JP2002051044A - Atm cell transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the operating speed, simplify the wiring design in mounting, increase the number of connected PHYs and suppress contention between transmission cells and reception cells so as to effectively utilize the band in cell transmission where an ATM switch and PHYs(Physical layers) are connected. SOLUTION: The ATM switch 1 and the PHYs 2-4 are connected side by side by using loop transmission lines 7-11 to transmit cells and control data for cell transmission reception control. The ATM switch 1 monitors cell transmission/reception signal from the PHYs 2-4 to decide to/from which of the PHYs 2-4 the cell transmission/reception is made, the control data generated on the basis of this decision are added to cells and transmitted to the 1st stage PHY 2. The ATM switch 1 receives the cells and the control data from the PHY 4 at the final stage to perform cell switching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ATM cell transmission system for processing an interface for transmitting cells between ATM cell termination devices (connection devices) in an asynchronous transfer mode (ATM) transmission.

[0002]

2. Description of the Related Art Conventionally, this type of ATM cell transmission uses an AT
M cell termination device (abbreviated as PHY) and ATM
Utopia levels 1 and 2 for cell transmission with the switch
There is an interface (abbreviated as I / F as appropriate).
Utopia level 1 I / F is for single connection.
The Utopia level 2 I / F is for a multi-device multipoint connection (1: n), and has an interface for connecting the main signal of each device through a common bus and transmitting control signals individually (for example, "ATM bus connection system" in JP-A-11-252122).

In such an ATM cell transmission, at the Utopia level 2 I / F, an ATM switch and a plurality of P
HY is multi-connected. This utopia level 2
Since the I / F is a bus type, waveform distortion such as waveform reflection easily occurs due to impedance change due to branching of a wiring pattern on a circuit board, for example. Therefore, it is difficult to increase the operation speed of the bus, and it is also difficult to connect a large number of PHYs. In addition, in order to suppress the waveform distortion, a detailed study is required in the mounting design.

FIG. 7 is a block diagram for explaining a conventional ATM cell transmission system using a Utopia level 2 interface. In FIG. 7, this example is an ATM
The switch 401 and the PHYs 402 to 404 are connected by a bus 405 for cell transmission and a bus 406 for cell reception. That is, it is configured in a 1: n bus format. The PHYs 402 to 404 notify the ATM switch 401 to the ATM switch 401 via the control bus 407 whether the cell can be received or not.

The ATM switch 401 determines whether or not reception is possible.
Based on the transmission availability information, the cell transmission to each PHY through the transmission bus 405 and the reception bus 406 and the PH
The cell reception control from Y is executed. The transmission of the transmission cell 461 and the reception of the reception cell 462 are performed by the cell reception control.

[0006]

The above conventional ATM cell transmission system based on Utopia Level 2 has the following problems.
There are the following problems. (1) The operation speed cannot be increased because cell transmission / reception is performed by the bus. For example, the upper limit of the operating frequency is 33 in Utopia level 2 I / F of a general multi-PHY transmission method.
MHz.

[0007] This is because, since a plurality of devices are connected to a single signal line for signal transmission by bus transmission, the transmission waveform is distorted due to waveform reflection or the like due to a change in impedance of the pattern branch, and until the waveform distortion converges. This is because it takes time.

(2) In order to suppress the waveform distortion, it is necessary to pay particular attention to the component mounting position and the wiring routing method, which complicates the mounting design. This is because the distortion of the transmission waveform due to the bus connection greatly changes due to the routing of the wiring pattern, and it is necessary to optimize the component arrangement and the routing of the wiring to avoid malfunction due to the waveform distortion.

(3) Because of 1: n bus connections, the number of connected PHYs is limited. This is because it is necessary to consider the drive capability and fan-out of the element in the 1: n connection.

The present invention solves such a problem in the prior art, and comprises an ATM switch and a plurality of P switches.
In the cell transmission connected to the HY, the operation speed can be increased, the wiring design in mounting can be simplified, the number of connected PHYs can be increased, and the competition between the transmission cell and the reception cell can be suppressed to reduce the bandwidth. An object of the present invention is to provide an ATM cell transmission system that can be used effectively.

