JP2003283551A - Communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for simultaneously performing VP unit shaping for protecting a contract band required for utilization based on the VP unit contract of a public ATM network and VC unit shaping for making possible the effective utilization of intra-VP bands. <P>SOLUTION: An ATM cell arriving at a traffic shaping device is temporarily stored in a cell buffer. In a planned VC transmitting time calculating circuit, a planned cell transmitting time is calculated according to a VC contract band and at the same time, in a planned VP transmitting time calculating circuit, a planned cell transmitting time according to the contract band of VP is calculated but the planned VP transmitting time is corrected in accordance with the planned VC transmitting time. The VP to be most preferentially transmitted is determined by a VP bisected tree sort circuit and the VC to be most preferentially transmitted within the VP is determined in a VC bisected tree sort circuit. When both the determined VP and VC can be transmitted, the cell is transmitted. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus having a traffic shaping function, an ATM terminal, an ATM switch, or an apparatus having a traffic shaping function for variable length packets.

[0002]

2. Description of the Related Art Asynchronous Transfer technology
r Mode: ATM) is capable of efficiently supporting various types of traffic such as voice, image and data using fixed length packets called cells, and is widely known as a communication technology suitable for multimedia communication. Has been.

In ATM, a user makes a contract regarding a transmission band with a network in a unit called VC (Virtual Connection) before transmitting a cell. The contents of the contract are the V
It depends on the type of information you want to transfer via C. For example, since low-delay transfer is required for voice / image traffic, a certain band is secured in advance in the line and cells are transmitted according to the band. In "The ATM Forum TM4.0" (conventional technology 1), a CBR (Constant Bit Rat) that completely secures a fixed bandwidth and transmits cells within the contract bandwidth as a service class for transferring voice / image traffic
e), and VBR (Variable B) in which the maximum transmission band and the average transmission band are contracted and the transmission band changes with the passage of time.
it Rate) is shown. On the other hand, since data traffic is generated and terminated in bursts (suddenly), if a band is secured in advance in the line, the line band cannot be used effectively. Therefore, in general, data traffic does not give much importance to delay as compared to voice, etc., so cells are transmitted without securing a band, and a node in which many cells are concentrated at one time temporarily stores cells ( If the node cannot accept the cell, the cell is discarded), thereby effectively using the line band.

In the prior art 1, the service class for transferring data traffic is ABR (Available Bit Rate) which has means for feeding back the congestion state in the network to the cell transmitting terminal to prevent cell discard, And in order to effectively use the line band, the transmitting terminal keeps transmitting cells if there is a vacant band on the line.
Bit Rate) is shown. Each VC belongs to one of the service classes. Due to the characteristics related to delay and discard of each service class described above, when VC cells belonging to four service classes compete (collide) with nodes in the network, VC cells belonging to CBR are transferred with the highest priority. , And then VBR, ABR, and UBR are preferentially transferred in this order.

Regarding the above-mentioned CBR, VBR, and ABR VCs, the terminal (user) makes a contract with the network regarding the transmission band such as the maximum transmission band. Regarding the UBR VC, there are cases where a contract for the maximum transmission band is made and cases where no contract is made for the transmission band. In a public ATM network,
The cell flow rate transmitted by the terminal is monitored at the entrance of the network, a VC violating the contract bandwidth is detected, and the cell is discarded for the cell of the VC. This function is called UPC (Usage
Parameter Control) function. Even if a cell is discarded during transmission, the receiving terminal usually recognizes that the cell has been discarded, notifies the transmitting terminal to retransmit the discarded information, and the transmitting terminal retransmits the information. However, it may cause a large final delay or cause secondary new congestion due to a retransmitted cell. Therefore, it is important for the terminal side to control and transmit the cell flow rate according to the contracted band so that the UPC function on the network side does not determine that the cell is a violation cell. The function of controlling the cell flow rate is traffic shaping.
Function. In addition to the terminals, the exchanges at key points in the network may be provided with a traffic shaping function in order to absorb fluctuations occurring in the network.

A traffic shaping device for realizing a traffic shaping function is disclosed in, for example, Japanese Patent Laid-Open No.
6-315034, "Cell flow controller and ATM communication network"
(Prior Art 2). If cells received in a band higher than the contracted band are transmitted to the network in the same band, excess cells will be transmitted, and will be discarded by the UPC function on the network side. Therefore, in the conventional technique 2, a memory (reference numeral 4 in the conventional technique 2) for temporarily storing cells is provided, and cells received in a band equal to or higher than the contract band are temporarily stored in the memory, and according to the contract band. It shows a method for realizing the traffic shaping function by reading. In the prior art 2, although it is stated that the function is the minimum required for performing traffic shaping, that is, the temporary storage in the memory, the specific implementation method, the required memory amount, and the processing time are described. Not mentioned.

Another example of the traffic shaping device is disclosed in Japanese Patent Laid-Open No. 9-307566, "Traffic shaping device" (prior art 3). In Conventional Technique 3,
The time when the cell can be transmitted next for each VC (hereinafter, scheduled transmission time) is stored using a binary tree structure. Since it is possible to perform the sorting by using the previous sorting result, it is stated that the VC to be transmitted with the highest priority can be selected in the processing time of the order of log (the number of VCs). In the traffic shaping device to which the prior art 3 is applied, the required memory amount is reduced, and the processing time for selecting a cell to be transmitted is significantly shortened as compared with the traffic shaping device according to the prior art 2.

[0008]

As a contract unit when a user uses a public ATM network, a contract is made on a VC basis as described above, and a VP (Virtual Path) that bundles a plurality of VCs.
There may be contracts in units. When a band contract is made in units of VP, the contract is usually made for each partner site as a communication partner. An example of such a network is shown in FIG. In FIG.
Terminals 300, 1901, 190 on the public ATM network 340
2, 1903 is shown connected. For example, if the terminal 300 is each terminal 1901, 1902, 1903.
When communicating with, a VP contract is made for each terminal.
That is, VP (0) 2 is provided between the terminal 300 and the terminal 1901.
90 Mbps contract as 10, terminal 300 to terminal 19
For example, VP (1) 220 has a contract of 30 Mbps between 02, and VP (2) 230 has a contract of 30 Mbps between terminal 300 and terminal 1903. And VP (0)
˜VP (2) are bundled into a 150 Mbps line connecting between the terminal 300 and the ATM switch 341 and transmitted.

FIG. 2 shows the terminal 300-AT in FIG.
It is a conceptual diagram which shows the relationship between the line between M switches 341, and VP and VC. In FIG. 2, VP (0) 21 of 90 Mbps
3 VCs 211, 212, 213 in 0 are 30Mb
Two VCs 221 and 222 in the VP (1) 220 of ps
Has two VC2s in a 30Mbps VP (2) 230.
31, 232 are bundled.

When a contract is made in units of VP, the network management side monitors only whether or not the band in units of VP is protected. That is, in the ATM switch 341 located at the entrance of the public ATM network 340 (see FIG.
9) For the VP, cells are discarded for the violating cell by the above-mentioned UPC function, but the band of each VC bundled in the VP is not monitored. U to VP
If the PC function determines that the cell is a violation cell and discards the cell, as described above, the transfer delay becomes large or it may cause new congestion. A traffic shaping function (hereinafter, VP shaping) for transmitting a cell while keeping a band of a certain VP is required. Also, because the bandwidth of each VC in the VP is not monitored on the network side, for example, the order in which the traffic shaping device received (the order in which the upper packet was divided for a transmitting terminal (described later), the switch for a switching device). If VC cells are transmitted in such a manner that they are transmitted in that order, it becomes impossible to guarantee a certain band for voice / image traffic and realize low-delay transfer over the entire network. Therefore, audio / video traffic (C
BR, VBR) is realized in order to realize low delay transfer.
A traffic shaping function (hereinafter, VC shaping) that controls the bandwidth of each VC bundled in P and performs priority control between different service classes is important.
However, in the traffic shaping devices shown in the related art 2 and the related art 3, only VP shaping or VC shaping is described, and traffic shaping in which both shapings are performed at the same time is not targeted. Moreover, in the prior art 3,
It does not mention traffic shaping considering both VP and VC.

