CN1614944A - Dynamic distribution control of upward band width in passive optical network - Google Patents

Abstract

The invention relates to a method for dynamic allocation and control of uplink bandwidth, which performs dynamic allocation and control of uplink bandwidth on a passive optical network composed of an OLT, an optical distribution network and a plurality of ONUs. Its dynamic allocation control of the upstream bandwidth of each ONU Ethernet service data includes: each online ONU encapsulates the size of its own cached data in a bandwidth request frame and reports it to the OLT; The basic bandwidth threshold converted by the upstream user bandwidth protocol of the ONU, calculates the authorization start time and authorized bandwidth length of the ONU, and encapsulates it in a bandwidth authorization frame and sends it to the ONU. Its dynamic allocation control of the uplink bandwidth of each ONU's E1 service data includes: OLT encapsulates the calculated first authorized sending time of each ONU E1 service data and the configured authorized bandwidth length in a bandwidth authorization frame and sends it to Each ONU; each ONU that receives the bandwidth authorization, starts sending E1 service data at the first authorization sending time, and then sends it periodically.

Description

Dynamic Allocation and Control Method of Passive Optical Network Uplink Bandwidth

technical field

The invention relates to an Ethernet-based multi-service passive optical network technology, which is a dynamic bandwidth allocation control method for uplink signals, which can effectively improve the utilization rate of uplink bandwidth and guarantee bandwidth rights and interests of users.

Background technique

The Ethernet-based multi-service passive optical network (EPON) system uses a local end device - Optical Line Terminal (OLT for short), and connects multiple remote devices - Optical Network Units through a passive optical distribution network. (Optical Net Unit, referred to as ONU), which constitutes a point-to-multipoint tree topology structure.

Referring to FIG. 1 and FIG. 2 , the figures respectively show the downstream data flow direction and the upstream data flow direction in the multi-service EPON (MS-EPON) system topology.

Referring to Figure 1, in the downlink direction, the optical signal transmitted by the downlink signal on the OLT11 side is generated by the same excitation source, such as 1, 2, and 3. Each signal frame is coherent, and the OLT11 broadcasts to each optical network at the far end. Unit 13 (ONU1 to ONU3) sends a data signal, through the splitter 12, each optical network unit 13 (ONU1 to ONU3) at the far end selects one or several related data from continuous data 1, 2, 3 frames of data and send them to their own users 14.

Referring to Fig. 2, in the uplink direction, each optical network unit 13 (ONU1 to ONU3) only sends data frames from respective users 14 in the time slot assigned to itself, and is in a sending waiting state at other times, and each optical network unit 13 The data frames are combined through the combiner 12 in the optical fiber and sent to the OLT11.

EPON upstream transmission is the time-division multiplexed upstream bandwidth of multiple ONUs, so it is very necessary to use an appropriate bandwidth allocation mechanism. The multi-service EPON system mainly provides users with data services based on Ethernet services, and should also support E1 services with quality of service (QoS) guarantees.

Multi-service EPON upstream bandwidth allocation can adopt the method of fixed bandwidth configuration, that is, the system configures the upstream bandwidth of each ONU according to the predetermined bandwidth of each ONU (or statically). Since EPON bears E1 (E1 Over EPON) technology is a technology that adapts E1 data to Ethernet data and sends it at a fixed time, this fixed bandwidth allocation method can organically integrate EPON bearer E1 technology to support traditional time division Multiplexing (TDM) business.

In the case of fixed bandwidth configuration, if the bandwidth is allocated at the peak rate of each ONU in order to ensure transmission performance, at this time, the data flow of each ONU is often not at the peak rate at the same time, which will cause the entire system bandwidth to not be fully utilized. Greatly reduces the utilization of system resources. And if in order to improve the utilization rate of system resources, allocate the bandwidth with the average rate of data transmission of each ONU, it often occurs that when some ONUs want to send larger burst packet data, the data cannot be sent out in time, thus Increase the packet loss rate and delay of data; while the data traffic of other ONUs is lower than the average rate, system resources will still not be fully utilized. It can be seen from this that, because the Ethernet data business with a strong bursting rate accounts for a considerable proportion, the static bandwidth allocation will lead to low bandwidth utilization of the EPON system.

