KR20030087881A - Dynamic bandwidth allocation method for gigabit ethernet passive optical network - Google Patents

Abstract

PURPOSE: A method for dynamically allocating bandwidths in a GE-PON(Gigabit Ethernet Passive Optical Network) is provided to efficiently use bandwidths. CONSTITUTION: An OLT(Optical Line Termination) downlinks a GRANT FOR BW REQUEST frame to an ONU(Optical Network Unit)(100). Receiving the GRANT FOR BW REQUEST frame, the ONU uplinks a REPORT DBA QUEUE INFORMATION frame to the OLT in order to inform the OLT how many bandwidths are required(102). In response to the bandwidth request data transmitted from the ONU, the OLT allocates a useful bandwidth to the OLT. Also the OLT allocates a bandwidth for each of the queues of the ONU within the granted bandwidth(104). The ONU compares GBWQs(Granted BandWidth per Queue), allocated bandwidths for the queues, with QDSs(data size in ONU queue), the data sizes stored in the queues(106). In case that all the GBWQs are larger than all the QDSs, the ONU judges that a queue information report is not necessary. Then the ONU loads a PDU(Packet Data Unit) on a data transmission frame and uplinks it to the OLT(108).

Description

DYNAMIC BANDWIDTH ALLOCATION METHOD FOR GIGABIT ETHERNET PASSIVE OPTICAL NETWORK}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive optical network (hereinafter referred to as "PON"), and more particularly to an ONU (Optical) in a gigabit Ethernet passive optical network (hereinafter referred to as "GE-PON"). The present invention relates to a method for allocating a bandwidth for data transmission to a network unit.

X-Digital Subscriber Line (xDSL), Hybrid Fiber Coax (HFC), Fiber To The Building (FTTB), Fiber To The Curb (FTTC), and Fiber To (FTTH) Various network structures and evolutionary methods such as The Home have been proposed. Among these various network structures, the implementation of FTTx (x = B, C, H) is divided into active FTTx by active optical network (hereinafter referred to as "AON") and passive FFTx by PON configuration. Can be. Among them, PON is proposed as an economical optical subscriber network implementation method in the future due to the network configuration having a point-to-multipoint topology by passive devices.

The PON is referred to as one optical line termination device (hereinafter referred to as "OLT") and a number of optical subscriber network devices, ONUs, referred to as 1 x N passive distribution network (ODN). By using), it is an optical subscriber network structure that forms a distributed topology of a tree structure. In the PON form, ATM-PON was first developed and standardized. Recently, the International Telecommunication Union-Telecommunication section (ITU-T) has standardized the contents of the Asynchronous Transfer Mode Passive Optical Network (hereinafter referred to as "ATM-PON") in ITU-T G.982, ITU. -T G.983.1, ITU-T G.983.3. In addition, the IEEE802.3ah TF of the Institute of Electrical and Electronics Engineers (IEEE) is in the process of standardizing G-PON systems based on Gigabit Ethernet.

Point-to-point Gigabit Ethernet and Medium Access Control (MAC) technologies for ATM-PON have already been standardized, and are described in IEEE 802.3z and ITU-T G. 983.1. In addition, US Patent No. 5,973,374, issued by Gigad Ghaib et al. And issued in the United States under the name "PROTOCOL FOR DATA COMMUNICATION OVER A POINT-TO-MULTIPOINT PASSIVE OPTICAL NETWORK", dated November 2, 1999 MAC technology in PON is disclosed in detail.