[0011]

In order to achieve the above object, an ATM cell transmission system according to the present invention comprises an ATM switch and a plurality of ATM switches in asynchronous transfer mode (ATM) transmission.
A cell is transmitted to and from a TM cell terminating device, and an ATM switch and a plurality of ATM cell terminating devices are connected by a single loop-shaped transmission line to transmit control data for controlling transmission and reception of cells and cells. This is a configuration characterized by transmission.

[0012] In the system of the present invention, as the transmission by connecting the loop-shaped one transmission line, the ATM switch comprises:
A cell transmission / reception signal from a plurality of ATM cell termination devices is monitored, which ATM cell termination device is to be used for transmission / reception of a cell is determined, and control data created based on the determination is added to the cell to add a first ATM cell. Transmitting to the cell termination device, and the ATM switch receiving the cell and control data from the last ATM cell termination device,
The configuration is characterized by executing cell switching.

Further, the system according to the present invention includes the plurality of A
Each of the TM cell terminating devices is provided with an identification number for self-identification, compares the identification number with the identification number in the control data, recognizes the data addressed to the self-ATM cell terminating device and the cell transmission request, and Each of the plurality of ATM cell terminating devices notifies the ATM switch of whether or not a cell can be received and whether or not there is a cell to be transmitted by a cell transmission / reception signal.

Further, in the system according to the present invention, the control data comprises an identification number for each ATM cell termination device and transmission information, and any of transmission, reception, and transmission instruction information is stored in the transmission information. The configuration is characterized by the following.

Further, in the system of the present invention, the ATM switch and the plurality of ATM cell terminating devices are connected in place of a configuration in which the ATM switch and the plurality of ATM cell terminating devices are connected by one loop-shaped transmission line. And a transmission line for transmitting a transmission cell by connecting a plurality of ATM cell terminating devices and an ATM switch, and transmitting a transmission cell through the transmission line. The configuration is characterized by transmitting control data.

Further, in the system of the present invention, the transmission information of the control data is a transmission destination identification number indicating a cell transmission destination and a reception destination identification number indicating an ATM cell termination device which permits cell transmission. This is a configuration characterized by the following.

In the ATM cell transmission system of the invention having such a configuration, an ATM switch and a plurality of ATM cell terminating devices are connected by one loop-shaped transmission line to transmit control data for controlling transmission and reception of cells and cells. are doing.

As a result, the following effects (I), (II) and (II)
I) is obtained. (I) Distortion of the transmission waveform such as reflection can be suppressed by the termination at the 1: 1 transmission line connection, and the operation speed can be increased.

(II) Since the transmission line connection is 1: 1, there is no need to consider wiring branching when connecting a plurality of PHYs, and wiring design in mounting is simplified.

(III) Since the transmission line connection is 1: 1,
There is no longer any limitation on the number of connections due to the drive capability of the elements or the fan-out, and the number of connected PHYs can be increased.

Further, the ATM cell transmission system of the present invention comprises:
A receiving-system transmission line for connecting an ATM switch and a plurality of ATM cell termination devices to transmit a received cell;
Two transmission paths are provided: a transmission path for transmitting a transmission cell by connecting an M cell termination device and an ATM switch. As a result, due to the two transmission paths that distinguish transmission and reception, competition between the transmission cell and the reception cell is less likely to occur,
The transmission (transmission / reception) characteristics are improved, and the band can be effectively used.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an ATM cell transmission system according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an embodiment of an ATM cell transmission system according to the present invention. In FIG. 1, in an ATM cell transmission system of this example, three PHYs (ATM cell termination devices) 2, 3, and 4 are provided in an ATM switch 1,
They are connected via transmission lines 8, 9, 10, 11 respectively. It should be noted that the same configuration can be realized when there are two or four or more PHYs, and the same operation is performed hereinafter.

