JP2967720B2 - ATM switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a line (VC (Virtual Channel)) having a variable transfer rate.
ATM (A) having a function of controlling a VP (Virtual Path) or a link (“VP” is a logical concept and “link” is a physical concept) that accommodates
Synchronous Transfer Mod
e) relating to the exchange.

[0002]

2. Description of the Related Art As a technique for controlling (variable control) the transfer rate of a VC in an ATM network, a technique comprising the following processes has been considered.

A receiving terminal or an ATM in an ATM network
Information for the transmitting terminal to determine the transfer rate (available transfer rate) of the data that can be transmitted by the exchange at that time in the VC (hereinafter, “transferable rate information”)
Is transmitted to the transmitting terminal.

The transmitting terminal determines the transfer rate of the VC according to the transferable rate information.

[0005] ATM Forum (The ATM Fo
rum) based on this idea, ABR (Avail
able Bit Rate) VC of service category
(Hereinafter, referred to as “ABR VC”).

[0006] "The Rate-Based Flo
w Control Framework fort
he Available Bit Rate ATM
Service (IEEE Network Mar
ch / April 1995, pp. 25-39)], the ABR VC uses an RM (Resource M) to notify the transmitting terminal of transferable rate information.
A cell for managing a transfer rate called an (anagement) cell is used.

Here, such an RM cell is handled in any of the following modes (see FIG. 2).

[0008] The message is generated at the transmitting terminal, transmitted to the receiving terminal, and returned to the return transmitting terminal (FIG. 2).
(A)).

[0009] The message is generated at the receiving terminal and transmitted to the transmitting terminal (see FIG. 2B).

It is generated by the ATM switch on the path of the VC to be controlled and transmitted to the transmitting terminal (see FIG. 2C).

When an RM cell is inserted into a VC from a receiving terminal or an ATM exchange and transmitted to a transmitting terminal, the RM cell is added to the RM cell by the receiving terminal and each ATM exchange.
Transferable rate information on C is written. The contents of the transferable rate information include a transfer rate that can be used at that time, a flag indicating whether there is a failure or congestion, and a flag indicating whether the transferable rate can be increased.
The transmitting terminal controls the transfer rate of the VC to be controlled according to the transferable rate information written in the transmitted RM cell.

[0012] In an ATM exchange on a path to which a transfer rate management cell such as an RM cell is transferred, a method for generating transferable rate information is to use a method in which congestion occurs in the own exchange (the ATM exchange). A method of generating transferable rate information by reflecting congestion has been proposed.
Note that "when congestion occurs in the local exchange"
It is conceivable that allocatable resources in the ATM exchange, such as buffers and ports, are not sufficiently allocated to the VC to be controlled. In this case (when congestion occurs in the local exchange), the ATM exchange uses a transfer rate management cell such as an RM cell to transmit transferable rate information indicating the occurrence of congestion to the transmitting terminal. Notice.

By the way, in the conventional "control method of VC transfer rate", it is necessary to change the transfer rate of the VC due to a failure or congestion event occurring in a place other than on the path of the VC to be controlled. In order to notify the transmitting terminal of the fact (necessity of changing the transfer rate), the RM
A method using a transfer rate management cell such as a cell (a method that enables a transmitting terminal to handle the transfer rate control when a failure or congestion occurs on the path of the VC to be controlled) is not known. .

Therefore, in the conventional ATM exchange, R
When writing transferable rate information to a transfer rate management cell such as an M cell (see FIG. 2), the transfer rate of the VC to be controlled is changed by a failure or congestion event occurring at a place other than on the path of the VC to be controlled. The processing for generating transferable rate information indicating that the necessity has occurred has not been performed.

[0015]

As described above, in the conventional ATM exchange, with respect to control of the transfer rate of a VC, a failure or congestion event occurring in a place other than the path of the VC to be controlled causes the VC to be controlled. When the transfer rate needs to be changed, there has been no method of notifying the transmission terminal using the transfer rate management cell that the transfer rate needs to be changed.

As a method of coping with a failure or congestion in the ATM network, the affected VP or VC
In this case, there is a method of changing the route of the route and bypassing the fault location or the congestion location. If the transfer rate of a “VC with a variable transfer rate” such as an ABR VC is reduced in the event of a failure or congestion, the transfer capacity resulting from the decrease can be used for bypassing other VPs and VCs described above. It becomes possible. Therefore, when it is necessary to change the transfer rate of a VC to be controlled due to a failure or congestion event occurring in a place other than the path of the VC to be controlled, the transfer rate is required (the transfer rate needs to be changed). The significance of notifying the transmitting terminal using the management cell is significant.

However, in a conventional transfer rate control method of a VC using a transfer rate management cell, and a conventional ATM exchange applied to realize such a method, there is a problem other than on a path of a VC to be controlled. It is not possible to generate transferable rate information to be written in the transfer rate management cell by reflecting the failure or congestion event occurring in the above.
As a result, a transfer rate management cell such as an RM cell is controlled based only on a failure or congestion that has occurred on the path of the VC to be controlled. Therefore, when a failure or congestion occurs on a link (logically a VP) through which a certain VC does not pass, it is not possible to use a transfer rate management cell to reduce the transfer rate of the VC. There was a point.

In view of the above, an object of the present invention is to use a transfer rate management cell to determine whether a failure or congestion has occurred in a location other than the path of a VC controlled by itself. An object of the present invention is to provide an ATM exchange which can notify a transmitting terminal. Thereby, in the transmitting terminal, the same as the normal “control of the transfer rate of the VC using the transfer rate management cell” (control when a failure or congestion occurs on the path of the VC to be controlled), It becomes possible to handle control when a failure or congestion occurs in a place other than on the path of the VC to be controlled.

