JPH0955743A - Method for setting composition timer value - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set the composition timer value of a convergence sublayer common part protocol data unit of the AAL type 3/4/5 of an ATM communication network. SOLUTION: A message for measurement is sent out from a measurement point through a message decomposition part 50 and a transmitting FIFO 110 and the value of a composition timer counter 120 is inputted to a transmission descriptor 10. The message for measurement is sent back at a measured point. The sent-back message for measurement is received at the measurement point and inputted to a message composition part 100 through a receiving FIFO 70 and an UU detection part 80 and the value of the composition timer counter 120 is inputted to a reception descriptor 20. The time-stamp value of the transmission descriptor 10 and the time-stamp value of the reception descriptor 20 are inputted to a subtracter 130, which calculates their difference S130. This difference S130 corresponds to the transmission time required for the message for measurement to go and, return, and is used as the composition timer value of CPCS-PDU.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM adaptation layer (ATM Adaptati) of an Asynchronous Transfer Mode (hereinafter referred to as ATM) communication network.
on Layer (hereinafter referred to as AAL), especially AAL
Type 3/4/5 Convergence / Sublayer Protocol Data Unit (Common Part Conv)
ergence Sublayer-Protocol Data Unit, CPC
S-PDU) and a method of setting an assembly timer value.

[0002]

2. Description of the Related Art In recent years, broadband ISDN (Integrated Servo)
vice Digital Network)
ATM technology that realizes
ATM networks are being constructed. In the ATM network, information is divided into fixed-length blocks called cells, and the destination information in the header of each cell is added to the cells for transfer within the ATM network. ATM
Communication is a communication method that does not depend on communication media, and handles various signals such as voice, data, and images in a cell form. For this reason, it is necessary to have a part that matches the upper layer and the ATM layer that does not depend on various services, and this part is the AAL. AAL has several types depending on the higher level application (eg AAL type 1, AAL type 2, AAL type 3).
/ 4, AAL type 5) is present. AAL type 1
(Hereinafter, referred to as AAL1) is an adaptation layer protocol that is supposed to provide fixed-rate services such as voice communication and existing leased line services.
AAL type 2 (hereinafter referred to as AAL2) is an adaptation layer protocol that is supposed to provide a variable rate type service such as a video packet and an audio packet which are variable rate coded and which has timing dependency of a transmission / reception end. AAL type 3/4 (hereinafter referred to as AAL3 / 4) is an adaptation layer protocol that is supposed to provide services such as connection-type data communication and connectionless-type data communication. Also, AAL
Type 5 (hereinafter referred to as AAL5) is an adaptation layer protocol proposed mainly for data communication, aiming for more efficient transfer. Generally, C in AAL3 / 4/5 in the conventional ATM communication network
The setting of the PCS-PDU assembly timer value is a setting from an external device or an upper layer, and the user sets an experiential value or a desktop calculated value as the setting value.

[0003]

However, the conventional setting of the assembly timer value of AAL3 / 4/5 has the following problems. (1) Since there is no clear standard for setting the assembly timer value, the user sets an arbitrary value. Therefore, in some cases, an assembly timeout (that is, cancellation of CPCS-PDU assembly) may be set to occur frequently. (2) Virtual Path (Virtual Path)
/ Virtual channel (hereinafter referred to as VC) is an SVC (Switched V) that switches the connected party.
irtual Channel) service, a different value is used each time the connection is set. Therefore, in the case of a large-scale network, the transmission time may change greatly for each connection setting, and the assembly timer value may exceed the user's expectation.

[0004]

In order to solve the above-mentioned problems, a first aspect of the present invention is to perform data processing of an ATM communication network.
In the method of setting the CPCS-PDU assembly timer value in the AL, the following processing is performed.
That is, in order to measure the data transmission time on the data transmission path, a code corresponding to the transmission of the measurement message is set in a predetermined field (hereinafter referred to as the UU field) of the convergence / sublayer common part of the CPCS-PDU of AAL. A transmission process of transmitting the measurement message from the measurement point to the measured point and a transmission time stamp process of recording the time in the transmission process are performed. Further, in the return processing for detecting the measurement message at the measured point, converting the code corresponding to the transmission of the measurement message into a code corresponding to the return and returning the measurement message, and the return processing. In the receiving process of receiving the returned measurement message at the measuring point, the receiving time stamp process of recording the time in the receiving process, the time recorded in the receiving time stamp process and the transmitting time stamp process. An assembly timer value calculation process for calculating the round-trip transmission time of the measurement message from the difference from the recorded time and using it as the assembly timer value is performed. Then, each processing described above is performed every time the measurement point or the measurement point is changed.

