JP2002252657A - Frame relay/atm interwork apparatus and atm switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide effective congestion control and an inexpensive device by interlocking respective buffers in ATM(asynchronous transfer mode) switches and a frame relay/ATM interwork apparatus. SOLUTION: The frame relay/ATM interwork apparatus 2 is equipped with a frame relay data processing unit 21 with frame buffers and an ATM cell data processing unit 22 with cell buffers. Cell/frame discard is avoided by interlocking respective buffers, notifying congestion to the ATM cell data processing unit 22 during congestion in the frame relay data processing unit 21 and notifying congestion to a common ATM cell buffer in a switch unit during congestion in the ATM cell data processing unit 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a frame relay /
The present invention relates to an ATM interworking device and an ATM switch.
In particular, the present invention relates to an ATM switch having a frame relay / ATM interworking device having a common ATM cell buffer and a plurality of interface boards in a switch unit, and having a frame relay network interface on one of the interface boards. The present invention relates to a frame relay / ATM interworking apparatus and an ATM switch which enable to control a band of a frame or a cell to be transmitted based on the congestion information of the device and the congestion state of a buffer in the apparatus.

[0002]

2. Description of the Related Art Congestion information in a conventional frame relay / ATM interworking apparatus is for transmitting congestion information of one network type to another network type (for example, see Japanese Patent Application Laid-Open No. 2000-115187). According to this, when it is desired to transmit the congestion information of one network to the other network as it is, or when it is desired to transmit the congestion information of one network to the other network only under certain conditions, or the congestion information of one network In any case, it is possible to flexibly cope with the transmission of congestion information to heterogeneous networks.

[0003]

The congestion information in the conventional frame relay / ATM interworking apparatus as described above transmits congestion information of one network type to the other network type. The recovery means was expected from a terminal having an ABR (Available Bit Rate) function connected to the ATM network or a frame relay terminal connected to the frame relay network. However, when passing through multiple networks, due to delays and fluctuations in the network,
A delay occurs before the congestion information is transmitted to the terminal. Also, it takes time for the terminal to start the means for recovering congestion such as lowering the throughput after recognizing the congestion information. For this reason, effective congestion control cannot be performed, and user data may be discarded without permission.

Further, when trying to control the bandwidth of a frame to be transmitted in the frame buffer of the interface board, a plurality of frames are multiplexed on one line.
nnection identifier), which requires an enormous amount of memory, so that the circuit configuration may become large or expensive.

In view of the above, the present invention controls the bandwidth of a frame or a cell to be transmitted based on the congestion information from the network and the congestion state of the buffer in the device, and provides an effective congestion control with less data discard. It is another object of the present invention to provide an inexpensive frame relay / ATM interwork apparatus.

According to the present invention, a switch unit having a common ATM cell buffer, a frame relay data processing unit having a frame buffer, and an ATM cell data processing unit having a cell buffer cooperate with each other to reduce congestion. It is an object of the present invention to provide a frame relay / ATM interworking apparatus and an ATM switch which can avoid the problem. Also, the present invention, without expecting a terminal having a network congestion recovery means that lowers the throughput,
Further, by detecting congestion information from RM cells of the ATM network, BECN (Back
ward ExplicitCongestion Notification) / FECN
It is an object of the present invention to provide a frame relay / ATM interwork apparatus and an ATM switch that enable control of (Forward Explicit Congestion Notification) and dynamically control the bandwidth of a cell to be transmitted to an ATM network.

[0007]

One of the features of the present invention is an ATM switch comprising a common ATM cell buffer and a plurality of interface accommodating units as a switch unit.
In a frame relay / ATM interworking apparatus having a frame relay interface in one of the interface accommodating sections, a frame relay data processing section having a frame buffer in an interface accommodating section, an ATM cell data processing section having a cell buffer, A means for notifying the ATM cell data processing unit of congestion when the frame relay data processing unit is congested, and a means for notifying the ATM cell data processing unit of congestion when the frame relay data processing unit is congested; Means for notifying congestion; means for notifying congestion to the common ATM cell buffer of the switch unit when the ATM cell data processing unit is congested; and means for notifying congestion to the ATM cell data processing unit when the common ATM cell buffer of the switch unit is congested. Characterized by having means for notifying To provide a Frame Relay / ATM interworking unit.

