JPH0420043A - Congestion control system - Google Patents

Abstract

PURPOSE:To eliminate congestion without aborting a cell by transferring a cell via other internal link with a margin for communication even when part of internal link in a channel equipment is in congestion. CONSTITUTION:A congestion monitor means 100 monitors a load state of each internal link L provided in a channel equipment 1 and identifies the internal link L and an incoming highway 2 and an outgoing highway 3 connecting to the internal link L. A congestion avoidance means 200 analyzes the incoming highway 2 and the outgoing highway 3 identified by the congestion monitor means 100 and call information CI relating to the internal link L and revises the setting so that a call via the internal link L in the congestion state is passed through other internal link L with lighter load. Thus, even when the part of the internal link L in the channel equipment 1 is in congestion, a cell is transferred via other internal link with margin to load. Thus, the congestion state is eliminated without aborting a cell.

Description

[Detailed Description of the Invention] [Summary] The purpose of this invention is to eliminate the congestion state that occurs in a congestion control type communication path device in an asynchronous transfer mode switch without discarding cells. In an asynchronous transfer mote exchange that has multiple connected internal links in the communication path device, the load status of each internal link provided in the communication path device is monitored, and if an internal link that is in a congested state is detected. a congestion monitoring means for identifying the internal link and an input highway and an output highway connected to the internal link;
Analyze call information related to input highways, output highways, and internal links identified by the congestion monitoring means, and set calls that go through an internal link that is in a congested state to go through another internal link that has a lighter load. The congestion avoidance means to be changed and, if desired, the order of cells transmitted to each output highway via the channel equipment are monitored for each call, and the cells transmitted via the internal links before the setting change are set. It is configured to provide cell order guarantee means for sending cells to the output highway ahead of cells transmitted via the changed internal link.

[Industrial application field]

The present invention relates to a congestion control method in an asynchronous transfer mode switch.

2. Description of the Related Art Asynchronous transfer mode (ATM) switching equipment has been widely studied as one of the exchange systems for uniformly exchanging and processing various types of information, such as voice, data, moving images, etc., having different transmission speeds and burst characteristics.

In such an asynchronous transfer mode switch, various types of information to be exchanged are divided into fixed length data called cells, and transferred via an internal route selected at the time of call setup. For example, if bursty information such as moving images is mixed, a temporary congestion state will occur in a part of the exchange, and there is a risk that cells will be discarded or transmission delays will occur.

[Conventional technology]

FIG. 1O is a diagram showing an example of a conventional asynchronous transfer mode switch, and FIG. 11 is a diagram showing an example of the configuration of a conventional cell.

In FIG. 10, the communication path device 1 includes an input highway 2
It is composed of a distribution device 11 that accommodates the output highway 3, and a concentrator 12 that accommodates the output highway 3.

When a call setup request arrives from any input highway 2,
The call path control processor 4 refers to the call information storage table 5 and selects the partial link L I provided in the distribution device 11.
f to LIRl and the secondary links LSI to L2n provided in the line concentrator 12, which connect the input highway 2 and output highway 3 specified in the call setting request, and which are declared in the call setting request. A portion of the information flow rate (hereinafter referred to as declared value) that can be transferred.
i and the partial link 1-zJ are selected, and the route information adding device 6 provided corresponding to the input highway 2 is provided with the call number ■CIK that identifies the set call and the selected partial link L. If and secondary link L2 are set.

Thereafter, the route information addition device 6 sets the call number ver to the cell arriving from the input highway 2, which is equipped with the call number CIK and the data block I of a predetermined length, by the channel control processor 4. The partially connected link L l i and the secondary link L2 . is added as route information RI and transmitted to the distribution device 11.

The distribution device 11 and the concentrator 12 are connected to the input highway 2
A cell arriving from the partial link L I i specified in the attached route information R1 and the -next link LZj
is transferred to the desired output highway 3 via .

Note that when the user transmits information exceeding the declared value, the partial link L I i and the secondary links L and zz become overloaded, and the communication path equipment W1 becomes congested.

In such a congestion state, the distribution device 11 and the line concentrator 12 discard cells of a predetermined value (hereinafter referred to as a dark value) or more that are added to the secondary link Lli and the secondary link L2J, respectively.

In addition, when discarding a cell, the same partial link LI
Measures are adopted such as preferentially discarding cells related to calls whose cell flow rate exceeds a declared value among calls that pass through i and secondary link L 2 j. [Problem] As is clear from the above explanation, in a conventional asynchronous transfer mode switch, some links in the communication path device 1
When L2J and the secondary link L2J become congested, the cells transferred via the corresponding partial link L2J and the secondary link L2J are discarded first, starting with those exceeding the declared value. was.

