KR20060081868A - Apparatus for port scheduling using queue transition event vector table and method thereof - Google Patents

Abstract

The present invention manages the port scheduling method, which was performed in a round robin manner, by grouping each port into a vector table having a hierarchical structure to efficiently schedule a plurality of ports and reduce packet forwarding by reducing queuing delay and waiting time in the output port scheduling process. The present invention provides a port scheduling apparatus using a queue state change event vector table for improving performance and a method thereof, and includes grouping ports by grouping a plurality of ports in a predetermined number and subgrouping a group of a certain number of queues in the grouped ports. In the state, a scheduler for performing management on enqueuing and dequeuing of each group and the ports in the group and the queues in the port; A vector table for layering and storing event information about a state of a queue; And a vector table manager to receive a state change event of a queue and store the same in a vector table.

Queue, transition, transition, vector, scheduling

Description

Apparatus for port scheduling using queue transition event vector table and method             

1 is a block diagram schematically showing an internal configuration of a scheduler to which the present invention is applied;

2 is a diagram of a multi-level vector table structure according to a preferred embodiment of the present invention;

3 is a flowchart illustrating a process of updating table contents in a vector table management unit when a state of a queue length managed by a queue length counting unit changes from empty to non-empty according to an embodiment of the present invention;

4 is a flowchart illustrating a process of updating table contents in a vector table management unit when a state of a queue length managed by a queue length counting unit changes from non-empty to empty according to an embodiment of the present invention;

5 is a flowchart illustrating a process of performing port scheduling after group scheduling using an empty vector and a mask vector of a group / port vector table according to an embodiment of the present invention;

6 is a flowchart illustrating a process of selecting a queue in a port scheduled by a group scheduler and a port scheduler using a queue vector table according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100: scheduler 110: queue length counting unit

120: vector table management unit 130: group scheduler

140: port scheduler 150: queue scheduler

200: Vector Table 210: Group Vector Table

220: port vector table 230: queue vector table

The present invention relates to a port scheduling apparatus and a method using a queue state change event vector table when scheduling an output port in the network processor of a router.

Generally, router devices are functionally classified into data plane, control plane, and management plane, and each function is installed in a network processor and a host processor.

Data planes running on network processors are fast paths that forward large amounts of packets, such as packet forwarding, to the switch part, and exception packets that require more complex processing than simple forwarding, such as control packets. Packet with header added, divided packet that is regarded as more than the basic packet size, etc.) to the host processor for processing.

The control plane and management plane running on the host processor are responsible for the configuration of routing tables through routing protocol message processing and management functions by the operator.

In this case, the port scheduling algorithm is generally implemented in a round robin method.

In the case of various devices supporting the conventional QoS, the research on the queue scheduling method in one port has been very active, and numerous scheduling algorithms have been conducted. However, the port scheduling scheme mainly uses a simple round robin scheme, which implies inefficiency in software scheduling in a system that needs to support more than a few hundred ports.

In particular, if only a few of the plurality of output ports are currently in service, since the port is selected linearly, an unnecessary process is required, and thus there is a problem that a packet transmission delay occurs.

Accordingly, the present invention is to solve the above problems, the port scheduling method that was performed in the round robin method to group each port in the form of a vector table having a hierarchical structure to efficiently schedule a plurality of ports and output port scheduling It is an object of the present invention to provide a port scheduling apparatus and a method using a queue state change event vector table for improving packet forwarding performance by reducing queuing delay and waiting time.

A port scheduling apparatus using a queue state change event vector table according to the present invention for achieving the above object, in the port scheduling apparatus, a plurality of ports are grouped into a predetermined number to group ports, and a predetermined number of queues in the grouped ports. A scheduler for performing management on enqueuing and dequeuing of each group, a port in the group, and a queue in the port in a grouped and sub-grouped state; A vector table for layering and storing event information about a state of a queue; And a vector table manager to receive a state change event of a queue and store the same in a vector table.