[0019]

An ATM exchange according to the present invention writes transferable rate information in a transfer rate managing cell and inserts the transferable rate information into a VC to be controlled to thereby transfer the transferable rate information. A transferable rate information control request for an ATM exchange having a function of notifying a transmitting terminal of information including either "notification of occurrence of failure or congestion" and "desired value of a transfer rate to be changed" from outside the own exchange. The transferable rate information control request receiving unit that receives the "
And an in-exchange fault / congestion monitoring unit that monitors the presence or absence of an event that causes the transfer rate to be changed, and the transferable rate information control request receiving unit receives a transferable rate information control request from outside the local exchange. In this case, the transferable rate information of the VC to be controlled is generated based on the transferable rate information control request and the monitoring by the fault / congestion monitoring unit in the exchange.
Rate information control request is "Notification of failure or congestion"
If the information contains "failure or congestion",
It occurred on a route other than the route of the VC to be controlled,
Also the “severity of failure or congestion”
Depending on the distance between the place of occurrence and the local exchange,
Generates transferable rate information containing "decrease instruction".
A VC control unit that writes the transfer rate management cell into the transfer rate management cell, and reads the transfer rate management cell flowing in the VC to be controlled and transmits it to the VC control unit. The transferable rate information generated by the VC control unit is A cell control unit that inserts the written transfer rate management cell into the VC to be controlled. Further, the ATM exchange of the present invention has a transfer rate control.
The transferable rate information is written to the
By inserting the transfer rate management cell into the VC,
Function to notify the transmitting terminal of transferable rate information
In the ATM switch that performs
"Notification of congestion occurrence" and "Transfer rate to be changed"
A rate information system that can transfer information containing either the desired value
Receive transferable rate information control request received as request
Section and the "change of transfer rate of VC to be controlled"
Exchanges that monitor for events that cause
Internal failure / congestion monitoring unit and transferable rate information control required
Calculated reception unit transferable record over preparative information control request from the own exchange outside
Is received, the transferable rate information control request and
On the basis of monitoring by the fault / congestion monitoring unit in the exchange
Generates transferable rate information of the VC to be controlled, and generates
In this case, it is necessary to control the transferable rate information from outside the local switch.
Request is information that includes "notification of failure or congestion occurrence"
In this case, the “failure or congestion” is the VC of the control target.
Even if the error occurred on a path other than the
Severity of congestion or location of failure or congestion and local switch
"Notification of failure or congestion occurrence" according to "Distance to
Generate transferable rate information to be the contents and transfer rate management
The VC controller that writes to the management cell and the flow to the VC to be controlled
Reads the transfer rate management cell that has been
To the control unit, and the transfer generated by the VC control unit is possible.
Controls the transfer rate management cell in which
And a cell control unit to be inserted into the VC to be controlled.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an ATM exchange according to the present invention will be described in detail with reference to the drawings.

(1) Configuration for realizing the embodiment

FIG. 1 is a block diagram showing the configuration of the first to fifth embodiments of the ATM switch of the present invention shown in the following (2) to (6) .

This ATM switch (ATM switch 101)
Is a transferable rate information control request receiving unit 102, a fault / congestion monitoring unit 103 in the exchange, a VC control unit 104,
It is configured to include a cell control unit 105 and a VC connection 106 (a connection part of the ATM switch 101 in a VC to be controlled). Note that the connection relationship indicated by the arrow in FIG. 1 indicates the relationship of information exchange between the units and the like.

Transferable rate information control request receiving section 102
Receives the transferable rate information control request. The transferable rate information control request is issued from the network management system or another ATM switch (an ATM switch other than the ATM switch 101), and includes a "notification of occurrence of a failure or congestion" and a "desired value of the transfer rate to be changed". One of them is required information. In addition, the transferable rate information control request may include information such as the location and scale of occurrence of a failure or congestion as information other than the above-mentioned essential information.

The fault / congestion monitoring unit 103 in the exchange
ATM exchange such as occurrence of congestion due to malfunction of allocation of resources such as buffers and ports inside the M exchange 101, occurrence of congestion in a link accommodating a VC to be controlled, and occurrence of a failure inside the ATM exchange 101 The presence / absence of an “event that causes a change in the transfer rate of the VC to be controlled” occurring inside 101 is monitored.

The VC control section 104 transmits the transferable rate information control request received by the transferable rate information control request receiving section 102 and the connection information from the failure / congestion monitoring section 103 in the exchange (“control in the ATM exchange 101”). Transferable rate information to be written to the transfer rate management cell is generated based on the monitoring of the presence / absence of an “event that causes a change in the transfer rate of the target VC”.

Here, as the contents of the transferable rate information generated based on the transferable rate information control request and the like, the transferable rate information control request indicates that the transfer rate to be changed (usually “reduced”) is desired. In the case of "value", there is no problem in setting "instruction to decrease transfer rate". However, if the transferable rate information control request is “notification of occurrence of failure or congestion”, not only “instruction of transfer rate reduction” but “notification of occurrence of failure or congestion” itself as transferable rate information It is also conceivable to use the contents ("Claim 1 " and "Claim 1 " in "Claims").
2 "). Here, the significance of setting “notification of occurrence of failure or congestion” as the content of the transferable rate information is that the transmission terminal determines a specific change value of the transfer rate and simplifies the processing on the ATM switch 101 side. In that

The cell control unit 105 reads the transfer rate management cell flowing through the VC connection 106 constituting the VC to be controlled, and transmits the transfer rate management cell to the VC control unit 104. Also, the VC control unit 104
The transfer rate management cell in which the transferable rate information generated by the above is written is inserted into the VC to be controlled.
Examples of the transfer rate management cell include an ABR class RM cell and the like.

