 receives the compressed audio signal from the audio CPU 302, it decodes and converts this to a 64k PCM audio signal and outputs it to the PCM highway.

By providing the voice compression and decoding circuits in the DSP 300 in this way, for example, a plurality of voice calls can be multiplexed and transmitted / received to / from a global network connected to the switching system. in this case,
The line trunk unit 62 performs protocol conversion inside and outside the network as a gateway in H.323 by ITU-T.

Next, each DS in the conversion processing circuit 62 shown in FIG.
Each of the Ps 300a, 300b, and 300c has an echo canceller circuit in addition to the processing function of each DSP 300 shown in FIG. Since voice signals in a switching system employing VoIP are transmitted in packet form, a packet transmission delay occurs between transmission and reception. When a hybrid circuit that performs 2-wire to 4-wire conversion is provided on the line interface board, the downstream audio signal from the DSP 300 to the line interface board is reflected, and the upstream audio signal from the line interface board to the DSP 300 is reflected. It gets mixed in the audio signal. In this case, the time required for the echo to return to the sender is twice as long as the delay time generated between the sender and the receiver. I recognize it clearly.

Therefore, each DSP 300 in the conversion processing circuit 62 provided with an echo canceller circuit has a function of erasing, from an upstream audio signal, a component that reflects a downstream audio signal and returns as an upstream audio signal. are doing. Each DSP 300 is configured to predict an echo component from a downstream audio component and remove the predicted echo component from an upstream audio signal for a predetermined period. In this case, the greater the echo cancellation time and the amount of attenuation for removing the echo component, the more effective the effect. As described above, in this embodiment, the echo cancellation function is provided for each DSP 300
, Good communication quality can be maintained.

In order to make the performance of the echo cancellation more effective, two DSPs 300 are provided for one line interface board.
May be used to process an audio signal with one line interface.

Next, another embodiment of the line trunk unit will be described with reference to FIG. The trunk unit 600 in this embodiment is different from the translation processing circuit 62 shown in FIG. 5 in that the function of controlling the synchronization between the trunk units is provided in the translation processing circuit 602 when transferring packets between the trunk units. And different. Other configurations may be the same as the configurations of the same reference numerals. Only one trunk unit 600 in this embodiment is connected to the switching system and has a clock master function for synchronizing the trunk units.

In this embodiment, the control signal / PACKET conversion section 604 in the conversion processing circuit 602 is the same as the control CPU shown in FIG.
A control CPU 606 having a configuration in which a clock master function is added to the functional configuration of 310 is provided. The control CPU 606 outputs a clock signal at its output 306 and assembles a synchronization packet for controlling synchronization with each trunk unit and the call processing unit 1 in the switching system.
The packet is transferred to each device via the media access control (MAC) circuit 312. At this time, the MAC circuit 31
In step 2, a header designating multicast within the switching system group is added to the synchronization packet, and the synchronization packet is transmitted to the external LAN switch 2. The multicast may be designated when the control CPU 606 assembles the IP packet.

The synchronization packet thus created is received by the conversion processing circuit of another trunk unit, and each received trunk unit becomes a clock slave. For example, when a synchronization packet is received by each of the conversion processing circuits 62 shown in FIGS.
The control CPU 310 in the conversion unit 32 corrects a synchronization shift between the reception time of the synchronization packet and the independently generated clock signal. In this case, the control CPU 310 can correct the delay or advance of the clock signal by inserting or deleting a clock several tens of clocks earlier than the generated clock signal. As a result, the PC
The highway clock 306 supplied to the M / PACKET converter 26 can be synchronized with the system clock.

As described above, the line trunk unit according to the present embodiment has a clock master function in the entire switching system. Therefore, when a plurality of line trunks exist in the system, the line trunk unit is not connected between the trunk units. Are kept synchronized. As a result, during data transmission between analog terminals, for example, during modem communication, facsimile communication, and even voice communication, it is possible to prevent communication errors, communication interruptions, and interruptions in voice due to synchronization errors. Alternatively, it can be reduced.

Next, another configuration example of the line trunk unit will be described with reference to FIG. The line trunk unit 700 shown in FIG.
In the conversion processing circuit 602, the built-in LAN switch 204 is removed, and the PCM / PACKET conversion unit 26 and the control signal
Each of the / PACKET conversion units 604 includes a conversion processing circuit 702 having a configuration provided with a priority control function. The other configuration in the trunk unit 700 may be the same as the configuration of the same reference numeral shown in FIG.