Dynamic bandwidth allocation means that the OLT makes an overall arrangement according to the bandwidth requests reported by each ONU in real time, and dynamically adjusts the bandwidth value authorized to the ONU. Since the dynamic bandwidth allocation can reflect the real-time request of the ONU, system resources can be fully utilized, and performance such as time delay can be improved at the same time.

However, in the case of dynamic bandwidth allocation, since the time for each ONU to send data is not fixed, it is not possible to directly use EPON to carry E1 technology to support traditional TDM services, and the dynamic bandwidth allocation mechanism of the current EPON system is based on the request of ONU users. The corresponding bandwidth cannot be managed, and the bandwidth requested by users can only be provided with best effort, so its service quality is also best effort, which cannot meet the operational and manageable requirements of telecom operators for the integrated service platform. Requirements, can not meet the actual market needs.

Therefore, a scientific and effective uplink bandwidth dynamic allocation control mechanism should be able to make up for the deficiency of dynamic bandwidth allocation in the current MS-EPON system: according to changes in the service flow of each ONU, the uplink bandwidth can be allocated in real time to improve bandwidth utilization; When users compete for system bandwidth, the bandwidth can be allocated fairly according to the pre-signed contract between the user and the operator, that is, the bandwidth obtained by the user is proportional to the amount paid by the user, so as to facilitate the operation and management of the operator; at the same time, EPON can be used The E1-carrying technology transmits E1 services with QoS guarantee to meet customers' needs for traditional telecommunication services.

Contents of the invention

The purpose of the present invention is to provide a kind of dynamic distribution control method of the upstream bandwidth of passive optical network, carry out dynamic distribution control to the upstream bandwidth in the multi-service passive optical network system based on Ethernet, not only can prevent each ONU upstream burst of EPON system Conflicts between sending data, and more importantly, bandwidth allocation can be performed in real time according to changes in the service flow of each ONU to improve bandwidth utilization; when users compete for system bandwidth, according to the contract signed by the user and the operator, fair Bandwidth allocation is carried out accurately, that is, the bandwidth that users get is proportional to the amount they pay, which ensures the fairness of bandwidth allocation and facilitates the operation and management of operators; the technology of EPON to carry E1 services can be used to transmit E1 services with guaranteed QoS to satisfy customers Demand for traditional telecom services.

The technical solution for realizing the object of the present invention is as follows: a method for dynamic allocation and control of upstream bandwidth of a passive optical network is to perform dynamic allocation and control of upstream bandwidth on a passive optical network composed of an OLT, an optical distribution network and a plurality of ONUs , characterized by including:

A method for dynamically allocating and controlling the upstream bandwidth of each ONU based on Ethernet service data, and a method for dynamically allocating and controlling the upstream bandwidth of the E1 service data of each ONU at the same time;

The described method for dynamically allocating and controlling each ONU based on the upstream bandwidth of Ethernet service data includes:

A1. Each online ONU encapsulates the size of its cached data in the bandwidth request frame of the Ethernet MAC control frame format containing the time tag value, and sends it to the Ethernet service data within the respective authorized bandwidth allocated by the OLT Report the bandwidth request frame to the OLT at the end of sending;

B1.OLT calculates the authorized start time and authorized bandwidth length of the ONU when polling the online ONU, and encapsulates it in the bandwidth authorization frame of the Ethernet MAC control frame format containing the time tag value, and sends it to the ONU. The calculation basis includes the cached data size reported by the ONU and the basic bandwidth threshold converted according to the ONU's upstream user bandwidth protocol;

The described method for dynamically allocating and controlling the upstream bandwidth of the E1 service data of each ONU includes:

A2. The OLT encapsulates the calculated first authorized sending time of each ONU E1 service data and the configured authorized bandwidth length in the bandwidth authorization frame of the Ethernet MAC control frame format containing the time tag value, and sends it to each ONU ;

B2. Each ONU that has received the bandwidth authorization will send the first E1 service data when its ONU clock is equal to its first authorized sending time, and then send E1 service data once every fixed time.

