JP3284801B2 - Congestion notification method in frame distribution / multiplexing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame distributing / multiplexing method for accommodating a plurality of lines for communication using a frame having a logical link identifier and distributing a received frame to a corresponding line or performing frame multiplexing. The present invention relates to a congestion notification method capable of reducing a logical link identifier conversion process and shortening a notification time when congestion occurs or congestion is released in a conversion device.

[0002]

2. Description of the Related Art In general, in a switching network, the ratio of the subscriber system cost to the network cost is high. Therefore, by multiplexing the frames, the entire network is made economical. When a multiplexed frame is received, it must be allocated to the corresponding line. An apparatus that performs these processes is a frame sorting / multiplexing apparatus. The frame sorting / multiplexing device can reduce software processing by sorting the packet information and the call control signal and transferring them to the layer 2 processing device. Frame sorting
If the load on the multiplexing device continues for a long time while exceeding the set value, it is necessary to take some measures.
Factors causing congestion include the case where the number of free buffers in the common buffer for temporarily storing transmitted and received frames is insufficient, and the case where the number of transmission waiting queues due to frame transmission waiting exceeding the transfer capacity of the output line increases. is there.
When congestion occurs in the conventional frame distribution / multiplexing device, the congestion target line number is notified to the control unit of the frame distribution / multiplexing device, and the control unit searches for a line paired with the line, and the control unit The congestion notification identifier is set for the frame transmitted to the target line and the pair line at the time of logical link identifier conversion in accordance with the instruction from.

[0003]

As described above, when congestion occurs in the conventional frame distribution / multiplexing apparatus, the congestion is notified to the control section of the frame distribution / multiplexing apparatus, so that the control section transmits the paired line. And a congestion notification identifier is set for the frame transmitted to the target line and the pair line when the logical link identifier is converted. However, if the processing of setting the congestion notification identifier is performed under the control of the control unit, there is a problem that it takes too much time from the detection of congestion to the setting of the congestion notification identifier. In addition, since the congestion notification identifier is set at the time of conversion of the logical link identifier, it is determined whether or not the congestion notification identifier is set at the time of the conversion of the logical link identifier for all received frames. Was getting bigger. An object of the present invention is to solve such a conventional problem, to shorten the notification time, and to reduce the processing load of the logical link identifier conversion by a congestion notification method in a frame sorting / multiplexing apparatus. To provide.

[0004]

In order to achieve the above object, a method for notifying congestion in a frame sorting / multiplexing apparatus according to the present invention comprises the steps of: (a) determining whether the common buffer free space for storing received frames has a predetermined lower limit; The congestion is detected at the point in time when the number falls below, and thereafter, after converting the logical link identifier for all frames to be transmitted, the forward and backward congestion notification identifiers are set to a congestion occurrence state and transmitted, and the common buffer is vacant. Congestion release is detected when the capacity exceeds a predetermined upper limit, and thereafter, the setting of the congestion occurrence state of the forward and backward congestion notification identifiers for all frames to be transmitted is stopped. Further, (b) the frame sorting / multiplexing apparatus detects congestion when the number of frames waiting to be transmitted on an arbitrary transmission line exceeds a predetermined upper limit, and thereafter, transmits from the transmission line. logical link forward congestion notification identifier for all frames after the identifier conversion and sets the congestion state, all logical phosphorus backward congestion notification identifier of the frame received from the receive line to form the transmission line and pairs
Set the congestion occurrence state before the conversion of the transmission identifier , detect the congestion release when the number of frames in the transmission waiting state of the transmission line falls below a predetermined lower limit, and thereafter transmit from the transmission line. Stop setting the congestion occurrence state of the forward congestion notification identifier of all frames and stop setting the congestion occurrence state of the rear congestion notification identifier of all frames received from the reception line forming a pair with the transmission line. Also features. Further, (c) the frame sorting / multiplexing apparatus does not perform the processing of setting the congestion notification identifier regardless of the setting state of the congestion notification identifier of the received frame when no congestion occurs, and When the congestion notification identifier is set, the frame is transmitted through the frame sorting / multiplexing device.