As described above, the VC connection 106 is a VC connection that constitutes a VC to be controlled.

The first to fifth embodiments described below are realized by the above configuration. Here, the first to fifth
That each of the embodiments is characterized from the other embodiments,
The difference lies mainly in the processing content of the VC control unit 104. Especially,
The VC control unit 104 transmits predetermined information (as described later, FIG.
Various methods are conceivable as to how to generate transferable rate information to be written in the transfer rate management cell based on the information read in step 205 in the figure). It is distinguished from the embodiment.

The VC control unit 104 which performs processing contents other than the processing contents in the following embodiment (including the processing contents obtained by combining a plurality of processing contents in the following embodiment) is also provided.
“The transferable rate information control request received by the transferable rate information control request
Based on the connection information from the congestion monitoring unit 103,
Anything that performs the process of “generating transferable rate information to be written to the transfer rate management cell” can be a component of the present invention.

Hereinafter, each embodiment will be sequentially described.

(2) First embodiment (an embodiment corresponding to the third aspect of the present invention)

FIG. 3 shows the processing (processing for controlling the transfer rate of VC) of the first embodiment of the ATM exchange according to the present invention.
3 is a flowchart showing the flow of the above. This processing includes a transfer rate management cell receiving step 201, a reception content transmitting step 202, a failure / congestion monitoring step 20 in the local exchange.
3 and transferable rate information control request receiving step 204
Information reading step 205, failure / congestion occurrence notification presence / absence determining step 206, minimum guaranteed value writing step 207, transferable rate calculation and writing step 2
08 and a transfer rate management cell VC insertion step 209
Consists of

Next, the operation of the ATM switch (ATM switch 101) of this embodiment will be described.

The ATM switch 101 performs a process for controlling the transfer rate of the VC as follows (see FIG. 3).

A transfer rate management cell (in FIG. 3 to FIG. 7, simply referred to as a “management cell”) is a control target V
In response to the reception by the cell control unit 105 via the VC connection 106 constituting C (step 20)
1), a process for controlling the transfer rate of the VC starts.

The cell control unit 105 transmits the contents of the received transfer rate management cell to the VC control unit 104 (step 202).

On the other hand, fault / congestion monitoring unit 103 in the exchange
Independently monitors the traffic of the VC to be controlled and the occurrence of a failure or congestion in the local exchange (ATM exchange 101) independently of the "reception processing in step 201" (step 203). That is, the fault / congestion monitoring unit 103 in the exchange always monitors whether there is an “event that causes a change in the transfer rate of the VC to be controlled”.

Also, the transferable rate information control request receiving unit 102 is independent of the “reception processing of step 201”
A transferable rate information control request from outside the local exchange is always accepted (a state in which a transferable rate information control request can be received) (step 20).
4).

The VC control unit 104 reads the connection information based on the monitoring in step 203 from the fault / congestion monitoring unit 103 in the exchange, and extracts the information contained in the transferable rate information control request actually received in the reception in step 204. It is read from the transferable rate information control request receiving unit 102 (step 205).

The VC control unit 104 determines (generates) transferable rate information to be written to the transfer rate management cell based on the information read in step 205 (steps 206 to 208).

That is, the VC control section 104 in the present embodiment (first embodiment) determines transferable rate information as described below, and writes the transferable rate information to the transfer rate management cell. (A transfer rate management cell in which predetermined transferable rate information is written is generated).

The presence / absence of a transferable rate information control request for notifying the occurrence of a failure or congestion based on the information read in step 205 (including the presence / absence of detection of a failure or congestion in its own switch by the failure / congestion monitoring unit 103 in the switch) )
Is determined, and whether or not a failure or congestion has occurred is confirmed (step 206).

If it is determined in step 206 that “failure or congestion has occurred”, “instruction to reduce the transfer rate to the minimum guaranteed value” is generated as transferable rate information, and the transferable rate is generated. The information is written in the transfer rate management cell (the transfer rate management cell received by the cell control unit 105 in step 201) (step 20).
7).

If it is determined in step 206 that “failure and congestion have not occurred”, the contents of the received transfer rate management cell and the VC to be controlled are accommodated by the conventional technique. Based on the state of the link or the VP, the transfer rate that can be used by the VC to be controlled is calculated, transferable rate information having the transfer rate is generated, and the transferable rate information is written to the transfer rate management cell ( Step 208). Note that the “transfer rate calculation method” here follows, for example, a calculation method standardized by the ATM Forum.

The VC control unit 104 finally transmits the transfer rate management cell (
Or, the transfer rate management cell in which the transferable rate information generated in step (a) is written) is transferred to the cell control unit 105. The cell control unit 105 inserts the transfer rate management cell transferred from the VC control unit 104 into the VC connection 106 configuring the VC to be controlled (step 20).
9). Thus, the process illustrated in FIG. 3 ends.

When the VC controller 104 in this embodiment confirms that a failure or congestion has occurred, the VC control unit 104 transfers the transferable rate information to be written to the transfer rate management cell regardless of the location or scale of the failure or congestion. The method of setting the minimum guarantee value is adopted. This method is suitable for small networks. In the case of a small-scale network, the effect of a failure or congestion that occurs at one location affects the whole. Therefore, inconvenience is unlikely to occur even if the transfer rate is controlled while ignoring information on the location and scale of the occurrence of a failure or congestion. On the other hand, by ignoring the information on the location and scale of the occurrence of the failure or congestion, the processing is simplified. Therefore, the method of the present embodiment is desirable for realizing appropriate control of the VC transfer rate in a small-scale network.