Next, the operation of this embodiment will be described. First, the basic operation of each unit will be described. Figure 1
, The ATM switch 1 includes a plurality of PHYs 2 to
4 to monitor the cell transmission / reception signal 5 and determine which PHY
And whether to transmit and receive cells. Based on this determination, the created control data 7 is added to the cell and transmitted to the PHY 2. The ATM switch 1 receives the cell 6 and the control data 7 from the PHY 4, and switches the cell 6.

The PHY 2 is connected to the ATM switch 1 by a transmission line 8 and monitors control data 7 received from the ATM switch 1. When the control data 7 by this monitoring is transmission data addressed to the own PHY 2, the cell 6 following the control data 7 is fetched. Control data 7 is self P
If the request is a cell transmission request addressed to HY2, the transmission cell is written in the cell 6 following the control data 7, and transmitted to the next PHY 3 through the transmission path 9.

The PHY 2 transmits the control data 7 to its own P
In the case of a data transmission request addressed to HY2 and a cell transmission request addressed to itself, the cell 6 following the control data 7 is fetched, the transmission cell is written, and transmitted to the next PHY 3 via the transmission path 9. If the control data 7 is not data addressed to the own PHY 2, it is transmitted to the PHY 3 as it is.

Next, the PHY 3 is connected to the PHY 2 by the transmission line 9, and monitors the control data 7 received from the PHY 2. In this monitoring, as in the case of the PHY 2, when the control data 7 is addressed to the own PHY 3, the cell 6 following the control data 7 is fetched and the transmission cell is written, and the transmission data is transmitted to the next PHY 4 through the transmission path 10. Send. If the control data 7 is not data addressed to the own PHY 3, it is transmitted to the PHY 4 as it is.

Further, the PHY 4 has the same PH as the PHY 3.
The control data 7 received from Y3 is monitored. When the control data 7 is addressed to the own PHY 4 in this monitoring, the cell 6 following the control data 7 is taken in and the transmission cell is written. Then, the packet is transmitted to the ATM switch 1 through the transmission line 11. If the control data 7 is not the data addressed to the own PHY 4, the control data 7 is transmitted to the ATM switch 1 as it is.

FIG. 2 is a diagram for explaining the contents of the control data 7. In FIG. 2, the control data 7 includes PHY identification numbers 71 and transmission information 72. The PHY identification number 71 stores the PHY identification number for performing cell transmission and reception.
One of the reception / transmission / reception instruction information is stored.

Next, an outline of the entire operation will be described.
Referring to FIG. 1, PHYs 2 to 4 are connected to ATM switch 1 by transmission lines 8 to 11, and cells are transmitted from PHY 4 to ATM switch 1. PHY2-4
The cell transmission / reception signal 5 is transmitted to the ATM switch 1. AT
The M switch 1 monitors the cell transmission / reception signal 5 and, if there is a PHY that can be transmitted or received, transmits the cell 6 and the control data 7.

PHY receiving cell 6 and control data 7
Monitors the control data 7. In this monitoring, the self PHY
If the control data is addressed to 7, the cell 6 is taken. If the control data 7 is a cell transmission request from the ATM switch 1 to the own PHY, the cell 6 is overwritten and the next PHY is
Send to If the control data 7 is not addressed to the own PHY, it is transmitted to the next PHY as it is.

Next, a specific operation example will be described. FIG. 3 is a diagram for explaining a specific operation of the embodiment. In FIG. 3, the cell transmission / reception signal 151 from the PHY 102 can be received, and the PHY 103
It is assumed that the cell transmission / reception signal 152 can be transmitted / received. Further, here, a case where the cell transmission / reception signal 153 from the PHY 104 can be transmitted will be described.

The PHYs 102 to 104 constantly determine whether or not a cell can be received and whether or not there is a cell to be transmitted.
1, 162, 163 to the ATM switch 101.

The ATM switch 101 which has received the cell transmission / reception signals 161 to 163 transmits the transmission information and transmits the control data storing the identification number of the PHY 102 and the cell to be transmitted to the PHY 102 (control data 17 in FIG. 3).
1, cell 161) and transmit it to PHY 102.