However, it is quite difficult for users to accurately predict and declare the planned transmission flow rate, and it is rare for users to unknowingly transmit information that exceeds the declared value. , which is not necessarily desirable from a service standpoint.

However, some of the information handled by the asynchronous transfer mode switch has burst characteristics, such as the above-mentioned moving image, and the congestion state may be caused by a specific part of the channel L i and the secondary link in the communication path device 1. LZj rarely occurs temporarily, and not all partial links Lli and secondary links L2J in the communication path device 1 are in a congested state.

SUMMARY OF THE INVENTION An object of the present invention is to resolve a congestion state occurring in a communication path device without discarding cells.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention (claim 1), and FIG. 2 is a diagram showing the principle of the present invention (claim 2).

In the first cabinet and Figure 2, 1 is the communication path device 2 is the input highway, 3 is the output highway, and L is the communication path device 1.
The internal six links and CI provided within the network are call information.

100 is a congestion monitoring means provided according to the present invention (claims 1 and 2).

200 is a congestion avoidance means provided according to the present invention (claims 1 and 2).

300 is a cell order guarantee means provided according to the present invention (claim 2).

[Effect]

The communication path device 1 includes a plurality of internal links L that connect the same input highway 2 and output highway 3.

The congestion monitoring means 100 monitors the load state of each internal link L provided in the communication path device 1, and when an internal link L in a congested state is detected, the congestion monitoring means 100 monitors the load state of each internal link L provided in the communication path device 1, and when an internal link L in a congested state is detected, Identify the input highway 2 and output highway 3 that are connected to the.

The congestion avoidance means 200 analyzes call information CI related to the input highway 2, the output highway 3, and the internal link L identified by the congestion monitoring means 100, and reduces calls via the internal link L in a congested state. Change the settings so that it passes through another internal link L with a light load.

The cell order guaranteeing means 300 monitors the order of cells transmitted to each output highway 3 via the channel device L for each call, and determines the order of cells transmitted via the internal link L before the setting change. The cell is sent to the output highway 3 in advance of the cell transmitted via the internal link L after the setting change.

Therefore, according to the present invention (claim 1), even when some of the internal links in the communication path device become congested, cells can be transferred via other internal links that have room, and the cells It becomes possible to resolve the congestion state without discarding the data.1. The serviceability of the asynchronous transfer mode switch is improved, and further, according to the present invention (claim 2), even if the internal link for transferring cells is changed, the cells are transferred to the output highway in the same order in which they arrived from the input highway. This improves the serviceability of the asynchronous transfer mode switch.

〔Example〕

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

FIG. 3 is a diagram showing an asynchronous transfer mode switch according to an embodiment of the present invention (claims 1 and 2), and FIG. 4 is a diagram showing an example of the congestion monitoring device in FIG.
FIG. 5 is a diagram showing an example of the call information storage table in FIG. 3, FIG. 6 is a diagram showing an example of the route information adding device in FIG. 3, and FIG. 7 is a diagram showing an example of the route information adding device in FIG. FIG. 8 is a diagram showing an example of the order preservation device in FIG. 3, and FIG. 9 is a diagram showing an example of the order preservation control process in FIG. 3. In addition,
The same reference numerals indicate the same objects throughout the figures.

In FIG. 3, a congestion monitoring device 7 is provided as the congestion monitoring means 100 in FIGS. 1 and 2, a congestion avoidance device 8 is provided as the congestion avoidance means 200 in FIGS. 1 and 2, and An order preservation device 9 is provided as the cell order guarantee means 300 in FIG.

In FIGS. 3 to 9, when a call setup request arrives from any input highway 2, the channel control processor 4 connects Lli and The secondary link Lz= is selected, and the route information setting unit 61 in the route information adding device 6 provided corresponding to the input highway 2 is given a selection value corresponding to the call number VCT that identifies the set call. A partial link L l i and a secondary link L2J are set.

Note that the first flag FF and the last flag LF corresponding to the call number VCI are currently both set to logic "0'°.

Thereafter, in the route information addition device 6, the addition control unit 62 sends a call to the route information setting unit 61 for the call number VC[K arriving from the input highway 2 and the set Ii'v that includes the data block I of a predetermined length. The first flag FF (“0°゛)” and the last flag LF (“0°゛”) set corresponding to the number VCIX
-“0”), -secondary links L1, 8 and secondary link Lz=
is added as route information R1 and transmitted to the distribution device 11.