A first object of the present invention is to control the band of each VC in the VP while keeping the contracted band of the VP, and to effectively use the band of the VP and the line.
An object of the present invention is to provide a device having a traffic shaping function, an ATM terminal or an ATM switch.

A second object of the present invention is to provide a device, an ATM terminal, or an ATM switch, which is capable of shaping a plurality of output lines with one traffic shaping device.

A third object of the present invention is to control the bandwidth for each packet within the contract bandwidth while protecting the contract bandwidth with the network for variable length packets. Another object of the present invention is to provide a device having a traffic shaping function for a packet transmission terminal or a packet switch, an ATM terminal or an ATM switch, which can effectively use the bandwidth of a line.

[0014]

To perform both traffic shaping for VP and VC simultaneously,
It is necessary to provide traffic shaping circuits for VP and VC, and to monitor whether both traffic shaping circuits are ready to transmit cells (the scheduled transmission time is reached). If the method of managing the scheduled transmission time with the binary tree structure described in the prior art 3 is used, the VP to be transmitted with the highest priority is selected from all the VPs, or among a plurality of VCs in the same VP. It is possible to select the VC to be transmitted with the highest priority. However, if the scheduled transmission time is calculated independently,
A situation may occur in which there is no VC that may be transmitted in the VC even in a state where the transmission may be performed (the scheduled transmission time is reached). In this case, by reducing the band of the own VP or by reducing the band of another VP,
Although cells can be transmitted, in either case, the bandwidth of the communication path and the bandwidth of the contracted VP cannot be effectively used. Therefore, it is necessary to consider linking the scheduled transmission time as the VP and the scheduled transmission time as the VC.

Further, when performing traffic shaping for a large number of low speed lines, providing a traffic shaping device for each line interface unit causes an increase in device cost. Therefore, if one traffic shaping device can perform traffic shaping on a plurality of output lines, it is possible to perform traffic shaping on a large number of lines at low cost.

Further, the above problem is not a problem specializing in traffic shaping for ATM cells of fixed length. For example, consider a case where a plurality of networks are connected using a shared line and the shared line is contracted for each of the networks, such as the Internet. FIG. 18 shows a net having such a form. 18, the network A 1810 and the network a 1820 are owned by the provider A, and the terminals 1811 and 1821 are users of the provider A. Similarly, the network B1830 and the network b1
840 is owned by provider B, and terminals 1831 and 184
1 is a user of provider B. Also, net A, net a,
The networks B and b are connected to the network C1800 by routers. Provider A and provider B respectively contract a transmission band with network C, and in network C, shared line 1801 is shared by provider A and provider B. In such a network environment, the terminal 1811 and the terminal 18
When the terminal 21 and the terminal 1831 and the terminal 1841 communicate with each other, at the entrance of the shared line 1801, while the band contracted for the shared line is protected (corresponding to VP in ATM), transfer is performed within the contracted band. It is desirable that a priority can be set for each packet that is set (for example, a packet for TELNET has priority over a packet for e-mail, etc.) and the bandwidth can be managed (corresponding to VC in ATM).
The network configuration as described above is not limited to the sharing of lines by providers, and various operating forms can be used, such as when multiple companies share long-distance communication lines, or when you want to manage traffic for each department within the same company. It is conceivable that it must be realized in a form corresponding to this.

From the above consideration, in order to achieve the object, a first transmission scheduled time calculating unit for calculating a first cell transmission scheduled time for transmitting a cell to a communication device based on a band contracted for each connection, Second, which transmits the cell based on a band contracted for each connection bundle in which a plurality of connections are collected
A second scheduled transmission time calculating unit for calculating a scheduled cell transmission time and means for selecting whether to use the second scheduled cell transmission time or the first scheduled cell transmission time when transmitting the cell . Since the scheduled first cell transmission time and the scheduled second cell transmission time can be used as necessary, the contract bandwidth can be protected.

From the above consideration, in order to achieve the above first to third objects, the present invention proposes a traffic shaping device which performs shaping in multiple stages. That is, in order to achieve the first object, a cell buffer unit for temporarily storing received cells in a terminal or a switching switch connected to an ATM network and a band contracted for each VC are used. A first scheduled transmission time calculating unit that calculates a first scheduled transmission time of a cell and that selects a VC whose cell first scheduled transmission time calculated by the first scheduled time calculation unit is earliest A sorting unit and the first
A traffic including a transmission control unit that determines whether or not a cell belonging to the VC selected by the sorting unit may be transmitted, and if the cell may be transmitted, reads the cell from the cell buffer unit and transmits the cell. In the shaping device, V
A second scheduled transmission time calculating unit that calculates a second scheduled transmission time of a cell that keeps a transmission interval according to a band contracted for each P, and a second scheduled transmission time of the cell calculated by the second scheduled transmission time calculation unit are A second sorting unit that selects the earliest VP is provided, and it is determined whether or not a cell belonging to the VP selected by the second sorting unit may be transmitted to the transmission control unit, and the cell is transmitted. If it is good, it is determined whether or not the cell belonging to the VC selected by the first sorting unit may be transmitted, and if the cell is allowed to be transmitted, the cell is read from the cell buffer unit and transmitted. Equipped with.

Further, in order to perform priority control among a plurality of service classes within a VP, the traffic shaping device sets priorities for VCs within each VP,
The first sorting unit has a function of selecting a VC having the earliest scheduled cell first transmission time for a group of VCs having the same priority in each VP, and the transmission control unit includes the second sorting unit. It is determined whether or not cells belonging to the VP selected by the unit may be transmitted, and when cells may be transmitted, from among the VCs selected for each priority by the first sorting unit, It is provided with a function of transmitting a cell that is in a state in which it can be transmitted and belongs to a VC having the highest priority.

Further, each VC is provided with a discrimination bit indicating whether or not there is a cell waiting to be transmitted in the cell buffer section. In addition, each VP is provided with a determination bit indicating whether or not there is a cell waiting to be transmitted in the cell buffer unit.

Furthermore, the first sorting circuit includes means for managing the cell first transmission scheduled time and the cell presence determination bit in a binary tree structure, and should be transmitted with the highest priority by using past sorting results. Select a VC. The second sorting circuit includes means for managing the cell second transmission scheduled time and the cell presence determination bit according to claim 4 in a binary tree structure, and uses the past sorting result to transmit the cell with the highest priority. Select the VP to be used.

Next, the second scheduled transmission time calculating unit further calculates the cell first transmission scheduled time of the VC selected by the first sorting unit, and the cell second transmission calculated by the second scheduled transmission time calculating unit. A time adjustment circuit that is later than the scheduled time and uses the cell first scheduled transmission time as the cell second scheduled transmission time when the cell presence determination bit of the VC selected by the first sorting unit is set. By including the above, the scheduled transmission time of the VP and the scheduled transmission time of the VC can be matched.

Furthermore, when priority control is performed between the service classes in the VP, the VCs selected by the first sorting unit in the second scheduled transmission time calculation unit for each priority are: Among the VCs in which the cell presence determination bit is set, the cell first transmission scheduled time of the VC having the earliest cell first transmission scheduled time is the cell second transmission scheduled calculated by the second scheduled transmission time calculating unit. When it is later than the time, the cell first transmission scheduled time is used as the cell second scheduled transmission time, and the cell presence determination is performed for all VCs selected for each priority by the first sorting unit. When the bit is not set, a time correction circuit that does not change the cell second scheduled transmission time is provided. At this time, when the cell existence determination bit is not set in all the VCs selected by the first sorting unit for each priority in the VP in the second scheduled transmission time calculation unit, the VP The cell presence determination bit for the VP is reset, and when the cell presence determination bit is set for any of the VCs selected by the first sorting unit for each priority within a certain VP, the cell for the VP is set. It has the function of setting the existence determination bit. As a result, it is possible to create a situation in which the VC in the VP selected by the second sorting circuit always contains a cell waiting to be transmitted.

The processing performed by the first sorting circuit and the processing performed by the second sorting circuit can be performed in parallel. As a result, the time required for the sorting process can be shortened.

The second object can be achieved by providing the traffic shaping device of the present invention as a trunk attached to the exchange switch and replacing the VP with a line (low speed line).