[0005]

In the present invention, all transmission / reception lines are accommodated in pairs, and the congestion notification identifier setting function is provided separately from the logical link identifier conversion function. The congestion detection and setting process detects the occurrence / release of congestion based on the free space in the buffer, and executes / stops the congestion state setting process for the forward / backward congestion notification identifier when transmitting the frame after the conversion of the logical link identifier. The setting and stopping of the congestion state in the congestion notification identifier are respectively performed in the transmission unit. Note that the forward congestion notification identifier is an identifier indicating whether or not congestion has occurred in the transmission direction, and the backward congestion notification identifier is an identifier indicating whether or not congestion has occurred in the reception direction. As another congestion detection method, occurrence / release of congestion is detected based on the number of transmission waiting frames of an arbitrary output line.
When the frame is transmitted from the line, the congestion state setting process is performed / stopped for the forward congestion notification identifier for the frame, and when the frame is received from the line paired with the line, the frame is For the backward congestion notification identifier, the congestion state setting processing is executed / stopped. In this case, setting and stopping of the congestion state to the congestion notification identifier are performed in the transmission unit and the reception unit, respectively. As a result, the time from the detection of occurrence / release of congestion to the execution / stop of the congestion state setting processing for the congestion notification identifier can be shortened, and the processing load during the logical link identifier conversion processing can be reduced. Become.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 4 is an overall configuration diagram of a switching system to which the present invention is applied. A and B are exchanges and 11, 1 respectively.
2 is a protocol processing device for performing protocol processing, 2 is a frame distributing / multiplexing device for distributing / multiplexing received frames, 31 and 32 are communication path switches for performing circuit switching, 4 is a subscriber terminating device, and 6 is software And 5, communication devices. Exchange A is controlled by software. On the other hand, the exchange B is a protocol processing device 1 that performs protocol processing of the frame multiplexed by the exchange A.
2 and a communication path switch 32 for performing line switching. The frame transmitted from the communication device 5 is transmitted through the subscriber terminating device 4 to the frame distribution / multiplexing device 2.
Where the translation of the frame logical link identifier,
The packet is distributed to the corresponding line, the frame is multiplexed, multiplexed, and sent to the protocol processing device 11 in the exchange A or to the protocol processing device 12 in another exchange B.
Further, the multiplexed frame from the protocol processing device 11 or the protocol processing device 12 is received by the frame distribution / multiplexing device 2 and distributed to the line corresponding to the logical link identifier of the frame, via the subscriber line termination circuit. It is sent to the communication device 5. The processing of the present invention is executed in the frame sorting / multiplexing device 2.

FIGS. 1, 2 and 3 show a first embodiment, a second embodiment and a third embodiment of the present invention, respectively.
It is a block diagram of a multiplexing apparatus. First, the embodiment of FIG. 1 will be described. FIG. 1 shows a normal process before reaching congestion. In the frame processing in the frame distribution / multiplexing device 2, a frame transferred from an arbitrary line is received by the receiving unit 21, and the frame information (hatched line) is stored in the common buffer 24. After the logical link identifier part (A) is converted by the logical link identifier conversion part 22, the transmission parts 23a to 23n of the corresponding line
(In FIG. 1, reference numeral 23a), the corresponding frame information is read from the common buffer 24, the converted logical link identifier (B) is added thereto, and the frame information is transmitted to the corresponding line.

Next, FIG. 2 shows a process in the case where the free space of the common buffer 24 is reduced in the frame sorting / multiplexing device 2. In the common buffer 24, a predetermined lower limit 25 of the free buffer capacity and a predetermined upper limit 26 of the free buffer capacity are set. In this case, as shown by hatching in FIG. 2, the common buffer 24 has already stored the frame information up to a nearly full state. When the free buffer capacity of the common buffer 24 falls below the lower limit 25 specified in advance, a congestion state of the frame distribution / multiplexing device 2 occurs. As a result, for all the frames transmitted from the frame sorting / multiplexing device 2, the transmitting / receiving units 23a to 23n set the forward / backward congestion notification identifier to a generated state and transmit it (the hatched portion is backward, and the black portion is forward). Represents each congestion notification identifier.) Further, in the frame sorting / multiplexing apparatus 2, when the free buffer capacity of the common buffer 24 exceeds the upper limit value 26 specified in advance, and congestion release is detected, the transmission units 23a to 23
The setting process of the congestion notification identifier in n is stopped.

Next, FIG. 3 shows a process performed when frames in which the number of transmission waits in the transmission section 23a exceeds a predetermined upper limit are concentrated. Note that the transmission unit 23a
As shown in 23a, a queue lower limit value 27 of the queue waiting capacity specified in advance and an upper limit value 28 of the queue waiting capacity specified in advance are set in the queues 23a to 23n. In this case, it is detected that frames exceeding the transmission capacity are concentrated on any of the arbitrary transmission units 23a to 23n. That is, when the number of transmission waiting frames in the transmission unit 23a exceeds the upper limit value 28 specified in advance, the occurrence of congestion on the line is detected. As a result, a congestion state (shown in black) is set in the forward congestion notification identifier for the frame transmitted from the transmission unit 23a of the line, and the frame is transmitted. In response, the reception unit 21 sets a congestion state (represented by oblique lines) in the backward congestion notification identifier.
Further, in the corresponding line, when the number of frames waiting to be transmitted falls below the lower limit value 27 specified in advance, the congestion release of the corresponding line is detected, and the setting of the congestion state to the forward congestion notification identifier in the transmission unit 23a of the corresponding line is performed. Receiving unit 21 for a frame received from a line paired with the line
The setting of the congestion state to the backward congestion notification identifier in is stopped.