Another feature of the present invention is that, as means for notifying congestion of a frame relay data processing unit and an ATM cell data processing unit, information of congested DLCI or VP / VC and information of each DLCI or VP / VC are provided. A function of adding a parameter of a light congestion state indicating a degree of congestion, a heavy congestion state, or a parameter of rate information and notifying can be provided. As another feature of the present invention, a function of adding VP / VC information can be provided as means for notifying congestion of the common ATM cell buffer of the ATM cell data processing unit and the switch unit. The present invention also provides, in a frame relay data processing unit, a frame buffer monitoring unit that detects congestion of a frame buffer, and a forward explicit congestion notification and a backward explicit congestion notification marked on frame relay data, and an integrated link layer. -It can be characterized by having a marking function unit for transmitting a management message.

The present invention also provides a method for marking forward explicit congestion notification and backward explicit congestion notification in frame relay data, and transmitting an integrated link layer management message from a frame relay data processing unit to a frame relay. It can be characterized by having means for reducing output data to the network or means for reducing output data from the frame relay data processing unit to the ATM cell data processing unit. The present invention is also characterized in that the frame buffer monitoring unit has a function of detecting a forward explicit congestion notification of frame relay data, a backward explicit congestion notification, and an integrated link layer management message. it can.

The present invention also provides a method for transmitting a frame relay data from a frame relay data processing unit to a frame relay network when detecting a forward explicit congestion notification, a backward explicit congestion notification, and an integrated link layer management message of frame relay data. It has means to reduce output data during congestion and restore the amount of data during congestion recovery, or reduce output data from the frame relay data processing unit to the ATM cell data processing unit during congestion, and reduce output data during congestion recovery. It can be characterized by having means for restoring the data amount. The present invention also provides an ATM cell data processing unit having a function of detecting an RM cell from a cell received from a switch unit.
It is characterized by having a cell detection unit, an RM cell transmission unit for realizing the VS / VD function, and a shaping function unit. The present invention can also be characterized in that it has a function of notifying congestion by marking the CI and DIR of the RM cell as means for notifying congestion of the common ATM cell buffer of the ATM cell data processing unit and the switch unit. . According to the present invention, the shaping function unit is also provided when the congestion occurs.
It is characterized by having means for reducing the amount of output data from the TM cell data processing unit.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a network configuration diagram to which the present invention is applied. In this network configuration, an FR (Frame Relay) terminal (51) is connected via an FR network (52) or a terminal having an interface (FR-UNI) (55) of the FR network directly to an ATM.
(Asynchronous Transfer Mode) Connect to the network (53)
It is a network that realizes interworking. ATM
The switch (1) has an FR-UNI (55) and an ATM network interface (ATM-UNI) (56), and transfers congestion information notified according to the congestion state of the network from one network to the other network. I do. In addition, FR terminal (51) and A
A BR (Available Bit Rate) terminal (54) controls the amount of data transmitted to the network based on the congestion information notified from the network side.

FIG. 2 shows an example of a configuration diagram of an ATM switch (1) to which the present invention is applied. The ATM switch (1) has a switch section (3) and a plurality of interface boards. Here, a relay interface unit (4) having an interface with the ATM network,
This figure shows a case where an interface board called a frame relay / ATM interworking device (2) having an R network interface and performing data conversion between a frame relay format and an ATM cell format is provided.