Similarly to the above, the distribution device 11 and the line concentrator 12 also route cells arriving from the input highway 2 as desired via the partial link Lli and secondary link L2J specified in the attached route information R1. Transfer to output highway 3.

On the other hand, in the congestion monitoring device 7, the monitoring unit 73 periodically measures the flow rate of cells transferred on each of the next links L11 to L11 in the distribution device 11, and calculates the actual measurement of the next link flow rate table 71. The value D1□ is accumulated corresponding to each secondary link Lli, and the monitoring unit 74 periodically records the flow rate of cells transferred on each secondary link L21 to LZn in the distribution device 11. Actual measurement value D2 of secondary link flow rate table 72
The information is accumulated in the column □ corresponding to each secondary link L2J.

Note that the dark value D11 column of the secondary link flow rate table 71 and the dark value column 21 of the secondary link flow rate table 72 contain the actual measured values D2 and D22 of each secondary link L4 and secondary link L2j. A value at which congestion is considered to occur when exceeds the threshold values D11 and D21 is set in advance.

The congestion information transfer unit 75 periodically refers to the -th link flow rate table 71 and the secondary link flow rate table 72, and determines the actual measured value, the partial sink L for which □ exceeds the threshold value D-11, or the actual measured value. Secondary link L2 where D22 exceeds the darkness value D2I. When detected, the input highway 2 and output highway 3 connected to the detected partial link Lli and the secondary link L2j are detected with reference to the connection information holding unit 76, and an input that identifies the detected input highway 2 is detected. Highway number HW
,,,Output highway number HW,,,-Next link L,□
and the secondary link I-zJ are transmitted to the congestion avoidance device 8 as congestion information CI.

When the congestion avoidance device 8 receives the congestion information GI transmitted from the congestion monitoring device 7, it updates the call information table 51, the next link usage status table 52, and the secondary link usage status table 53 in the call information storage table 5. is used from among the combinations of a plurality of partial links L l i and secondary links L2j that connect the input highway number HW, and the output highway number HW, included in the received congestion information CI. Band B
The combination with the smallest R is selected, and the call (=call number VCIK) that was set on the combination of the partial link Lli and the secondary link L2J included in the congestion information CI is
Newly selected new-next link L1. ' and the new secondary links L, -, l, and the call information table 51, -next link usage status table 52, and secondary link usage status table 53 in the call information storage table 5 are changed. After updating the input highway number HW1. The call number setting unit 63, new-to-next link setting unit 64, and new secondary link setting unit 65 in the route information addition device R6 provided corresponding to the input highway 2 specified by , new-next link L1.1 and new secondary link L
2J" and requests the addition control unit 62 to change the setting of the route information RI.

In the route information addition device 6, the addition control unit 62 that has received the setting change request for the route information R1 changes the call number setting unit 63
When the call number CIK set in the call number CIK is identified, the final flag LP corresponding to the call number CIK in the route information setting unit 61 is set to the partial link L Ii and the secondary link L2 . After changing the setting to logic ``1'' indicating that the cell is the last cell to be transferred via the input highway 2, the route information setting unit 61 assigns the call number VC1, The first flag FF (="0") and the last flag LF (="
'1' L-order link L l i and secondary link LZj
After adding route information R1 consisting of After updating the partial link Ll, □ corresponding to the call number VCIK in the route information setting unit 61 and the secondary link L2J by L2jl, the head flag FF (currently logical ° "0") corresponding to the call number VCT is updated. ) is set to new -
Next link L l i and new secondary link L2. The last flag LF, (currently the logic “I Ii
) is set to logic "0", the route information setting section 61 stores the information corresponding to the call number CIK in the cell having the next arriving call number 'v C1 from the input highway 2. The route information R [consisting of the first flag FF (="1"), the last flag LF (="O"), the -next link L1□, and the secondary link LzJ was added and transmitted to the communication path device 1. After that, the head flag FF (currently logical “1”) corresponding to the call number ver in the route information setting unit 61 is set.
(currently being set) to logic "0", and also initializes the call number setting section 63, new-to-next link setting section 64, and new secondary link setting section 65.

In the channel device 1, the distribution device 11 and the concentrator 12 select the cells assigned the corresponding call number VCI,
Up to the cell for which the final flag LF is set to logic "1", the output highway 3 is routed through the partial link L I i and the secondary link L2J set in the route information R1 before the setting change. After transferring to , the first flag FF becomes logic “
The cell number set in 0.0 is the new-next link set in route information R1. ° and transfer to output highway 3 via new secondary link 2J.