In the case of FIG. 3, since it is detected that the number of transmission waiting frames exceeding the upper limit value 28 of the hatched transmission unit 23a is connected to the queue, the forward of the frame transmitted from the transmission unit 23a is detected. A congestion state (shown in black) is set in the congestion notification identifier. At the same time, the receiving line (CH # k) paired with the line (CH # k)
The receiver 21 sets a congestion state (indicated by oblique lines) in the backward congestion notification identifier in the frame received from. The frame in which the backward congestion notification identifier is set is converted into another identifier by the logical link identifier conversion unit 29, so that it is connected to the queue of another transmission unit 23, and the frame in which the backward congestion notification identifier is set is The data is transmitted from the transmission unit 23 to the line. In the hatched transmission unit 23a, when the number of frames connected to the queue falls below the lower limit 27, the congestion is released, the setting of the congestion state to the forward congestion notification identifier is stopped, and the reception unit 21 and the transmission unit 23 are stopped. Then, the setting of the congestion state to the backward congestion notification identifier is also stopped. In the present invention, no congestion has occurred.
In such a state, when a frame with a congestion state set in the forward and backward congestion notification identifiers is received, the frame is transmitted through the frame distribution / multiplexing apparatus. The transparency means that the identifier is inherited without looking at the state of the identifier. As a result, the load of the logical link identifier conversion processing can be reduced. At the same time, the notification time to the communication device is reduced.

FIG. 5 is a diagram showing a connection configuration in a case where all transmission / reception lines are accommodated as a pair in a frame distribution / multiplexing apparatus. FIG. 6 shows a case where common buffer congestion and transmission waiting frame congestion occur simultaneously. FIG. 6 is a diagram showing conditions at the time of transmission. When the common buffer congestion shown in FIG. 2 and the transmission frame congestion shown in FIG. 3 occur simultaneously, when the forward congestion identifier and the rear congestion identifier are set in the transmission unit, the OR condition of each function is used. Set these identifiers. That is, as shown in FIG. 6, when setting for transmission, both forward congestion notification and backward congestion notification are performed when only the common buffer is congested, and only forward congestion notification is performed when only the transmission waiting frame is congested. When both the common buffer congestion and the transmission-standby frame congestion occur, both the forward congestion notification and the rear congestion notification are performed.

As shown in FIG. 5, in the present invention, all transmission / reception lines are accommodated in pairs. That is, in each of the devices A, B, and C, both the transmission line and the reception line are accommodated in the frame sorting / multiplexing device in pairs. The reason for setting the occurrence state in one or both of the forward and backward congestion identifiers is as follows. (A) In the case of common buffer congestion: All the frames received by the frame distribution / multiplexing device become a congestion factor. In other words, since all the frames transmitted from the frame sorting / multiplexing device become congestion factors,
A forward congestion notification identifier is set for all transmitted frames. Further, when viewed from the device A, since the frame from the device A is a congestion factor, it is necessary to set a backward congestion notification identifier for the frame transmitted to the device A, and the same applies to the devices B and C. Therefore, a backward congestion notification identifier is set for all transmitted frames. (B) In the case of transmission-congested frame congestion: Since the frame transmitted from the target line is a factor of congestion,
A forward congestion notification identifier is set for the transmission frame.
In addition, since the backward congestion notification identifier needs to be notified to the device that transmitted the frame that causes the congestion, the backward congestion notification identifier is set to the rear of the frame transmitted from the device to which the line to be congested is connected. Since the congestion notification identifier is to be set, the identifier is set for a frame received from the target receiving line.

[0013]

As described above, according to the present invention,
When notifying the congestion of the frame distributing / multiplexing device, it is possible to reduce the load of the logical link identifier conversion process and to shorten the notification time to the communication device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the operation of a frame sorting / multiplexing apparatus according to a first embodiment of the present invention (in a normal state).

FIG. 2 is a second embodiment of the present invention (when a common buffer is abnormal).
FIG. 4 is an explanatory diagram of the operation of the frame sorting / multiplexing apparatus showing the above.