(3) Second embodiment (Embodiment corresponding to the fourth aspect of the invention)

FIG. 4 is a flowchart showing a processing flow of the second embodiment of the ATM exchange according to the present invention. This process
Transfer rate management cell receiving step 201, received content transmitting step 202, failure / congestion monitoring step 203 in the local exchange, transferable rate information control request receiving step 204, information reading step 205, failure / congestion occurrence Notification presence / absence determination step 206, transferable rate calculation and writing step 208, transfer rate management cell VC insertion step 209, failure / congestion occurrence location local switch hop number determination step 210, failure / congestion occurrence notification writing step 211 and a transfer rate decrease instruction writing step 212. Although the processing contents of steps 201 to 205 in FIG. 4 are not explicitly shown, FIG.
This is the same as the processing contents of steps 201 to 205 in FIG. Further, the determination and processing in steps 206, 208, and 209 in FIG.
This is the same as the judgment and processing of 208 and 209.

Next, the operation of the ATM switch (ATM switch 101) of this embodiment will be described. The following description focuses on operations specific to the present embodiment (only processing and determination after step 206 in FIG. 4 will be described).

The VC controller 104 determines (generates) transferable rate information to be written in the transfer rate management cell based on the information read in step 205 (steps 206, 208, 210-212).

That is, the VC control unit 104 in this embodiment (second embodiment) determines transferable rate information as described in the following and writes the transferable rate information to the transfer rate management cell. (A transfer rate management cell in which predetermined transferable rate information is written is generated).

The presence or absence of a transferable rate information control request for notifying the occurrence of a failure or congestion based on the information read in step 205 (including the presence / absence of detection of a failure or congestion in the local exchange by the failure / congestion monitoring unit 103 in the exchange) )
Is determined, and whether or not a failure or congestion has occurred is confirmed (step 206).

If it is determined in step 206 that “failure or congestion has occurred” (when it is known that a failure or congestion has occurred somewhere in the network), the “failure or congestion is found” Is generated at a location within N hops from the local exchange to the link (step 210). Note that N is a preset threshold. By this determination, "the distance between the location where the failure or congestion occurs and the local exchange" can be confirmed.

If it is determined in step 210 that “the location of the failure or congestion is within N hops from the local exchange”, “notification of the occurrence of the failure or congestion” is generated as transferable rate information, and The transferable rate information is written into the transfer rate management cell (step 21).
1). This is because it has been confirmed that a failure or congestion has occurred near the local exchange based on the determination in step 210 (the effect thereof is large), and this fact is reflected in the control of the transfer rate of the VC. is there. As a method of coping with the case where the influence of the failure or the congestion is large, there is a method of reducing the transfer rate to the minimum guaranteed value. But,
In the present embodiment, the above-mentioned “notification of occurrence of failure or congestion”
Is transmitted to the transmitting terminal, thereby simplifying the processing on the ATM exchange 101 side.

If it is determined in step 210 that the location of the failure or congestion is farther than N hops from the local exchange, an instruction to reduce the transfer rate with the minimum guaranteed value as a limit is provided by transferable rate information. Generated as
The transferable rate information is written into the transfer rate management cell (step 212). The decrease width is, for example, half of the current amount.

If it is determined in step 206 that “failure and congestion have not occurred”, the contents of the received transfer rate management cell and the VC to be controlled are accommodated by the conventional technique. Based on the state of the link or the VP, the transfer rate that can be used by the VC to be controlled is calculated, transferable rate information having the transfer rate is generated, and the transferable rate information is written to the transfer rate management cell ( Step 208). Note that the “transfer rate calculation method” here follows, for example, a calculation method standardized by the ATM Forum.

Finally, the VC control section 104
The transfer rate management cell generated as described above is transferred to the cell control unit 105. Cell control unit 105
Inserts the transfer rate management cell transferred from the VC control unit 104 into the VC connection 106 constituting the VC to be controlled (step 209). Thus, the process illustrated in FIG. 4 ends.

The method of determining the transfer rate available information of the VC control unit 104 in the present embodiment is based on a problem that occurs when the ATM switch 101 of the present embodiment is applied to a large network. This is an effective method when trying to prevent the transfer rate from being excessively reduced due to traffic or congestion.

(4) Third Embodiment (Embodiment corresponding to the fifth aspect of the present invention)

FIG. 5 is a flowchart showing a processing flow of the third embodiment of the ATM exchange according to the present invention. This process
Transfer rate management cell receiving step 201, received content transmitting step 202, failure / congestion monitoring step 203 in the local exchange, transferable rate information control request receiving step 204, information reading step 205, failure / congestion occurrence Notification presence / absence determination step 206, transferable rate calculation and writing step 208, transfer rate management cell VC insertion step 209, failure / congestion occurrence notification writing step 211, transfer rate decrease instruction writing step 212, failure / congestion And the affected traffic amount determination step 213. Step 20 in FIG.
Although the processing contents of steps 1 to 205 are not explicitly shown, they are the same as the processing contents of steps 201 to 205 in FIG.
Steps 206, 208, and 209 in FIG.
Are determined and processed in steps 206 and 20 in FIG.
8 and 209 are the same as those in the determination and processing. Further, the processing of steps 211 and 212 in FIG. 5 is the same as the processing of steps 211 and 212 in FIG.

Next, the operation of the ATM switch (ATM switch 101) of this embodiment will be described. The following description focuses on operations specific to the present embodiment (only processing and determination after step 206 in FIG. 5 will be described).

