JP2005151276A - Minimum band guarantee circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a minimum band guarantee circuit in packet ring transmission of a simple structure without complex control. <P>SOLUTION: A byte counter 1 is provided in a node device in a packet ring and calculates the number of bytes of an input packet from an external device connected with the node device. If the number of bytes for a specified minimum band exceeds, a priority class converter 3 changes priority information in the packet and classifies the bytes into a packet to be band-guaranteed (priority class A) and a packet not to be band-guaranteed (priority class B). An add buffer 6 accumulates only packets of the priority class A if the quantity of the packets input from the priority class converter exceeds a first threshold. A ring buffer 9 accumulates only the packets of the priority class A if the quantity of the packets destined to its own node device input from the packet ring exceeds a second threshold (larger than the first threshold). A reading control unit 7 reads the ring buffer prior to the add buffer and sends the packet to the packet ring. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a minimum bandwidth guarantee circuit, and more particularly to a minimum bandwidth guarantee circuit that performs priority control and bandwidth control in packet ring transmission. The minimum bandwidth guarantee refers to guaranteeing transmission of a set amount of data without being discarded even when the traffic in the packet ring is overloaded.

  Conventionally, this kind of minimum bandwidth guarantee is to manage the queue length of the means for multiplexing in the connection unit to which the arriving packet belongs in the multiplexing device, constantly monitor the queue length value, and use that value as a continuous function. And the packet length belonging to the connection whose queue length is equal to or smaller than the permitted queue length is permitted to be accepted (see, for example, Patent Document 1).

  Also, the time information is added to the input data, and the buffer that stores the data is read at a speed corresponding to the set bandwidth, and the time that the data read from the buffer stays in the buffer exceeds the specified time. Are output out of the guaranteed bandwidth, and when congestion occurs, the data is preferentially discarded to guarantee the minimum bandwidth when traffic is overloaded (for example, Patent Document 2). reference).

JP 2003-23456 (1st page-10th page, FIG. 1) Japanese Patent Laid-Open No. 2002-185501 (first page to eleventh, FIG. 1)

  However, in the above-described conventional technology, in packet ring transmission, with respect to data input from a plurality of devices connected in the same packet ring, the data for the minimum bandwidth set in each device is identified by each device. Furthermore, in order to preferentially conduct the data, the temporal control of input / output data and the amount of input data are always calculated, and the output is controlled according to the calculation result. There is a problem that it becomes complicated.

  An object of the present invention is to realize a minimum bandwidth guarantee in a packet ring transmission of a simple configuration, which can be realized without complicated control, and which is set up in all node devices connected in the packet ring, without complicated control. It is to provide a circuit.

  According to the first aspect of the present invention, there is provided a minimum bandwidth guarantee circuit that guarantees a transmission amount of a set amount of data without being discarded even if traffic in the packet ring is overloaded. A byte counter unit (1 in FIG. 2) that calculates the number of bytes of an input packet from an external device connected to the node device, and when the number of bytes for the set minimum bandwidth is exceeded, A priority class conversion unit (3 in FIG. 2) that changes priority information in a packet and classifies the packet into a bandwidth guaranteed (priority class A) and non-bandwidth guaranteed (priority class B) packet, and a packet input from the priority class conversion unit If the amount of the packet exceeds the first threshold, the add buffer unit (6 in FIG. 2) that stores only the packets of the priority class A, and the amount of packets addressed to the own node device input from the packet ring When the second threshold value (greater than the first threshold value) is exceeded, the ring buffer unit (9 in FIG. 2) that accumulates only priority class A packets, and the ring buffer unit is preferentially read from the add buffer unit and the packet is sent to the packet ring. And a read control unit (7 in FIG. 2).

  According to the second aspect of the present invention, a timer unit (2 in FIG. 2) that inputs a flag signal to the byte counter unit every unit time, and the number of bytes that allow passage of the minimum bandwidth guarantee within the time set by the timer unit, A comparison unit (4 in FIG. 2) that compares the number of bytes counted by the byte counter unit, and the priority class conversion unit determines whether or not the number of bytes for the minimum bandwidth has been exceeded based on the comparison result. To do.

