JP3301045B2 - Congestion control method of layer 2 processing in switching equipment - Google Patents

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 restricting an input to a switching device when a predetermined amount of input or more, that is, a call is added, so that a normal switching operation can be performed. It is.

[0002]

2. Description of the Related Art A congestion control method in a signal device for processing a layer 2 (data link layer) in a conventional switching device will be described with reference to the drawings. 1 and 2 are diagrams illustrating a congestion control method of a layer 2 processing signal device used in a storage switching device such as a signal relay exchange. FIG. 1 shows a device configuration, and FIG. 2 shows a congestion control method. 2 shows a functional configuration. 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 Input restrictions. The signal device for layer 2 processing to which this method can be applied must have a condition that the processing capability is sufficiently larger than that of the device for upper layer processing, that is, the condition that the queuing in the processing queue always occurs from the processing queue in the upper layer. In addition, there is a drawback that the queue waiting for processing stays until the congestion is resolved, so that there is much internal stagnation at the time of congestion, and the processing delay of the queue increases.

FIGS. 3 and 4 are diagrams for explaining a conventional congestion control method in a layer 2 processing signal device (ISE) used in an ISDN switching device. FIG. 1 shows a functional configuration of a conventional congestion control method. The difference of the device configuration from FIG. 1 is that a plurality of layer 2 processing signal devices (ISE) share 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. 4 (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, even if excessive traffic occurs from a specific line, thereby causing congestion in the queue waiting for processing, all the lines must be regulated at the same time. There was a drawback that the line could not be used.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to regulate the normal input by restricting only the input of a specific line that has caused congestion regardless of the level of processing capability between the devices having a hierarchical function. In addition to minimizing the adverse effect on traffic communication of simple lines, if the congestion is not resolved only by input control of each line, smooth and quick congestion control of signal equipment by restricting input to all lines is there.

For this reason, the present invention relates to a congestion control system for Layer 2 processing in a switching apparatus which accommodates at least a plurality of lines and includes a Layer 2 processing signal device for controlling a Layer 2 protocol of the lines. The apparatus has a first threshold for input restriction and release in the apparatus, and periodically monitors a queue length of a signal processed queue of the signal apparatus, and the queue length exceeds a value of the first threshold. When the queue length exceeds the threshold value, each of the plurality of lines is selected to select the line with the longest processing queue length corresponding to the line, and input control is performed. The method is characterized in that the input-restricted line selection and the input restriction are sequentially performed on the lines other than the input-restricted line in each cycle.

Further, the present invention is characterized in that when the continuation time of the input restriction line selection and the input restriction exceeds a predetermined time, the input restriction is performed for all the lines accommodating the signal device.

Further, according to the present invention, when the queue length of the signal processed queue of the signal device exceeds a second threshold value,
Input control is performed for all the lines accommodating the signal device.

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

[0009]

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

The layer 2 protocol generally defines a transmission control procedure and an error detection procedure. A frame in this layer generally includes a flag sequence, an address field, a control field, an information field, and a frame check sequence. . However, some frames have no information field depending on the contents of the command and response information transmitted in the control field. The flag sequence indicates the start and end of the frame and uses a fixed pattern. The address field indicates a command reception destination or a response transmission destination address. The control field has a command or response and a necessary sequence number. In the following embodiment of the present invention, a method for controlling input using the above-described 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. Layer 2 processing signal unit (ISE) 2 ₁ Layer 2 processing signal unit in (ISE) of the processed queue Q _C1 and 3 _1i of the line interface process queue Q _L1i
Congestion detection in congestion control unit 4 _11, regulating the release performed on.

The control is performed as shown in FIG.
It is performed based on 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 identifies congestion induced line, starts its input restriction (hereinafter referred to as primary regulation) of Q _c1 threshold, N2 starts collective input regulations all lines (hereinafter, referred to as secondary regulation ) Threshold of Q _c1 , and N 3 is Q _c1 to start the restriction release during input restriction
Is the threshold value. Further, τ is a time limit for shifting to the secondary regulation when the congestion cannot be reduced by the primary regulation. Note that N
1, N2 and N3 have a relationship of N2>N1> N3.