The switch section (3) includes a common ATM cell buffer (5) and a control section (6). Switch part (3)
Performs routing by storing cells in a common ATM cell buffer (5) and controlling the reading order by a control unit (6). It is known that this configuration is more excellent in traffic characteristics by providing a large-scale buffer in common. Here, the common cell buffer is described as an example, but the present invention is not limited to this, and an appropriate cell buffer may be used. Generally, an interface board cannot have a large-scale buffer in terms of implementation and price. Therefore, by notifying the buffer congestion (7) of the frame relay / ATM interworking device (2), data is temporarily stored in the common ATM cell buffer (5), thereby suppressing cell discard. .

FIG. 3 shows the configuration of the frame relay / ATM interworking apparatus (2). Frame relay / A
The TM interworking device (2) includes a frame relay data processing unit (21) to an ATM cell data processing unit (22).
Then, the congestion notification (8) is performed from the ATM cell data processing unit (22) to the frame relay data processing unit (21).

The frame relay data processing section (21)
Holds frame relay data for conversion between the frame relay format in the FR network and the ATM cell format in the ATM network. The ATM cell data processing section (22) holds ATM cell data in order to assemble and disassemble frame relay data into ATM cells. The congestion information processing unit (23) includes an ATM cell data processing unit (2).
From the message type field of the RM (Resource Management) cell received from 2), the CI (Cong
estion Indication) bit, DIR (Directio)
n) ER (Explicit Ce) for bits and explicit cell rate
ll Rate) bit is detected, and B of the backward explicit congestion notification is detected.
ECN (Backward Explicit Congestion Notificatio
n), Forward explicit congestion notification FECN (Forward Expli
cit Congestion Notification) and integrated link layer management CLLM (Consolidated Link)
Layer Management) (21) and the AT in order to dynamically perform transmission and switching of Layer Management) and bandwidth control of transmission cells to a frame relay network.
An instruction is given to the M cell data processing unit (22).

FIG. 4 shows a frame relay data processing unit (2
The configuration diagram of 1) is shown. Receive frame buffer (31)
Holds frame relay data from the frame relay network. The transmission frame buffer (32) converts the ATM cell data from the ATM cell data processing unit into frame relay data and holds it. A frame buffer monitoring unit (33) monitors the usage rates of the transmission frame buffer (32) and the reception frame buffer (31), and informs that congestion has occurred in the frame relay network. From the address field of the frame relay format. The marking function unit (34) marks the BECN bit and the FECN bit from the congestion information processing unit on the frame relay data transmitted from the transmission frame buffer (32) and the reception frame buffer (31).

FIG. 5 shows an ATM cell data processing section (22).
FIG. A transmission cell buffer (41) converts the frame relay data from the frame relay data processing unit into an ATM cell and transmits the ATM cell to the switch unit. The shaping function unit (44) transmits the transmission cell buffer (4
When the ATM cell from 1) is transferred to the switch unit, the band is dynamically controlled in accordance with an instruction from the congestion information processing unit. The reception cell buffer (42) receives the ATM cell from the switch unit and transfers it to the frame relay data processing unit. The cell buffer monitoring unit (43) includes the reception cell buffer (42) and the transmission cell buffer (4).
It has a function of monitoring the usage rate of 1). The RM cell detector (45) detects an RM cell from the ATM cell in the reception cell buffer (42). The RM cell transmission unit (46)
In order to realize an S / VD (Virtual Source / Virtual Destination) function, the RM cell from the switch unit is looped back and transmitted to the transmission cell buffer (41).

When receiving the congestion notification (8) from the frame relay data processing unit, the cell buffer monitoring unit (43) determines the usage rate of the reception cell buffer (42) and notifies the switch unit of the congestion notification (8). Perform 7). When the congestion notification (7) is received from the switch unit, the usage rate of the transmission cell buffer (41) is determined, and the congestion notification (8) is performed to the frame relay data processing unit.