The technical scheme of the present invention utilizes time division multiplexing and statistical multiplexing means to realize the dynamic allocation and control of the uplink shared link bandwidth by the EPON system. This scheme uses the bandwidth request frame in the Ethernet MAC control frame format to transmit the ONU buffer data size information; for the ONU users whose agreement requires a smaller bandwidth, the OLT adjusts according to the comparison result of the authorized bandwidth threshold and the maximum Ethernet frame length. The size of the authorized bandwidth threshold, so as to ensure that the maximum Ethernet frame can be sent without occupying the bandwidth of other ONUs; OLT gives each ONU a bandwidth that does not exceed its authorized bandwidth threshold according to the buffered data size information reported by each ONU Authorize and avoid sending time slots for E1 services; use bandwidth authorization frames in the Ethernet MAC control frame format to transmit clock synchronization messages and bandwidth authorization messages between the OLT side and each ONU side, and time-divisionally control the data transmission in the upstream transmission buffer of each ONU; use The bandwidth authorization frame transmits the configuration information of E1, including the first authorization sending time of each ONU and the length of E1 authorization, so that each ONU adapts E1 data in Ethernet frame format, starting from the first authorization sending time, in the The fixed time slot is sent uplink periodically.

The method of the invention can manage and control the uplink bandwidth of each ONU in the EPON system economically, effectively and flexibly according to the bandwidth agreement between the OLT and each ONU and the real-time business conditions of each ONU.

In the technical scheme of the present invention, each ONU configures an uplink sending register according to the received Ethernet bandwidth authorization content from the OLT, so as to realize uplink sending control of Ethernet data and E1 data.

The present invention utilizes the bandwidth request frame of the Ethernet MAC control frame format to realize the reporting of the cache data size information of the ONU; the bandwidth request frame contains the time label value of the ONU, and the OLT can realize the distance measurement of the ONU by using the traditional technology.

The present invention utilizes the bandwidth authorization frame of the MAC control frame format to realize the downlink transmission of the authorization message; the bandwidth authorization frame contains a time label value and is used to realize the system clock synchronization between each ONU side and the OLT side.

In the technical solution of the present invention, the bandwidth management mode is centralized and easy to control, and the configuration and management of the upstream bandwidth of each ONU side can be realized only on the OLT side; the time-division control of the upstream bandwidth can be realized independently by each ONU side.

The uplink bandwidth control method adopted in the present invention can make full use of line resources and provide reliable uplink connection channels on the low-cost EPON platform; the supported agreement bandwidth has a wide range and small granularity, which can meet the needs of users as much as possible; Flexible control of uplink bandwidth according to business conditions, providing better services for ONUs with heavy traffic without reducing the service quality of all ONUs; at the same time supporting traditional TDM services with QoS guarantees, realizing multiple Service access; it also provides telecom operators with a simple and convenient upstream bandwidth management method to ensure the rationality of the operation charges of the access network segment, that is, the bandwidth enjoyed by the access network users can be kept in direct proportion to their payment.

The method of the invention can improve the access network operator's ability to control and manage the uplink shared bandwidth of the EPON system, provide uplink bandwidth utilization, and guarantee the bandwidth rights and interests of EPON users.

Description of drawings

Fig. 1 is a schematic diagram of the downstream data flow direction in the multi-service EPON (MS-EPON) system topology;

Fig. 2 is a schematic diagram of the upstream data flow direction in the multi-service EPON (MS-EPON) system topology;

Fig. 3 is the present invention to multi-service EPON (MS-EPON) system upstream dynamic bandwidth allocation process schematic diagram;

Fig. 4, Fig. 5 are the format description of the used MAC control frame of multi-service EPON system uplink dynamic bandwidth allocation, wherein Fig. 4 is the format of the bandwidth request frame, and Fig. 5 is the format of the bandwidth authorization frame;

Fig. 6 is a multi-service EPON system, a block diagram of the calculation process of the authorization content when the OLT allocates the uplink dynamic bandwidth to the ONU;

Fig. 7 is a functional block diagram of uplink dynamic bandwidth allocation in the multi-service EPON system of the present invention.