The detection of congestion is performed at a constant period (hereinafter referred to as T).
And it compares the processed queue length staying in the queue Q _C1 (hereinafter referred to as N) and congestion parameter values N1, N2, N3 of 2 ₁ Layer 2 processing signal unit (ISE) to. This is done by congestion control unit 4 _11. As a result of the comparison, when it is detected that the queue length N is N2> N ≧ N1, the congestion control unit has detected that it is in the primary congestion state.

[0014] The primary restriction method is to examine the queue length remaining in the processing queue Q _L1i of each line corresponding unit of 3 _1i when it becomes the primary congestion state as shown in FIG. 6, the queue length Input restriction is applied to the longest line. Here, the input control uses the monitoring frame shown as an example of the protocol which is a premise of the present invention. An RNR frame in the command / response of the monitoring frame is used for input restriction. The RNR frame is a monitoring frame generally indicating a busy state, that is, a state in which a subsequent frame cannot be temporarily received. The busy state is canceled by a reception enable command (RR frame) or the like.

[0015] In the above method, when the input restriction of the target line, the congestion control unit 4 ₁₁ measures the queue length of the processed queue Q _C1 in period T, the (N ≦ N3 until congestion is resolved ), This input restriction is repeated in a cycle T. That is, to investigate the queue length staying in the processed queue Q _C1 of 2 ₁ Layer 2 processing signal unit (ISE), which is N>
In the case of N3, further restriction is applied to the longest line within 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
And so on. 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 restriction method, input restriction (transmission of an RNR frame) is performed on all the links accommodated in the signaling device when the secondary congestion state shown in FIG. 6 occurs.

[0018]

As described above, according to the present invention, when the cause of congestion is caused by a specific line, the restriction is performed sequentially from the line with the largest number of inputs, and the processing delay of the upper layer processing unit or a large In the case of congestion caused by a large number of inputs from a line, by implementing a method of restricting all lines accommodating the signal device, it is possible to realize congestion control that secures a throughput of a line that is not a cause of congestion.

In addition, congestion is caused by excessive input from a specific line.
Even if it occurs, 3_1iLine handling section
Waiting queue Q_L1iDo not ask individually,
2 ₁Processed queue Q of the signal device for layer 2 processing of_C1
Is necessary for congestion detection.
Processing to a minimum and maximize the processing power of the signaling device.
There is an advantage that can be utilized in.

[Brief description of the drawings]

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

FIG. 2 is a functional configuration diagram of a congestion control method in the storage and exchange device.

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

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

FIG. 5 is a functional configuration diagram of the congestion control method of the present invention.

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

[Explanation of symbols]

1 ₀ Processing queue Q _{S0 of the} upper layer processing device (SPU) 2 ₀ Processed queue Q _C0 3 _{0i of the} layer 2 processing signaling device (CSU) Processing queue Q _L0i (i = 1 to n) 1 ₁ upper layer processing unit processing queue Q _S1 2 ₁ layer 2 processing signal unit (ISE) of the processed queue Q _C1 3 _1i line unit processing queue _{Q L1i (i = 1m) 4} 10 conventional (INP) 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 lines input regulation transition time limit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H04Q 11/04 (72) Inventor Naohide Kato 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) Reference Document JP-A-2-246559 (JP, A) JP-A-2-104150 (JP, A) JP-A-1-286548 (JP, A) JP-A-3-201854 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H04M 3/22 H04L 12/54 H04L 12/58 H04M 3/00 H04Q 3/545 H04Q 11/04

Claims (3)

(57) [Claims] 1. A congestion control method for layer 2 processing in a switching device that accommodates at least a plurality of lines and includes a layer 2 processing signal device that controls a layer 2 protocol of the line. A first threshold value for release; periodically monitoring a queue length of a signal processed queue of the signaling device; when the queue length exceeds a value of the first threshold value,
Of the plurality of lines, the line corresponding to the line has the longest processing wait queue length, and performs input control.While the queue length exceeds the threshold value, for each monitoring cycle, A congestion control method for layer 2 processing in a switching device, wherein the input restriction line selection and the input restriction are sequentially performed on a line other than the line under the input restriction. 2. The switching device according to claim 1, wherein when the continuation time of the input restriction line selection and the input restriction exceeds a predetermined time, the input restriction is performed for all the lines accommodating the signal device. Congestion control method for layer 2 processing. 3. The method according to claim 1, wherein when the queue length of the signal-processed queue of the signaling device exceeds a second threshold value, input control is performed for all lines accommodating the signaling device. 3. A congestion control method for layer 2 processing in the switching device as described above.