FIG. 6 shows an operation explanatory diagram (1) when congestion occurs in a network configuration to which an embodiment of the present invention is applied. Hereinafter, the case where the congestion (61) occurs in the FR network (52) will be described in detail. A
In the data flow (62) from the TM network (53) to the FR network (52), congestion (61) occurs in the FR network (52).
Occurs, the FR network (52) sets the FECN (63) bit in the address field of the frame relay format to thereby forward the congested traffic, that is, the network congestion at the receiving FR terminal (51). The state can be recognized. In addition, by setting BECN (64) bits in the address field, the reverse direction of the congested traffic, that is, the ABR on the transmission side is set.
The terminal (54) can recognize the congestion state of the network.
If the receiving terminal that detects the FECN does not send a frame to the transmitting terminal, basically, the transmitting terminal sends a BEC to the transmitting terminal.
There is no way to notify congestion at N, but the FR network (52) autonomously transmits a CLLM (65) message to the originating terminal to notify congestion.

In the frame relay / ATM interworking apparatus (2) shown in FIG. 3, the frame relay data from the frame relay network is transmitted to the frame relay data processing unit (2).
Receive in 1). In the frame relay data processing unit (21) in FIG. 4, the frame relay data from the frame relay network is converted to a DLCI (Data Link Connection Identif).
ier) is stored in the reception frame buffer (31). At this time, the frame buffer monitoring unit (33) monitors the address field of the frame relay format,
When a frame with the BECN bit set is detected, the ATM cell data processing unit is notified of congestion (8),
From the M cell data processing unit to the transmission frame buffer (32)
By temporarily suppressing data transmission to the frame relay network, the amount of frames transmitted to the frame relay network is suppressed, and effective congestion control is performed. Here, the means for performing the congestion notification (8) includes suppression of cell transmission by a back pressure signal.

When the frame relay / ATM interworking device (2) detects the CLLM message from the frame relay network, the frame relay / ATM interworking device (2) similarly sends a congestion notification (8) to the ATM cell data processing section and performs the ATM cell data processing. By temporarily suppressing data transmission from the unit to the transmission frame buffer (32), the amount of frames transmitted to the frame relay network is suppressed, and effective congestion control is performed.
At this time, in the ATM cell data processing unit (22) of FIG. 5, the cell buffer monitoring unit (43) receives the congestion notification (8),
If there is room in the reception cell buffer (42), the data is temporarily stored in the reception cell buffer (42). If there is no room in the reception cell buffer (42), the switch unit is further notified of the congestion (7). ) Is transferred, and the data is temporarily held in the common ATM cell buffer of the switch unit.

FIG. 7 shows an operation explanatory diagram (2) when congestion occurs in a network configuration to which an embodiment of the present invention is applied. In the figure, in the data flow (72) from the FR terminal (51) to the FR network (52), when the congestion (71) occurs in the FR network (52),
The FR network (52) sends BECN (74) to the address field of the frame relay format to transmit the congested traffic in the reverse direction, that is, the originating FR terminal (5).
Inform 1) the network congestion state. At this time, the originating FR
When there is no frame to be transmitted to the terminal (51), the FR network (52) autonomously transmits a CLLM (75) message to the originating terminal to notify of the congestion. Further, the FECN (73) bit is set in the forward direction of the congested traffic, and transmitted to the ATM switch (1).

Although the terminal that has received the FECN bit is not the direct cause of the congestion, the terminal that has received the FECN bit reduces the number of frames flowing into the network. It is believed that any reduction in processing will speed recovery from network congestion. The frame buffer monitoring unit (33) of the frame relay data processing unit (21) in FIG.
When a frame with the CN bit set is detected, a congestion notification (8) is similarly sent to the ATM cell data processing unit, and A
The transmission frame buffer (3
By temporarily suppressing data transmission to 2), the amount of frames transmitted to the frame relay network is suppressed and effective congestion control is performed. At this time, in the ATM cell data processing unit (22) of FIG. 5, when there is no free space in the reception cell buffer (42), the common ATM cell buffer of the switch unit is notified of congestion (7), and the data from the switch unit is transmitted. Transmission is temporarily suppressed.