Please note that some links before the setting change are as follows: 2. and secondary link L
2j and the new-next link L l
There is no guarantee that the cells transferred via "i" and the new secondary link L24" will be transferred to the output highway 3 in the order in which they were sent from the route information adding device 6 to the channel device l.

For information (for example data) for which reversal of the cell transfer order for the output highway 3 has a significant effect, an order preservation device 9 is provided corresponding to each output highway 3.

In the order preservation device 9, the order preservation control unit 92 analyzes the route information R1 of the cell transferred from the line concentrator 12,
Both the first flag FF and the last flag LF are logic “0”
It is determined that the cell set to 1-ZJ is a cell for which the setting of the -next link LH and the secondary link 1-ZJ has not been changed, and is sent to the output highway 3 (steps S1 to S3 in FIG. 9). ), only the final flag LF is logic °“1
”, that is, the last cell to be transferred via the partial link Li before the setting change and the secondary link LZj (step S2), the call number registration table 91 is referred to, Call number VCIK included in the received cell
It is searched whether or not the call has already been registered as a new route call (step S3).

If the cell transfer order is not reversed due to a change in the settings of the partial link LIi and the secondary link L-2j, the first flag will be transferred before the cell whose last flag LF is set to logic "1". Since a cell whose FF is set to logic "1" is never transferred, the call number VCIK included in the received cell is not registered as a new route call.

If it is not registered, the call number VCTx is registered in the call number registration table 91 as an old route call, and the cell is transferred to the output highway 3.
(step S5).

Eventually the new-next link L l i' and the new secondary link L
The first cell transferred via 2j° is concentrator 1.
2 to the order preservation device 9, the order preservation control unit 92 analyzes the route information R1 of the cell and sets the leading flag FF.
When it is detected that VC is set to logic "l" (step S1), the call number registration table 91 is referred to, and the call number VC is set to logic "l".
A search is made to see if the IK has been registered as an old route call (step S6).

As mentioned above, the -order link L I i and the secondary link L
If the transfer order of cells is not reversed by changing the settings of 2j, the cell whose first flag FF is set to logic "I11" is transferred before the cell whose last flag LF is set to logic "1". Since it has never been done, the call number■
CIK is registered as an old route call, and in such a case, the order preservation control unit 92 deletes the registration of the call number VCIK registered as an old route call from the call number registration table 91,
Cells whose leading flag FF is set to logic "1" are sent to the output highway 3 (step S7).

On the other hand, the -order link L l i and the secondary link I-zJ
If the cell transfer order is reversed by changing the settings,
The cell whose first flag FF is set to logic "1" is transferred to the order preservation device 9 before the cell whose last flag LF is set to logic "1".

In the order preservation device 9, the order preservation control unit 92 analyzes the route information R1 of the cell, and the head flag FF is set to logic "l".
” is detected (step S1)
, with reference to the call number registration table 91, and as a result of searching whether or not the call number VCI has been registered as an old route call, the final flag L
Cells in which P is set to logic "1°" have not yet been transferred to the order storage device 9, and the call number CIK is not registered as an old route call in the call number registration table 91 (step S5 ), the order preservation control unit 92 registers the call number VC1 as a new route call in the call number registration table 91, and puts the cell on standby without sending it to the output highway 3 (step S8).

Note that cells having the same call number ■CIK via the new route are also placed on standby.

Eventually, the last cell transferred via the partial link Lli and secondary link L2j before the setting change is transferred to the line concentrator 12.
When the data is transferred to the order preservation device 9, the order preservation control unit 9
2 analyzes the route information R1 of the cell, and the leading flag FF is logical "'0"! This is set, and the final flag LF becomes logic “1”.
’° is detected (step Sl
and S2), when referring to the call number registration table 91 and detecting that the call number VCI included in the received cell has been registered as a new route call (step S3), the order preservation control unit 92 registers the call number as a new route call. Registered call number VCIK
After deregistering the cell from the call number registration table 91 and sending the cell whose final flag LF is set to logic "1" to the output highway 3, the leading flag F waiting in the order storage device 9 is deleted.
The cells in which F is set to logic ``1'' are sent to the output highway 3 (step S9).

As is clear from the above description, according to this embodiment, the partial link L i in the communication path device l and the secondary link L
The actual measured values D1□ and D2□ of cells transferred via 2j are the thresholds D11 and D! If it exceeds +, the lightest loaded new-order link L1,° and the new secondary link between the input highway 2 and the output highway 3 connected by the −-order link L l i and the secondary link L 2 j Since the call setting is changed to link LZj', the congestion state is resolved without discarding cells.

