JPH0715506A - Congestion control system for layer 2 processing in exchange - Google Patents

Abstract

PURPOSE:To obtain a congestion control method in which normal exchange is executed by regulating special inputs independently of the capability of processing ability. among equipments whose functions are formed hierarchically. CONSTITUTION:In an exchange provided with a layer 2 processing signal equipment ISE accommodating plural lines, a congestion control section 4 monitors periodically a length of a queue 2, of the signal equipment whose signal has already been processed, and selects a line whose processing wait queue length corresponding to the line is longest among plural lines to regulate the input when the length of the queue exceeds a 1st threshold level. Moreover, the control section 4 executes sequentially the selection of input regulation and the regulation of input sequentially while the length of the queue exceeds a 1st threshold level and regulates the input as to all lines accommodated in the signal equipment when the consecutive time for the selection of input regulation line and the input regulation exceeds a predetermined time. Furthermore, when the length of the queue of the signal equipment whose signal is processed exceeds a 2nd threshold level, the input is regulated as to all lines accommodated in the signal equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a congestion control system for regulating an input to a switching device so that a normal switching operation can be performed when a predetermined amount of input, that is, a call is applied. Is.

[0002]

2. Description of the Related Art A congestion control method in a layer 2 (data link layer) processing signaling device in a conventional switching device will be described with reference to the drawings. 1 and 2 are diagrams for explaining a congestion control system of a layer 2 processing signaling device used in a store and exchange device such as a signal relay exchange. FIG. 1 shows a device configuration and FIG. 2 shows a congestion control system. The functional configuration is shown. As shown in FIG. 1, the storage and switching apparatus of this example has a configuration in which a layer 2 processing signal unit (CSU) accommodating a plurality of lines is individually connected to a corresponding upper layer processing unit (SPU). ing. The mechanism of this congestion control scheme 1 process queue Q ₀ upper layer processing unit represented by (SPU) _S0
The residence, line by layer 2 processing signal unit represented by 2 ₀ (CSU) treated queue Q _C0 stagnates, process queue Q _L0i line interface unit represented by 3 ₀₁ (CSU) stays It imposes input restrictions on. The layer 2 processing signal device to which this method can be applied has a processing capacity sufficiently higher than that of the upper layer processing device, that is, the condition that the staying of the processing waiting queue always occurs from the processing waiting queue of the upper layer. In addition, there is a drawback that the queue for processing remains in the queue until the congestion is resolved, so that there is a lot of internal retention during congestion and the processing delay of the queue increases.

3 and 4 are diagrams for explaining a conventional congestion control method in a layer 2 processing signaling device (ISE) used in an ISDN switching device. FIG. 3 is a device configuration and FIG. The functional structure of the conventional congestion control method is shown. The difference in the device configuration from FIG. 1 is that a plurality of layer 2 processing signal devices (ISE) have a common upper layer processing device (I
NP). The mechanism of this congestion control scheme is to place a congestion control unit 4 ₁₀ in each layer processing signal unit as shown in FIG. 2 (ISE), treated queue Q _C1 of the layer 2 processing signal unit (ISE) is becomes a certain value or more, it determines that congestion at the congestion control unit 4 _10, which restricts the input of all the lines layer processing signal unit (ISE) accommodated. In this method, for example, excessive traffic occurs from a specific line, even if congestion of the processing queue occurs thereby, all lines must be regulated at the same time, and normal traffic other than the specific line There was a drawback that the line could not be used.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to regulate the input of a specific line, which has caused congestion, irrespective of the size of the processing capability between the functionally hierarchized devices, thereby ensuring normal operation. In addition to minimizing the adverse effect on the traffic communication of various lines, if the congestion cannot be solved only by controlling the input of each line, control the input to all lines to perform smooth and prompt congestion control of signaling devices. is there.

Therefore, the present invention provides a congestion control method for layer 2 processing in a switching apparatus which accommodates at least a plurality of lines and is provided with a layer 2 processing signaling device for controlling a layer 2 protocol of the lines. A first threshold value for input restriction and release in a device, the queue length of a signal processed queue of the signaling device is periodically monitored, and the queue length exceeds a value of the first threshold value. In this case, among the plurality of lines, the line with the longest queue queue length corresponding to the line is selected to restrict the input, and while the queue length exceeds the threshold value, the input The feature is that the regulated line selection and the input regulation are sequentially executed.