  In the present invention, when outputting a packet from each node device, the number of bytes of the packet per unit time is counted, and the guaranteed bandwidth (priority class A) packet and the other bandwidth (priority class B) packet are counted. Divide and output. Then, according to the accumulation state of the packets in the add buffer, the writing of the priority class B packet to the add buffer and the ring buffer is controlled (packet discarding process), and the bandwidth guaranteed (priority class A) packet is preferentially output. I am doing so.

  In the read control of the add buffer and the ring buffer, the ring buffer that stores packets input from the packet ring is read preferentially over the add buffer that stores packets output from the own node device. In order to accumulate input packets from external devices connected to the node device, two threshold values are provided, and when the amount of packets exceeds the first threshold value (a value lower than the second threshold value), it is output from the own node device. Packets that are out of bandwidth guarantee (priority class B) are discarded (they are not written to the add buffer under the control of the writing side). If this state continues over time, only the bandwidth guaranteed packets (priority class A) are accumulated in the add buffer.

  Also, when the amount of packets output from the own node device exceeds the second threshold, packets outside the bandwidth guarantee (priority class B) set by other node devices that are input from within the packet ring are discarded (write) Is not written to the ring buffer under the control of the side).

  By performing such processing, the operation of the entire packet ring is as follows: when traffic is overloaded, priority class A of other node device> priority class A of own node device> priority class B of other node device> own node device Packets can be output with priority in the order of priority class B. This guarantees the minimum bandwidth when transmitting packets by packet ring.

  According to the present invention, input packets from an external device connected to a node device are classified into priority classes and stored in a buffer. The minimum bandwidth guarantee circuit that can be implemented without complicated control and has a simple configuration because it does not store the incoming packets or the lower priority class packets that are input from the packet ring in the buffer. Can be provided.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  A minimum bandwidth guarantee circuit according to the present invention is a minimum bandwidth guarantee circuit that guarantees a transmission amount of a set data amount without being discarded even if traffic in the packet ring is overloaded. A byte counter unit that calculates the number of bytes of input packets from external devices connected to the node device and guarantees bandwidth by changing the priority information in the packet when the number of bytes for the set minimum bandwidth is exceeded. A priority class conversion unit that divides the packet into packets that are not guaranteed for bandwidth and a bandwidth, an ad buffer unit that stores only packets of priority class A when the amount of packets input from the priority class conversion unit exceeds a first threshold, and a packet ring A ring buffer unit that stores only priority class A packets when the amount of input packets addressed to the own device exceeds a second threshold; The is that a read control section for sending a packet to preferentially read out packet ring than add buffer.

  FIG. 1 shows a configuration of a packet ring device that circulates packets between node devices 100, 101, 102, and 103 provided with a minimum bandwidth guarantee circuit of the present invention. The node devices 100, 101, 102 and 103 all have the same configuration, and the packet signal a and the packet signal q are input / output to / from an external device outside the packet ring to which the node device is connected, for example, a personal computer. m is input from the previous node device, and the packet signal p is output to the next node device. In FIG. 1, the connection of the input / output packet signals a, m, p, and q is for the purpose of grasping the image, and is omitted boldly. See FIG. 2 for the exact connection. In addition, the following description along FIG.

  In FIG. 1, when a packet signal m is input from the node device 103 to the node device 100, the node device 100 recognizes the destination information added to the inside of the packet, and if the packet is addressed to the own node device, Outputs packet signal q. On the other hand, if the packet is addressed to another node device, the packet output signal p is output to the node device B. Also, the idle time (packet non-passing time) of the packet input signal m is monitored, and when there is the idle time, the packet signal a input from the external device connected to the node device is sent to the packet ring as the packet output signal p. To do.