The audio CPUs 300a, 300b, and 300c of the PCM / PACKET conversion unit 704 in this embodiment have the audio CPU 300
Priority control circuits 706a, 706b, and 706c are connected corresponding to the first and second MAC circuits 708a, 708b, and 708c and the second MAC corresponding to the voice CPU 300, respectively.
It is connected to circuits 710a, 710b, 710c. First MAC circuit
A connection line 714 connects the first MAC circuit 708b and the second MAC circuit 710c via a connection line 712 between the first MAC circuit 708a and the second MAC circuit 710b.
Through the connection line 716 to the second MAC circuit 720 in the control signal / PACKET conversion unit 718.
Each is cascaded. The control signal / P
The ACKET conversion section 718 includes a second MAC circuit 720 and a first MAC circuit 720.
The first MAC circuit 722 is connected to the PHY circuit 206 via the connection line 726 by MII.

The priority control circuit 706 that interfaces the voice CPU 302 determines whether to output a packet transmitted from the connected voice CPU 302 to another or a packet transferred from another MAC circuit with priority. Control. When a packet transferred from a MAC circuit corresponding to another voice CPU is further transferred to a MAC circuit corresponding to another voice CPU, packets must be transferred between two MAC circuits corresponding to the own voice CPU. Then, the packet is output from the other MAC circuit. The priority control circuit 706 is provided with a buffer for temporarily storing and waiting for a packet to be waited for when a priority packet is transmitted.

The priority control circuit 724 for interfacing with the control CPU 606 is connected to an upstream packet addressed to the call processing unit 1 from the control CPU 606 via a first line connected via a connection line 716.
Of the packet transferred from the MAC circuit 708c to the second MAC circuit 720 is controlled with priority given to the output from the output 726 of the first MAC circuit 722. Also, priority control circuit
Reference numeral 724 denotes a packet output from the control CPU 606 to the voice CPU 302 side, and a packet output from the call processing unit 1 to each voice CPU 302.
It controls which of the packets transferred to the first MAC circuit is output to the output side 716 of the second MAC circuit 720 with priority. The priority control unit 724 includes a buffer for temporarily storing and waiting for a packet to be waited when a priority packet is transmitted.

The transmission clocks (for example, 100 MHz or 10 MHz) between the respective MAC circuits 708, 710, 720, 722 and the trunk unit 700 and the external LAN switch 1 match, and further, the communication systems such as full-duplex or half-duplex match. Thus, when the transfer rates of the packets in the predetermined unit are the same, the storage capacity of the buffer can be reduced. In the case where the transfer speeds of these packets are partially different, for example, the storage capacity of the buffer may be set to a storage capacity adapted to the case where the transmission speed and the communication method are the slowest.

As described above, in this embodiment, the audio CPU and the control
The number of MAC circuits that interfaced with the CPU is two, and priority control circuits that control the priority of each MAC circuit are provided. The MII interface output of each MAC circuit is cascaded, and finally the control signal
The first MAC circuit 722 of the / PACKET converter 718 and the phi circuit
The number of built-in LAN switches 204 in the embodiment shown in FIG. For this reason, the production cost of the trunk unit can be significantly reduced.

[0073]

As described above, according to the present invention, since the line trunk unit is constituted by a housing independent of the call processing unit 1 and the external LAN switch, the number of trunk units 12 can be flexibly increased or decreased. Can be set up. In addition, the line trunk unit is
Since the connection is made by the N interface, the switching system can be operated by arranging the call processing device, the LAN switch, and the line trunk unit at any positions according to the network. In addition, conventional PBX
Since each existing line interface board used in such as is housed in the line trunk unit case and used, it is possible to convert voice signals and control signals and packets without developing a new line board. , Can be interfaced with LAN. Therefore, the switching system can be constructed by freely installing the line trunk unit in a place satisfying the accommodation conditions of the LAN.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a switching system to which the present invention is applied.

FIG. 2 is a block diagram showing another embodiment of the switching system.

FIG. 3 is a block diagram illustrating a configuration example of a conversion processing circuit in the line trunk unit.

FIG. 4 is a block diagram showing another configuration example of the conversion processing circuit in the line trunk unit.

FIG. 5 is a block diagram showing still another configuration example of the conversion processing circuit in the line trunk unit.

FIG. 6 is a block diagram showing one embodiment of a switching system including a line trunk unit having a clock master function.

FIG. 7 is a block diagram showing one embodiment of a switching system including a line trunk unit in which a built-in LAN switch is eliminated.