Further, in order to achieve the above third goal,
According to the present invention, a packet transmission terminal or a packet switch is provided with a packet buffer unit for temporarily accumulating packets received by a packet and a packet first scheduled time for keeping a transmission interval according to a band determined for each packet priority. A first scheduled transmission time calculating unit for calculating, and a first sorting unit for selecting a packet priority with the earliest packet first scheduled transmission time calculated by the first scheduled transmission time calculating unit,
A second scheduled transmission time calculating unit for calculating a second scheduled transmission time of the packet, which protects the transmission interval according to the contracted bandwidth for each packet transfer destination, and a second scheduled transmission of the packet calculated by the second scheduled transmission time calculating unit. A second sorting unit that selects a packet transfer destination having the earliest time, and whether or not a packet belonging to the packet transfer destination selected by the second sorting unit may be transmitted is determined. If it is good, it is determined whether or not the packet belonging to the packet priority selected by the first sorting unit may be transmitted,
If the packet can be transmitted, the traffic shaping device is provided with a transmission control unit that reads the packet from the packet buffer unit and transmits the packet.

Further, when the packet is read from the packet buffer, a function of extracting the packet length information described in the header of the packet is provided, and in the first scheduled transmission time calculating unit, it is proportional to the packet length information. The first scheduled transmission time of the packet is calculated using the transmission interval, and the second
The scheduled transmission time calculation unit calculates the packet second scheduled transmission time using a transmission interval proportional to the packet length information.

The traffic shaping apparatus for the packet transmitting terminal or the packet switch is the above-mentioned A.
It has the same structure as the traffic shaping device for the TM transmission end or ATM switching switch.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION A traffic shaping apparatus to which the present invention is applied will be described in detail below as an embodiment of the present invention (Embodiment 1). The embodiment shown below is based on AT
The M transmitting terminal simultaneously performs VP shaping and VC shaping, and four service classes (CBR, V
(BR, ABR, UBR) is an example of a traffic shaping device that performs priority control between classes.

FIG. 3 shows a block diagram of an ATM transmission terminal 300 connected to the public ATM network 340.
The ATM transmission terminal 300 is composed of an upper layer processing unit 360 including a CPU and a memory, and a line interface unit 324 for the public network 340. The upper layer processing unit operates an upper protocol (for example, IP (Internet Protocol)) for transferring information using the ATM network, and generates an upper packet which can be recognized by the upper protocol.
Terminate.

The line interface section 324 further includes the following components. SAR (Segmentation And Rea
(ssembly) 350 is a part for converting (dividing / assembling) the upper packet generated by the upper layer processing unit 360 and the ATM cell (fixed length of 53 bytes). Therefore, the processing from the SAR to the upper layer processing unit is performed in the form of an upper packet, and the processing from the SAR to the public ATM network side is performed in the form of an ATM cell. The conversion may be done by hardware or software. The traffic shaping unit 100 transmits cells at transmission intervals that protect the band contracted with the public ATM network 340. The present invention mainly relates to the traffic shaping unit 100. The optical module 374 converts an ATM cell into a signal corresponding to a physical line such as an optical fiber and transmits / receives the signal. still,
SAR is not required when variable length packets are used.

FIG. 1 shows a traffic shaping unit 100.
3 is a block diagram showing the configuration of FIG. Further, FIG. 4 is an operation flow diagram of the traffic shaping unit 100, and FIG.
Is the time chart. The traffic shaping unit 100 to which the present invention is applied includes the following components. The traffic shaping unit includes a cell buffer unit 110 that queues cells in a queue for each VC, a VC scheduled transmission time calculation unit 130 that calculates a scheduled transmission time according to the contracted bandwidth of the VC, a same VP, and a same service class. A VC sorting unit 135 that selects the VC to be transmitted with the highest priority from among the VCs that belong to it, a scheduled VP transmission time calculation unit 140 that calculates a scheduled transmission time that also conforms to the scheduled VC transmission time according to the contracted bandwidth of the VP, and all Transmission control that determines the final cell transmission using the sorting results of the VP sorting unit 145, the VP sorting unit 145, and the VC sorting unit 135 that selects the VP that is most preferentially transmitted from among the VPs and that is transmitted to the cell buffer unit 110 It is composed of a section 120.

The cell buffer unit 110 stores a cell buffer 111, which is a buffer for temporarily storing cells, and a cell buffer address for realizing ATM cell queuing for each VC in the cell buffer. Also, V
A cell buffer address memory 112 which is a buffer for storing information on the queue length for each C and each VP;
The cell buffer write control circuit 113 is a control circuit that writes the cells received from the AR 350 into the cell buffer, and the cell buffer read control circuit 114 that reads the cells to be transmitted from the cell buffer to the optical module.

The scheduled VC transmission time calculation unit 130 includes a scheduled VC time calculation circuit 131 that calculates a scheduled transmission time of a VC that has received or transmitted a cell (a concrete calculation method will be described later).

The VC sorting unit 135 receives cells,
Alternatively, the VP to which the transmitted VC belongs and the V that selects the VC to be transmitted with the highest priority in the service class
It has a C binary tree sort circuit 136. Furthermore, the information necessary for the VC binary tree sort circuit to perform sorting (VC
Identification number, scheduled VC transmission time, VLD of VC (flag indicating whether or not there is a cell waiting to be transmitted in the VC) (hereinafter,
These three are collectively referred to as VC sorting information)) and have a VC sorting information memory 137. This VP sorting information is managed by a binary tree, and its memory map is shown in FIG. 7 (details will be described later).

The VP scheduled time calculation unit 140 calculates the scheduled transmission time according to the contracted band of the VP on which the cell is received or transmitted, and a VP scheduled time calculation circuit 141.
The scheduled VP transmission time calculated by the scheduled P time calculation circuit is
It is composed of a VP time adjustment circuit 142 that corrects the value to a scheduled transmission time of the VC (a specific calculation method will be described later).

The VP sorting section 145 has a VP binary tree sorting circuit 146 that selects the VP to be transmitted with the highest priority among all the VPs. Furthermore, the VP binary tree sort circuit 1
Information required for 46 to perform sorting (VP identification number, scheduled VP transmission time, VLD of VP (flag indicating whether or not there is a transmission waiting cell in the VP) (hereinafter, these three are collectively referred to as VP It has a VP sorting information memory 147 in which (hereinafter referred to as sorting information) is stored.
The VP sorting information is also managed by the binary tree, and its memory map is shown in FIG. 6 (details will be described later). The traffic shaping unit 100 to which the present invention is applied receives one cell within one cell processing time and transmits one cell by repeating the following six processes during one cell processing time. Here, the 1-cell processing time means the time required for the traffic shaping device to transmit / receive 1 cell (53 bytes). For example, 155.88 Mbps
In a traffic shaping device with (Bit Per Second) shaping capability, the processing time per cell is 2.72μ.
Seconds.

(Process 1) Reception cell determination process (Process 2) Scheduled transmission time calculation (at cell reception) (Process 3) Sorting process (at cell reception) (Process 4) Transmission VC selection process (Process 5) Scheduled transmission time Calculation (during cell transmission) (Process 6) Sorting process (during cell transmission) Of the above six processes, (Process 1) to (Process 3) are processes at the time of cell reception, and (Process 4) to (Process 6) are This is a process at the time of cell transmission. The respective processes will be described in detail below with reference to FIGS. 1, 4 and 5. Further, in the following, in order to identify a plurality of VPs, a VP identification number p is added, and
Notated as P (p). Similarly, VCs belonging to VP (p)
In order to identify, VC (p,
Notated as c). (Process 1) Received cell determination process This process is a process performed at time 500 in FIG. Note that FIG. 5 shows a time chart of the traffic shaping unit to which the present invention is applied.

The cells arriving at the traffic shaping unit 100 are temporarily stored in a queue for each VC. Specifically, first, the cell buffer write control circuit 113
Based on the VPI (Virtual Path Identifier) for identifying the VP and the VCI (Virtual Connection Identifier) for identifying the VC described in the header of the received cell, the VP to which the cell belongs or the VC is determined. Next, the traffic shopping unit reads an address of an unused cell buffer from the cell buffer address memory 112 in order to perform queuing of the received cell for each VC, and an area indicated by the cell buffer address in the cell buffer 111. Write the received cell to (400, 40 in FIG. 4)
1). The cell buffer address is stored in the cell buffer address memory 112 as a cell buffer address in which the received cell is recorded.