The VC control unit 104 determines (generates) transferable rate information to be written in the transfer rate management cell based on the information read in step 205 (steps 206, 208, 211 to 213).

That is, the VC control section 104 in the present embodiment (third embodiment) determines transferable rate information in the following manner and writes the transferable rate information to the transfer rate management cell. (A transfer rate management cell in which predetermined transferable rate information is written is generated).

The presence or absence of a transferable rate information control request for notifying the occurrence of a failure or congestion based on the information read in step 205 (including the presence / absence of detection of a failure or congestion in the local exchange by the failure / congestion monitoring unit 103 in the exchange) )
Is determined, and whether or not a failure or congestion has occurred is confirmed (step 206).

If it is determined in step 206 that “failure or congestion has occurred” (when it is known that a failure or congestion has occurred somewhere in the network), the “failure or congestion” is determined. It is determined whether or not the amount of traffic affected by “” is greater than or equal to M [Mbps] (step 213), and it is checked how much traffic the “failure or congestion” has affected. Note that M is a preset threshold value. By this determination, the “severity of failure or congestion” can be confirmed.

If it is determined in step 213 that “the traffic amount affected by the failure or the congestion (the traffic amount that needs to bypass the failure or the congestion) is equal to or more than M [Mbps]”, "Notification of occurrence" is generated as transferable rate information, and the transferable rate information is written to the transfer rate management cell (step 211). This is because the fact that the failure or the congestion is serious (the effect is large) is confirmed based on the determination in step 213, and that fact is reflected in the control of the transfer rate of the VC. The transmission of the “notification of occurrence of a failure or congestion” to the transmitting terminal without giving an instruction to reduce the transfer rate to the minimum guaranteed value is based on the same intention as in the case of the above-described second embodiment.

If it is determined in step 213 that “the amount of traffic affected by the failure or congestion is less than M [Mbps]”, an instruction to reduce the transfer rate with the minimum guaranteed value as the limit is set as the transferable rate. The transferable rate information is generated as information, and the transferable rate information is written in the transfer rate management cell (step 212). The decrease width is, for example, half of the current amount.

If it is determined in step 206 that “failure and congestion have not occurred”, the contents of the received transfer rate management cell and the VC to be controlled are accommodated by the conventional technique. Based on the state of the link or the VP, the transfer rate that can be used by the VC to be controlled is calculated, transferable rate information having the transfer rate is generated, and the transferable rate information is written to the transfer rate management cell ( Step 208). Note that the “transfer rate calculation method” here follows, for example, a calculation method standardized by the ATM Forum.

Finally, the VC control section 104
The transfer rate management cell generated as described above is transferred to the cell control unit 105. Cell control unit 105
Inserts the transfer rate management cell transferred from the VC control unit 104 into the VC connection 106 constituting the VC to be controlled (step 209). Thus, the process illustrated in FIG. 5 ends.

The method of determining the transfer rate available information of the VC control unit 104 in this embodiment changes the handling method depending on the scale (severity) of a failure or congestion, and a large ATM network (network) for a small failure or congestion. This is an effective method when trying to prevent the reconstruction of ()). Since the control is performed according to the traffic volume affected by the failure or the congestion, the optimal control is easily performed, and the resources can be effectively used.

(5) Fourth embodiment (Embodiment corresponding to the sixth aspect of the invention)

FIG. 6 is a flowchart showing a processing flow of the fourth embodiment of the ATM exchange according to the present invention. This process
Transfer rate management cell receiving step 201, received content transmitting step 202, failure / congestion monitoring step 203 in the local exchange, transferable rate information control request receiving step 204, information reading step 205, failure / congestion occurrence Notification presence / absence determination step 206, transferable rate calculation and writing step 208, transfer rate management cell VC insertion step 209, failure / congestion occurrence notification writing step 211, transfer rate decrease instruction writing step 212, failure / congestion The number of affected connections is determined at step 214. Step 20 in FIG.
Although the processing contents of steps 1 to 205 are not explicitly shown, they are the same as the processing contents of steps 201 to 205 in FIG.
Steps 206, 208, and 209 in FIG.
Are determined and processed in steps 206 and 20 in FIG.
8 and 209 are the same as those in the determination and processing. Further, the processing of steps 211 and 212 in FIG. 6 is the same as the processing of steps 211 and 212 in FIG.

Next, the operation of the ATM switch (ATM switch 101) of this embodiment will be described. The following description focuses on operations specific to the present embodiment (only processing and determination after step 206 in FIG. 6 will be described).

The VC control unit 104 determines (generates) transferable rate information to be written to the transfer rate management cell based on the information read in step 205 (steps 206, 208, 211, 212, 214).

That is, the VC control section 104 in the present embodiment (fourth embodiment) determines transferable rate information in the following manner and writes the transferable rate information to the transfer rate management cell. (A transfer rate management cell in which predetermined transferable rate information is written is generated).

The presence or absence of a transferable rate information control request for notifying the occurrence of a failure or congestion based on the information read in step 205 (including the presence / absence of detection of a failure or congestion in the local exchange by the failure / congestion monitoring unit 103 in the exchange) )
Is determined, and whether or not a failure or congestion has occurred is confirmed (step 206).

If it is determined in step 206 that “failure or congestion has occurred” (when it is known that a failure or congestion has occurred somewhere in the network), the “failure or congestion” is determined. It is determined whether or not the number of connections affected by “” is L or more (step 214), and it is checked how many connections the “failure or congestion” has affected. Note that L is a preset threshold value. By this determination, the “severity of failure or congestion” can be confirmed.