According to the first aspect of the present invention, since the method of setting the assembly timer value is configured as described above, the measuring message is transmitted from the measuring point to the measured point in the transmitting process. At this time, a code corresponding to the transmission of the measurement message is set in the UAL field of AAL5 in order to measure the data transmission time on the data transmission path. In the transmission time stamp process, the time in the transmission process is recorded. Further, in the loopback process, the measurement message is detected at the measured point, and the measurement message is looped back. At this time, the code corresponding to the transmission of the measurement message is converted into the code corresponding to the return. In the reception process, the measurement message returned in the return process is received at the measurement point. In the reception time stamp process, the time in the reception process is recorded. In the assembly timer value calculation process, the difference between the time recorded in the reception time stamp process and the time recorded in the transmission time stamp process is calculated, and this difference becomes the round-trip transmission time of the measurement message. This transmission time is used as the assembly timer value. Each processing described above is performed every time the measurement point or the measured point is changed. Therefore, even if the user changes, the correct assembly timer value is set by the same method. Further, the optimum assembly timer set value is set even for channels having different transmission times.

In the second invention, in the method of setting the assembly timer value of the convergence / sublayer common part protocol data unit of the first invention, the transmission time between the end systems of the communication connection is measured, and the assembly is performed from the transmission time. The timer value is calculated. Third
In the transmission time stamp processing of the first invention, an assembly timer counter value used for monitoring the assembly time of the CPCS-PDU is recorded, and the assembly is performed in the reception time stamp processing of the first invention. The timer counter value is recorded. According to the second and third aspects, the assembly timer counter value is recorded in the transmission time stamp process, and further, the assembly timer counter value is recorded in the reception time stamp process. Therefore, the unit of the measurement value of the transmission time (that is, the count value of the assembly timer counter) is used as the assembly timer value without conversion. Therefore,
The above problems can be solved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is an AA of an embodiment of the present invention.
It is a schematic block diagram of an assembly timer value setting device for carrying out a method of setting an assembly timer value of a CPCS-PDU in L5. In this assembly timer value automatic setting device, a CPU (not shown) is connected to a transmission descriptor 10, a reception descriptor 20, a transmission buffer 30, and a reception buffer 40 via a CPU bus B. Descriptors and buffers exist for channels required for data processing. The transmission descriptor 10 is composed of a memory and is connected to the message decomposition unit 50.
The transmission buffer 30 is also composed of a memory and is connected to the message decomposing unit 50. The message decomposing unit 50 is connected to the first input terminal of the selector 60. The reception FIFO (First In First Out) 70 is connected to a UU (user / user) detector 80. UU detector 80
The first output terminal of the UU detector 80 is the UU converter 90.
Of the UU detector 80, and the second output terminal of the UU detector 80 is connected to the message assembler 100. UU
The output side of the conversion unit 90 is connected to the second input terminal of the selector 60. The output terminal of the selector 60 is the transmission FI.
It is connected to the FO 110. Assembly timer counter 1
20 is connected to the message assembling unit 100, and is connected to the message disassembling unit 50 on the other hand. The message assembly unit 100 is further connected to the reception descriptor 20 and the reception buffer 40. The input terminals of the subtractor 130 are connected to the transmission descriptor 10 and the reception descriptor 20, respectively, and the output side of the subtractor 130 is connected to the message assembly unit 100.

FIG. 2 is a schematic block diagram of the message disassembling unit 50 shown in FIG. This message decomposition unit 5
0 has a transmission descriptor read unit 51.
The transmission descriptor read unit 51 includes a message length that is information for transmitting a message from the transmission descriptor 10 and a logical channel identifier (that is, VPI (Virt
ual path identifier) and VCI (Virtual Channel)
Identifier)), and notifies the message length to the transmission buffer read control unit 52 and the channel identifier to the cell header addition unit 53. The transmission buffer read control unit 52 has a function of outputting a request signal S52 to the transmission buffer read unit 54 so that the message length data is read from the transmission buffer 30 at a fixed timing for each cell payload length (48 bytes). ing. The transmission buffer read unit 54 has a function of reading the message S30 from the transmission buffer 30 based on the request signal S52 from the transmission buffer read control unit 52.
The data read by the transmission buffer read unit 54 is attached with an ATM header by the cell header addition unit 53, and is sent to the transmission FIFO 110 via the selector 60. Further, the message disassembling unit 50 receives the counter value (that is, the time stamp value) S120 from the assembling timer counter 120, and sends the transmission descriptor 10
The transmission descriptor write unit 5 that writes the value above
5 is provided.