  FIG. 2 is a block diagram of the minimum bandwidth guarantee circuit provided in each of the node devices 100 to 103. The byte counter unit 1, the timer unit 2, the priority class conversion unit 3, the comparison unit 4, the write control unit 5, the add control unit It comprises a buffer unit 6, a read control unit 7, a write control unit 8, a ring buffer unit 9, and a drop determination unit 10.

  The byte counter unit 1 receives the packet valid signal b of the packet signal a, and counts the number of bytes of the packet valid signal b per unit time defined by the flag signal d input from the timer unit 2 every unit time. To do. The comparison unit 4 compares the number of bytes (set byte number e) that allows passage of the minimum bandwidth guarantee for the time set by the timer unit 2 with the number of bytes c counted by the byte counter unit 1. The number of set bytes e is set from outside the node device.

  When the number of bytes c exceeds the value set by the set number of bytes e, the comparison unit 4 gives priority to the signal f (priority information change signal f) for changing the priority class bits mapped on the packet signal a. Output to the class conversion unit 3. At this time, it is determined that the number of packets by the packet signal a has exceeded the minimum bandwidth guarantee within the unit time, and a predetermined measure is taken.

  When the priority information change signal f from the comparison unit 4 is invalid (logic L), the priority class conversion unit 3 outputs the packet signal s of the priority class A without changing the priority class bit of the packet signal a. When the priority information change signal f is valid (logic H), the priority class bit of the packet signal a is changed and output as the priority class B packet signal s.

  The add buffer unit 6 accumulates the packet signal s output from the priority class conversion unit 3. Then, the number of accumulated packets (buffer amount) is monitored, and when the buffer amount exceeds the first threshold value, the threshold excess signal k is output to the write control unit 5, and when the second threshold value is exceeded. The threshold excess signal j is output to the writing control unit 8. The first threshold value is always smaller than the second threshold value.

  When the threshold value excess signal k is not input, that is, when the buffer amount stored in the add buffer unit 6 is equal to or less than the first threshold value, the write control unit 5 outputs all packet signals output from the priority class conversion unit 3 Write control is performed by a write control signal t so that s is stored in the add buffer unit 6.

  Next, when the threshold value excess signal k is input, that is, when the buffer amount accumulated in the add buffer unit 6 exceeds the first threshold value, the priority class A packet signal output from the priority class conversion unit 3 Only s is stored in the add buffer unit 6 by the write control signal t, and the priority class B packet is not written but discarded. This does not change even when the buffer amount accumulated in the add buffer unit 6 exceeds the second threshold. Note that the priority class A and the priority class B are determined based on the priority class signal g in the packet signal s input from the priority class conversion unit 3.

  On the other hand, the drop determination unit 10 latches the destination information added in units of packets inside the packet signal m input from the packet ring, and outputs the packet signal q when the packet is addressed to the own node device. . On the other hand, if the packet is addressed to another node device, the packet signal r is output to the ring buffer unit 9. In this way, the packet signal m is distributed.

  The write control unit 8 performs write control for storing the packet signal r output from the drop determination unit 10 in the ring buffer unit 9. When no threshold excess signal j output from the add buffer unit 6 is input, that is, when the buffer amount accumulated in the add buffer unit 6 is equal to or smaller than the second threshold value, all packet signals r are stored in the ring buffer unit 9. The writing control is performed by the writing control signal u. This does not change even when the buffer amount stored in the add buffer unit 6 is equal to or smaller than the first threshold value.

  Next, when the threshold excess signal j is input, that is, when the buffer amount accumulated in the add buffer unit 6 exceeds the second threshold value, the priority class A packet signal r output from the drop determination unit 10 Is stored in the add buffer unit 6 by the write control signal u, and the packet signal r of the priority class B is not written but discarded. Note that the priority class A and the priority class B are determined based on the priority class signal h in the packet signal r input from the drop determination unit 10.