ATM-PON includes one OLT 10 and multiple ONUs 12a, 12b, 12c, as shown in the example shown in FIG. 1, and the OLT 10 and ONUs 12a, 12b, 12c. ) Is connected via ODN 16. The OLT 10 is located at the root of the tree structure and plays a central role in providing information to each subscriber in an access network. The OLT 10 has a tree topology structure and distributes downstream data frames transmitted from the OLT 10 to three ONUs 12a, 12b, and 12c, and vice versa. An ODN 16 is connected which multiplexes upstream data frames from the ONUs 12a, 12b, 12c and transmits them to the OLT 10. The ONUs 12a, 12b, 12c receive downlink data frames and provide them to the end users 14a, 14b, 14c and output the data output from the end users 14a, 14b, 14c as uplink data frames. 16) to the OLT 20. The end users 14a, 14b, and 14c, which show three examples, refer to various types of subscriber network terminators that can be used in a PON including a network terminal (NT).

In the ATM-PON as described above, downlink and uplink transmission is performed in the form of a data frame in which ATM cells having a size of 53 bytes are bundled in a predetermined size. In the tree-shaped PON structure as shown in FIG. 1, the OLT 10 properly inserts a downlink cell to be distributed to each of the ONUs 12a, 12b, and 12c in the downlink frame. In addition, in case of uplink transmission, the OLT 10 accesses data transmitted from the ONUs 12a, 12b, and 12c in a time division multiplexing (TDM) manner. At this time, the ODN 16 connected between the OLT 10 and the ONUs 12a, 12b, and 12c is a passive element. Accordingly, the OLT 10 prevents data from colliding with the passive element ODN 16 through virtual distance correction using an algorithm called ranging. In addition, when the OLT 10 transmits downlink data to the ONUs 12a, 12b, and 12c, the OLT 10 and the ONUs 12a, 12b, and 12c are encrypted keys for encryption and maintenance for confidentiality. It is designed to send and receive OAM (Operations, Administration and Maintenance) messages for each other. To this end, up / down frames have corresponding data fields in dedicated ATM cells or general ATM cells that can send and receive messages at regular intervals.

On the other hand, with the development of Internet technology, subscribers require more bandwidth, which requires relatively expensive equipment, bandwidth limitations (up to 622Mbps), and ATMs that need to segment Internet Protocol (IP) packets. It is aimed at end-to-end transmission in Gigabit Ethernet technology, which is relatively inexpensive and secures high bandwidth (about 1 Gbps) .In the PON structure of the subscriber network, the Ethernet method is not ATM. Came to ask.

In the case of Gigabit Ethernet, however, the point-to-point and collision-type MAC protocols have already been standardized and the MAC controller chip has been commercialized, but the point-to-multipoint GE-PON architecture includes MAC scheduling. (scheduling) procedures are currently being standardized in the IEEE 8023.ah Ethernet in the First Mile (TFM) TF.

Meanwhile, ATM-PON performs Dynamic Bandwidth Allocation (DBA) for data transmission of ONUs. In such ATM-PON, ONUs have four independent queues according to service classes defined according to parameters such as Variable Bit Rate (VBR), Constant Bit Rate (CBR), and Real-time. This queue ensures the quality of service (QoS) by storing the data traffic coming into the ONU and making dynamic bandwidth allocation in consideration of this class of service.

However, in the case of GE-PON, unlike ATM, the protocol base is Ethernet, so there is no defined service class. In addition, since the packet size of Ethernet, which is an underlying technology, is variable, it must be distinguished from the bandwidth allocation method in ATM-PON based on ATM having a cell having a fixed packet size. Bandwidth allocation scheduling in GE-PON is problematic when considering that it is a PON with a point-to-multipoint structure that has not been used in Ethernet-based networks. The downlink traffic from the OLT to the ONU is broadcasting, so there is no difference compared to conventional Ethernet. However, since traffic from each ONU to the OLT is multiplexed and arrives at the OLT, in order to avoid collisions, the OLT must allocate time to transmit data at different times to each ONU. In addition, since the amount of traffic that ONUs want to send is different, dynamic bandwidth allocation is required to effectively transmit to the OLT without incurring much delay.

Accordingly, an object of the present invention is to provide a dynamic bandwidth allocation method essential for GE-PON implementation.

Another object of the present invention is to provide a dynamic bandwidth allocation method that can efficiently use bandwidth.