If it is determined in step 214 that the number of connections affected by the failure or congestion (the number of connections that need to bypass the failure or congestion) is L or more, "Notification" is generated as transferable rate information, and the transferable rate information is written in the transfer rate management cell (step 21).
1). This is because the fact that the failure or congestion is serious (the effect is large) is confirmed based on the determination in step 214, and that fact is reflected in the control of the VC transfer rate. The transmission of the “notification of occurrence of a failure or congestion” to the transmitting terminal without giving an instruction to reduce the transfer rate to the minimum guaranteed value is based on the same intention as in the case of the above-described second embodiment.

If it is determined in step 214 that “the number of connections affected by a failure or congestion is less than L”, an instruction to decrease the transfer rate with the minimum guaranteed value as a limit is set as transferable rate information. Generate
The transferable rate information is written into the transfer rate management cell (step 212). The decrease width is, for example, half of the current amount.

If it is determined in step 206 that “failure and congestion have not occurred”, the contents of the received transfer rate management cell and the VC to be controlled are accommodated by the conventional technique. Based on the state of the link or the VP, the transfer rate that can be used by the VC to be controlled is calculated, transferable rate information having the transfer rate is generated, and the transferable rate information is written to the transfer rate management cell ( Step 208). Note that the “transfer rate calculation method” here follows, for example, a calculation method standardized by the ATM Forum.

The VC control unit 104 finally makes the above
The transfer rate management cell generated as described above is transferred to the cell control unit 105. Cell control unit 105
Inserts the transfer rate management cell transferred from the VC control unit 104 into the VC connection 106 constituting the VC to be controlled (step 209). Thus, the process illustrated in FIG. 6 ends.

The method of determining the transfer rate available information of the VC control unit 104 in this embodiment changes the handling method depending on the scale (severity) of a failure or congestion, and a large ATM network (network) for a small failure or congestion. This is an effective method when trying to prevent the reconstruction of ()). Since control is performed according to the number of connections affected by a failure or congestion, control is simplified, and control can be performed at high speed.

[0085] (6) the fifth embodiment

FIG. 7 is a flowchart showing a processing flow of the fifth embodiment of the ATM exchange according to the present invention. This process
Transfer rate management cell receiving step 201, received content transmitting step 202, failure / congestion monitoring step 203 in the local exchange, transferable rate information control request receiving step 204, information reading step 205, transferable rate calculation And write step 208, transfer rate management cell VC insertion step 209, transfer rate designation transferable rate information control request presence / absence determination step 215
, A transfer rate calculation step 216, a calculated transfer rate / requested transfer rate comparison determination step 217, a calculated transfer rate writing step 218, and a requested transfer rate writing step 219. Step 2 in FIG.
Although the processing contents of 01 to 205 are not explicitly shown, they are the same as the processing contents of steps 201 to 205 in FIG. Further, the processing in steps 208 and 209 in FIG. 7 is the same as the processing in steps 208 and 209 in FIG.

The process of the present embodiment shown in FIG. 7 is a process in the case where the "desired value of the transfer rate to be changed" is specifically specified in the transferable rate information control request. This point is different from the above-described first to fourth embodiments.

Next, the operation of the ATM switch (ATM switch 101) of this embodiment will be described. The following description focuses on operations specific to the present embodiment (only the processing and determination after step 215 (including steps 208 and 209) in FIG. 7 will be described).

The VC controller 104 determines (generates) transferable rate information to be written in the transfer rate management cell based on the information read in step 205 (steps 208, 215 to 219).

That is, the VC control section 104 in the present embodiment (fifth embodiment) determines transferable rate information in the following manner and writes the transferable rate information into the transfer rate management cell. (A transfer rate management cell in which predetermined transferable rate information is written is generated).

Based on the information read in step 205, it is determined whether there is a transferable rate information control request to change the transfer rate to K [Mbps] (a specific value of the transfer rate to be changed) (step 215). .

In the step 215, “Set the transfer rate to K
(There is a transferable rate information control request failure to change to [Mbps]. "(The transferable rate information control request receiving unit 102 determines that the transferable rate information control request is" a desired value of the transfer rate to be changed. " Is received), first, in step 205, independently of the designation (designation by the transferable rate information control request).
Then, the transfer rate of the VC to be controlled is calculated based on the information (the state of the link or VP in which the VC to be controlled is accommodated) read (step 216). The transfer rate calculated in this way is called a “calculated transfer rate”.

It is determined whether the calculated transfer rate calculated in step 216 is higher than the transfer rate specified in the transferable rate information control request (referred to as “requested transfer rate”) (step 217).

If it is determined in step 217 that “the calculated transfer rate is lower than or equal to the requested transfer rate”, transferable rate information containing “instruction to change the transfer rate to the calculated transfer rate” is generated. The transferable rate information is written into the transfer rate management cell (step 21).
8).

If it is determined in step 217 that “the calculated transfer rate is higher than the requested transfer rate”,
The transferable rate information containing "instruction to change the transfer rate to K [Mbps] of the requested transfer rate" is generated, and the transferable rate information is written to the transfer rate management cell (step 219).

In step 215, “Set transfer rate to K
If there is no transferable rate information control request to change to [Mbps] ", the contents of the received transfer rate management cell and the VC to be controlled are accommodated by a conventional technique. A transfer rate that can be used by the VC to be controlled is calculated based on the state of the link or the VP, transferable rate information having the transfer rate is generated, and the transferable rate information is written to the transfer rate management cell (step 208). Note that the “transfer rate calculation method” here follows, for example, a calculation method standardized by the ATM Forum.

Finally, the VC control unit 104 sets the above
The transfer rate management cell generated as described above is transferred to the cell control unit 105. Cell control unit 105
Inserts the transfer rate management cell transferred from the VC control unit 104 into the VC connection 106 constituting the VC to be controlled (step 209). Thus, the process illustrated in FIG. 7 ends.