Further, according to the present invention, when the continuation time of the input regulation line selection and the input regulation exceeds a certain time, the input regulation is performed on all the lines accommodated in the signaling device.

Furthermore, the present invention provides that when the queue length of the signal processed queue of the signaling device exceeds a second threshold,
It is characterized in that the input restriction is applied to all the lines accommodated in the signaling device.

Embodiments of the present invention will be described in detail with reference to the drawings.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the layer 2 processing protocol of the present invention will be described with reference to FIGS. 3, 5 and 6. Here, an example of a layer 2 processing protocol on the premise before describing an embodiment of the present invention will be described.

The layer 2 protocol generally defines a transmission control procedure and an error detection procedure, and a frame in this layer is generally composed of a flag sequence, an address field, a control field, an information field and a frame check sequence. . However, depending on the contents of the command or response information transmitted in the control field, there are some frames that do not have the information field. The flag sequence indicates the start and end of a frame, and a fixed pattern is used. In the address field, a command reception destination or a response transmission destination address is indicated. The control field has a command or response and a required sequence number. In the following embodiments of the present invention, a method of performing input restriction using the above-mentioned monitoring frame will be described.

As shown in FIG. 5, the switching apparatus of the present invention includes a congestion control unit 4 ₁₁ in each layer 2 processing signaling device (ISE).
have. The processed queue Q _{C1 of the} layer 2 processing signal equipment (ISE) of 2 _{1 in} the layer 2 processing signal equipment (ISE) and the line corresponding part processing waiting queue Q _{L1i of} 3 _1i
Then, the congestion control unit _41i performs congestion detection, regulation and cancellation.

The control is, as shown in FIG. 6, N1, N
It is executed on the basis of four types of congestion parameters of 2, N3 and τ. These parameters are held as fixed values in the congestion control unit, for example. Here, N1 specifies a congestion inducing line and starts its input regulation (hereinafter referred to as primary regulation) a threshold value of Q _c1 , and N2 starts collective input regulation of all lines (hereinafter referred to as secondary regulation). ) Q _c1 threshold, and N3 starts deregulation during input regulation Q _c1
Is the threshold of. Further, τ is the time limit for shifting to the secondary regulation when the congestion does not fall under the primary regulation. Note that N
1, N2 and N3 have a relationship of N2>N1> N3.

Congestion is detected in a fixed cycle (hereinafter referred to as T).
Then, the queue length (hereinafter referred to as N) accumulated in the processed queue Q _c1 of the layer 2 processing signal equipment (ISE) of 2 ₁ is compared with the congestion parameter values N1, N2, N3. Congestion control unit 4 ₁₁ detects a queue length of the processed queue Q _c1 at fixed intervals, and compares the above parameter values N1, N2, N3. As a result of the comparison, the queue length N is N2> N ≧ N1
If it is detected, the congestion control unit has detected that it is in the primary congestion state.

As shown in FIG. 6, the primary regulation method is to check the queue length accumulated in the process waiting queue Q _L1i of each line interface of 3 _1i at the time of the primary congestion state, Input restriction is applied to the largest number of lines. here,
For the input regulation, the supervisory frame shown as an example of the protocol which is the premise of the present invention is used. The RNR frame in the command / response of the monitor frame is used for input regulation. This RNR frame is generally busy,
That is, it is a supervisory frame for temporarily indicating a state in which a subsequent frame cannot be received. In addition, a receive ready command (RR frame) is required to clear the busy state.
Etc.

When the input control of the target line is performed by the above method, the congestion control unit 411 measures the queue length of the processed queue Q _{C1 in} the cycle T until the congestion state is resolved (until N3 ≦ N). ), This input restriction is repeated at cycle T. That is, the queue length accumulated in the processed queue Q _C1 of the layer 2 processing signaling device (ISE) of 2 ₁ is investigated, and this is N>
In the case of N3, restriction is applied to the largest number of lines in the _QL1i queue length other than the input restriction. Also, when the congestion is resolved (i.e. when it is detected that the congestion at the time of a N ≦ N3 state is eliminated), the congestion control unit 4 ₁₁ releases the input restriction, for example, above the RR frame or the like.

