KR950009428B1 - The distributed queue dual bus communication system - Google Patents

Abstract

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Description

Traffic Load Measurement Method of Distributed Queue Dual Bus Communication System with Adaptive Cancel Node Function

1 is a structural diagram of a distributed queue dual bus communication system.

2 is a frame and slot configuration diagram.

3 is an operation diagram of an RQ count at an idle node.

4 is an operation diagram of an RQ and CD counter at a node in a countdown state.

5 is a configuration block diagram of an adaptive erasing node (AEN).

6 is a schematic flowchart of the present invention.

7 is a detailed flowchart of the present invention.

* Explanation of symbols for main parts of the drawings

1: Node 2: SESEM (Segment Erasing State Machine) state machine

3: Request Cancellation State Machine (RCSM) state machine

4: Load Monitoring State Machine (LMSM) state machine

5: Distributed Queue State Machine (DQSM) State Machine

The present invention provides a distributed queue double bus (DQDB) having an adaptive erasure node (hereinafter referred to as an AEN) function used to perform a multimedia transmission service such as data, voice, and video at a high transmission rate of 150 Mbps. Queue Dual Bus) The present invention relates to a method for measuring traffic load in a network in a communication system.

Distributed queue dual bus communication system is a communication system that imagined and standardized high-speed local network by American Association of Electrical and Electronic Engineers, and is used to provide high-speed multimedia transmission service. However, in the distributed queue dual bus communication system, each node in the network has an unfair access opportunity according to the position of the node when accessing the bus. This unfairness is even worse when the traffic load on the network is high.

The distributed queued dual bus communication system with AEN function showed very low overall access latency even with increasing traffic load and fairness according to the efficient distribution of increased bandwidth. In particular, the efficient use of bandwidth in the network increases the utilization of the bus, thereby improving the throughput, and the access delay time is hardly affected by the change in the full speed or transmission distance of the network, thereby effectively providing high-speed multimedia communication services. There is a viable advantage.

However, the effective operation of the distributed queue dual bus communication system having the AEN function operated according to the traffic load in the network is due to the measurement of the traffic load in the network.

Accordingly, an object of the present invention is to provide a method for measuring traffic load in a network having accuracy simplicity and efficiency.

In order to achieve the above object, the present invention includes two unidirectional buses (forward bus A and reverse bus B) and a head node and a plurality of nodes connected along the unidirectional buses (bus A and bus B). The node is a REQ counter indicating a distributed queue state machine (DQSM) state machine with a request counter (hereinafter referred to as RQ counter) and a countdown counter (hereinafter referred to as CD counter) to have an adaptive erasure node function. Measures the traffic load in the network and the Request Cancellation Stat Machine (RCSM) state machine that performs the state supersedence and the request cancellation function of the SSM (REQ Queue Machine) state machine and RQM In a method of operating a distributed queued dual bus communication system in which a Load Monitoring State Machine (LMSM) state machine is provided, each node has a slot. The first step of determining the slot time period for measuring the traffic load in the network each time access, and after the first step, the number of scheduled segments to be transmitted from its own node and the lower nodes, the reference load threshold (ATH) The second step of measuring the time average value of the traffic load by increasing the value of the traffic monitor counter (LMC) in the LMSM state machine according to whether the variable is exceeded, and after performing the second step, the monitor counter (LMC) value is the reference Performing a purge function in the SESM state machine with a third step of changing and ending the slot counter (ESC) value and the monitor counter (LMC) value in the LMSM state machine in accordance with whether or not the load sustain value (HTH) variable persists. It features.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

1 is a structural diagram of a distributed queue transfer bus (DQDB) communication system to which the present invention is applied, and a head node connected along two unidirectional buses (bus A and bus B) and the unidirectional buses (bus A and bus B). (1a or 1n) and several nodes (1), logically having a bus structure, but physically in the form of a ring. Each bus has a head node (1a for bus A, 1n for bus B) and an end node (1n for bus A and 1a for bus B).

Both buses A and B allow bidirectional communication between any two nodes in the network. Therefore, it is necessary to know which bus to use to communicate with the node 1 to which the node 1 to communicate with. If both buses are used for communication at the same time, the communication capacity of the network is twice that of using a single bus.

The operation of both buses is independent in transferring data, and data on each bus is loaded into a slot of fixed length, which is generated by the head node 1a or 1n of each bus. In other words, node 1 writes data to the slot by a bus access procedure, and this flow ends at end node 1n or 1a. Here, the bus A used to transmit data is called a forward bus, the bus B used to request a request is called a reverse bus, and the nodes 1 are configured as adaptive erasing nodes having an adaptive erasing function. do.