When the congestion information is received from the frame relay network in this way, the frame relay / ATM interworking device interlocks with the frame buffer monitoring unit (33) and the cell buffer monitoring unit (43) using two-stage buffers. By doing so, the amount of frames transmitted to the frame relay network can be suppressed, and effective congestion control can be performed.
Further, even when both the transmission frame buffer (32) and the reception cell buffer (42) of the frame relay / ATM interworking device have no free space, by holding data in the common ATM cell buffer (5) of the switch unit, It is possible to suppress the amount of frames transmitted to the frame relay network and perform effective congestion control.

Next, a case where the transmission frame buffer of the frame relay data processing unit becomes congested in the frame relay / ATM interworking apparatus will be described. FIG. 8 shows a flowchart when congestion occurs in the transmission frame buffer of the frame relay data processing unit.

When the transmission frame buffer becomes congested (S101), the frame relay data processing unit (2) shown in FIG.
The frame buffer monitoring unit (33) of 1) monitors the usage rate of the transmission frame buffer (32), and when the transmission frame buffer (32) is likely to overflow, notifies the ATM cell data processing unit of the congestion (8). The transmission of data from the ATM cell data processing unit to the transmission frame buffer (32) is temporarily suppressed (S103). In the ATM cell data processing unit (22) of FIG. 5, upon receiving the congestion notification (8) from the frame relay data processing unit, the cell buffer monitoring unit (43) (S105) sets the reception cell buffer (4).
The presence or absence of the free space in 2) is determined (S107). If there is a free space in the reception cell buffer (42), the data is temporarily stored in the reception cell buffer (42) (S109) to avoid cell / frame discard (S111). On the other hand, if there is no free space, a congestion notification (7) is made to the common ATM cell buffer of the switch unit (3) (S115). When the common ATM cell buffer (5) of the switch unit (3) receives the congestion notification (S115), the common ATM cell buffer (5)
If there is free space (S117), the cell is temporarily held there, and the transmission of the cell from the switch unit to the reception cell buffer (42) is temporarily suppressed (S119). This is prevented (S121). On the other hand, if there is no free space in the common ATM cell buffer (5), the cell / frame is discarded (S
123).

FIG. 9 is a flowchart showing a case where congestion occurs in the reception cell buffer of the ATM cell data processing unit. When the receiving cell buffer (42) of the ATM cell data processing unit (22) in FIG. 5 is likely to overflow (S20).
1) The cell buffer monitoring unit (43) detects it,
A congestion notification (7) is sent to the switch unit (S203). When the common ATM cell buffer (5) of the switch unit (3) receives the congestion notification (S205), if there is free space in the common ATM cell buffer (5) (S207), the common ATM cell buffer (5) temporarily holds the cell there, To receive cell buffer (42)
(S20) by temporarily suppressing cell transmission to
9) Prevent the user data from being discarded unintentionally (S211). On the other hand, if there is no free space in the common ATM cell buffer (5), the cell / frame is discarded (S213).

As described above, since a plurality of buffers can be linked to store cells in a large-scale common cell buffer, the frame relay / ATM interworking apparatus does not need to have a large-scale frame buffer. An inexpensive configuration with a small circuit scale is possible. Next, a case where the common ATM cell buffer is congested in the switch section of the ATM switch will be described. FIG. 10 shows a flowchart when congestion occurs in the common ATM cell buffer of the switch unit.