It is still another object of the present invention to provide a dynamic bandwidth allocation method that can efficiently use time and bandwidth for dynamic bandwidth allocation when data to be transmitted remains in the ONU even after data is transmitted according to the allocated bandwidth.

In accordance with the above object, the present invention, a Gigabit Ethernet Passive Optical Network in which one Optical Line Terminal (OLT) and a plurality of Optical Network Units (ONU) are connected through an Optical Distribution Network (ODN) In the dynamic bandwidth allocation method, the ONU receives the bandwidth allocated by the OLT in response to the bandwidth allocation request of the ONUs requiring bandwidth allocation, and the ONU compares the bandwidth allocated from the OLT with the size of data to be transmitted. If the bandwidth is sufficient, the data is loaded in the first data transmission frame and transmitted upward to the OLT. If the size of the data to be transmitted is larger than the allocated bandwidth, a portion of the data to be transmitted and bandwidth request information for bandwidth allocation request Is carried out in a second data transmission frame to the upstream transmission to the OLT .

1 is a block diagram showing an example of a typical ATM-PON,

2 is a block diagram showing an example of a GE-PON to which the present invention is applied;

3 is a band allocation request frame format proposed by IEEE 802.3ah TF;

4 is a protocol diagram between an OLT and an ONU for explaining a dynamic bandwidth allocation procedure according to an embodiment of the present invention;

5 is a control flowchart of a dynamic bandwidth allocation procedure according to an embodiment of the present invention;

6 is a normal data transmission frame format diagram;

7 is a data transmission frame format diagram in which bandwidth request information is added.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are represented by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

2 shows a block diagram of a GE-PON to which the present invention is applied, an ODN 20 consisting of an intensive station OLT 20, an optical splitter serving as a passive element, and three example ONUs 22a. 22b and 22c and end users 24a, 24 and 24c are connected like the ATM-PON of FIG. 1 described above, and use the TDM scheme for uplink transmission according to the tree structure of the point-to-multipoint connection. . However, unlike ATM-PON of FIG. 1, uplink and downlink frames are configured based on a variable length Ethernet frame. For this purpose, the procedure of variable length Ethernet frame format structure and GE-PON functions related to the variable length Ethernet frame, namely initial ONU registration, periodic ONU registration, ranging, and bandwidth dynamic allocation, are described by the applicant in 2002. Korean Patent Application No. 2765 No. 2765 filed on Jan. 17, 2002, discloses a method for implementing operation in a Gigabit Ethernet passive optical subscriber network system and its Ethernet frame structure.

The operation of the GE-PON of FIG. 2 with reference to 2002 Patent Application No. 2765 is as follows. First, the ONUs 22a, 22b, and 22c register to the OLT 20 to inform their location and existence, and are assigned respective ONU IDs. Then, ranging, which is a distance correction procedure, is performed. The reason is that the ONUs 22a, 22b, and 22c compensate for synchronization errors with respect to the up and down time delays during the registration process, but are not precisely corrected for errors that may be caused by other external variables such as temperature. Because it is. When the ONUs 22a, 22b and 22c that have completed the ONU registration and distance correction are given an opportunity for the OLT 20 to transmit data through the uplink data grant opportunity frame, the ONUs 22a and 22b are provided. 22c measures the amount of data in the buffer it has and transmits this queue value to the OLT 20 in a band allocation request frame. The uplink data transmission opportunity grant frame is a downlink packet used when the OLT 20 wants to give one of the ONUs 22a, 22b, and 22c an opportunity to transmit data upward, and a bandwidth allocation request frame. Is an uplink packet used when one of the ONUs 22a, 22b, 22c makes a band allocation request to the OLT 20 with the permission of the OLT 20. The OLT 20 receives bandwidth requests for a certain time in a time slot, and then allocates an appropriate data transmission bandwidth through scheduling. The result is included in the uplink data transmission opportunity grant frame of the next time slot and transmitted to the ONUs 22a, 22b, and 22c. At this time, the allocation information is composed of a time to start transmission and a time to maintain the transmission, and the ONUs 22a, 22b, and 22c receiving the data transmit data to the OLT 20 as much as the time given at the allocated time.