Detailed ways

The uplink of the present invention adopts the mode of time-division multiplexing, that is, in the round of authorization that the OLT allocates bandwidth to each online ONU, the OLT is all based on the agreement bandwidth between each ONU and the OLT and the situation of each ONU real-time service flow. The uplink is fairly divided into time slots of different sizes, which are respectively authorized to corresponding ONUs; each ONU can only send or receive data in the authorized time slot allocated to itself.

In the point-to-multipoint system of EPON, the maximum period T is defined. The OLT first obtains the bandwidth agreement between each ONU customer and the operator through the network management interface, and calculates the basic bandwidth threshold of each ONU: BTh=BW×T, where BW is the bandwidth size of the agreement, and the basic bandwidth threshold is also the maximum value of the ONU customer. Bandwidth authorization value. Then, through the EPON management channel, the basic bandwidth threshold BTh of each ONU is stored in the Field Programmable Logic Array (FPGA) chip on the OLT side. The online status of each ONU is also saved in the FPGA chip on the OLT side through the EPON management channel.

The scheme of the present invention needs to complete the calculation of the maximum bandwidth authorization (that is, the basic bandwidth threshold), the calculation of the authorization start time, the calculation of the length of the data service authorization, the calculation of the E1 first authorization sending time, the synchronization of the EPON system clock, the transmission of bandwidth request information, and the transmission of bandwidth authorization information , Data cache, time-division control of data transmission and other subtasks. The subtasks in the solution of the present invention will be further described below by taking the implementation of the technical solution of the present invention on a multi-service EPON system as an example and in conjunction with the accompanying drawings.

Referring to Fig. 3, it illustrates the dynamic allocation process of the uplink bandwidth of the MS-EPON system. The figure shows that the OLT receives upstream data (data services based on Ethernet services), upstream bandwidth requests and E1 service data from each ONU, and the OLT sends upstream bandwidth grants to each ONU. The E1 service data of each ONU is sent collectively at n×500μs points (n=0, 1, 2,...), as shown by the dotted line arrow in the figure; the upstream bandwidth request frame of each ONU is in its Ethernet service data Send at the end of the transmission, as shown by the thick and thin dotted arrow in the figure; OLT immediately processes and allocates bandwidth after receiving an upstream bandwidth request frame from an ONU, and notifies the ONU through the bandwidth authorization frame, as shown by the fine and thin dotted arrow in the figure.

The MS-EPON system software calculates the upstream basic bandwidth threshold (maximum bandwidth authorization) of each ONU according to the bandwidth protocol, and then calculates the bandwidth authorization of each ONU per transmission cycle T through FPGA, including the authorization start time ST and authorization length G (uplink The broadcast frames sent by each ONU in the direction, such as some management information, still occupy the data channel of the ONU, that is, occupy the bandwidth). The MS-EPON system provides independent logical link channels for the data transmission of each ONU through bandwidth request-bandwidth authorization, and ensures that the size of the logical link channels is not less than the bandwidth agreement with the user.

In Figure 3, the MS-EPON system fixes the transmission of E1 service data at a fixed time point of n×500μs (n=0, 1, 2,...), that is, provides authorization at each fixed time point, using It is used to transmit E1 data packets in Ethernet frame format. The MS-EPON system can fully guarantee the quality of service (QOS) of E1 services by adding smoothing jitter measures (buffering data of different periods) at the receiving end. Each round of authorization provides n authorizations for the transmission of ordinary Ethernet data ONU1 DATA1 to ONUn DATAn of n online ONUs, which are used to transmit n ordinary Ethernet data frames correspondingly. In Figure 3, ONU1, ONU2, ..., ONUn at different distances from the OLT side to the ONU side perform uplink ordinary Ethernet data transmission in mutually independent logical transmission channels, as shown by the solid arrows in the figure.