In the following, the VP to which the receiving cell belongs is set to VP.
(r), the VC to which the receiving cell belongs is VC (r, s).
Upon receiving the cell, the cell buffer write control circuit 113 outputs the cell reception signal 99 indicating that the cell has been received to the VC.
VC scheduled time calculation circuit 131 and V of the scheduled transmission time calculation unit
Notify the VP scheduled time calculation circuit 141 of the P transmission scheduled time calculation unit. Simultaneously with the cell reception signal 99, the VC scheduled time calculation circuit 131 is notified of the VC identification number r, s, and the VP scheduled time calculation circuit 141 is notified of the VP identification number r. (Process 2) Scheduled Transmission Time Calculation (At Cell Reception) This process is a process performed at times 502-1 and 502-2 in FIG. Upon receiving the cell reception signal 99, the VC transmission scheduled time calculation circuit 131 calculates the VC transmission scheduled time of VC (r, s) (the unit is “1 cell processing time”). The calculation result is stored in the VC sorting information memory 137. Upon receiving the cell reception signal 99, the VC scheduled transmission time calculation circuit 131 reads out the VC read from the VC sorting information memory 137 of the VC sorting unit 135 in order to determine whether or not a transmission waiting cell exists in the VC. (r,
It is checked whether the VLD of s) is "0" or "1" (402 in FIG. 4). When VLD is '1', it indicates that a cell waiting to be transmitted already exists in the VC, and if the scheduled transmission time is updated, the contracted bandwidth cannot be protected. Should not be changed. On the other hand, when VLD is “0”, if the calculated VC transmission scheduled time is in the future when the current time is used as the standard, updating the scheduled transmission time makes it impossible to keep the contracted bandwidth. Although the scheduled time should not be updated, if the already calculated scheduled VC transmission time is past or the same time as the current time as a reference, the cell is ready for transmission. Therefore, the scheduled transmission time may be updated to an appropriate time. Therefore, when VLD is '0', V that has already been calculated
The scheduled C transmission time is read from the VC sorting information memory 137, and it is checked whether the time is in the future or the same as the past or the current time with reference to the current time (404 in FIG. 4). In the former case (future), the scheduled VC transmission time is not changed. In the latter case (past or present), in order to transmit the cell of the VC earliest (I do not know whether it is actually transmitted), the scheduled VC transmission time = current time + 1 is updated (405 in FIG. 4). . In any of the above cases, when the cell reception signal 99 is received, the VLD of the VC is
= “1” is set (403 in FIG. 4). Similarly, the VP transmission scheduled time calculation circuit 140 which receives the cell reception signal 99 calculates the VP transmission scheduled time. The calculation of the scheduled VP transmission time is performed in exactly the same procedure as the calculation of the scheduled VC transmission time. That is, the VLD of VP (r) is checked, VLD is '0', and the VP that has already been calculated is checked.
Only when the scheduled transmission time is the same as the past or the current time, the scheduled VP transmission time = current time + 1 is updated, and in other cases, the already calculated scheduled VP transmission time is not updated.

The calculation of the scheduled VP transmission time can be performed in exactly the same procedure as the calculation of the scheduled VC transmission time, so that the same circuit can perform the calculation in time series.
Calculation of scheduled VC transmission time and calculation of scheduled VP transmission time
By using a VC scheduled time calculation circuit and a VP scheduled time calculation circuit, which are independent circuits, it is possible to perform calculations in parallel in time and shorten the calculation time. In FIG. 4, calculation steps in the VP scheduled transmission time calculation circuit are not shown. The VP transmission scheduled time calculation circuit
In parallel with steps 402 to 405 of FIG.
P Calculate the scheduled transmission time. (Process 3) Sorting process (when a cell is received) This process can be divided into the following three processes.

(Process 3-1) VC Sorting Process (When Cell is Received) (Process 3-2) Corrected VP Transmission Time (When Cell is Received) (Process 3-3) VP Sorting Process (When Cell Is Received) explain. (Process 3-1) VC Sorting Process (at Cell Reception) This VC sorting process is shown in FIG.
This is a process performed at time 506 after. VC (r, s)
When the scheduled VC transmission time of is updated in VP (r),
In addition, since there is a possibility that the VC to transmit the cell earliest in the service class to which VC (r, s) belongs (hereinafter, temporary transmission VC) may change, the VC binary tree sorting circuit 13
In step 6, sorting is performed to obtain the provisional transmission VC (406 in FIG. 4). Hereinafter, a method of selecting a provisional transmission VC within the same VP and the same service class will be described. 8 VCs (VC (p, 0) ~ VC for simplicity)
An example of selecting from (p, 7)) will be described with reference to FIGS. 9 and 10. First, the relationship of information stored in each element of the binary tree will be described. Hereinafter, in FIG. 9, the vertex 900 of the binary tree is referred to as a root, the bases 930 to 937 are referred to as leaves, an element on the root side as viewed from an arbitrary element is referred to as a parent, and two elements on the leaf side are referred to as children. The binary tree leaves 930 to 937 (arranged in order of VC identification number) store the scheduled transmission time of each VC and VLD (numerical value (0 or 1) in parentheses indicates VLD). Other than the leaf, the VC identification number, the scheduled transmission time, and the VLD are stored, and finally the information of the VC satisfying the following conditions is stored in the root. (Condition 1) VLD is "1". (A VC with a transmission waiting cell is selected with priority over a VC without a transmission waiting cell) (Condition 2) The scheduled transmission time is earlier. (Always select the VC to be transmitted with the highest priority) In order to select a VC that satisfies the above (Condition 1) and (Condition 2) as a VC to be stored in the root, other elements except leaves are ]-[3], the information of either of the two children is stored as it is.

[1] When both VLDs of the children are "1",
In order to satisfy the above (condition 2), a child whose scheduled transmission time is earlier is selected. For example, in the element 920 of the binary tree, the information of the element 931 is stored as it is, and the VC identification number is VC (p, 1). If the time is the same, it doesn't matter.

[2] When the VLD of one child is "1" and the other is "0", the one whose VLD is "1" is unconditionally selected in order to satisfy the above (condition 1). For example, in the element 922 of the binary tree, the element 935 is selected and the information thereof is stored as it is, even though the scheduled transmission time of the element 934 is earlier.

[3] When both VLDs of the children are "0",
In order to satisfy the above (condition 2), a child whose scheduled transmission time is earlier is selected. For example, in the element 921 of the binary tree, the information of the element 932 is stored as it is, and the VC identifier is VC (p, 2). If the time is the same, it doesn't matter.

There are four binary trees having such a structure for each VP, and they are assigned to CBR, VBR, ABR and UBR. For example, in the root of the CBR binary tree, the identification number of the VC (provisional transmission VC) to be transmitted with the highest priority in the CBR, the scheduled transmission time, and the VLD are stored.

The binary tree is constructed according to the above rules, but when the cell is received, the scheduled transmission time and VLD are set.
, The binary tree information changes, and the provisional transmission VC
Can change. However, not all information on the binary tree is updated here. For example, in FIG. 9, when a cell of VC (p &# 604) (corresponding to the leaf 934) is received and the scheduled transmission time of the VC and VLD are updated, the elements of the binary tree are updated. , Only the element on the route from the element 934 storing the information of the VC to the root 900. In the case of this example, 922 and 91
Only the information of the elements of 1,900 is [1] in this order.
By updating according to the rule of [3], the VC to be transmitted with the highest priority is stored in the root 900 of the binary tree, and the above-described binary tree structure is maintained (FIG. 10).