The bandwidth allocation request frame, which is an uplink packet used when one of the ONUs 22a, 22b, and 22c of the dynamic bandwidth allocation procedure makes a bandwidth allocation request to the OLT 20 with the permission of the OLT 20, has recently been IEEE 802.3. Ah TF has been proposed in the frame format as shown in FIG.

3 is a band allocation request frame format proposed by IEEE 802.3ah TF. Referring to FIG. 3, a 6-byte DA field is a field for recording a destination address, and a 6-byte SA field is a field for recording a source address. The 2-byte TYPE / LENGTH field is a field for recording the type (control frame, data frame) and length of the frame. The 2-byte OPCODE (operation code) field is a field for recording control information for identifying what kind of message the control frame is, and the 4-byte TIME STAMP field is for recording the time at which the frame message is transmitted. . The REPORT BITMAP field 32 of 1 byte and the QUEUE REPORT field 34 of 4 * N (where N is the number of bandwidth requests) bytes are the bandwidth request field 30 for the bandwidth request. The REPORT BITMAP field 32 is a field for recording the presence or absence of bandwidth request queue data according to the queue report priority, and the QUEUE REPORT field 34 records the bandwidth request size according to the queue report priority indicated by the REPORT BITMAP. This field is for The FCS is a field for recording information for checking a frame check sequence error.

In order to guarantee the Quality of Service (QoS) and Class of Service (CoS) in the GE-PON, a bandwidth request field 30 for bandwidth request is shown in FIG. 32) and the QUEUE REPORT field 34 are currently being discussed in the IEEE 802.3ah TF. Guarantees of QoS and CoS are optional depending on the type of system and service type when the vendor designs the actual system, and the operator has at least one queue report (no priority) or up to eight queues. Bandwidth requirements can be prioritized up to reports (up to 8 priorities). One queue is provided for each ONU when bandwidth is requested as one queue report. For example, eight queues are provided for each ONU when bandwidth is requested as eight queue reports. In the embodiment of the present invention, the bandwidth request by prioritizing up to eight queue reports will be described as an example.

4 is a protocol diagram between an OLT and an ONU for explaining a dynamic bandwidth allocation procedure according to an embodiment of the present invention, and FIG. 5 is a control flowchart of a dynamic bandwidth allocation procedure according to an embodiment of the present invention. 6 is a data transmission frame format diagram for data transmission, and FIG. 7 is a data transmission frame format diagram in which bandwidth request information is added.

First, referring to FIG. 6, a data transmission frame includes a 6-byte DA field, a 6-byte SA field, a 2-byte VLINK HEADER (virtual link header) field, a PHY ID (physical identification) field, a TYPE / LENGTH field, and 46 bytes. It consists of a PDU (packet data unit) field 36 of 1,500 bytes and an FCS field of 4 bytes. The 6-byte DA field is a field for recording a destination address, and the 6-byte SA field is a field for recording a source address. The 2-byte VLINK HEADER field is for recording EP-PON-only frames, and the 2-byte PHY ID field is for recording point-to-point emulation functions. The 2-byte TYPE / LENGTH field is a field for recording the type (control frame, data frame) and length of the frame, and the PDU (packet data unit) field 36 of 46 to 1500 bytes is a field for recording data. to be. The FCS is a field for recording information for checking a frame check sequence error.

In the embodiment of the present invention, even if the data to be transmitted to the ONUi 22i remains even after the ONUi 22i transmits the data up to the bandwidth allocated by the OLT 20 at a given time, the procedure for dynamically allocating the bandwidth is performed once again. Instead of going through the data transmission frame for data transmission as shown in Figure 6, the bandwidth request information field 30, REPORT BITMAP field 32 and QUEUE REPORT field 34 is added to transmit data and bandwidth request information together to efficiently bandwidth Its main purpose is to enable it. The new data transmission frame of FIG. 7 includes a bandwidth request information field 30 for carrying bandwidth request information and a PDU field 36 for carrying data.