  The read control unit 7 recognizes the accumulation state of the packets stored in the add buffer unit 6 and the ring buffer unit 9 as described above, and performs the read control by the read control signal n. That is, reading is started when all the data of one packet is written in either the add buffer unit 6 or the ring buffer unit 9. The reading algorithm is performed with priority given to the ring buffer unit 9 as follows.

  When there is a packet in only one of the add buffer unit 6 and the ring buffer unit 9, the packet is read from there. When packets are accumulated in both the add buffer unit 6 and the ring buffer unit 9, the packet is read first from the ring buffer unit 9. Each time reading of one packet is completed, the accumulation state of both the buffers 6 and 9 is detected, and only when no packet is accumulated in the ring buffer unit 9, the data is read from the add buffer unit 6.

  Next, the operation of this embodiment will be described.

  First, a case where there is no packet signal a input from an external device connected to the node device, but only the packet signal m input from the packet ring will be described. In this case, of course, writing to the add buffer unit 6 is not performed, and therefore, the over-threshold signal k and the over-threshold signal j are not generated. In most cases, the packet signal m is a mixture of the priority class A and the priority class B as will be described later.

  The packet input signal m input from the packet ring is distributed to the packet signal q and the packet signal r by the drop determination unit 10, and all the packet signals r are stored in the ring buffer unit 9. Then, the read control unit 7 sends the packet signal p to the packet ring.

  FIG. 3 shows an example of a timing chart when there is an input of the packet signal a from the own node device. The packet signal a is always input as a priority class A to the node device. In FIG. 3, it can be seen that five packets are input during the flag signal d. If the packet signal a is an 8 parallel bit signal, the value of the number of bytes c indicates the number of bytes of the packet signal a. Initially, the priority information change signal f is logic L, and the packet signal s is stored in the add buffer unit 6 while maintaining the priority class A.

  As described above, since the number of bytes c is for the packet valid signal, the number of bytes c is not eight times the number of packets of the packet signal a as shown in FIG. The number of bytes c finally reaches 15 in the fourth packet of the packet signal a, and is 24 within the unit time (between the flag signal d).

  In this example, the value of the number of set bytes e is 15, so that the minimum bandwidth guarantee amount in the unit time is the first packet of the fourth packet signal a after the flag signal d indicating the unit time is input. It is recognized that the number of bytes has been exceeded, and the priority information change signal f transitions from logic L to logic H. The priority information change signal f is reset by the next flag signal d.

  When the priority information change signal f becomes logic H, the packet signals a of the fourth packet and the fifth packet are converted to the priority class B and stored in the add buffer unit 6 as the packet signal s. When the packet signal a of the sixth packet is input, the flag signal d is input, so that the number of bytes in the unit time (for the set bandwidth) is calculated again. Has been changed to logic L. Thereby, the byte signal c starts again from 1, and the packet signal s becomes the priority class A.

  In the above description, the number of bytes c within the unit time has exceeded the set number of bytes e. However, when the number of bytes c within the unit time does not exceed the set number of bytes e, the priority information change signal f never changes to logic H, and the packet signal s changes while maintaining the priority class A.

  Now, the operation when there is a packet signal a and a packet signal m will be described with the passage of time using the schematic diagrams of FIGS.

  FIG. 4 shows a state in which three packets of priority class A and three packets of priority class B are accumulated in the add buffer unit 6 and thereby reach the first threshold value. On the other hand, priority class A and priority class B packets are stored in the ring buffer unit 9. In this state, since packets are accumulated in the ring buffer unit 9, reading from the ring buffer unit 9 has priority over reading from the add buffer unit 6, and reading from the add buffer unit 6 is not performed.

  In FIG. 4, two new priority class B packets and three subsequent priority class A packets are about to be input from the priority class conversion unit 3 by the packet signal a. If this input is present, the add buffer unit 6 exceeds the first threshold value, and therefore outputs an over-threshold signal k to the write control unit 5. Therefore, priority class B packets are not written to the add buffer unit 6, and only priority class A packets are accumulated in the add buffer unit 6 as shown in FIG. 5.