FIG. 3 shows a message assembling unit 10 shown in FIG.
It is a schematic block diagram of 0. The message assembling unit 100 has a cell header removing unit 101.
The cell header removal unit 101 has a function of inputting a received cell from the UU detection unit 80 and removing a cell header.
At this time, the channel identifier (VPI / VCI) is written in the reception descriptor 20 via the reception descriptor write unit 102. UU determination unit 1
03 has a function of determining whether or not the value of the UU field of the data from which the cell header has been removed by the cell header removal unit 101 is FE, and discarding it if FE. The reception descriptor read unit 104 has a function of reading address information for writing to the reception buffer 40 when there is data that has passed through the UU determination unit 103 and notifying the reception buffer write control unit 105 of the address information. There is. The reception buffer write control unit 105 has a function of notifying the transmission buffer write unit 106 of write timing and address information. The transmission buffer write unit 106 has a function of writing the data S103 received from the UU determination unit 103 in the reception buffer 40. The assembly timeout value obtained as the output signal S130 of the subtractor 130 is stored in the assembly timeout determination unit 107. The assembly timeout determination unit 107 compares the difference between the output signal S120 of the assembly timer counter 120 and the time of the last arrived cell with the assembly timer value. If the difference is larger than the assembly timer value, the assembly timeout (that is, CPCS-PDU). As a result of (assembly stop), the result information is written to the reception descriptor 20 via the reception descriptor writing unit 102.

FIG. 4 is a diagram showing a transmission / reception sequence of a measurement message. The operation of FIG. 1 will be described with reference to FIG. First, the CPU (not shown) initializes the transmission descriptor 10, the reception descriptor 20, and the transmission buffer 30. A transmission time stamp valid bit (that is, a bit for selecting whether or not to perform transmission) is set to an ON state in the transmission descriptor 10, and a reception time stamp valid bit (that is, whether to perform reception or not) in the reception descriptor 20. Select bit) is set to ON.

Transmission Process When the transmission descriptor 10 is set, the message disassembling unit 50 provides information necessary for transmission to the transmission descriptor 1.
If the transmission time stamp valid bit is in the ON state, the measurement message for measuring the data transmission time is loaded from 0 and the message decomposition unit 50 and the transmission F
The data is transmitted via the IFO 110 sequentially. At this time, in order to distinguish the measurement message from the user message, the AA
A code (for example, FF) corresponding to the transmission of the measurement message is set in the UU field of L5, and the measurement message (that is, the transmission message s) is transmitted from the measurement point a to the measured point b via the gateway g.

FIG. 5 is a diagram showing the format of the measurement message. The measurement message is 1 cell length AA
The L5 message is transmitted to the measured point designated by the channel identifier set in the transmission descriptor 10. Transmission time stamp process The time in the transmission process is recorded. In the present embodiment, for example, the value of the assembly timer counter 120 is input to the transmission descriptor 10 via the message decomposition unit 50. The measurement message transmitted by the loopback processing is processed by the UU detection unit 80 in the assembly timer value automatic setting device having the same configuration as that shown in FIG. 1 installed at the measured point where the AAL5 is terminated. User information message or measurement message). Then, the UU converter 9
0 converts the value of the UU field from the FF to a code (for example, FE) corresponding to the loopback, and outputs the loopback via the selector 60 and the transmission FIFO in order. Reception Processing The measurement message sent back by the return processing is received at the measurement point and received by the reception FIFO 7.
0 and the UU detection unit 80 are sequentially passed and input to the message assembly unit 100.

The reception time stamp processing measurement message is discarded and the time in the reception processing is recorded. In the present embodiment, for example, the value of the assembly timer counter 120 at this time is the message assembly unit 100.
Is input to the reception descriptor 20 via. Assembly Timer Value Calculation Processing The time stamp value of the transmission descriptor 10 and the time stamp value of the reception descriptor 20 are input to the subtractor 130, and the difference S130 between the reception time stamp value and the transmission time stamp value is calculated. This difference S130 corresponds to the round trip transmission time of the measurement message, and this time is C
It is input to the message assembler 100 because it is used as a PCS-PDU assembly timer value. The assembling timeout is monitored by comparing the assembling timer set value and the assembling timer counter value. That is, the assembly time-out determination unit 107 compares the difference between the output signal S120 of the assembly timer counter 120 and the time of the last-arriving cell with the assembly timer value. If the difference is greater than the assembly timer value, the assembly time-out (that is, stop ), The result information is written to the reception descriptor 20 via the reception descriptor writing unit 102. The above measurement of the transmission time and the setting of the assembly timer are performed every time the measurement point or the measured point is changed.