Hereinafter, a dynamic bandwidth allocation procedure between the OLT and the ONU according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4 to 7.

(1) As in step 1) of FIG. 4 and step 100 of FIG. 5, the OLT 20 transmits a GRANT FOR BW REQUEST frame informing the ONUi 22i when the bandwidth request report can be posted.

(2) The ONUi 22i temporarily stores transmission scheduled data classified according to queue report priorities in each of up to eight queues. When the GRANT FOR BW REQUEST frame is received, the REPORT DBA QUEUE INFORMATION frame is transmitted upward to the OLT 20 to inform the OLT 20 how much bandwidth is required for each queue. The REPORT DBA QUEUE INFORMATION frame is a band allocation request frame having the format described above with reference to FIG. 3. An example in which bandwidth request information is recorded in the REPORT BITMAP field 32 and the QUEUE REPORT field 34 of FIG. 3, which is the bandwidth request field 30 for the bandwidth request, will be described below. In the REPORT BITMAP field 32 of one byte, for example, bit information of "10101100" may be recorded. This means that there is a bandwidth request report in the priority 1 queue, the priority 3 queue, and the priority 5 and 6 queues. Accordingly, the QUEUE REPORT field 34 includes a 4-byte bandwidth request report value corresponding to the priority 1 queue, a 4-byte bandwidth request report value corresponding to the priority 3 queue, and a queue of priority 5 and 6 respectively. Four bytes of bandwidth request report values are recorded. Therefore, the QUEUE REPORT field 34 is composed of 4 * N (where N = 4) = 16 bytes.

(3) The OLT 20 stores the bandwidth request information in each of the REPORT DBA QUEUE INFORMATION frames transmitted from the ONUs 22i, i.e., in the REPORT BITMAP field and the QUEUE REPORT field of FIG. Gathers the available information, allocates the bandwidth available to each ONU 22i, and allocates the available bandwidth (BW) for each queue within each ONU 22i within the bandwidth available to each ONU 22i. 22i). In FIG. 4, 3) shows that each ONUi 22i transmits bandwidth allocated for each queue.

(4) As shown in step 106 of FIG. 5, the ONUi 22i may be assigned to each of the current queues by the bandwidth-per-band bandwidth GBWQ allocated from the OLT 20 and the data size in ONU queue (QDS). Compare The allocated bandwidth per GBWQ is obtained by the bandwidth allocation request of the ONUi 22i in the previous timeslot (cycle), and the data size QDS stored in each of the current queues is stored in each of the queues in the current timeslot (cycle). The data size. Therefore, there is a high possibility that the data size QDS stored in each of the current queues and the allocated bandwidth GBWQ do not coincide with each other.

(5) In the ONU 22i, as shown in step 106 of FIG. 5 and 4) of FIG. 4, the data size in ONU queue (QDS) stored in each of the maximum eight queues is stored from the OLT 20. If at least one is greater than the allocated bandwidth GBWQ for each of the queues, it is determined that a queue information report is required. If not, that is, if GBWQ> QDS for all queues, then it is determined that no queue information report is required.

(6) If it is determined that the queue information report is not necessary, the ONU 22i transmits the data, ie, a packet data unit (PDU), upward in a data transmission frame for data transmission as shown in FIG. 6 (step 108 of FIG. 5). 4-1 of FIG. 4). The data transmission frame at this time (Fig. 6) is a normal data transmission frame.