With the above procedure, the provisional transmission VC in the same VP and the same service class can be selected. The actual address allocation of the VC sorting information memory 137 will be described later. (Processing 3-2) VP transmission scheduled time adjustment (at the time of cell reception) Next, the VP time adjustment circuit 142 calculates the VP transmission scheduled time according to the VP contracted band calculated by the VP scheduled time calculation circuit 141 as the VC transmission schedule. It is corrected to a value that matches the time (407 in FIG. 4). This process is a process performed at time 507 in FIG. FIG. 8 shows the VP time adjustment circuit 14
2 shows a detailed block diagram of FIG. VP scheduled time calculation circuit 1
Using the estimated VP transmission time calculated in step 41 as it is, V
When P-sorting is performed, there occurs a case in which even a VC that is in a transmittable state is not in a transmittable state even in a VC that should be transmitted with the highest priority in the VP. In this case, the bandwidth of the own VP and the bandwidth of the other VP cannot be used to the maximum extent, so that the above VP scheduled time adjustment processing is necessary. Specifically, the following processing is performed. The provisional transmission VC of CBR in VP (r) selected by the VC binary tree sort circuit 136 is set to VC (r,
c), the provisional transmission VC of VBR is VC (r, v), the provisional transmission VC of ABR is VC (r, a), and the provisional transmission VC of UBR is V
Let C (r, u). First, the selection circuit 810 of FIG.
VC read from C sorting information memory 137
(r, c), VC (r, v), VC (r, a) and VC (r, u)
Among the scheduled transmission times of 1, the time that is the earliest in time is calculated as the provisional VC scheduled transmission time. However, a VC whose VLD is '0' is not included in this time calculation. VC
(r, c), VC (r, v), VC (r, a) and VC (r, u)
If all the VLDs are 0, the provisional VC transmission scheduled time is set as the current time. This provisional VC transmission scheduled time indicates the earliest possible transmission time among the plurality of VCs belonging to VP (r). In other words, if the current time reaches the provisional VC transmission scheduled time, at least one VC in VP (r) can transmit a cell (VP
(It is a separate issue whether or not the contracted bandwidth of (r) is kept). next,
The selection circuit 811 of FIG. 8 is the VP scheduled time calculation circuit 141.
And the provisional VC obtained by the selection circuit 810
Compare the scheduled transmission times, select a future time, and select V
It is the scheduled transmission time of P (r). By this, the selected V
The scheduled transmission time of P (r) indicates the earliest time at which one or more transmittable VCs exist in VP (r) while also keeping the contracted band as VP (r). In other words,
If the current time reaches the scheduled transmission time of VP (r), VP (r)
At least one of the VCs can transmit cells (which also protects the contracted bandwidth of VP (r)). On the other hand, the OR circuit 820 of FIG.
VC (r, c), VC (r, v), VC (r, a) obtained from
If any of the VLDs of VC and r (u) is "1", the VLD of the VP is set to "1". (Processing 3-3) VP Sorting Process (during Cell Reception) This process is a process performed at time 508 in FIG. As described above, the VP sorting information of each VP is also managed by the binary tree. As with VC, VP
When the scheduled VP transmission time of (r) is updated, there is a possibility that the VP that should transmit the cell earliest (hereinafter, provisional transmission VP) may have changed, so the VP binary tree sorting circuit 146 performs sorting. (408 in FIG. 4). The operation of the VP binary tree sort circuit 146 is performed by the VC binary tree sort circuit 13
The operation is the same as that of No. 6, and the root of the VP binary tree is
Among them, the VP identification number of the VP to be transmitted with the highest priority, the scheduled transmission time, and the VLD are stored. The actual address allocation of the VP sorting information memory 147 will be described later. (Process 4) Transmission VC Selection Process This process is a process performed at time 509 in FIG. Below, as a result of comparing the current time with the scheduled VC transmission time (or the scheduled VP transmission time), when the scheduled VC transmission time (or the scheduled VP transmission time) is the same time as the past or the current time with reference to the current time, The VC (or VP) will be called a transmittable state. The provisional transmission VP selected by the VP binary tree sort circuit 146 is set to V
The provisional transmission VCs for each service class of P (i) and VP (i) are VC (i, c), VC (i, v), VC (i, a), and VC (i, u). Transmission control circuit (transmission control unit) 1
Reference numeral 20 always reads the VLD and the scheduled transmission time from the address corresponding to the root of the VP sorting information memory 147, compares VLD = '1' and the scheduled transmission time with the current time, and sets VP (i) to the transmittable state. Monitor whether or not
In order to transmit the cell in the transmission enabled state, the transmission permission signal 95 is sent to the cell buffer read control circuit 114. V
When P (i) is not ready for transmission, no cell is transmitted. When VP (i) is in the transmittable state, provisional transmission VC of each service class, that is, VC (i, c), V
Inter-class priority control regarding the transmission order is performed among C (i, v), VC (i, a), and VC (i, u) (40 in FIG. 4).
9, 410). Interclass priority control is, for example, perfect priority control (Head of Line) or weighted forward priority control (Weight
ed Round Robin) etc. Strict priority control is a priority control method in which the upper class is completely prioritized, and when there is a cell waiting to be transmitted in the upper class (CBR>VBR>ABR> UBR), the cells of the lower class are not transmitted. .
In this case, VC cells belonging to the highest class are transferred with the smallest delay, but lower class cells are not transmitted until there are no higher class cells. Further, the weighted forward priority control allocates a constant band to the lower class. For example, it is possible to control the cell transmission ratio (= transmission band ratio) of “upper class: lower class” to 2: 1 or 4: 1. In either case of priority control, V
C (i, c), VC (i, v), VC (i, a), and VC
The VC whose (i, u) VLD is '0' and the VC which is not in the transmission enabled state (the scheduled transmission time is in the future based on the current time) are the cells to be transmitted even if they are finally selected. Since there is no, it is treated as the lowest priority. VC (i,
c), VC (i, v), VC (i, a), and VC (i, u), the selected VC is the VC selected as a result of the interclass priority control.
(i, j), and the cell of VC (i, j) is transmitted.

Specifically, the transmission permission signal 95 is sent to the cell buffer read control circuit 114. Transmission permission signal 9
The cell buffer read control circuit 114 which has received 5 reads the cell from the cell buffer 110 using the cell buffer address read from the cell buffer address memory 112. Then, the cell buffer read control circuit 11
4 transmits the cell to the line interface unit 324 (411 in FIG. 4). The VP (i), VC (i,
In order to correct the next scheduled cell transmission time of j), the transmission control circuit (transmission control unit) 120 outputs the cell transmission signal 98 to V
C transmission time calculation circuit 130 and VP transmission time calculation circuit 14
Notify 0. Further, the transmission control circuit 120 sends the VC identification number i, j to the VC scheduled time calculation circuit 131 at the same time as the cell transmission signal 98, and the VP scheduled time calculation circuit 14
The VP identification number i is notified to 1. (Process 5) Scheduled transmission time calculation (during cell transmission) This process is a process performed at times 512-1 and 512-2 in FIG. The VC transmission time calculation circuit 130 and the VP transmission time calculation circuit 140 which have received the cell transmission signal 98
Calculates the next scheduled cell transmission time according to the contracted bandwidth (412 in FIG. 4). The next scheduled cell transmission time is calculated using, for example, the leaky bucket method. Regarding the leaky bucket method, for example, “The ATM Forum TM4.0 N
ormative Annex C: Traffic Contract Related Algori
thms and Procedures (P.71) ”(Prior Art 3).

Alternatively, as another method for calculating the scheduled cell transmission time, the transmission interval value corresponding to the contracted bandwidth may be stored and the following calculation may be performed.

Next cell transmission scheduled time = current cell transmission scheduled time + transmission interval value VC (i, j) Even if a cell is transmitted, there is still a cell remaining in the queue for each VC (transmission waiting cell In some cases, it is natural to calculate the next scheduled transmission time, but even if the queue for each VC is emptied by transmitting cells (there is no cell waiting to transmit), the next scheduled transmission time is calculated. calculate.
This is, for example, VC (i, j) at the next cell reception timing.
It is necessary to keep the contracted band and to transmit cells even when receiving cells. If a contract for the transmission band is not made in a UBR class VC, the next cell transmission scheduled time = this cell transmission scheduled time + 1 in order to be able to transmit cells at any time. .

Further, VLD is set to "1" when cells remain in the queue for each VC, and is set to "0" when the queue for each VC becomes empty.