As described above, this embodiment has the following advantages. (1) Since the actual transmission time of the measurement message is measured to determine the assembly timer value, an accurate assembly timer value is set in the same manner for all users. (2) Since the measurement of the transmission time of the measurement message and the setting of the assembly timer are performed every time the measurement point or the measured point is changed, the optimum assembly timer setting value is set even for channels with different transmission times. Is set without user involvement. (3) Since the assembly timer counter is used for the transmission time stamp and the reception time stamp, it is used as the assembly timer value without converting the unit of the count value of the assembly timer counter. (4) Since the UU field is used to identify the measurement message, there is no need to be aware of a special channel or protocol for measurement, and since it can be identified by collating 8-bit data, network operation and maintenance are performed. OAM
(Operation And Maintenance) It can be configured by a circuit simpler than identification by payload such as cell. The present invention is not limited to the above embodiment, and various modifications can be made. For example, there are the following modifications.

(A) In the embodiment, the example in which the method for setting the AAL assembling timer is applied has been described. However, the output signal S130 of the subtractor 130 is input to the CPU, and the CPU
If the output signal S130 is read at
It is also applicable to the transmission time measuring method for M communication. (B) In the embodiment, the value of the UU field of the measurement message is set to FF for transmission and FE for return, but other values may be used as long as the transmitted message and the returned message can be identified. . (C) C without identifying and discarding the measurement message
The PU can also add / check the UU field. (D) In the embodiment, only the setting of the AAL type 5 assembly timer value is described, but the assembly timer value obtained in the measurement message is the AAL3 and AA having the assembly timer.
It can also be applied to L4.

[0016]

As described in detail above, according to the first invention, the following effects are obtained. (1) Since the assembly timer value is determined by measuring the actual transmission time of the measurement message, an accurate assembly timer value can be set for any user in the same manner. (2) Since the measurement of the transmission time of the measurement message and the setting of the assembly timer are performed every time the measurement point or the measured point is changed, the optimum assembly timer setting value is set even for channels with different transmission times. Can be set without user involvement. (3) Since the UAL field of AAL5 is used to identify the measurement message, in the case of an end system that communicates with AAL5, it is not necessary to be aware of a special channel or protocol for measuring the data transmission time. Since it can be identified by collation, it can be configured with a simpler circuit than identification by a payload such as an OAM cell. According to the second and third aspects, since the assembly timer counter is used for the transmission time stamp and the reception time stamp, the unit of the measured value of the data transmission time (that is, the count value of the assembly timer counter) is converted. Can be used as an assembly timer value without.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an assembly timer value setting device showing an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a message decomposing unit in FIG.

3 is a schematic block diagram of a message assembling unit in FIG. 1. FIG.

FIG. 4 is a diagram showing a transmission / reception sequence of a measurement message.

FIG. 5 is a diagram showing a format of a measurement message.

[Explanation of symbols]

a Measurement point b Measured point r Received message s Transmitted message

Claims (3)

[Claims] 1. A method of setting an assembly timer value of a convergence / sublayer common protocol data unit in an asynchronous transfer mode system adaptation layer for performing data processing of an asynchronous transfer mode system communication network, comprising measuring a data transmission time in a data transmission line. To do this Asynchronous transfer mode method Convergence / sublayer common part of the adaptation layer A code corresponding to the transmission of the measurement message is set in a predetermined field of the convergence / sublayer common part in the protocol data unit, and the measurement message is sent from the measurement point. A transmission process of transmitting to the measurement point, a transmission time stamp process of recording the time in the transmission process, detecting the measurement message at the measurement point, and returning a code corresponding to the transmission of the measurement message Return processing for converting the measurement message into a code corresponding to, and returning the measurement message, reception processing for receiving the measurement message returned by the return processing at the measurement point, and reception for recording time in the reception processing From the time stamp process and the difference between the time recorded in the reception time stamp process and the time recorded in the transmission time stamp process, the round trip transmission time of the measurement message is calculated and used as the assembly timer value. A method of setting an assembly timer value of a convergence / sublayer common part protocol data unit in an adaptation layer in an asynchronous transfer mode method, characterized in that an assembly timer value calculation process is performed every time the measurement point or the measured point is changed. 2. A method of setting an assembly timer value of a convergence / sublayer common part protocol data unit according to claim 1, wherein a transmission time between end systems of a communication connection is actually measured, and the assembly timer value is calculated from the transmission time. A method for setting a timer value for assembling a protocol data unit in a common part of a convergence / sublayer in an adaptation layer in an asynchronous transfer mode method, characterized by: 3. In the transmission time stamp processing,
2. An assembly timer counter value used to monitor an assembly time of the convergence / sublayer common part protocol data unit is recorded, and the assembly timer counter value is recorded in the reception time stamp process. Alternatively, the method for setting the assembling timer value described in 2 above.