(7) However, if it is determined that the queue information report is necessary, the ONU 22i resets the maximum data size that the ONUi 22i can send in step 110. Subsequently, the process proceeds to step 112 of FIG. 5, and as shown in FIG. 7, the bandwidth request information as well as data (ie, PDU) is additionally loaded in the data transmission frame for data transmission. In this case, the data transmission frame (FIG. 7) is a new type of data transmission frame in which bandwidth request information is further included in the normal data transmission frame (FIG. 6). The bandwidth request information included in the data transmission frame of FIG. 7 is information recorded in the REPORT BITMAP field 32 and the QUEUE REPORT field 34 and is the same information as that described with reference to FIG. 3.

When the bandwidth request information included in the data transmission frame of FIG. 7 is received, the OLT 20 proceeds directly to 3) of FIG. 4 without the process of 1) and 2) of FIG. 4 to set the available bandwidth for each queue to ONUi ( 22-i). By loading the bandwidth request information together in the data transmission frame for data transmission, it is possible to secure the time and bandwidth of the processes 1) and 2) of FIG. 4. In short, there is an advantage of securing the time corresponding to the transmission time of the GRANT FOR BW REQUEST frame and the REPORT DBA QUEUE INFORMATION frame, and the time and the corresponding bandwidth of two inter frame gaps (IFGs).

Before performing step 112 of FIG. 5, in step 110 of FIG. 5, the ONUi 22i indicates bandwidth request information, that is, 4 * N bytes (QUEUE REPORT field, N is the number of bandwidth requests) + 1 byte in the normal data transmission frame. Considering that the (REPORT BITMAP field) is newly added, the maximum data size that can be sent must be reset.

The total bandwidth allocated from the OLT 20 is defined as A (e.g., 270 bytes), and the size of data of each of the queues that the ONUi 22i can send to the OLT 20 within the total bandwidth A allocated from the OLT 20 If the sum is defined as B, and the bandwidth request information is newly added to the data transmission frame, the maximum data size that ONUi 22i can send is defined as C.

i) if A ≥ B + 4 * N + 1, then C is equal to B,

ii) If A <B + 4 * N + 1, then C is the sum of the data sizes of each of the queues that can be sent within the A- (4 * N + 1) size.

Here, 4 * N + 1 is a size (unit is byte) occupied by bandwidth request information. That is, 4 * N bytes (QUEUE REPORT field, N is the number of queues for bandwidth request) + 1 byte (REPORT BITMAP field).

By performing the processes of i) and ii), the maximum data size that the ONUi 22i can send can be determined. Thus, even if 4 * N + 1 bytes occupied by the bandwidth request information are added to the normal data transmission frame, the data transmission frame can be transmitted upward from the ONUi 22i to the OLT 20 without any problem.

Meanwhile, in order to distinguish whether the data transmission frame received from the ONUi 22i by the OLT 20 is a normal data transmission frame as shown in FIG. 6 or a data transmission frame in a new format as shown in FIG. 7 including band request information, According to the embodiment, a new type is further specified in the VLINK HEADER field of the data transmission frame shown in FIGS. 6 and 7 or one bit is allocated in the PHY ID field. Thus, the OUNi 22i and the OLT 20 use the VLINK HEADER field or the PHY ID field of the data transmission frame promised to each other so that the OLT 20 determines whether the received data transmission frame is a normal data transmission frame as shown in FIG. It may be identified whether the data transmission frame has a new format as shown in FIG. 7 including the bandwidth request information.

In the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the equivalent of claims and claims.

As described above, in the embodiment of the present invention, when data to be transmitted to the ONU remains after the ONUi transmits data up to the bandwidth allocated by the OLT at a given time, the present invention does not go through the procedure of allocating the dynamic band once again. By transmitting not only data but also bandwidth request information in a data transmission frame, bandwidth can be efficiently used. This increases bandwidth efficiency and reduces overhead in uplink data transmission from the ONU to the OLT in the EP-PON.