The above calculation of the scheduled transmission time is exactly the same for the VP. (Process 6) Sorting process (during cell transmission) (Process 6-1) VC sorting process (during cell transmission) (Process 6-2) Corrected scheduled VP transmission time (during cell transmission) (Process 6-3) VP sorting process (During Cell Transmission) This process is a process performed at times 513 to 515 in FIG. The details of sorting are exactly the same as when receiving cells. When the scheduled cell transmission time is modified, the provisional transmission VC and the provisional transmission VP may have changed, so the VC binary tree sorting circuit 136 and the VP binary tree sorting circuit 146 perform sorting (see FIG. 4 from 413 to 415).

The above processes (Process 1) to (Process 6) are 1
The processing is performed within the cell processing time, and the processing from (Process 1) is repeated again.

Next, the VP sorting information memory 147.
A method of managing the VP sorting information of the above and the VC sorting information of the VC sorting information memory 137 will be described with reference to FIGS. 6 and 7. In the following, the number of VPs that can be supported is M (= 2 to the m-th power), and the number of VCs bundled in each VP is N (= 2 to the n-th power).

FIG. 6 shows the VP sorting information memory 14
7 shows the relationship between the storage format of No. 7 and the binary tree for VP. VP
Elements of the binary tree for use and the VP sorting information memory 14
The relationship of the 7 addresses is as shown below. In the following, the address is represented by a binary number (m + 1 bit). [1] The address corresponding to the root of the binary tree is 000 ... 00
It is number 1. [2] Address: The parent address of the element at address xyy ... yyz is address 0xy ... yyy, and the addresses of the two children are address yyy ... yz0 and address yyy ... yz1.

When information is stored according to the rules [1] and [2], the address corresponding to the leaves of the binary tree is 10
0 ... 000 to 111 ... 111 (2 m in total)
Exponentiation = M). If the addresses of the memory are managed according to the above rules, the address generation circuit for memory access performed at the time of sorting can be easily configured. That is, the comparison partner at address xyy ... yyz is x
Information stored in addresses yy ... yy (z) ((z) indicates "0" ← → "1 'inversion of z), and the comparison result is written in addresses 0xy ... yyy.

Therefore, the sorting of M elements is m
It can be performed by shifting operation for m times and inverting operation for m times.
As an example, a memory map of the VP sorting information memory 147 in the case of 8VP (m = 3) is shown in FIG. As described above, the VP sorting information memory 147 stores the VP identification number 600, the scheduled VP transmission time 601, and the VLD 602 of the VP.

Although the method of managing the VP sorting information has been described above with reference to FIG. 6, the VC sorting information can be managed in exactly the same manner. 7 is 2
7 shows a memory map of a VC sorting information memory 137 when supporting four service classes within a VP (m = 1). The VC sorting information memory 137 stores V
It is stored in exactly the same manner as the P sorting information memory 147, except that the sorting is terminated when one VC is selected for each VP and each service class (8 VCs in this example). Sorting ends when is selected).

In the above-described embodiment, the information of the scheduled VC transmission time is reflected in the scheduled VP transmission time in order to make maximum use of the contracted bandwidth of the own VP and the bandwidth of the line. (Depending on operation), scheduled VP transmission time and VC
It is also possible to calculate the scheduled transmission time completely independently. In this case, as described above, when the current time has reached the VP transmission scheduled time but has not reached the VC transmission scheduled time, it is possible to skip the transmission timing of the own VP (the current time is Waiting until the scheduled VC transmission time is reached significantly reduces the bandwidth utilization rate). This slightly reduces the transmission band of the own VP, but as shown in the time chart of FIG. 11, VC sorting and VP sorting can be performed in parallel, so that the processing time required for sorting is greatly reduced. You can When the number of supported VPs (= M) and the number of VCs bundled in each VP (= N) are almost equal, the time required for sorting can be reduced to a maximum of 1/2.

Further, in the above-mentioned embodiment, an example in which the traffic shaping device of the present invention is applied to an ATM transmission terminal has been shown. However, as described above, the traffic shaping device is not limited to the ATM transmission terminal and is private. It may be installed at important points in the network such as relay points from the network to the public network.

FIG. 12 shows a configuration diagram in which the traffic shaping device of the present invention is applied to an ATM switch 301 connected to a public ATM network 340. ATM switch 30
Reference numeral 1 is a line interface unit 320, 321, a switch unit 310, and a public A for the ATM terminals 330, 331.
The line interface unit 325 for the TM network 340, the traffic shaping unit 100 compatible with the public ATM network, and the optical module 375 are included.

As another embodiment of the present invention, a trunk type traffic shaping device in which traffic shaping of a plurality of lines is performed by one traffic shaping device will be described (second embodiment).

FIG. 13 shows an example in which an ATM switch is constructed as a trunk type traffic shaping device. The cell flow generated by the terminals 332 and 333 is AT
Line interface units 322 and 323 of the M switch 302
Is input to the switch unit 311 via. Switch part 3
No matter which output destination line is determined in 11, the cell is temporarily transferred to the traffic shaping unit 101. The traffic shaping unit 101 considers the VP sorting of the first embodiment as line sorting and performs exactly the same operation. The output cells of the traffic shaping unit 101 are sent to the public ATM network 3 from the line interface units 326 and 327 of the respective output lines via the switch unit 311 again.
40 is transmitted. When the cells output from the traffic shaping unit 101 are accumulated in the cell buffer of the switch, the performed traffic shaping becomes meaningless. Therefore, the traffic shaping unit 101
The cells transmitted from the cell must be transferred to the network with the highest priority.

As an example in which the shaping devices of the first and second embodiments are combined, a VP shaping device using a trunk system can be constructed (third embodiment). Although the structure is exactly the same as that of the shaping apparatus of FIG. 13, the traffic shaping unit 101 performs traffic shaping in three stages: VC-based shaping, VP-based shaping, and line-based shaping. Each of the VC unit, the VP unit, and the line unit is provided with a scheduled transmission time calculation circuit and a sorting circuit, and when all are ready for transmission, a cell is transmitted. As in the second embodiment, the transmission cells of the traffic shaping unit 101 must be transferred to the public ATM network 340 with the highest priority.

Although the embodiment of the present invention for the ATM network has been described above, the present invention is not an invention specialized for ATM, and traffic shaping can be similarly performed for a variable length packet. Next, a traffic shaping apparatus for IP packets will be described (Example 4).

FIG. 15 is a diagram showing an example of the configuration of the router. The router 1500 uses the packet transfer network 1 (155
0), the network interface units 1520 and 1530 corresponding to the packet transfer network 2 (1551) and the destination by referring to the header of the IP packet, and the routing unit 1 which sends the destination to the network interface unit for each destination.
It is composed of 510. Further, the network interface units 1520 and 1530 are composed of a traffic shaping unit 1400 and an optical module 1522 for converting a packet into a signal corresponding to a physical line such as an optical fiber and transmitting the signal. The reverse conversion is also performed by the optical module.

FIG. 14 is a block diagram showing the configuration of the traffic shaping unit 1400 of FIG. 15 for IP packets. The traffic shaping unit 1400 corresponding to the IP packet to which the present invention is applied is the point that the processing for the ATM cell of the traffic shaping apparatus 100 shown in FIG. 1 is converted into the processing for the IP packet, and the packet read control circuit 1413 converts the IP packet The configuration is different only in that a packet packet length identification circuit 1499 for identifying the IP packet length information described in the IP packet header when reading is read. The identified packet length is the priority scheduled time calculation circuit 143 of the first scheduled transmission time calculation unit 1430.
1 and the contract scheduled time calculation circuit 1441 of the contract transmission scheduled time calculation unit 1440, which is used when calculating the scheduled transmission time.