Maximum bandwidth authorization (that is, the basic bandwidth threshold) calculation subtask: the process of converting the ONU user bandwidth agreement into the maximum bandwidth authorization by the EPON system is called the maximum bandwidth authorization calculation process. In the present invention, in the OLT side CPU, through the system software, the maximum bandwidth allocation table (BW) of each ONU formulated in the protocol is used to calculate the upstream maximum bandwidth authorization of each ONU: BTh=T*BW.

Authorization start time calculation subtask: The process of EPON system determining each authorization start time of each ONU is called the authorization start time calculation process. In the OLT side FPGA, the present invention utilizes the value in the authorized time register, the loop time delay of the ONU, the authorized time starting point of the E1 data packet, and the current clock to determine the authorized starting time of the ONU by hardware (concrete calculation process See accompanying drawing 6 description).

Calculation subtask of data service authorization length: The process of EPON system determining the bandwidth authorization size of ONU data service in the next sending cycle is called the data service authorization length calculation process. In the FPGA of the OLT side, the present invention compares the maximum bandwidth allocation table, the ONU bandwidth request table and the difference between the authorization start time and the next E1 sending time by hardware, and determines the data service bandwidth authorization of the ONU in the next sending cycle ( The specific calculation process is shown in Figure 6).

E1 first authorization sending time calculation subtask: The process of EPON system determining the first E1 data sending time of each ONU is called E1 first authorization sending time calculation process. In the OLT side FPGA of the present invention, by hardware, start counting continuously from system counter 0, add the value of each E1 authorization length (register) that the system configures for each ONU successively, just can calculate each ONU E1 bandwidth successively The start time of authorization; the start time of each ONU E1 bandwidth authorization is subtracted from the loop delay of each ONU to obtain the sending time of each ONU E1 bandwidth authorization.

EPON system clock synchronization sub-task: The EPON upstream behavior is a multipoint-to-point topological structure mode. The consistency between the sending time slot of each ONU and the time slot allocated by the OLT is the basis for preventing the collision of the upstream data of each ONU. Therefore, the clock on the ONU side should be Synchronized with the clock on the OLT side. This scheme adopts the clock synchronization technology with the time tag value as the core (use the time tag value to carry out the clock synchronization of each ONU side and the OLT side, its implementation technology can refer to the application number submitted by the applicant on December 6, 2002. 02153928.6, patent application document titled "Method for Bidirectional Bandwidth Control in Ethernet Passive Optical Network System").

Bandwidth request information transfer subtask: This process is a process of transferring the information from the FPGA on the ONU side to the FPGA on the OLT side. In this scheme, the process is to utilize the EPON MAC control frame (frame type identifier=0x8808) to carry the cached data size information sent by the ONU side, that is, the bandwidth request information.

Bandwidth authorization information transfer subtask: This process is the process in which the uplink bandwidth authorization information is transferred from the FPGA on the OLT side to the FPGA on the ONU side. In this solution, the process is to use the EPON MAC control frame (frame type identifier = 0x8808) to carry the uplink bandwidth authorization information.

Data cache sub-task: Due to the time-division control strategy, each ONU can only send or receive data in its own authorized time slot. Therefore, the EPON system in the uplink direction needs to cache data on the ONU side.

Time division control subtask of data transmission: This task is the core of EPON system bandwidth control strategy. In the upstream direction, each ONU configures the upstream authorization register according to the bandwidth authorization after receiving the bandwidth authorization frame, and uses the register to control the start time point and duration of the upstream transmission.