Port scheduling method using the queue state change event vector table according to the present invention for achieving the above object, the table in the vector table management unit when the state of the queue length managed in the queue length counting unit changes from empty to non-empty In the method of updating the contents, if a state change occurs from 0 (Empty) to 1 (Non-Empty) of any queue, the current queue vector state is checked to update the value for the state change. Determining whether all queues are empty; If it is determined that all the queues are empty, a state change has occurred from empty to non-empty, so that setting the bit values of the ports in the group and the queue vector table; Obtaining a group ID and an entry ID of a port in the group since the values of the port and group vector table need to be updated; Determining whether all ports in the current group are empty when the group ID and the entry ID in the group are obtained; And if it is determined that all the ports are empty, the group vector table needs to be updated, and thus setting an empty vector of the corresponding port of the corresponding group and an empty vector for the group.

Before describing the embodiments of the present invention, the basic concepts for implementing the present invention will be described.

According to the present invention, in order to fundamentally solve the packet processing delay on the network caused by the conventional port scheduling method being leanier, a vector having a hierarchical structure by grouping ports so as to efficiently perform port scheduling Create a table and manage this vector table to dequeue / enqueue packets for each port in a network with more than a hundred ports.

The structure of the vector table of the present invention creates a port group by dividing a plurality of output ports into 32 so as to have a hierarchical structure, and maintains a Port Empty / Mask Bit vector table corresponding to 32 bits for each group, and 32 in each group. Creates a Group Empty / Mask Bit vector representing the two port information.

In addition, up to 32 queue empty / mask bit vectors in each port are maintained and the port empty / mask bit vector represents queue information in the corresponding port.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

1 is a block diagram schematically showing an internal configuration of a scheduler to which the present invention is applied.

Referring to FIG. 1, the present invention includes a scheduler 100 that manages enqueuing and dequeuing of a queue, and a vector table 200 which stores layered event information regarding queue states.

The scheduler 100 performs a queue length counting unit 110 to dynamically maintain a current queue length while enqueuing / dequeuing a packet to an actual queue, and the queue length counting unit 110. A vector table manager 120 for updating the vector table 200 by receiving a state change event (Empty-> Non-Empty, Non-Empty-> Empty) for the queue length from the group, and grouping for transmission of the enqueued packet. A group scheduler 130 for selecting a selected port group, a group scheduler 130, and a port scheduler 140 for selecting an appropriate port according to a weight given to each port, and a port scheduler 140 and a scheduled port. It includes a queue scheduler 150 that is responsible for queue selection in.

The vector table 200 maintained in each scheduler includes a group vector table 210, a port vector table 220, and a queue vector table 230.

The vector table 200 can be configured on the same board as the scheduler 100, and it should be noted that in the present invention, the vector table 200 is separated into a separate table form in order to emphasize functional differences.

The vector table structure will be described in detail with reference to FIG. 2.

2 is a diagram of a multi-level vector table structure according to a preferred embodiment of the present invention.

Assume that there is a network device having 512 ports and 16 queues for each port as shown in FIG.

If only a few queues are in intensive service, a total of 8192 (512 ports x 16 queues) of queues can be scheduled in a simple round-robin fashion. Therefore, due to this unnecessary queue checking process, dequeuing / enqueuing waiting time is long for queues that need to be serviced.

Therefore, in order to service such a packet queue, the value of each queue state is provided in the form of a vector table, and the value of the vector table is used to determine whether or not the port where the queue to process packets is located. Check it out.

Then, 512 ports are grouped by 32 to create 16 port groups. At this time, each group ID may be set as G0 to G15.

In each group, the port ID may be set as P0 to P31.

Next, whether or not scheduling is required using a bit vector of 32 bits corresponding to 32 ports existing in each group is indicated. At this time, each Empty Vector in the group vector table represents an Empty Vector of ports in the group.

That is, whether a port to be scheduled among the ports in the group exists is managed using a bit vector.

The scheduling of 16 queues existing in each port is represented by a port bit vector in the group, and whether or not the scheduling target for each final queue is indicated by the queue Empty Vector itself.

By grouping each queue into ports as described above and grouping the ports again, in determining whether to queue or dequeue a queue, a group is first selected, a port in the group is selected, and a queue in the port is then selected.