  Thereafter, only the priority class A packets are accumulated in the add buffer unit 6. On the other hand, the ring buffer unit 9 stores all packet signals regardless of the priority class A and the priority class B. Actually, as shown in FIG. 6, the priority class A and priority class B packets increase in the ring buffer unit 9 as compared with the state of FIG. 5, but only the priority class A packets exist in the add buffer unit 6. It can be seen that is increasing. Then, the add buffer unit 6 has reached the second threshold value.

  In FIG. 6, three new priority class B packets, three priority class A packets, and one priority class B packet are about to be input to the ring buffer unit 9 by the packet signal r. FIG. 7 shows that three packets of priority class A are added to the add buffer unit 6 in the state of FIG. 6, and the accumulated buffer amount exceeds the second threshold value.

  At this time, the add buffer unit 6 outputs the threshold excess signal j to the write control unit 6. As a result, after that, the priority class B packets are not written to the ring buffer unit 9, and only the priority class A packets are accumulated in the ring buffer unit 9, as shown in FIG. In this way, the time that can be read from the add buffer unit 6 is secured by the priority class B packet discarded in the packet signal r, and the priority class A packet is read out in the packet signal a. To get.

  From the above description, it can be understood that the priority order in which the packet signal is accumulated in the buffer unit when the packet traffic is overloaded is as follows.

1st rank: packet of priority class A to ring buffer unit 9 2nd rank: packet of priority class A to add buffer section 6 3rd rank: packet of priority class B to ring buffer section 9 4th rank: add As described above, the ring buffer unit 9 gives priority to reading packets from the buffer unit. The higher the probability stored in the buffer unit is, the higher the probability of reading out is. Therefore, the above priority of storage is also the priority of reading.

Block diagram showing the configuration of the packet ring device Block diagram of minimum bandwidth guarantee circuit of the present invention Timing chart when there is an input of packet signal a from its own device 1st schematic diagram for demonstrating operation | movement in case there exists packet signal a and packet signal m Second schematic diagram for explaining the operation when there is packet signal a and packet signal m 3rd schematic diagram for demonstrating operation | movement when there exists packet signal a and packet signal m 4th schematic diagram for demonstrating operation | movement when there exists packet signal a and packet signal m

Explanation of symbols

1 byte count unit 2 timer unit 3 priority class conversion unit 4 comparison unit 5 write control unit 6 add buffer unit 7 read control unit 8 write control unit 9 ring buffer unit 10 drop determination unit
100 to 103 node device α to γ path

Claims (2)

In the minimum bandwidth guarantee circuit that guarantees the transmission amount of the set data amount without being discarded even if the traffic in the packet ring is overloaded,
The minimum bandwidth guarantee circuit is provided in a node device in the packet ring,
A byte counter unit that calculates the number of bytes of an input packet from an external device connected to the node device, and if the number of bytes for the set minimum bandwidth is exceeded, the priority information in the packet is changed and the bandwidth guaranteed A priority class conversion unit that divides the packet into a packet whose bandwidth is not guaranteed;
An ad buffer unit that stores only packets of the priority class A when the amount of packets input from the priority class conversion unit exceeds a first threshold;
A ring buffer unit that stores only the packets of the priority class A when the amount of packets addressed to the own node device input from the packet ring exceeds a second threshold (greater than the first threshold);
A minimum bandwidth guarantee circuit, comprising: a read control unit that reads the ring buffer unit preferentially over the add buffer unit and sends packets to the packet ring. A timer unit that inputs a flag signal to the byte counter unit every unit time; and
A number of bytes that allow passage of the minimum bandwidth guarantee in the time set by the timer unit, and a comparison unit that compares the number of bytes counted by the byte counter unit;
3. The minimum bandwidth guarantee circuit according to claim 2, wherein the priority class conversion unit determines whether or not the number of bytes corresponding to the minimum bandwidth is exceeded based on the result of the comparison.

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