In the method of determining the transfer rate possible information of the VC controller 104 in this embodiment, the network management system or the like notifies the ATM switch 101 of the optimum value of the transfer rate considering the entire ATM network as a transfer rate information control request. This is an effective method to take appropriate measures in such cases.

(7) How to give a transferable rate information control request to the ATM switch (ATM switch 101 shown in FIG. 1) of the present invention

FIGS. 8A and 8B are diagrams showing two types of methods for giving a transferable rate information control request to the transferable rate information control request receiving section 102 in the ATM exchange 101. FIG.

The control channel 107 in FIG.
This is a control channel connecting the network management system 110 or another ATM exchange (hereinafter, referred to as “other exchange 111”) and the transferable rate information control request receiving unit 102.

The connection 108 in FIG.
This connection handles a main signal and a control signal flowing on the same connection as the main signal between the TM exchanges (between the ATM exchange 101 and the other exchanges 111).

The connection management unit 109 in FIG.
Monitors a control signal flowing on the same connection as the main signal.

The following two methods are provided for giving the transferable rate information control request.

The first method is a method that is transmitted from the control channel 107 to the transferable rate information control request receiving unit 102 directly, as shown in FIG. 8A.

In the second method, as shown in FIG. 8B, the occurrence of a failure or congestion is transmitted to the connection management unit 109 by a connection management signal in the connection 108 connected to the ATM switch 101. This is a method in which it is transmitted to the transferable rate information control request receiving unit 102.

Note that these two types of methods can be used in parallel.

Here, when the first method is adopted, it is necessary to distinguish between failure and congestion, the location where the failure or congestion occurs, the amount of traffic or the number of connections that need to be bypassed due to the failure or congestion, Link, VP or VC ID
(IDentification), the transfer rate after control, and the like are information that can be included in the transferable rate information control request.

As an example of a signal for connection management when the second method is adopted, VP F4OAM
Cell or VC F5OAM cell. When the second method is adopted, the connection manager 109 notifies the transferable rate information control request receiver 102 of the distinction between the failure and the congestion, and the location of the occurrence of the failure or the congestion.

[0110]

As described above, according to the ATM switching system of the present invention, "the VC to be controlled," such as another place in a network (ATM network), another link connected to the ATM switching system, or a VP. In order to cope with a failure or congestion occurring at a place other than on a route, there is an effect that it becomes possible to control the transmitting terminal using the transfer rate management cell. This control appears to the transmitting terminal as equivalent to the normal (prior art) "transfer rate control". Therefore, without newly providing a special control mechanism to respond to failures and congestion in the transmitting terminal,
It is possible to perform control for dealing with a failure or congestion that has occurred in “a place other than the path of the VC to be controlled”.

Hereinafter, this effect will be described in more detail.

According to the first and second aspects of the present invention, the transferable rate information is generated based on the transferable rate information control request received from outside the local exchange, so that "the location other than on the route of the VC to be controlled" The transferable rate information based on the failure or the congestion that has occurred in (1) can be generated (it becomes possible to notify the transmitting side terminal of the transferable rate information), and the above-described effect is obtained.

Further, the above makes it possible to use the transfer capacity caused by the transmitting terminal reducing the transfer rate for bypassing a failure or congestion.

According to the first aspect of the present invention, when information including “notification of occurrence of failure or congestion” is received as a transferable rate information control request, “instruction to decrease transfer rate”
By generating the transferable rate information having the content as described above and notifying the transmission side terminal, there is an effect that it is possible to control the transfer rate finely in accordance with the degree of failure or congestion.

According to the second aspect of the present invention, when information including "notification of occurrence of failure or congestion" is received as a transferable rate information control request, transferable information including "notification of occurrence of failure or congestion" is available. By generating rate information and notifying the transmitting terminal and leaving specific measures to be taken in the event of a failure or congestion to the transmitting terminal, processing within the ATM exchange is simplified (simplified). There is an effect that the load can be distributed from the exchange to the transmitting terminal.

According to the third aspect of the present invention, the processing in the ATM exchange and the processing in the transmitting terminal are generated by generating transferable rate information containing "instruction to reduce the transfer rate to the minimum guaranteed value". Is simplified.

According to the fourth aspect of the present invention, the influence of the failure or congestion is estimated by measuring the distance between the location where the failure or congestion occurs and the local exchange by the number of hops, and the amount of decrease in the transfer rate or the failure or congestion is accordingly determined. By determining whether or not to include the occurrence notification in the transferable rate information, it is possible to prevent the effect of a failure or congestion occurring at a remote place from affecting the entire network.

According to the fifth aspect of the present invention, the severity of a failure or congestion is measured based on the amount of traffic that needs to bypass the failure or congestion to estimate the approximate effect of the failure or congestion, and the transfer rate is reduced accordingly. By deciding whether or not to include the notification of occurrence of volume, failure, or congestion in the transferable rate information, it is possible to appropriately separate the handling of minor failures and congestion from the handling of large-scale failures and congestion. There is an effect that it becomes possible.

According to the sixth aspect of the present invention, the severity of a failure or congestion is measured by the number of connections that need to bypass the failure or congestion to estimate an outline of the effect of the failure or congestion, and the transfer rate is reduced accordingly. By deciding whether or not to include the notification of occurrence of volume, failure, or congestion in the transferable rate information, it is possible to appropriately separate the handling of minor failures and congestion from the handling of large-scale failures and congestion. There is an effect that it becomes possible.

[0120]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first to a fifth embodiment of an ATM exchange according to the present invention.