The authorization time of E1 is fixed, and the E1 authorization of all ONUs configured with E1 links is continuous, from 0:00 to the E1 authorization of the first ONU, until the E1 authorization of the last ONU configured with E1 links Finish. Through the network management interface, the length of the E1 configured by each ONU can be obtained and stored in the FPGA. Next, start from the OLT counter 0 through the FPGA, continuously calculate the first authorization start time of each ONU E1, and then continuously calculate the first authorization sending time of each ONU E1, and then send the first authorization The time and the configured E1 grant length are encapsulated in the bandwidth grant frame in the MAC control frame format and sent to the ONU.

Calculate the first authorization start time of each ONU E1, starting from OLT counter 0, which is the first authorization start time of the first ONU, and add the first authorization start time of this ONU to the ONU The E1 authorization length is to calculate the authorization start time of the next ONU E1 of the ONU, and so on until the first authorization start time of the last ONU E1 configured with an E1 link is calculated.

The calculation of the first authorized sending time of each ONU E1 starts from the calculation of the first authorized sending time of the first ONU until the calculation of the first authorized sending time of the last ONU E1 configured with an E1 link ends. The process is: read out the loop delay of each ONU, subtract the first authorized start time of the ONU from its loop delay, if the difference is negative, add the cycle of the counter, which is the ONU The first authorized sending time for sending E1 service data, if the difference is a positive number, the difference is the first authorized sending time for this ONU to send E1 service data.

The first authorized sending time of each ONU E1 and the corresponding authorized length are encapsulated into a bandwidth authorization frame in MAC control frame format and sent to the ONU, that is, the OLT sends E1 bandwidth configuration information to each ONU through the bandwidth authorization frame. After the ONU receives the bandwidth authorization for E1, it separates the sending time of the first E1 authorization and the size of the E1 authorized bandwidth. When the clock of the ONU is equal to the first E1 authorized sending time, the E1 data is sent, and then the ONU automatically sends the E1 data once every 500us.

As long as there is a change in the E1 configuration of an ONU (including the increase or decrease of ONU users configuring E1 links and their configuration changes), the system will recalculate and send the E1 configurations of all ONUs once.

In addition, in order to ensure the synchronization of each ONU, it is necessary to synchronize the clocks of each ONU to be consistent with the OLT clock.

Through the above-mentioned bandwidth control process, the EPON system provides each ONU with a data transmission channel that is independent of each other, has bandwidth guarantee, and can flexibly allocate bandwidth according to business busyness and idleness on the Gigabit Ethernet-based PON platform, and utilizes time-division The bandwidth authorization for control and allocation ensures that the data channels of each ONU do not interfere with each other, and at the same time periodically sends E1 services at a fixed point in time, and guarantees the QoS of E1 services.

Figure 4 and Figure 5 show the frame formats of the bandwidth request frame and the bandwidth grant frame respectively. Fig. 4 is a frame format of a bandwidth request frame, and Fig. 5 is a frame format of a bandwidth grant frame.

The bandwidth request frame is generated and sent by the FPGA at the ONU side, received by the OLT and terminated at the FPGA chip at the OLT. The bandwidth request frame is the way for the OLT to obtain the ONU cache data size information. It adopts the structure of the MAC control frame and includes all fields in the general Ethernet frame format.

In Fig. 4, the bandwidth request frame contains the following information: a preamble of 8 bytes, including a broadcast LLID (LogicalLink Identification, which is a logical link identification, and is an identification of a point-to-point logical link channel established on an EPON platform through a bandwidth control strategy) ; The destination MAC (DA, medium access control layer, a sublayer of the Ethernet data link layer) of 6 bytes is the OLT MAC address; the source MAC (SA) of 6 bytes is the ONU MAC address; 2-byte unique type identifier 0x8808, used for frame type identification (EPON OAM MAC control frame); 2-byte MAC manipulation code 0x0003, used to distinguish different EPONMAC control frames; 4-byte Time tag (timestamp, which can be used for ranging from the OLT to the ONU), is the time tag value sent by the bandwidth request frame.

The request content contained in the bandwidth request frame includes: 2-byte LLID; 3-byte request, which is used to report the size of the ONU cache data to the OLT, for the OLT to calculate the authorized bandwidth of the ONU in the next sending cycle .