2 is a frame and slot configuration diagram of the distributed queue transport bus communication system of FIG. 1, wherein one frame includes a plurality of slots, a frame header, and a spare area, to provide non-isochronous services. The fixed information length of the queued-arbitrated (QA) slot used is called a QA segment. Each slot has a size of 53 octets, and consists of an access control field (hereinafter referred to as ACF) and one segment that forms slot information. The segment is composed of a segment header and a segment payload. .

Within the slot's ACF, there are control bits such as busy bits and request bits. In this case, the busy bit indicates whether a slot is used, and the request bit indicates that there is data waiting in the queue for transmission, and three bits are used as three priorities are provided.

The PSR (Previous Segment Received) bit is used for slot reuse. When set to "1" in a slot, the segment of the previously arrived slot is copied and passed from the upper node on the same bus. In this case, the previously arrived slots can be reused. The slot type bit indicates whether the data carried in the slot is a QA segment, and the reserved area is a reserved bit stored for later use. Each node 1 operates a counter for each bus, and uses them to determine when data queued in its own node can transmit.

3 is an operation explanatory diagram of a request (hereinafter referred to as RQ) counter in an idle state of a distributed queue dual bus communication system, where an idle node indicates a node that does not have data to transmit. Say.

When a node (1) has data to send to the forward bus, it makes the request bit of the slot passing through the bidirectional bus '1', and when that slot passes through an idle node, its RQ The value of the counter is increased by one. When an empty slot passes through the forward bus, the value of the RQ counter is decreased by one, which is expected to be taken in advance that the empty slot will be used by a lower node after a while. When the value of the RQ counter is managed in this way, each node 1 can read the current value of the RQ counter to know how many segments are currently waiting in its lower node.

4 is an operation explanatory diagram of an RQ counter and a CountDown (hereinafter referred to as CD) counter in a node in a countdown state of a distributed queue dual bus communication system, where a countdown state node includes a QA segment to be transmitted. Refers to a node.

That is, in the node where the QA segment to be transmitted is generated, the current value of the RQ counter 2 is moved to the CD counter, the RQ counter value is cleared to '0', and the countdown state is entered. At this time, the CD counter value of this node is a value indicating whether the QA segment to be transmitted is a segment generated in time among the QA segments waiting in the queue of the lower node including the node. When the request bit passes through the reverse bus at the node entering the countdown state, the value of the RQ counter is increased by one. When an empty slot passes through the forward bus, the value of the CD counter is decreased by one. When the CD counter value becomes '0', the segment can be transmitted to the next empty slot of the forward bus. In this case, the value of the CD counter being '0' means that there is no longer a waiting segment generated before the segment transmitted by the lower node.

As can be seen from the description of FIG. 3 and FIG. 4, in order to transmit a QA segment in a node, it is necessary to wait until there is no QA segment created and waiting before the segment to be transmitted in its own node. Also, if the CD counter value is '0' even if the request bit is not written on the reverse bus, access is possible because the operation of writing the request bit and transmitting the QA segment are independent. In this way, in accessing the forward bus, the network of the distributed queued dual bus communication system constitutes a first-in first-out (FIFO) queue, so that slots are wasted in the network if there is always a segment to transmit. It doesn't work.

On the other hand, the RQ counter and CD counter described in FIGS. 3 and 4 are logical components of the DQSM state machine 5 which will be described later in FIG.

5 is a configuration diagram of the adaptive erasing node 1.