FIG. 2 is a diagram for explaining a concept of a method of controlling a transfer rate of a VC of an ABR using an RM cell using a conventional ATM exchange.

FIG. 3 is a flowchart showing a processing flow of a first embodiment of the ATM exchange of the present invention.

FIG. 4 is a flowchart showing a processing flow of a second embodiment of the ATM exchange of the present invention.

FIG. 5 is a flowchart showing a processing flow of a third embodiment of the ATM exchange of the present invention.

FIG. 6 is a flowchart showing a processing flow of a fourth embodiment of the ATM exchange according to the present invention.

FIG. 7 is a flowchart showing a processing flow of a fifth embodiment of the ATM exchange according to the present invention.

8 is a diagram showing a specific method of giving a transferable rate information control request to a transferable rate information control request receiving unit in FIG. 1;

[Explanation of symbols]

Reference Signs List 101 ATM switch 102 Transferable rate information control request receiving unit 103 Fault / congestion monitoring unit in switch 104 VC control unit 105 Cell control unit 106 VC connection 107 Control channel 108 Connection 109 Connection management unit 110 Network management system 111 Other exchange 201 Transfer Rate management cell receiving step 202 Received content transmitting step 203 Monitoring / failure monitoring step in own switch 204 Transferable rate information control request receiving step 205 Information reading step 206 Failure / congestion occurrence notification presence / absence determination step 207 Minimum guarantee value writing step 208 Transferable rate calculation and writing step 209 Transfer rate management cell VC insertion step 210 Failure / congestion occurrence location Self-switch hop number determination step 211 Failure / Congestion occurrence notification writing step 212 Transfer rate reduction instruction writing step 213 Failure / congestion affected traffic volume determination step 214 Failure / congestion affected connection number determination step 215 Transfer rate specification transferable rate information control request existence determination step 216 Transfer rate calculation Step 217 Calculated transfer rate / requested transfer rate comparison judgment step 218 Calculated transfer rate writing step 219 Requested transfer rate writing step

Claims (6)

(57) [Claims] An ATM switch having a function of writing transferable rate information to a transfer rate management cell and inserting the transfer rate management cell into a VC to be controlled to notify the transmission terminal of the transferable rate information. A transferable rate information control request receiving unit for receiving, as a transferable rate information control request, information including either a "notification of occurrence of a failure or congestion" and a "desired value of a transfer rate to be changed" from outside the local exchange; A failure / congestion monitoring unit for monitoring whether there is an “event that causes a change in the transfer rate of the controlled VC” in the local exchange; and a transferable rate information control request receiving unit for the local exchange. When a transferable rate information control request is received from outside, the transferable rate information control request and the monitoring by the fault / congestion monitoring unit in the exchange are performed. It generates a transferable rate information VC of the control object on the basis of, in generating either self exchange outside
If the transferable rate information control request is
If the information includes a notification of occurrence,
Or congestion occurs outside the route of the VC to be controlled.
Even if the “failure or congestion severity” or “failure
Or the distance between the location of the congestion and the local exchange.
Transfer rate information that contains "instruction to reduce transmission rate"
A VC control unit that generates a report and writes it to a transfer rate management cell; reads a transfer rate management cell flowing in a VC to be controlled and transmits it to the VC control unit; and a transfer generated by the VC control unit. An ATM exchange having a cell control unit for inserting a transfer rate management cell in which possible rate information is written into a VC to be controlled. (2)Transferable rate to transfer rate management cell
Writes information and manages its transfer rate to the VC to be controlled
Transferable rate information by inserting
ATM switch with the function of notifying the receiving terminal
hand,  From outside your own exchange"Notification of failure or congestion" and
Information that includes any of the "desired transfer rate to be changed"
InformationTransfer possible received as transferable rate information control request
Rate information control request receiving unit,"The transfer rate of the VC to be controlled is changed in the local switch.
Events that cause you to be In the exchange to monitor for
/ Congestion monitoring unit, Said The transferable rate information control request receiving unitOutside your own exchange
When a transferable rate information control request is received from
Transferable rate information control request and fault / congestion in the exchange
VCs to be controlled can be transferred based on monitoring by the monitoring unit
Rate information is generated.
If the transferable rate information control request is
If the information contains "notification of occurrence"The "failure
Or congestion occurs outside the route of the VC to be controlled.
Even if the “failure or congestion severity” or “failure
Or the distance between the location of the congestion and the local exchange.
Transferable rails containing "Notification of the occurrence of harm or congestion"
VC that generates transfer information and writes it to the transfer rate management cell
Control unit and, Reads the transfer rate management cell flowing to the VC to be controlled.
And transmits it to the VC control unit.
Transfer rate in which the generated transferable rate information is written.
Control unit for inserting a cell for cell management into a VC to be controlled
When Characterized by havingToATM switch. 3. The transferable rate information generated by the VC control section and having the content of “instruction to decrease the transfer rate” is the transferable rate information having the content of “instruction to reduce the transfer rate to the minimum guaranteed value”. Claims characterized by the following
The ATM switch according to 1 . 4. A VC control unit for measuring a “distance between a place where a failure or congestion occurs and a local exchange” by using a “hop count between the place where a failure or congestion occurs and a local switch”. The ATM exchange according to claim 1 or 2 . 5. The ATM of claim 1 or claim 2, wherein "a disorder or congestion severity" a characterized by having a VC control unit which measures the "traffic that needs to bypass the failure or congestion" switch. 6. The ATM of claim 1 or claim 2, wherein "a disorder or congestion severity" a characterized by having a VC control unit for measuring the "number of connections that need to bypass the failure or congestion" switch.