Hereinafter, the operation of the present invention using the vector table structure as described above will be described.

3 is a flowchart illustrating a process of updating table contents in a vector table management unit when a state of a queue length managed by a queue length counting unit changes from empty to non-empty according to an embodiment of the present invention.

Referring to FIG. 3, first, variables for a port number and a queue number are designated (S110).

If the status of any queue is changed from 0 (Empty) to 1 (Non-Empty), it should be updated in the order of queue, port, and group vector table.

In order to update the value for the state change, the current queue vector state is checked to determine whether all the queues are empty (S120).

If it is determined in S120 that all the queues are not empty and even one queue is non-empty, the previous value may be maintained without having to update the vector table.

Therefore, setting the empty vector of the corresponding queue of the corresponding port becomes the same value as before (S150). In this case, set means to set the bit value to 1. Therefore, when the bit value of the empty vector becomes 1, this may indicate that it is not empty.

However, if it is determined in S120 that all the queues are empty, the state change has occurred from empty to non-empty, so the bit values of the ports and the queue vector table in the group must be set.

Therefore, the empty vector of the corresponding queue of the corresponding port may be set to indicate that the empty vector of the corresponding queue of the corresponding port is not empty (S130).

Thereafter, since the values of the port and group vector table need to be updated, the group ID and the entry ID of the port in the group must be obtained (S140).

Since every 32 ports belong to a group, the group ID and the entry entry ID in the group can be obtained as follows.

Group ID = real port number / 32;

If the port number is 0 to 31, the group ID is 0. If the port number is 32 to 63, the group ID is 1. If the port number is 64 to 95, the group ID is 2.

-Entry ID in group = actual port number% 32; (using modulo operation, which calculates the rest)

If the port number is 0 to 31, the entry ID in the group is 0 to 31, and the port number is 32 to 63, but the group ID is 0 to 31 although the group ID is different.

When the group ID and the entry ID in the group are obtained, it is determined whether all ports in the current group are empty (S160).

If it is determined in S160 that all ports are not empty and even one port is non-empty, the previous value may be maintained without having to update the vector table.

Accordingly, when the empty vector of the corresponding port of the corresponding group is set (S190). In this case, set means to set the bit value to 1. Therefore, when the bit value of the empty vector becomes 1, this may indicate that it is not empty.

However, if it is determined in S160 that all ports are empty, the group vector table must be updated. Therefore, by setting the empty vector of the corresponding port of the group, it can be known that the empty vector for the corresponding port of the group is not empty (S170).

If the empty vector for the corresponding port is not empty, the empty vector of the group including the port is also not empty, so the empty vector of the group vector table must be set (S180).

4 is a flowchart illustrating a process of updating table contents in a vector table management unit when a state of a queue length managed by a queue length counting unit changes from non-empty to empty according to an embodiment of the present invention.

Referring to FIG. 4, when the length of an arbitrary queue changes from 1 (Non-Empty) to 0 (Empty) after scheduling, the queue, port, and group vector table should be updated in order.

First, variables for the port number and the queue number are specified (S210).

In order to update the value for the state change, the Empty vector of the corresponding queue of the corresponding port is cleared (S220). That is, it indicates that the queue is excluded from future scheduling target.

Thereafter, it is determined whether all the queues are empty (S230). If it is determined in S230 that all the queues are not empty, the update process is terminated because the bit value of the upper vector table does not need to be cleared.

However, if it is determined in S230 that all the queues are empty, the port vector table in the group is updated.

Thereafter, since the values of the port and group vector table need to be updated, the group ID and the entry ID of the port in the group must be obtained (S240).

Since every 32 ports belong to a group, the group ID and the entry entry ID in the group can be obtained as follows.

Group ID = real port number / 32;

If the port number is 0 to 31, the group ID is 0. If the port number is 32 to 63, the group ID is 1. If the port number is 64 to 95, the group ID is 2.

-Entry ID in group = actual port number% 32; (using modulo operation, which calculates the rest)

If the port number is 0 to 31, the entry ID in the group is 0 to 31, and the port number is 32 to 63, but the group ID is 0 to 31 although the group ID is different.