The ATM switch 101 which has received the cell transmission / reception signals 161 to 163 transmits and receives the transmission information, and transmits the control data storing the identification number of the PHY 103 and the transmission cell to the PHY 103 (control data 172 in FIG. 3). , Cell 162) and transmit it to the PHY 102.

Further, the ATM switch 101 which has received the cell transmission / reception signals 161 to 163 receives the transmission information, and stores the control data storing the identification number of the PHY 104 and the dummy cell (the control data 173 in FIG. 3). A cell 163) is created and transmitted to the PHY 102.

The PHY 102 extracts control data from cells and control data received from the ATM switch.
Then, the PHY 102 determines whether the PHY identification number in the control data 171 to 173 matches the identification number of its own PHY.

In FIG. 3, when the control data 171 is received, the identification number in the control data 171 is set to the own PHY.
Next, the transmission information in the control data 171 is examined. As a result, the next cell 161 is taken in for transmission of transmission information. Also, the control data 172, 1
73, the identification number in the control data does not match the own PHY, so the control data 172 and the cell 1
62, the control data 173 and the cell 163 are
Transmit to HY103.

Similarly to the PHY 102, the PHY 103 first extracts control data from cells and control data received from the PHY 102. Then, the control data 172,
It is determined whether the PHY identification number in 173 matches the identification number of the own PHY. In FIG. 3, the control data 172
Is received, since the identification number in the control data 172 matches the own PHY, the transmission information in the control data 172 is checked next.

As a result, since the transmission information is transmitted / received, the following cell 162 is taken in. Thereafter, the cell 164 to be transmitted is overwritten on the cell 162 and transmitted to the PHY 104. When the control data 173 is received, the identification number in the control data does not match the own PHY.
Send to 4.

The PHY 104 is, like the PHY 102,
First, control data is extracted from the control data and cells received from the PHY 103. Then, the control data 17
It is determined whether the PHY identification number in 2,173 matches the identification number of the own PHY. In FIG. 3, when the control data 172 is received, the control data 172 and the cell 164 are transmitted to the ATM switch 101 as they are because the identification number in the control data does not match the own PHY.

The PHY 104 stores the control data 173
Is received, since the identification number in the control data 173 matches the own PHY, the transmission information in the control data 173 is checked next. As a result, since the transmission information is received, the cell 165 to be transmitted is overwritten on the cell 163, and
It transmits to the ATM switch 101.

The ATM switch 101 finally switches the PHY 1
04, control data 172, cell 164, control data 173, and cell 165 are received. ATM switch 101
Confirms the transmission information in the control data 172,173. In the case of reception / transmission / reception by this confirmation, the following cell 16
4, 165 is taken in and cell switching is performed.

In this manner, in this embodiment, a plurality of PHYs can be connected similarly to the Utopia Level 2 interface. In this case, an ATM switch and a plurality of PHs
Y is connected by one loop-shaped transmission line to transmit cells and control data for cell transmission / reception control. That is, the cell transmission methods are all 1: 1 transmission connection, and the following operation and effect can be obtained. (A) All cell transmission methods are 1: 1 transmission connections,
The termination makes it possible to suppress distortion of the transmission waveform such as reflection. For example, the operating speed of several tens MHz in the conventional multiple PHY connection can be increased to 100 MHz or more.

(B) Since all cell transmission methods are 1: 1 transmission connections, it is not necessary to consider branching in a plurality of PHY connections as in the prior art, and the wiring mounting design on a substrate or the like can be simplified. Will be able to

(C) Since the cell transmission methods are all 1: 1 transmission connections, there is no limit on the number of connections due to the drive capability of the elements or the fan-out, and the number of connected PHYs can be increased.

Next, another embodiment of the present invention will be described. FIG. 4 is a block diagram showing the configuration of another embodiment. Referring to FIG. 4, in the ATM cell transmission system, the transmission lines 9 and 10 in FIG. 1 are separated into a receiving direction from the ATM switch 1 and a transmitting direction to the ATM switch 1. Transmission lines 208 to 210 (corresponding to the transmission line in the claims) for transmitting received cells from the ATM switch are provided. Further, transmission lines 211 to 213 (corresponding to a transmission system transmission line in the claims) for transmitting transmission cells to the ATM switch are provided. Here, Figure 1
In the same manner as described above, control data 270 for cell transmission / reception control is transmitted.