If congestion of the common ATM cell buffer (5) occurs in the switch section (3) of the ATM switch (1) in FIG. 2 (S301), and the common ATM cell buffer (5) is likely to overflow, Is detected, the congestion notification (7) is performed to the frame relay / ATM interworking device (2) (S303). Frame relay / A of FIG.
ATM cell data processing unit (2
The cell buffer monitoring unit (43) of (2) receives the congestion notification (7) (S305), and the cell buffer monitoring unit (4)
In 3), if there is a free space in the transmission cell buffer (41) (S307), the data is temporarily stored in the transmission cell buffer (41) (S309), and the transmission of data to the switch unit is suppressed. Avoid frame discard (S31
1). On the other hand, when there is no free space in the transmission cell buffer (41) (S309), the cell buffer monitoring unit (43) sends a congestion notification (8) to the frame relay data processing unit (21) (S313). The frame buffer monitoring unit (33) of the frame relay data processing unit (21) in FIG. 4 determines the free space of the reception frame buffer (31) (S31).
5) If there is an empty space, the data is temporarily held in the reception frame buffer (31) (S317).
Suppress data transmission to the TM cell data processing unit,
The frame discard is avoided (S319). On the other hand, if there is no free space in the reception frame buffer (31), the cell / frame is discarded (S321).

Next, FIG. 11 shows a flowchart in the case where congestion occurs in the transmission cell buffer of the ATM cell data processing unit. When the transmission cell buffer (41) of the ATM cell data processing unit (22) in FIG. 5 is likely to overflow (S40).
1) The cell buffer monitoring unit (43) detects it,
Congestion notification to frame relay data processing unit (21) (8)
Is performed (S403). The frame buffer monitoring unit (33) of the frame relay data processing unit (21) in FIG. 4 receives the congestion notification (8) (S405), and if there is an empty space in the reception frame buffer (31) (S407), By temporarily storing data in the reception frame buffer (31) (S409), transmission of data to the ATM cell data processing unit is suppressed, and user data is prevented from being accidentally discarded (S411). On the other hand, if there is no free space in the reception frame buffer (31), the cell / frame is discarded (S413).

Further, when the frame buffer monitoring unit (33) of the frame relay data processing unit (21) of FIG. 4 detects the congestion of the reception frame buffer (31),
The congestion information processing unit (23) is notified of congestion (35), and the BECN bit, the FECN bit and the CLLM message from the congestion information processing unit (23) are marked by the marking function unit (3).
At 4), by marking the frame relay data transmitted from the transmission frame buffer (32) and the reception frame buffer (31), the FR terminal and A
Notify the BR terminal of the congestion.

Next, the operation of the RM cell will be described. The frame relay / ATM interworking apparatus according to the present invention has an ABR function in the ATM layer service category. The ABR can increase or decrease the cell transmission rate according to the traffic conditions of the network and the receiving terminal. The traffic conditions of the network and the receiving terminal are notified to the transmitting terminal by the RM cell. In addition, VS / VD control is defined for the switch operation.

FIG. 12 is a diagram illustrating the structure of the RM cell. ATM header (81) is octets 1 to 5,
The message type field (82) is octet 7,
The ER (83), which indicates the explicit cell rate, is located in octets 8-9. FIG. 13 is an explanatory diagram showing a detailed configuration of the message type field (82).
In the message type field is a DIR indicating the direction.
(91) and CI (92) of the congestion display are arranged.

In the ATM cell data processing section (22) of FIG. 5, the RM cell detection section (45) detects an RM cell from the reception cell buffer (42). In this example, the RM cell has a PTI (Payload Type Identifier) = 110 in its header and OAM (Operation, Administration a).
nd Maintenance) cells and data cells, and in the case of ABR for VP (Virtual Path), VCI
(Virtual Channel Identifier) = 6 and PTI =
At 110, it is specified as a VP RM cell. From this,
The detection of the RM cell is performed by using the VCI =
6 and PTI = 110. The RM cell is transferred from the RM cell detection unit (45) to the RM transmission unit (45) for VS / VD control, and transmitted to the switch unit via the transmission cell buffer (41) and the shaping function unit (44). Is done.