The bandwidth authorization frame is generated and sent by the FPGA chip on the OLT side, received by the ONU side and terminated by the FPGA chip on the ONU side. The bandwidth authorization frame is the way for the ONU to obtain the upstream bandwidth authorization information. It adopts the structure of the MAC control frame and includes all fields in the general Ethernet frame format.

In Fig. 5, the bandwidth authorization frame contains the following information: a preamble of 8 bytes, including broadcast LLID or ONULLID (ONUID+0x00), and a corresponding table of the ONU Ethernet destination MAC address and the destination ONU_ID is set up at the OLT side, and is checked by hardware The LLID number of the corresponding ONU can be obtained by means of the table, and written into the preamble; the 6-byte destination MAC (DA) is the broadcast address or the destination ONU MAC address; the 6-byte source MAC (SA) address, Is the OLT MAC address; 2-byte unique type identifier 0x8808, used for frame type identification (EPON OAM MAC control frame); 2-byte MAC manipulation code 0x0002, used to distinguish different EPON MAC control frames ; The 4-byte time tag (timestamp) is the time tag value sent by the authorization frame, which is used for EPON system clock synchronization.

The authorization content contained in the bandwidth authorization frame includes: 1-byte authorization number/flag domain (MSG), including 1-bit pon port flag, indicating the corresponding OLT port; 1-bit discovery flag, indicating whether It is the sign of initializing the authorization; the first 2 and the last 4 are 6 bits of reserved, which are reserved bits; 2 bytes of LLID, indicating the LLID to which the authorization belongs (used to distinguish whether the ONU is sending the bandwidth authorization frame of E1 bandwidth configuration or The bandwidth authorization frame of Ethernet service data bandwidth configuration); 4 bytes of StartTime (marked as ST in the present invention) represent authorization start time; 3 bytes of Length represent authorization length (marked as ST in the present invention) for G).

By using the bandwidth request frame and the bandwidth authorization frame in the above MAC control frame format, system clock synchronization, ranging, uplink transmission of bandwidth request information and downlink transmission of authorization messages are realized.

To sum up, whenever an authorization update involving E1 configuration occurs, the MS-EPON system will send a bandwidth authorization frame related to E1 configuration to each online ONU through the OLT; after the OLT receives the bandwidth request frame from the ONU , to send a bandwidth authorization frame to the ONU; the ONU sends a bandwidth request frame to the OLT when each uplink data transmission is about to end.

Referring to FIG. 6 , the calculation process for generating ONU authorization frame content for the OLT.

Step 600, the FPGA on the OLT side reads the online status of each ONU cyclically, if it finds that the current ONU is not online, it reads the online status of the next ONU; if it finds that a certain ONU (i) is online, it stops reading the next ONU ( i+1) online state operation, read out the last authorization end time T_end(i-1) of ONU(i) at the same time, and read this ONU when the read last authorization end time is consistent with the OLT system time The bandwidth request information of the ONU, i.e. the cache data size, is represented as Re(i), and the loop time delay RTT(i) of this ONU calculated by the time tag value in the bandwidth request frame by the FPGA at the OLT side;

Step 601, comparing the difference between the authorization end time T_end(i-1) of the last ONU(i-1) of the ONU and the system time T_sys (the system time is automatically calculated by the OLT after power-on, reflected by the counter value) whether Greater than the loop delay RTT (i), if the difference is greater than the loop delay RTT (i) of the ONU (i), execute step 603, otherwise execute step 602;

Step 602, the difference between T_end(i-1) and T_sys is less than RTT(i), then the authorized initial start time IT_begin(i) of ONU(i) is equal to T_sys plus RTT(i);

Step 603, if the difference between T_end(i-1) and T_sys is greater than or equal to RTT(i), then the authorized initial start time IT_begin(i) of ONU(i) is equal to T_end(i-1).