By clearing the Empty vector bit of the entry ID in the group, it indicates that this port is excluded from future scheduling in the group.

Thereafter, it is determined whether all ports in the current group are empty (S260).

In S260, if all of the ports are non-empty and non-empty, the update process is terminated.

However, when it is determined in S260 that all ports are empty, the bit value of the vector table corresponding to the group ID is cleared in order to update the group vector table (S270).

Hereinafter, a process of scheduling an arbitrary port or queue will be described.

The actual scheduling process is performed in the reverse order of the vector table update process.

That is, group scheduling is always performed first, then port scheduling in the group, and then queue scheduling in the port is performed.

5 is a flowchart illustrating a process of performing port scheduling after group scheduling using an empty vector and a mask vector of a group / port vector table according to an embodiment of the present invention.

Referring to FIG. 5, the bit value of the empty vector for the group ID is determined (S310). If the bit value of the empty vector is '0', the packet is not present in any queue of any port in the current system. There is no need to perform the scheduling process. Therefore, the subsequent process is terminated.

If the bit value of the empty vector is '1' in S310, a group ID to be scheduled is calculated using an empty vector and a mask vector in the group vector table (S320).

Thereafter, the mask vector is shifted to specify a group to be scheduled in the next round (S330 and S340). A schedule ID that can be scheduled in the group is obtained using the selected group ID (S350), and the mask vector Mask Vector is updated to specify an entry to be scheduled in the next round (S360, S370).

Based on the group ID to be scheduled and the entry ID in the group, the port number to be actually scheduled is calculated through the following operation (S380).

Port number = (Group ID << 5) + Entry ID in Group

The << bitwise operator is an operator that shifts a bit to the left.

Therefore, each bit of the group ID is shifted left by five digits.

In this way, by specifying the ID of each group and then adding the entry IDs in each group, each port number is obtained.

The queue empty vector and the mask vector are obtained by using the actual port number obtained through the above process as an offset of the queue vector table.

6 is a flowchart illustrating a process of selecting a queue in a port scheduled by a group scheduler and a port scheduler using a queue vector table according to an embodiment of the present invention.

Referring to FIG. 6, it is determined whether the port ID is valid (S410), and if it is not a valid number, the subsequent process is terminated.

If the port ID is valid in S410, after obtaining a queue ID that can be scheduled in the port (S420), the mask vector is updated to designate an entry to be scheduled in the next round (S430).

The final scheduled queue number is obtained through the following operation (S440).

Queue number = (port number << 4) + queue ID in the port;

The above formula is the same as the method of obtaining the port number.

Although the above has been described in detail with respect to the preferred embodiment of the present invention, the present invention is a scheduling scheme in the router equipment for the purpose of illustration, the general scheduling scheme RR / DRR (round robin / deficit round robin) or the main traffic It is applicable to various fields that support weight round robin (WRR) and the like, and various modifications, changes, and additions are possible within the scope of the present invention. Therefore, changes in the future embodiments of the present invention will not be able to escape the technology of the present invention.

As described above, the present invention provides a vector table having a hierarchical structure in which a group of hundreds or more ports are divided by a predetermined number and grouped, and the queues in the ports are grouped and subgrouped by a predetermined number. By determining enqueuing / dequeuing scheduling according to the presence or absence of packets in the queue provided in real time, more efficient scheduling can be expected than the conventional round robin method.

In addition, since the packetless port can be skipped, there is no need to read the packetless port, thereby reducing the queuing delay and waiting delay.