The congestion control unit 4 ₁₁ in the input restriction, the input regulation time is shifted to the state of the secondary regulation exceeds the congestion parameter tau. Detection of an input regulation time in excess of tau, for example, the queue length investigation period T is performed many times in the input restriction, or, (not shown) timer arranged to congestion control unit 4 within ₁₁
Etc. are detected. Also, congestion control unit 4 ₁₁ queue length of the processed queue Q _C1 is when it becomes N ≧ n2 state, detects that it is now the secondary restriction state.

In the secondary regulation method, input regulation (transmission of RNR frame) is performed on all the links accommodated in the signaling device at the time of the secondary congestion shown in FIG.

[0018]

As described above, according to the present invention, when the cause of congestion is a specific line, the line with the largest number of inputs is used to sequentially restrict the traffic, and the processing delay of the upper layer processing device In the case of congestion due to a large number of inputs from the line, by implementing a method of restricting all the lines accommodated in the signaling device, it is possible to realize congestion control that secures the throughput of the line that is not the cause of congestion.

Also, congestion is caused by excessive input from a specific line.
Congestion detection 3 even if it occurs_1iLine support department
Waiting queue Q_L1iSingle rather than seeking individually
2 ₁Processed queue Q of the layer 2 processing signal device_C1
Congestion detection is required by determining the queue length of
Processing to a minimum and the processing capacity of the signaling device is maximized
There is an advantage that can be put to use.

[Brief description of drawings]

FIG. 1 is a block diagram of a conventional storage and exchange device.

FIG. 2 is a functional block diagram of a congestion control method in a store and forward switch.

FIG. 3 is a configuration diagram of an ISDN exchange device.

FIG. 4 is a functional block diagram of a conventional congestion control method in an ISDN switching apparatus.

FIG. 5 is a functional block diagram of a congestion control system of the present invention.

FIG. 6 is a diagram showing control characteristics of a congestion control unit of the present invention.

[Explanation of symbols]

1 ₀ Higher layer processing unit (SPU) processing waiting queue Q _S0 2 ₀ Layer 2 processing signaling unit (CSU) processed queue Q _C0 3 _0i Line _interface processing waiting queue Q _L0i (i = 1 to n) 1 ₁ Higher layer processing device (INP) processing waiting queue Q _S1 2 ₁ Layer 2 processing signaling device (ISE) processing queue Q _C1 3 _1i Line _interface processing waiting queue Q _L1i (i = 1 m) 4 ₁₀ Conventional congestion control unit of the ISDN device 4 _eleven specific input restriction start of congestion control unit N1 congestion induced line ISDN device in the invention Q _C1 threshold N2 of Q _C1 threshold N3 input deregulation start of all lines input restriction start Q _C1 threshold τ All-line input regulation transition time limit

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical indication location H04Q 3/545 8843-5K 11/04 (72) Inventor Naohide Kato 1-6-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A congestion control method of layer 2 processing in a switching apparatus, which accommodates at least a plurality of lines and comprises a layer 2 processing signaling device for controlling a layer 2 protocol of the lines, wherein an input regulation in the signaling device, Having a first threshold for release, periodically monitoring the queue length of the signal processed queue of the signaling device, and when the queue length exceeds the value of the first threshold,
Among the plurality of lines, the line with the longest queue queue length corresponding to the line is selected to perform input regulation, and while the queue length exceeds the threshold value, the input regulation line selection and A congestion control method for layer 2 processing in a switching device, characterized in that input restriction is sequentially executed. 2. The switching apparatus according to claim 1, wherein when the continuation time of the input regulation line selection and the input regulation exceeds a certain time, the input regulation is performed for all the lines accommodated in the signaling device. Congestion control method for layer 2 processing. 3. The input control for all the lines accommodated in the signal device when the queue length of the signal processed queue of the signal device exceeds a second threshold value. A congestion control method for layer 2 processing in the exchange apparatus described.