FIG. 3 is a diagram illustrating the operation of a frame sorting / multiplexing apparatus according to a third embodiment of the present invention (when a transmitting unit wait queue is abnormal).

FIG. 4 is an overall configuration diagram of a switching system to which the present invention is applied.

FIG. 5 is a diagram showing a connection configuration in which all transmission / reception lines are accommodated in pairs in the present invention.

FIG. 6 is a diagram illustrating conditions at the time of transmission when congestion of a common buffer and congestion of a frame waiting to be transmitted occur simultaneously in the present invention.

[Explanation of symbols]

A, B · · · exchange, 11 · · · protocol processing device, 2 ·
· Frame distribution · Multiplexers, 31, 32 · · · Channel switches, 4 · · · Subscriber termination devices, 5 · · · Communication devices,
6 software, 21 receiving section, 22 logical link identifier converting section, 23a to 23n transmitting section, 24
· Common buffer, 25 · · · Empty buffer lower limit, 26 ·
-Empty buffer upper limit, 27-Transmission queue lower limit, 28-Transmission queue upper limit, 29-Logical link identifier conversion unit.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshikazu Suzuki 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Jiro Shibata 216 Totsukacho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Shares (72) Inventor Akio Kawase 180 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi Communication Systems Co., Ltd. (56) References JP-A-2-14645 (JP, A) JP-A-1 -272245 (JP, A) JP-A-2-170646 (JP, A) Practical frame relay, Rick Telecom, April 30, 1994

Claims (3)

(57) [Claims] [Claim 1] houses a plurality of transmitting and receiving lines in pairs, each receiving
Common buffer for storing frames received from the communication line
When the logic phosphorus to convert the logical link identifier assigned to the frame by referring to the logical link identifier conversion table
And an identifier conversion means.
Each frame is converted by the above logical link identifier converting means.
And distributed to the transmission line corresponding to each logical link identifier
Multiplexing and transmission
A kicking congestion notification method, to detect congestion when the free space of the shared buffer is below a predetermined lower limit value, thereafter, congestion in the transmit direction
Forward congestion notification identifier and receive indicating that There has occurred
A backward link congestion notification identifier indicating that congestion is occurring in the communication direction is identified by the logical link identifier converting means.
Besshi transmits to set to all frames that have been converted detects the congestion released when a value above the upper limit of the free space is predetermined for the common buffer, the forward congestion notification
Frame by a stop setting <br/> to the frame identifier and the backward congestion notification identifier distributing -
A congestion notification method in a multiplexing device. 2. A plurality of transmission / reception lines are accommodated in pairs, and
Common buffer for storing frames received from the communication line
And the logical link identifier assigned to the frame
Logical link that converts by referring to the link identifier conversion table
And an identifier conversion means.
Each frame is converted by the above logical link identifier converting means.
To the transmission line corresponding to each logical link identifier
Met congestion notification method in a frame distribution and multiplexing apparatus for transmitting by multiplexing, the lower limit the free space is predetermined for the common buffer
Detecting a first congestion At that point, the detected second congestion when the number of frames exceeds the predetermined upper limit value in the transmission waiting state in any of the transmission line, the first congestion If detected, congestion occurs in the transmit direction and
In the forward congestion notification identifier and the receiving direction
A backward congestion notification identifier indicating that congestion has occurred,
The logical link identifier is changed by the logical link identifier conversion means.
And transmits the set for all frames that have been conversion, the upper limit of free space is predetermined for the common buffer
At the point of time when the first congestion is released,
On the forward congestion notification identifier and the backward congestion notification identifier
When the setting for the frame is stopped and only the second congestion is detected, the logical link identifier change is performed for all the frames transmitted from the transmission line.
The forward congestion notification identifier after the conversion of the logical link identifier by the conversion means is set , and paired with the transmission line.
The above discussion applies to all frames received from
Logical link identifier conversion by logical link identifier conversion means
To set the backward congestion notification identifier before, by detecting the release of the second congestion when the number of frames in the transmission waiting state of the transmission line falls below a predetermined lower limit value, the transmission line All frames transmitted from
It stops the setting of the forward congestion notification identifier for, the transmission line and frame distribution and multiplexing, characterized by stopping the setting of the backward congestion notification identifier for all frames received from the receiving line pairs A congestion notification method in a device. 3. The method according to claim 1 or 2,
A congestion notification method in a frame distribution and multiplexing apparatus according to any, in a state in which congestion does not occur, the received frame,
Inherit without checking the setting status of the congestion notification identifier of the frame
A method of notifying congestion in a frame sorting / multiplexing apparatus, characterized in that transmission is performed.