As shown in the figure, each adaptive erasing node 1 includes a first-in first-out (FIFO) queue 7 which stores a QA segment generated for each node to transmit to a destination node, and the FIFO queue ( 7) to perform the functions of the RQ counter and CD counter described in FIGS. 3 and 4, i.e. when in idle state and having at least one segment in the FIFO queue 7, Distributed Queue State Machine (DQSM) state machine that counts down to send a segment through A and outputs a segment when bus A passes an empty slot (when the busy bit is '0'). 5) is connected to the FIFO queue 7 and receives request information at the same time when the DQSM state machine 5 receives the QA segment from the FIFO queue 7, and receives the reverse bus of the DQSM state machine 5 Empty slot (request bit) in In-B bus Whenever 0 passes, it controls to send a request and receives information about whether a play slot is generated and when a play slot is generated in its node, it wants to send a request at the same time. Is connected to receive information from the DQSM state machine 5 and the FIFQ queue 7 to perform a request bit transmission control function and to output related information. LMSM (Load Monitoring State Machine) state machine (4) for measuring the time average value of the traffic load to its own node and the lower node in the network and outputs the result, and a playback slot input to the RQM state machine (6) It provides information on whether or not to generate and receives information on whether or not to perform a segment erase function from the LMSM state machine (4) and also request bit information from the RQM state machine (6), Segman When performing the erase function, buffer the segment of each slot passing through the forward bus, and if the bit is set to '1' according to the PSR bit of the frame, erase the previously arrived and buffered segment, and the result is the RQM state machine. (6) a segment cancellation state machine (SESM) state machine (2) performing a function of informing, and receiving segment erasing-related information from the SESM state machine (2) and receiving the DQSM state machine (5) and the SESM state machine Request Cancellation State Machine (RCSM) that receives request cancellation related information from (2), cancels a request arriving from a lower node side through a reverse bus, and notifies the result to the SESM state machine (2). ) A state machine 3.

On the other hand, the DQSM state machine, RQM state machine, SESM state machine, RCSM state machine, LMSM state machine is composed of a memory holding, a buffer element, a counter and various logic to perform the function of storing, processing and sending messages.

The effective implementation of the adaptive method that adapts to the traffic load, such as the distributed queue dual bus communication system with AEN function, is due to the accuracy of the traffic load measurement method in the network and directly affects the performance improvement. According to this importance, the measurement of traffic load status in the network in the distributed queue double bus communication system with AEN function is based on the basic characteristics of the distributed queue double bus communication system and the functional characteristics of the segment erasing method. Is performed by.

First, the bandwidth is evenly distributed for each node location.

Second, the segment erase function is variably performed according to the traffic load.

Third, the segment erasing method is applied to the mode nodes in the network.

Fourth, the segment erasing function is temporarily performed only when the traffic load is high.

Fifth, slots reproduced by the segment erase function are used by their own nodes and subnodes.

Sixth, the measurement of the traffic load at each node is performed by monitoring the size and duration of the number of pending transmission segments for its own node and lower nodes in slot time units.

Seventh, the measurement of each node's own intended segment of transmission uses the length of its FIFO queue 7.

Eighth, the measurement of the segment to be transmitted to the lower nodes based on each node uses its own RQ counter value and CD counter value. According to the above eight basic principles, each node measures the traffic load in the network.

6 is a schematic flowchart of an intra-network traffic load measurement method for a distributed queue double bus communication system network having an adaptive erasing node.

In order to measure the traffic load in the network, first, in the traffic load measurement period determination step 8, each node accesses each slot, and determines a slot time period for measuring the traffic load in the network.

Subsequently, in the step (9) of measuring the excess level of the host traffic load, the number of segments to be transmitted from the own node and the lower nodes exceed the reference load threshold (ATH: Active THreshod for AEN) variable. Accordingly, the time average value of the traffic load is measured by reducing the value of the traffic monitoring counter (hereinafter referred to as LMC) in the LMSM state machine.

Finally, in the duration measurement step 10 of the reference traffic load, the LMC value in the LMSM state machine lasts for a time corresponding to a reference load sustain value (HTH: Holding Threshold of traffic load for AEN) variable. The Erasable Slot Counter (ESC) value in the SESM state machine and the LMC value in the LMSM state machine are changed depending on whether or not.

The above-described method for measuring the traffic load in a network is characterized in that the traffic load on its own nodes and lower nodes is measured in terms of a temporal average value.

Here, LMC is a counter of the average measured value with the slot time exceeding the ATH value, ESC is the number of slots to be played counter, ATH is a reference load threshold variable used to determine whether to perform the segment erase function , HTH represents a reference load duration variable used to measure the duration of traffic load exceeding ATH.

7 is a detailed flowchart illustrating a traffic load measuring method in a distributed queue dual bus communication system network having an adaptive erasing node according to the present invention.

When the traffic load in the network starts to be measured, first, it is in the standby state (11) and then, as a slot time measurement process, determines whether the QA (Queued-Arbitratad) slot for the slot passing through the bus is determined to determine the traffic load measurement period ( 12). If it turns out to be a QA slot, the monitor used to measure the traffic load adds both its RQ counter value and CD counter value in its current state to the length of the FIFO queue in its node (13), and monitors Check that the sum exceeds the value of the ATH variable (14).