Furthermore, by changing the settings of the partial link L1□ and the secondary link Lz=, it is also possible to prevent the sending order of the cells to the output highway 3 from being reversed.

Note that FIGS. 3 to 9 are only one embodiment of the present invention, and for example, the congestion monitoring means 100 and the congestion avoidance means 2
The configuration of 00 is not limited to what is illustrated,
Although many other modifications may be considered, the effects of the present invention remain the same in any case.

Furthermore, it goes without saying that the asynchronous transfer mode switch to which the present invention is applied is not limited to that shown in the drawings.

〔Effect of the invention〕

As described above, according to the present invention (claim 1), even when some of the internal links in the communication path device become congested, cells can be transferred via other internal links that have room, and the cells It becomes possible to resolve the congestion state without discarding the cell, and the serviceability of the asynchronous transfer mode switch improves.Furthermore, according to the present invention (claim 2), when the internal link for transferring cells is changed, In this case, the cells are sent to the output highway in the same order in which they arrived from the input highway, improving the serviceability of the asynchronous transfer mode switch.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the principle of the present invention (Claim 1), Fig. 2 is a diagram showing the principle of the present invention (Claim 2), and Fig. 3 is a diagram showing the principle of the present invention (Claim 2).
FIG. 4 is a diagram showing an example of the congestion monitoring device in FIG. 3; and FIG. 5 is a diagram showing the call information storage table in FIG. 3. FIG. 6 is a diagram showing an example of the route information addition device in FIG. 3, FIG. 7 is a diagram showing the configuration of a cell according to an embodiment of the present invention, and FIG. FIG. 9 is a diagram showing an example of the order preservation control process in FIG. 3; FIG. 10 is a diagram showing an example of a conventional asynchronous transfer mode switch; FIG.
The figure is a diagram showing an example of the configuration of a conventional cell. In the figure, l is a communication path device, 2 is an input highway, and 3
4 is an output highway, 4 is a communication path control processor, 5 is a call information storage table, 6 is a route information addition device, 7 is a congestion monitoring device, 8 is a congestion avoidance device, 9 is an order preservation device, 11
12 is a distribution device, 12 is a concentrator, 51 is a call information table, 52 is a partial link usage status table, 53 is a secondary link usage status table,
61 is a route information setting section, 62 is an addition control section, 63 is a call number setting section, 64 is a new-to-next link setting section, 65 is a new secondary link setting section, 71 is a partial link flow rate table, and 72 is a second link setting section. Next link flow rate table, 73 and 74 are monitoring units, 75 is a congestion information transfer unit, 76 is a connection information holding unit, 9■ is a call number registration table, 2 is a sequence preservation control unit, 0 is a congestion monitoring means, 200 is congestion Avoidance means, principle diagram of the present invention (Claim 1) Figure 171 of the present invention (Claim 2) t''I scream + 1 report x circle tape 1 disease diagram 3 diagram 2 growth prediction path + blue report force 0 device diagram? figure

Claims (2)

[Claims] (1) In an asynchronous transfer mode switch which includes a plurality of internal links (L) connecting the same input highway (2) and output highway (3) in the channel device (1), the channel device (1) Monitors the load status of each internal link (L) provided in the internal link (L), and connects to the internal link (L) and the internal link (L) when a congested internal link (L) is detected. input highway (2)
and congestion monitoring means (
100) and call information (CI) related to the input highway (2), output highway (3) and internal link (L) identified by the congestion monitoring means (100);
A call via the internal link (L) in the congestion state,
A congestion control method characterized by comprising a congestion avoidance means (200) that changes settings so that the internal link (L) passes through another internal link (L) with a lighter load. (2) In an asynchronous transfer mode switch, the channel device (1) includes a plurality of internal links (L) connecting the same input highway (2) and output highway (3), wherein the channel device (1) Monitors the load status of each internal link (L) provided in the internal link (L), and connects to the internal link (L) and the internal link (L) when a congested internal link (L) is detected. input highway (2)
and congestion monitoring means (
100) and call information (CI) related to the input highway (2), output highway (3) and internal link (L) identified by the congestion monitoring means (100);
A call via the internal link (L) in the congestion state,
congestion avoidance means (200) for changing settings so that cells are transmitted to each output highway (3) via another internal link (L) with a lighter load; The order is monitored for each call, and the cells transmitted via the internal link (L) before the setting change are
A congestion control system characterized by providing a cell order guaranteeing means (300) for sending cells to the output highway (3) in advance of cells transmitted via the internal link (L) after the setting has been changed.