The CI bit, the DIR bit and the ER bit of the message type field of the RM cell detected by the RM cell detecting section (45) are output by the congestion information processing section (23). To BECN and FECN in frame relay format
To the frame relay data processing unit (21)
And is sent to the frame relay network and the ATM cell data processing unit (22). Further, based on the ER bit detected by the congestion information processing unit (23), the bandwidth of the cell to be transmitted to the switch unit (3) is instructed to the shaping function unit (44) of the ATM cell data processing unit (22), and the value of the ER bit is The bandwidth is dynamically controlled in accordance with. By these, frame relay / A
TM interwork can be realized.

[0036]

According to the present invention, the bandwidth of a frame or a cell to be transmitted is controlled based on the congestion information from the network and the congestion state of the buffer in the device, and the effective congestion control with less data discarding is performed. An inexpensive frame relay / ATM interworking device can be provided.

Further, according to the present invention, the buffers are linked in the switch section having the common ATM cell buffer, the frame relay data processing section having the frame buffer, and the ATM cell data processing section having the cell buffer. Congestion can be avoided. Further, according to the present invention, without expecting a terminal having a network congestion recovery means that lowers the throughput, the congestion information is further detected from the RM cells of the ATM network, whereby the BECN / FECN control of the frame relay format is performed. And ATM
It is possible to dynamically control the band of cells transmitted to the network.

[Brief description of the drawings]

FIG. 1 is a network configuration diagram to which an embodiment of the present invention is applied.

FIG. 2 is a configuration diagram of an ATM switch to which the frame relay / ATM interworking device of the present invention is applied.

FIG. 3 is a configuration diagram of a frame relay / ATM interworking device of the present invention.

FIG. 4 is a configuration diagram of a frame relay data processing unit of the frame relay / ATM interworking apparatus of the present invention.

FIG. 5 is a configuration diagram of an ATM cell data processing unit of the frame relay / ATM interworking apparatus of the present invention.

FIG. 6 is an operation explanatory diagram (1) when congestion occurs in a network configuration to which an embodiment of the present invention is applied;

FIG. 7 is an operation explanatory diagram (2) when congestion occurs in a network configuration to which an embodiment of the present invention is applied;

FIG. 8 is a flowchart when congestion occurs in a transmission frame buffer.

FIG. 9 is a flowchart when congestion occurs in a reception cell buffer.

FIG. 10 is a flowchart when congestion occurs in the ATM cell buffer.

FIG. 11 is a flowchart when congestion occurs in a transmission cell buffer.

FIG. 12 is a configuration diagram of an RM cell.

FIG. 13 is a configuration diagram of a message type field of an RM cell.

[Explanation of symbols]

1. ATM switch 2. 2. Frame relay / ATM interworking device Switch section 4. Relay interface unit 5. Common cell buffer 6. Control unit 7. 7. Congestion notification Congestion notification 21. Frame relay data processing unit 22. ATM cell data processing unit 23. Congestion information processing unit 31. Receive frame buffer 32. Transmission frame buffer 33. Frame buffer monitoring unit 34. Marking part 35. Congestion notification 41. Transmission cell buffer 42. Receive cell buffer 43. Cell buffer monitoring unit 44. Shaping function unit 45. RM cell detector 46. RM cell transmission unit 51. FR terminal 52. FR network 53. ATM network 54. ABR terminal 55. FR-UNI 56. ATM-UNI 61. Congestion occurrence point in FR network 62. Data flow from ATM network to FR network 63. Frame relay format data with the FECN bit set 64. 65. Frame relay format data with BECN bit set CLLM message 71. Congestion occurrence location in FR network 72. Data flow from FR terminal to FR network 73. 74. Frame relay format data with FECN bit set 75. Frame relay format data with BECN bit set CLLM message ATM header of RM cell RM cell message type field ER of RM cell 91. DIR in message type field of RM cell 92. CI of the message type field of the RM cell

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toru Aramaki 890 Kashimada, Saiwai-ku, Kawasaki-shi, Kanagawa F-term in the Social Network Systems Division, Hitachi, Ltd. 5K030 HA09 HA10 KA03 KX00 LB15 LC11 MA13 MB15 5K034 EE11 HH50 HH56 HH61 KK27