However, if the QA slot does not arrive in step 12 of checking whether the QA slot is received, step 12 of checking whether the QA slot is performed while continuing to wait (11).

If it is determined that the sum of the above monitors exceeds the ATH value in the check step 14, the LMC counter value is increased by one (15). Otherwise, the LMC counter value is not lower than '0'. Decrease by one (16).

Then it is checked whether the LMC counter value is maintained by the value of the HTH variable (17). If it maintains as much as HTH variable value, it adds LMC counter value to current ESC counter value and clears LMC counter value to '0' (18) and returns to standby state (11). Return to state 11 and continue with the subsequent process.

As a result of measuring the traffic code in the above manner (9), the LMC counter value lasting as much as the HTH variable value means that the traffic load state in the network was maintained for a reference duration exceeding the reference load value. From this point on, node 1 performs segment erasing in addition to the basic node function only for a certain time until a play slot corresponding to the ESC counter value is generated, and the PSR of the slot that arrives while segment erasing is performed. If the bit is set, it can be seen that the segment arrived earlier creates a slot that can be erased and reused before being transmitted.

Therefore, in the network traffic load measuring method of the distributed queued dual bus communication system having the AEN function according to the present invention, the direct traffic for its own node and the lower nodes that directly use the playback slot generated by the segment erase function Since load measurement is performed, there is an advantage that accuracy, simplicity and efficiency of traffic load measurement can be obtained.

Claims (4)

Two unidirectional buses (forward bus A, reverse bus B), a head node 1a or 1n and several nodes 1 connected along the unidirectional buses (bus A, bus B), the nodes (1) is a distributed queue state machine (DQSM) state machine (5) having a request counter (hereinafter referred to as RQ counter) and a countdown counter (hereinafter referred to as CD counter) to have an applied erase node function and a request generation. REQ Queue Machine (RQM) state machine (6) having a REQ counter indicating the number, Segment Erasing State Machine (SESM) state machine (2) performing segment erasing function, and Request Canellation Stat (RCSM) performing a request cancel function. In a method of operating a distributed queue dual bus communication system having a state machine (3) and a load monitoring state machine (LMSM) state machine (4) for measuring traffic load in a network, each node accesses every slot. when doing The first step (8) of determining the slot time period for measuring the traffic load in the network, and after performing the first step, the number of segments scheduled to be transmitted from the own node and the lower nodes is the reference load threshold (ATH). A second step (9) of measuring a time average value of the traffic load by increasing or decreasing the value of the traffic monitor counter (LMC) in the LMSM state machine according to whether the parameter is exceeded, and after performing the second step (9), the monitor counter The third step of changing and terminating the erase function in the SESM state machine and the monitor counter (LMC) value in the LMSM state machine according to whether the (LMC) value is the reference load sustain value (HTH) variable. 10. A traffic load measuring method for a distributed queued dual bus communication system having an adaptive erasing node function, comprising: (10). The method of claim 1, wherein the first step (8) of determining a traffic load measurement period is a step (11, 12) of checking whether a slot is QA for a slot passing through the bus as a slot time measurement process. Traffic load measurement method of a distributed queued dual bus communication system having an adaptive erase node function, characterized in that performed by). 2. The second step (9) of claim 1, wherein the second step (9) of measuring the excess of the reference traffic load is such that the monitor used to measure the traffic load has its own RQ counter value and CD counter value and its node in its current state. Step 13 of obtaining the sum of the monitors by adding the lengths of the FIFO queues in the inside, and after confirming whether the sum of the monitors exceeds the reference load threshold value (ATH), the monitor sum is the reference load threshold value ( If it is determined to exceed ATH), increase the monitor counter (LMC) value by one in the LMSM state machine, and if it does not exceed, decrease the monitor counter (LMC) value so that it is not less than or equal to '0' (14). To 16) a traffic load measurement method for a distributed queued dual bus communication system having an adaptive erasing node function. The method of claim 1, wherein the third step of measuring the duration of the reference traffic load comprises: checking whether a monitor counter (LMC) value in the LMSM state machine is maintained by the reference load duration value (HTH) value. (17) and, if the reference load sustain value (HTH) is maintained after the step (17), the monitor counter (LMC) value in the LMSM state machine is set to the erasable slot counter (ESC) value in the current SESM state machine. And returning to the standby state after clearing the monitor counter (LMC) value to '0' (18), and returning to the standby state if it is kept smaller than the reference load sustain value (HTH). A traffic load measurement method for a distributed queue dual bus communication system having an adaptive cancellation node function.