Claims (16)

In the port scheduling apparatus, Grouping ports by grouping a plurality of ports into a certain number, and performing grouping and subqueueing of each group, the ports in the group, and the queues in the ports, in a group of a certain number of queues in the grouped ports. A scheduler; A vector table for layering and storing event information about a state of a queue; And A port scheduling apparatus using a queue state change event vector table, comprising a vector table manager which receives a state change event of a queue and stores the same in a vector table. The method of claim 1, wherein the scheduler is A queue length counting unit that dynamically maintains a current queue length while performing packet enqueuing / dequeuing to a real queue; A vector table manager which receives a state change event (Empty-> Non-Empty, Non-Empty-> Empty) for the queue length from the queue length counting unit and updates a vector table; A group scheduler for selecting a group of port groups grouped for transmission of an enqueued packet; A port scheduler for selecting an appropriate port according to the group scheduler and a weight given to each port; And a queue scheduler that is in charge of queue selection within the scheduled port with the port scheduler. The method of claim 1, wherein the vector table is A group vector table for storing state change event information for the group; A port vector table that stores state change event information for the port; And Port scheduling apparatus using a queue state change event vector table, characterized in that it comprises a queue vector table for storing state change event information for the queue. The method of claim 1, wherein the vector table is A port scheduling apparatus using a queue state change event vector table, which indicates whether scheduling is required using bit vectors corresponding to a plurality of ports existing in each group. The method of claim 4, wherein the vector table is Each Empty Vector in a group vector table represents an Empty Vector of ports in a group. Port scheduling apparatus using a queue state change event vector table. The method of claim 5, wherein the vector table is A port scheduling apparatus using a queue state change event vector table, which manages whether a port to be scheduled among ports in a group exists using a bit vector. 7. The method of claim 6, wherein the vector table is Port scheduling apparatus using a queue state change event vector table, characterized in that the scheduling of a plurality of queues existing for each port is represented by a port bit vector in the group. The method of claim 7, wherein the vector table is A port scheduling apparatus using the queue state change event vector table, wherein whether or not a final target is scheduled for each queue is indicated by the queue Empty Vector itself. In the method of updating the table contents in the vector table management unit when the status of the queue length managed by the queue length counting unit changes from empty to non-empty, When the length of an arbitrary queue is changed from 0 (Empty) to 1 (Non-Empty), the current queue vector state is checked to determine if all queues are empty to update the value for the state change. Doing; If it is determined that all the queues are empty, a state change has occurred from empty to non-empty, so that setting the bit values of the ports in the group and the queue vector table; Obtaining a group ID and an entry ID of a port in the group since the values of the port and group vector table need to be updated; Determining whether all ports in the current group are empty when the group ID and the entry ID in the group are obtained; And If all ports are determined to be empty, the group vector table needs to be updated, and thus a port scheduling method using the queue state change event vector table including setting an empty vector of the corresponding port of the corresponding group and an empty vector of the group. 10. The method of claim 9, wherein if a single queue is determined to be non-empty, the previous value is maintained without having to update the vector table. The method of claim 10, A port scheduling method using a queue state change event vector table, wherein a previous value is maintained by setting an empty vector of a corresponding queue of a corresponding port. The method of claim 9, wherein obtaining a group ID and an entry ID of a port in the group includes: The group ID is calculated by dividing the actual port number by the dividend and dividing the number of ports in each group. The entry ID in the group is calculated by dividing the number of ports in each group by using the actual port number as the dividend. Port scheduling method using a queue state change event vector table, wherein the value is used. 10. The method of claim 9, wherein if it is determined that all ports are not empty and even one port is nonempty, the previous state is maintained without updating the vector table. How to schedule a port. In the method of updating the table contents in the vector table management unit when the status of the queue length managed by the queue length counting unit changes from non-empty to empty, Clearing an empty vector of the corresponding queue in the corresponding port in order to update the value for the state change when the length of the arbitrary queue changes from 1 (Non-Empty) to 0 (Empty) after scheduling; Determining whether all queues are empty, and if all queues are determined to be empty, updating the port vector table in the group; Obtaining a group ID and an entry ID of a port in the group since the values of the port and group vector table need to be updated; Indicating that this port is subsequently excluded from scheduling in the group by clearing the Empty vector bit of the corresponding Entry ID in the group; Determining whether all ports in the current group are empty; And And if all ports are determined to be empty, clearing the bit values of the vector table corresponding to the group ID to update the group vector table. 15. The method of claim 14, wherein if it is determined that all queues are not empty, the update process is terminated because the bit value of the higher vector table does not need to be cleared. 15. The method of claim 14, wherein the update process is terminated when all ports are not empty and at least one port is non-empty.

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