FIG. 16 shows the concept of bandwidth control of the traffic shaping unit 1400 for IP packets. The received IP packet has the priority control circuit 1521.
At 0, it is sorted into a queue for each transfer destination and for each packet priority, and is queued in the packet buffer 15211. At the time of packet transmission, a transfer destination that is in a state in which the first read circuit 15213 may transmit it is selected (in FIG. 16, one transfer destination is selected from a plurality of transfer destination candidates), and the first transfer circuit corresponding to the selected transfer destination is selected. The second read circuit 15212 performs priority control on the transmission order of each packet, reads an IP packet with a high priority from the packet buffer, and transfers it to the optical module 1522. By doing so, the packets having the highest priority among the transfer destinations in the transmission-enabled state are transmitted in order. When each circuit of FIG. 16 is made to correspond to the circuit of FIG. 14, the priority control circuit 15210 of FIG. 16 serves as the packet buffer write circuit 1413 of FIG.
The reading circuit 15212 of FIG. 14 is used as the first sorting unit 1435 of FIG.
5213 can be realized as the contract sorting unit 1445 in FIG. 14, respectively.

In order to send and receive IP packets, the AT
Similar to the M cell, the following (Process 1) to (Process 6) are performed.

(Process 1) Received packet determination process (Process 2) Scheduled transmission time calculation (at packet reception) (Process 3) Sorting process (at packet reception) (Process 4) Transmission packet selection process (Process 5) Scheduled transmission time Calculation (at the time of packet transmission) (Process 6) Sorting process (at the time of packet transmission) The above-mentioned processes (Process 2) to (Process 4) and (Process 6) are the same as the process for the ATM cell (fixed length). Hereinafter, (Process 1) received packet determination process and (Process 5) scheduled transmission time calculation will be described. (Process 1) Received Packet Judgment Process In the case of the above ATM cells, the VPI is added to the header of each cell.
(Virtual Path Identifier) and VCI (Virtual
Since the Connection Identifier) is described, it is possible to determine the VP or VC to which the cell belongs based on these. On the other hand, in the case of an IP packet, the unit (corresponding to VP) with which the user has a contract with the network can be associated from the source address and the destination address described in the IP packet header. The packet priority (corresponding to VC) is also described in the TOS (Type of Service) field (0th to 2nd bits) in the IP packet header.

In the traffic shaping device to which the present invention is applied, the packet buffer write circuit 1413 is used.
Then, the header of the received IP packet is referred to, the transfer destination and the priority of the received packet are determined, and the packet is queued in a queue provided in the packet buffer 1411 for each transfer destination and each priority. (Processing 5) Scheduled transmission time calculation (during packet transmission) In the priority schedule time calculation circuit 1431 and contract schedule time calculation circuit 1441 which received the packet transmission signal 93, A
Similar to the case of the TM cell, the next packet transmission scheduled time according to the contracted bandwidth is calculated. At this time, unlike the case of the ATM cell, since the packet length is variable, a fixed value transmission interval cannot be used.

FIG. 17 shows that when a fixed value transmission interval is used, (1) packets 1700 and 170 having a short packet length are used.
The transmission intervals are shown when 1 and 1702 are continuously transmitted and when (2) packets 1710, 1711 and 1712 having a long packet length are continuously transmitted. Comparing the case of (1) and the case of (2), it can be seen that the number of transmitted bytes is larger in the case of (2). Therefore, when performing traffic shaping for variable length packets,
It is necessary to make the transmission interval variable according to the packet length.

In the present invention, the packet length identification circuit 1499 for identifying the packet length is provided, and the packet buffer read circuit 1414 is used for the packet buffer 1411 to I.
When the P packet is read, the packet length information described in the IP packet header is referred to. The packet length information 91 referred to is the priority scheduled time calculation circuit 1431.
And the scheduled contract time calculation circuit 1441. Priority scheduled time calculation circuit 14 that received the packet length information 91
In 31 and the contracted scheduled time calculation circuit 1441, for example, the following calculation is performed to determine the transmission interval used for the scheduled transmission time calculation.

Transmission interval = (transmission interval of ATM cells according to contract bandwidth) × (transmission IP packet length) / 53 Here, the IP packet length is expressed in bytes.
By normalizing with 53 bytes in this way, when an IP packet with a short packet length is transmitted, the time until the next packet is transmitted is short, and when an IP packet with a long packet length is transmitted, the next packet is transmitted. You can leave a long time until. Therefore, the packet transmission interval according to the contract band can be shortened regardless of the packet length, and efficient transfer can be performed within the contract band.

In the above example, the contract bandwidth is preferentially controlled based on the priority of the IP packet.
Low delay request (3rd bit), high throughput request (4th bit), high reliability information (5th bit) of S field
You may use information such as.

[0077]

As described above, according to the present invention, when a contract is made with a public ATM network on a VP basis, it is possible to effectively use the VP band while protecting the VP contract band. It is also possible to provide a traffic shaping device capable of performing priority control among a plurality of VCs within the same VP. Further, it is possible to provide a traffic shaping device capable of shaping a plurality of output lines with one traffic shaping device. Furthermore, the present invention is not an invention specific to ATM, and can also perform traffic shaping for variable length packets.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a traffic shaping device to which the present invention is applied.

FIG. 2 is a diagram showing a concept of a line, a VP, and a VC.

FIG. 3 is a diagram showing a configuration when a traffic shaping device to which the present invention is applied is applied to an ATM transmission terminal as a VP shaping device.

FIG. 4 is a flow chart of cell reception / transmission operations of a traffic shaping unit to which the present invention is applied.

FIG. 5 is a time chart of a traffic shaping unit to which the present invention is applied.

FIG. 6 is a diagram showing a relationship between a storage format of a VP sorting information memory 147 and a VP binary tree.

FIG. 7 is a diagram showing a relationship between a storage format of a VC sorting information memory 137 and a VC binary tree.

FIG. 8 is a detailed block diagram showing the structure of a VP time adjustment circuit 142.

FIG. 9 is a diagram showing a relationship of information stored in each element of a binary tree for VC.

FIG. 10 is a diagram showing a relation of information stored in each element of a binary tree for VC.

FIG. 11 is a time chart of a traffic shaping unit when a set of a scheduled transmission time calculation circuit and a sorting circuit is used in a time division manner.

FIG. 12 is a diagram showing a configuration when a traffic shaping device to which the present invention is applied is applied to an ATM exchange as a VP shaping device.

FIG. 13 is a diagram showing the configuration of a traffic shaping device to which the present invention is applied when it is applied to an ATM exchange as a trunk-type shaping device.

FIG. 14 is a block diagram showing a configuration of an embodiment of an IP packet traffic shaping device to which the present invention has been applied.

FIG. 15 is a block diagram showing an example of a configuration of a router.

FIG. 16 is a diagram showing the concept of bandwidth control of an IP packet traffic shaping unit.

FIG. 17 is a diagram showing the relationship between packet length and transmission interval.

FIG. 18 is a diagram showing a network configuration according to a fourth embodiment of the present invention.

FIG. 19 is a diagram showing a network configuration when a contract is made for each VP.

[Explanation of symbols]

100, 101: Traffic shaping unit, 110:
Cell buffer unit, 120: transmission control unit, 130: VC scheduled transmission time calculation unit, 135: VC sorting unit, 14
0: Scheduled VP transmission time calculation unit, 142: VP time correction circuit, 145: VP sorting unit, 300: ATM transmission terminal, 301, 302: ATM switch, 310, 31
1: switch unit, 320 to 326: line interface unit, 330 to 333 ATM terminal, 340: public ATM
Network, 350: SAR (upper packet / ATM cell conversion circuit), 360: upper layer processing unit, 1400: IP packet compatible traffic shaping device, 1499: packet length identification circuit.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takemi Yazaki             1-280, Higashi Koikekubo, Kokubunji, Tokyo             Central Research Laboratory, Hitachi, Ltd. (72) Inventor Noriyuki Tanaka             810 Shimo-Imaizumi Stock Exchange, Ebina City, Kanagawa Prefecture             Hitachi, Ltd. Server Development Division (72) Inventor Yoshinori Yamamura             810 Shimo-Imaizumi Stock Exchange, Ebina City, Kanagawa Prefecture             Hitachi, Ltd. Server Development Division F term (reference) 5K030 GA03 HA10 HB28 HB29 KX12                       LA03 LB19 LC02

Claims (21)