FIG. 5 shows control data 2 according to another embodiment.
FIG. 7 is a diagram for explaining 70 transmission information. In FIG. 5, the transmission information of the control data 270 is a transmission destination identification number 271 indicating the transmission destination of the cell 206 and a reception destination identification number 272 indicating the PHY permitting the transmission of the cell.

A specific operation in the other embodiment will be described. FIG. 6 is a diagram for explaining a specific operation of another embodiment. 6, the ATM switch 301 receives cell transmission / reception signals 351 to 353 from the PHYs 302 to 304. ATM switch 301
Is the transmission destination identification number of the PHY that performs cell transmission and the PH that performs reception from the cell transmission / reception signals 351-353.
Control data 371 and 37 storing the destination identification number of Y
Generate 2. In addition, the ATM switch 301
The control data is added to the head of the cells 361 and 362 to be transmitted to Y and transmitted to the PHY 302.

Hereinafter, description will be made assuming that the cell transmission / reception signal 351 from the PHY 302 can be received, and in FIG. 6, it will be described that the cell transmission / reception signal 352 from the PHY 303 can be transmitted / received. Further, in FIG. 6, a description will be given assuming that the cell transmission / reception signal 353 from the PHY 304 can be transmitted.

An example of the control data and cell contents is shown below. (I) Control data 371: Transmission destination identification number = PHY30
2. Reception destination identification number = PHY 304 (ii) Control data 372: transmission destination identification number = PHY 30
3. Reception destination identification number = PHY303 (iii) Cell 361: Transmission cell to PHY302 (iv) Cell 362: Transmission cell to PHY303

The PHY 302 determines whether the destination identification number in the control data 371 received from the ATM switch 301 matches the identification number of its own PHY. In this determination, under the conditions of FIG. 6 (see (i) to (iv) above), the destination identification number matches the identification number of the own PHY, so that the cell 361 following the control data 371 is taken in.

Subsequently, it is determined whether or not the destination identification number in the control data 371 matches the identification number of the own PHY.
In this determination, since the destination identification number does not match the identification number of the own PHY, the cell transmission processing is not performed. Regarding the control data 372 and the cell 362, no particular processing is performed since the destination identification number and the destination identification number do not match. The control data and cells received from the ATM switch 301 are transmitted to the PHY 303 as they are.

The PHY 303 checks whether the transmission destination identification number and the reception destination identification number of the control data 371 received from the PHY 302 match or not. In this check, the PHY 303 does not match the identification signal of its own PHY under the conditions of FIG. The PHY 303 fetches the cell 362 for the control data 372 and the cell 362 subsequently received because the destination identification number and the destination identification number match. The PHY 303 transmits the cell 363 to the PHY 304 via the cell transmission transmission path. The control data and cell received from the PHY 302 are transmitted to the PHY 304 as they are.

The PHY 304 has a transmission destination identification number in the control data 371 received from the PHY 303 and has its own PHY.
Is determined to match the identification number. In this determination, under the condition of FIG. 6, the destination identification number matches the identification number of the own PHY, so that the AT
The cell 364 is transmitted to the M switch 301.

The ATM 363 to the ATM switch 301 received from the upper PHY 303 is transmitted to the ATM switch 301 without any particular processing.
Subsequently, regarding the received control data 372 and the cell 362, since the receiving destination identification number and the transmitting destination identification number do not match, no particular processing is performed. Note that the control data and cell received from the PHY 303 have no next destination PHY, and are discarded here.

With the operation up to this point, the ATM switch 301
Receives cells 363 and 364 from PHY 304.
The ATM switch 301 takes in a cell and performs cell switching.

By the cell transmission / reception system provided with such two transmission paths of reception and transmission, competition between a transmission cell and a reception cell can be suppressed, and the band can be used effectively.