Claims (12)

In a dynamic bandwidth allocation method in a Gigabit Ethernet Passive Optical Network (OLT) in which one optical line terminal (OLT) and a plurality of optical network units (ONUs) are connected through an optical distribution network (ODN), Receiving, by the ONU, the bandwidth allocated by the OLT in response to a bandwidth allocation request of the ONUs requiring bandwidth allocation; The ONU compares the bandwidth allocated from the OLT with the size of data to be transmitted, and if the bandwidth is sufficient, loads the data in the first data transmission frame and transmits the data upward to the OLT, and the data size to be transmitted is larger than the allocated bandwidth. If it is large, the dynamic bandwidth allocation method comprising the step of transmitting the portion of the data to be transmitted and the bandwidth request information for the bandwidth allocation request to the OLT in a second data transmission frame. The method of claim 1, wherein the portion of data to be transmitted is data of a size obtained by subtracting a bandwidth request information size of data from a data size that an ONU can transmit within the allocated bandwidth. 2. The method of claim 1 wherein an OLT uses predetermined fields in the first and second data transmission frames to distinguish between the first data transmission frame and the second data transmission frame. 4. The method of claim 3, wherein the predetermined field is a field for recording an EP-PON dedicated frame. 4. The method of claim 3, wherein the predetermined field is a field for recording a point-to-point emulation function. In a dynamic bandwidth allocation method in a Gigabit Ethernet Passive Optical Network (OLT) in which one optical line terminal (OLT) and a plurality of optical network units (ONUs) are connected through an optical distribution network (ODN), Receiving, by the ONU, the bandwidth allocated by the OLT in response to a bandwidth allocation request of the ONUs requiring bandwidth allocation; The ONU compares the bandwidth allocated from the OLT with the size of the data to be transmitted. If the allocated bandwidth is larger than the data size to be transmitted, transmitting the data to be transmitted in a first data transmission frame and transmitting the data to the OLT; If the allocated bandwidth is smaller than the data size to be transmitted, resetting a maximum data size that ONU can send in consideration of the fact that bandwidth request information for bandwidth allocation request is added to the first data transmission frame; And transmitting up to the OLT data of the reset data size and the bandwidth request information in a second data transmission frame. The dynamic bandwidth allocation method of claim 6, wherein the data of the size of the reset data is the size of data obtained by subtracting the bandwidth request information size of the data from the data size that an ONU can transmit within the allocated bandwidth. 7. The method of claim 6 wherein the OLT uses predetermined fields in the first and second data transmission frames to distinguish between the first data transmission frame and the second data transmission frame. 7. The method of claim 6, wherein the second data transmission frame includes at least a bandwidth request information field for carrying the bandwidth request information and a data field for carrying data. In a dynamic bandwidth allocation method in a Gigabit Ethernet Passive Optical Network (OLT) in which one optical line terminal (OLT) and a plurality of optical network units (ONUs) are connected through an optical distribution network (ODN), ONU receives the queue-specific bandwidth allocated by the OLT in response to the bandwidth allocation request for each queue of the ONUs requiring bandwidth allocation, ONU compares the bandwidth of each queue allocated from the OLT with the size of data for each queue to be transmitted; If the allocated bandwidth for each queue is larger than the data size for each queue to be transmitted, transmitting the data to be transmitted in a first data transmission frame and transmitting the data to the OLT upwardly; If the allocated bandwidth for each queue is at least one smaller than the data size for each queue to be transmitted, the maximum data size that ONU can send may be reconsidered considering that bandwidth request information for the bandwidth allocation request for each queue is added to the first data transmission frame. Setting up process, And transmitting up to the OLT data of the reset data size and the bandwidth request information in a second data transmission frame. 11. The method of claim 10, wherein the data of the size of the reset data is the size of data obtained by subtracting the bandwidth request information size from the sum of the data sizes of each of the queues that the ONU can send to the OLT within the allocated total bandwidth. Bandwidth Allocation Method. The method of claim 10, wherein the OLT uses a predetermined field in the first and second data transmission frames to distinguish the first data transmission frame and the second data transmission frame.