[Claims] 1. A first scheduled transmission time calculating unit for calculating a first scheduled cell transmission time for transmitting a cell based on a bandwidth contracted for each connection, and a bandwidth contracted for each connection bundle in which a plurality of the connections are collected. A second scheduled transmission time calculation unit that originally calculates a scheduled second cell transmission time for transmitting the cell, and uses the second scheduled cell transmission time when transmitting the cell or determines the scheduled first cell transmission time. And a means for selecting whether or not to use the communication apparatus. 2. The first cell transmission scheduled time is set as the second cell transmission scheduled time when the first cell transmission scheduled time is after the second cell transmission scheduled time and a cell exists in the connection. The communication device according to claim 1, wherein the communication device is used. 3. A first scheduled transmission time calculating unit for calculating a first scheduled packet transmission time for transmitting a variable-length packet based on a band contracted for each connection, and a contract is made for each connection bundle in which the plurality of connections are grouped. A second scheduled transmission time calculating unit for calculating a scheduled transmission time of a second packet for transmitting a variable length packet based on a band; and using the scheduled transmission time for the second packet when transmitting a variable length packet, or the first packet And a means for selecting whether to use the scheduled transmission time. 4. The first based on the bandwidth contracted for each connection
A first scheduled transmission time calculating section for calculating a scheduled cell transmission time; a first sorting section for selecting a connection having the earliest scheduled first cell transmission time calculated by the first scheduled transmission time calculating section; Calculates the scheduled second cell transmission time based on the transmission control unit that transmits cells when the cells belonging to the connection selected by the sorting unit may be transmitted, and the band contracted for each connection bundle in which the plurality of connections are grouped A second scheduled transmission time calculating section for
A second sorting unit that selects the connection bundle having the earliest scheduled transmission time of the second cell calculated by the transmission scheduled time calculation unit, and a cell that belongs to the connection bundle selected by the second sorting unit may be transmitted. In this case, a communication device is provided with means for operating the transmission control unit. 5. A means for setting a priority for a connection in each of the connection bundles, wherein:
The sorting unit selects a connection having the earliest scheduled first cell transmission time for a group of connections having the same priority in each connection bundle, and the transmission control unit is in a state where transmission is possible, and The communication device according to claim 4, wherein a cell belonging to a connection having a high priority is transmitted. 6. The second cell transmission schedule when the first cell transmission schedule time is after the second cell transmission schedule time and a cell exists in the connection selected by the first sorting unit. The communication device according to claim 4, wherein the scheduled transmission time of the first cell is used as the time. 7. There is a cell to be transmitted to a connection selected for each priority by the first sorting unit,
The communication device according to claim 5, wherein when the scheduled cell transmission time is in the future from the scheduled second cell transmission time, the scheduled first cell transmission time is used as the scheduled second cell transmission time. 8. A first scheduled transmission time calculating unit for calculating a scheduled first packet transmission time for transmitting a variable-length packet based on a bandwidth contracted for each connection, and contracted for each connection bundle in which a plurality of the above-mentioned connections are collected. A communication device comprising: a second scheduled transmission time calculating unit that calculates a second scheduled packet transmission time for transmitting a variable-length packet based on a band. 9. A first calculation unit for calculating a first transmission interval for transmitting a variable-length packet based on a band contracted for each connection; and a variable band based on a band contracted for each connection bundle in which the plurality of connections are collected. And a second calculation unit that calculates a second transmission interval for transmitting a long packet. 10. A cell buffer unit for temporarily storing received cells in a terminal or a switching switch connected to an asynchronous transfer network for starting cell transfer after setting a connection in advance, and for each connection. A first scheduled transmission time calculating unit that calculates a first scheduled transmission time of a cell that keeps a transmission interval according to a contracted band, and a connection that has the earliest scheduled first transmission time of the cell calculated by the first scheduled transmission time calculation unit. It is determined whether or not a cell belonging to the connection selected by the first sorting section for selecting the cell and the connection selected by the first sorting section may be transmitted, and if the cell may be transmitted, the cell is transmitted from the cell buffer section. In a traffic shaping device equipped with a transmission control unit for reading and transmitting a packet, a plurality of the above-mentioned connections are bundled according to a contracted band for each connection bundle. A second scheduled transmission time calculating unit that calculates a second scheduled transmission time of a cell that adheres to the transmission interval; and a connection bundle that selects the earliest cell second scheduled transmission time calculated by the second scheduled transmission time calculation unit. Two sorting units are provided, it is determined whether or not cells belonging to the connection bundle selected by the second sorting unit may be transmitted to the transmission control unit, and if the cells may be transmitted, the first sorting unit may be used. The sorting unit determines whether or not a cell belonging to the connection selected can be transmitted, and if the cell can be transmitted, a function of reading the cell from the cell buffer unit and transmitting the cell is provided. Traffic shaping equipment. 11. A means for setting a priority for a connection in each of the connection bundles, and the first sorting unit for setting a cell first for a group of connections having the same priority in each connection bundle.
The transmission control unit has a function of selecting a connection having the earliest scheduled transmission time, the transmission control unit determines whether or not a cell belonging to the connection bundle selected by the second sorting unit may be transmitted, and transmits the cell. If it is acceptable, the first sorting unit has a function of transmitting a cell belonging to a connection having the highest priority, which is in a state in which transmission is possible from among the connections selected for each priority. The traffic shaping device according to claim 10, wherein the traffic shaping device is provided. 12. The traffic shaping apparatus according to claim 10, further comprising a discrimination bit indicating whether or not a cell waiting to be transmitted exists in the cell buffer unit for each connection. 13. The traffic shaping apparatus according to claim 10, further comprising a discrimination bit indicating whether or not there is a cell waiting to be transmitted in the cell buffer unit for each of the connection bundles. . 14. A connection in which the first sorting unit includes means for managing a cell first transmission scheduled time and the cell presence determination bit in a binary tree structure, and a connection to be transmitted with the highest priority by using a past sorting result. The traffic shaping device according to claim 10 or 11, wherein the traffic shaping device is selected. 15. The connection, wherein the second sorting unit includes means for managing the cell second scheduled transmission time and the cell presence determination bit in a binary tree structure, and a connection to be transmitted with the highest priority by using a past sorting result. The traffic shaping device according to claim 10 or 11, wherein a bundle is selected. 16. The first scheduled cell for the connection selected by the first sorting section is used for the second scheduled transmission time calculating section.
When the scheduled transmission time is in the future from the cell second scheduled transmission time calculated by the second scheduled transmission time calculation unit and the cell presence determination bit of the connection selected by the first sorting unit is set The traffic shaping apparatus according to claim 12, further comprising a time correction circuit that uses the cell first transmission scheduled time as the cell second transmission scheduled time. 17. The traffic shaping device according to claim 12, wherein the second scheduled transmission time calculation unit is a connection selected for each priority by the first sorting unit, and a cell for each connection. Among the connections in which the presence determination bit is set, the cell first transmission scheduled time of the connection with the earliest cell first transmission scheduled time is the cell second transmission schedule calculated by the second transmission scheduled time calculation unit. When it is in the future than time,
The cell first transmission scheduled time is used as the cell second transmission scheduled time, and the cell presence determination bit for each connection is set for all the connections selected for each priority by the first sorting unit. 13. The traffic shaping apparatus according to claim 12, further comprising a time correction circuit that does not change the second scheduled cell transmission time when there is no time. 18. A cell presence determination for each connection to the second scheduled transmission time calculation unit for all connections selected by the first sorting unit for each priority within the certain connection bundle. When the bit is not set, the cell existence determination bit for the connection bundle is reset, and for any one of the connections selected for each priority in the certain connection bundle by the first sorting unit, 14. The traffic shaping apparatus according to claim 13, further comprising a function of setting a cell presence determination bit for the connection bundle when the cell presence determination bit for each connection is not set. 19. A process performed by the first sorting unit,
The traffic shaping apparatus according to claim 10 or 11, wherein the processing performed by the second sorting unit is performed in parallel. 20. A VC (Virtua) is used as the connection.
l Connection), and the VP is used as the connection bundle.
(Virtual Path) is used, Claim 10 characterized by the above-mentioned.
20. The traffic shaping device according to claim 19. 21. The traffic shaping device according to claim 10, wherein a VC is used as the connection, and a line is used as the connection bundle.