[0058]

As is clear from the above description, according to the ATM cell transmission system of the present invention, it is possible to suppress the distortion of the transmission waveform such as the reflection due to the termination in the bus transmission, and the operation speed is reduced. Faster and more PH
This eliminates the need to consider branching in the Y connection, simplifies the wiring design in mounting, eliminates the limitation on the number of connections due to the drive capability of the element and the fan-out, and increases the number of connected PHYs.

Further, according to the ATM cell transmission system of the present invention, a receiving system transmission line for connecting an ATM switch and a plurality of ATM cell terminating devices to transmit a received cell, and a plurality of ATM cell terminating devices and an ATM switch. Two transmission paths including a transmission system transmission path for transmitting transmission cells in a connected manner are provided. As a result, competition between the transmission cell and the reception cell is less likely to occur due to the two transmission paths that distinguish transmission and reception, and the transmission (transmission and reception) characteristics thereof are improved, and the band can be effectively used. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an ATM cell transmission system according to the present invention.

FIG. 2 is a diagram for explaining the contents of control data in the embodiment.

FIG. 3 is a diagram for explaining a specific operation of the embodiment.

FIG. 4 is a block diagram illustrating a configuration of another embodiment.

FIG. 5 is a diagram for explaining transmission information of control data in another embodiment.

FIG. 6 is a diagram for explaining a specific operation of another embodiment.

FIG. 7 is a block diagram for explaining a conventional ATM cell transmission system using Utopia Level 2.

[Explanation of symbols]

1,101,201,301,401 ATM switch 2,3,4,102-104,202-204,302
PHY (ATM cell termination device) 5,151-153,205,351-353 Cell transmission / reception signal 6,161-165,206,361-364,46
1,462 cell 7,171-173,207,371,372 control data 8,9,10,11,208-213 transmission line 71 PHY identification number 72 transmission information 271 destination identification number 272 destination identification number 405 ATM cell Transmission bus 406 ATM cell reception bus 407 Cell transmission / reception control bus 461 Transmission ATM cell 462 Reception ATM cell

Claims (6)

[Claims] 1. An ATM cell transmission system for transmitting cells between an ATM switch and a plurality of ATM cell termination devices in an asynchronous transfer mode (ATM) transmission, wherein the ATM switch and the plurality of ATM cell termination devices are connected in a loop. AT for transmitting cells and control data for transmission / reception control of cells by connecting the two transmission paths
M cell transmission system. 2. An ATM switch monitors cell transmission / reception signals from a plurality of ATM cell termination devices and transmits / receives cells to / from any of the ATM cell termination devices as transmission by connection of one loop-shaped transmission line. Is determined, and the control data created based on this determination is added to the cell, and the first-stage AT
2. The ATM cell transmission according to claim 1, wherein the ATM switch transmits cells and control data to the M cell termination device, and the ATM switch receives cells and control data from the last ATM cell termination device. system. 3. Each of the plurality of ATM cell termination devices is provided with an identification number for self-identification, and compares the identification number with an identification number in control data to determine a self-AT number.
Recognize the data and cell transmission request addressed to the M cell termination device, and notify each of the plurality of ATM cell termination devices of whether or not to receive a cell and the presence or absence of a cell to be transmitted to an ATM switch by a cell transmission / reception signal. The ATM cell transmission system according to claim 1, wherein: 4. The control data comprises an identification number for each ATM cell termination device and transmission information, and the transmission information stores any one of transmission, reception, and transmission / reception instruction information. Item 4. An ATM cell transmission system according to any one of Items 1, 2, and 3. 5. An ATM switch and a plurality of ATM cell terminating devices are connected to each other by a single loop transmission line, and an ATM switch and a plurality of ATM cell terminating devices are connected to transmit a received cell. And a transmission line for transmitting transmission cells by connecting a plurality of ATM cell terminating devices and an ATM switch, and transmitting control data through the transmission line. The method according to claim 1, wherein
TM cell transmission system. 6. The transmission information of the control data is a transmission destination identification number indicating a cell transmission destination and a reception destination identification number indicating an ATM cell termination device which permits transmission of the cell. Item 6. The ATM cell transmission system according to Item 5.