[Explanation of symbols]

 1 Call processing unit 2 LAN switch 10 Switching system 12 Line trunk unit 20 Conversion processing circuit 26 PCM / PACKET conversion unit 32 Control signal / PACKET conversion unit 204 Built-in LAN switch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Seiichi Shimoyama 3-20-2 Shibaura, Minato-ku, Tokyo Inside Oki Comtech Co., Ltd. (72) Inventor Shinta 3-20-2 Shibaura, Minato-ku, Tokyo Oki Comtech F-term (reference) 5K030 GA05 HA01 HB01 HB28 HC01 JA05 KA01 KA19 LB05 LB13

Claims (14)

[Claims] 1. A line trunk unit in which a communication path interface is formed by a PCM highway, and a voice circuit board for performing voice communication between lines is housed in a housing, and a voice signal of the voice circuit board; A line trunk unit for converting and controlling voice packets on a network, a first connecting means for connecting a voice circuit board for transmitting and receiving voice frames by time division multiplex communication, and a second connecting means for connecting the voice circuit board Connection means, a conversion processing means for performing conversion processing between the audio signal and the audio packet, and a third connection means connected to the conversion processing means for inputting and outputting the audio packet, The means comprises: first conversion means connected through first connection means for performing a conversion process between the voice frame and the voice packet; and second connection means. A second conversion unit connected via a line for performing a conversion process between a control signal and a control packet on the audio circuit board side, and transmitting and receiving the audio packet and the control packet to and from a network side. Trunk unit. 2. The line trunk unit according to claim 1, wherein said conversion processing means is a first LAN of a separate housing from said line trunk unit via a third connection means by a medium independent interface. A line trunk unit connected to a switch. 3. The line trunk unit according to claim 2, wherein a call processing device for performing call control on said voice circuit board is connected to a first LAN switch, and wherein said second conversion means includes a voice circuit. A control packet corresponding to an event addressed to the call processing device is formed from the board, and the control packet is output via a third connection means, and control is performed according to an order addressed to the voice circuit board from the call processing device. A line trunk unit comprising: receiving a packet via a third connection unit; forming a control signal from the control packet; and outputting the control signal to the audio circuit board. 4. The line trunk unit according to claim 1, wherein said conversion processing means includes: first conversion means;
A line trunk unit, comprising: a second LAN switch for connecting to a second conversion means by the medium independent interface, wherein the third connection means is connected to a second LAN switch. 5. The line trunk unit according to claim 1, wherein the first conversion means corresponds to the audio circuit board, and a frame processing means for inputting / outputting a PCM frame signal; Voice packet processing means for performing MAC processing, and a first processing means for processing MAC frames of voice packets.
The second converting means includes a control packet processing means for performing a disassembly / reassembling process of a control packet, and a second MAC processing means for processing a MAC frame of the control packet. And a second trunk means connected to the second LAN switch. 6. The line trunk unit according to claim 5, wherein said control packet processing means generates a clock signal for controlling synchronization of frame processing means and voice packet processing means corresponding to said voice circuit board, A line trunk unit for supplying the frame processing means and the voice packet processing means. 7. The line trunk unit according to claim 6, wherein when the second MAC processing unit receives a synchronization packet, the control packet processing unit generates the clock signal synchronized with the synchronization packet. A clock slave line trunk unit, characterized in that: 8. The line trunk unit according to claim 5, wherein said frame processing means compresses a PCM frame signal output from said audio circuit board, and outputs the compressed PCM frame signal to said audio packet processing means. A line trunk unit which expands a PCM frame signal output from a processing means and outputs the expanded signal to the audio circuit board. 9. The line trunk unit according to claim 5, wherein said frame processing means includes a removing means for removing an echo component contained in a PCM frame signal output from said audio circuit board. Line trunk unit. 10. The line trunk unit according to claim 6, wherein said control packet processing means generates a synchronization packet synchronized with said clock signal, and outputs said synchronization packet to said second MAC processing means. A clock trunk line trunk unit characterized by controlling synchronization with another line trunk unit. 11. The line trunk unit according to claim 10, wherein said second MAC processing means adds a header indicating a multicast to said synchronization packet. 12. The line trunk unit according to claim 10, wherein the control packet processing means adds a header indicating multicast to the synchronization packet. 13. The line trunk unit according to claim 1, wherein the first converting means comprises: a frame processing means for inputting / outputting a PCM frame signal; a voice packet processing means for disassembling and assembling a voice packet; Priority control means for controlling a packet transmission timing, and a set of first MAC processing means connected to the priority control means for processing a MAC frame of a voice packet, each corresponding to the voice circuit board; The second conversion processing means includes control packet processing means for disassembling and assembling the control packet, and a set of second MAC processing means connected to the control packet processing means for processing a MAC frame of the control packet. Wherein the set of first MAC processing means is cascaded to one of the other sets of first MAC processing means provided for the plurality of audio circuit boards, respectively. A pair of second MAC processing means, one of which is a first MAC
A line trunk unit connected to one of the processing means and the other to a network side. 14. A line trunk unit according to claim 1, a first LAN switch connected to said conversion processing means via third connection means, and said line switch connected to said first LAN switch. A packet switching system to which a call processing device that performs call control on a trunk unit is connected.