Claims (6)

[Claims] 1. A frame relay / ATM interworking apparatus for interfacing a frame relay network with an ATM network, comprising: a transmission and reception frame buffer for holding frame relay data; and a frame for monitoring the transmission and reception frame buffer. A frame relay data processing unit having a buffer monitoring unit; a reception and transmission cell buffer respectively connected to the transmission and reception frame buffers for holding ATM cell data; and a cell buffer monitoring unit for monitoring the reception and transmission cell buffers. An ATM cell data processing unit having the following. In the frame data processing unit, the frame buffer monitoring unit monitors the transmission frame buffer, and detects the congestion of the transmission frame buffer.
Performing a congestion notification to the M cell data processing unit, In the ATM cell data processing unit, upon receiving the congestion notification from the frame data processing, the cell buffer monitoring unit detects the presence or absence of free space in the reception cell buffer, A frame relay / ATM interworking device that holds data in the reception cell buffer when there is free space, and notifies the switch unit of congestion when there is no free space. 2. A frame relay / ATM interworking apparatus for interfacing a frame relay network with an ATM network, comprising: a transmission and reception frame buffer for holding frame relay data; and a frame for monitoring the transmission and reception frame buffer. A frame relay data processing unit having a buffer monitoring unit; a reception and transmission cell buffer respectively connected to the transmission and reception frame buffers for holding ATM cell data; and a cell buffer monitoring unit for monitoring the reception and transmission cell buffers. An ATM cell data processing unit having the following. In the ATM cell data processing unit, the cell buffer monitoring unit monitors the transmission cell buffer, and when detecting the congestion of the transmission cell buffer, the frame relay data processing unit To the congestion notification, In the frame relay data processing unit, upon receiving the congestion notification from the ATM cell data processing unit, the frame buffer monitoring unit detects the presence or absence of free space in the reception frame buffer. A frame relay / ATM interworking device that holds data in a frame buffer and suppresses transmission of data to the transmission cell buffer. 3. The frame relay according to claim 1 or 2,
An ATM interworking device; and a switch unit having an ATM cell buffer and transmitting and receiving cells to and from the ATM cell data processing unit. The switch unit receives a congestion notification from the ATM cell data processing unit. An ATM switch configured to hold data in the ATM cell buffer when the ATM cell buffer has a free space, thereby suppressing data transmission to the reception cell buffer; 4. The frame relay according to claim 1 or 2,
An ATM interworking device; and a switch unit having an ATM cell buffer and transmitting and receiving cells to and from the ATM cell data processing unit. In the ATM cell data processing unit, the cell buffer monitoring unit includes the reception unit. The cell buffer is monitored, and when the congestion of the reception cell buffer is detected, the switch unit notifies the switch unit of congestion. When the switch unit receives the congestion notification from the ATM cell data processing unit, the ATM unit stores a free space. If there is an ATM switch, the ATM switch stores data in the ATM cell buffer and suppresses transmission of data to the reception cell buffer. 5. The frame relay according to claim 1 or 2,
ATM including an ATM interworking device, and a switch unit having an ATM cell buffer and transmitting and receiving cells to and from the ATM cell data processing unit
When the ATM cell buffer congestion is detected by the switch unit, the ATM cell data processing unit notifies the ATM cell data processing unit of the congestion. In the ATM cell data processing unit, the cell buffer monitoring unit includes: Upon receiving the congestion notification from the switch unit, the free space of the transmission cell buffer is detected, and if there is free space, the transmission cell buffer data is held. If there is no free space, the frame relay processing unit is congested. ATM switch for notifying. 6. The frame data processing section, wherein the frame buffer monitoring section detects a free space of the reception frame buffer when receiving a congestion notification from the ATM cell data processing section, and when there is a free capacity, 6. The ATM switch according to claim 5, wherein data is temporarily stored in said reception frame buffer.