Through the above steps 601 to 603, the authorized initial start time IT_begin(i) of the online ONU(i) is obtained. Steps 601 to 603 can also be described as: the OLT adds the system time to the loop delay value of the ONU, compares the sum with the last authorization end time of the ONU, and takes the larger value as the initial authorization start time.

Step 609, compare whether the difference between the last E1 data transmission time T_E1 of the ONU (i) and IT_begin (i) is greater than or equal to the upstream minimum bandwidth authorization of the ONU (i), if the difference is greater than or equal to the upstream minimum bandwidth authorization, execute Step 610, if the difference is less than the uplink minimum bandwidth authorization, execute step 611 (the front and rear protection bandwidth size and the size of the MAC control frame summed by the network management to obtain the uplink minimum bandwidth authorization, which is a fixed value);

Step 610, when the difference is greater than or equal to the uplink minimum bandwidth authorization, the authorization start time T_begin(i) is the authorization initial start time IT_begin(i);

Step 611 , when the difference is less than the uplink minimum bandwidth grant, postpone the grant start time T_begin(i) of the ONU(i) until after its E1 data is sent.

Through steps 609 to 611, the authorization start time T_begin(i) of the ONU(i) is obtained.

Step 612, calculate the number of bytes that can be sent within the interval between the E1 sending time point T_E1 and the authorization start time T_begin(i) of the ONU(i), record it as the authorized limit value, and record the authorization start time, the calculated authorization The limited value is sent to step 613 for calculating the final authorization value G(i), and the authorization start time T_begin(i) is sent to step 614 for generating an authorization frame.

Step 604, at the same time as step 601, compare the size of the bandwidth request information Re(i) of ONU(i) and its threshold value Th(i) (during initial authorization, the threshold value is equal to the basic bandwidth threshold BTh), if Re (i) is less than or equal to Th(i), then execute step 605, otherwise execute step 606;

Step 605, if Re(i) is less than or equal to Th(i), the initial authorized bandwidth IG(i) allocated to ONU(i) by the OLT is equal to its bandwidth request value Re(i), and the threshold value is restored to the initial value at the same time, That is, restore to the basic bandwidth threshold BTh;

Step 606, if Re(i) is greater than the threshold value Th(i), then compare Th(i) with the size of the maximum Ethernet frame length MF, and execute step 607 when Th(i) is greater than or equal to MF, and Th(i) is less than Step 608 is executed during MF, and step 606 is set to prevent that when the buffer frame length on the ONU side is larger than its basic bandwidth threshold, the frame can be sent by accumulating its own basic bandwidth threshold without occupying other OUN bandwidth and avoiding The occurrence of this frame cannot be sent;

Step 607, when Th(i) is greater than or equal to MF, the initial authorized bandwidth IG(i) is equal to Th(i), and the restoration threshold value is the initial value, that is, the threshold value is restored to the basic bandwidth threshold BTh;

Step 608, when Th(i) is smaller than MF, the initial authorized bandwidth IG(i) is equal to the bandwidth request value Re(i) of the bandwidth request frame, and the threshold is increased with the basic bandwidth threshold BTh as the granularity.

In the above steps 604 to 608, the initial authorized bandwidth IG(i) in different situations is obtained.

Step 613, compare the initial authorized bandwidth IG(i) from step 605 or 607 or 608 with the authorized limited value from step 612, take the smaller one as the final authorized value G(i), and send it to step 614, Used to generate authorization frames;

Step 614, the authorization start time T_begin (i) (i.e. StartTime in Figure 5) and the final authorization value G (i) (i.e. Length in Figure 5) are assembled into a bandwidth authorization frame in MAC control frame format and sent to the ONU, At the same time, the end time T_end(i) of this authorization is recorded for use in the next authorization of the ONU.

After receiving the bandwidth authorization frame, the ONU separates the authorization start time and the final authorization value G(i) (authorization length). When the clock of the ONU is equal to the authorization start time, the ONU sends the operation and management (Operation&Manage: OAM) frame sequentially and Ethernet data. When it is found that the remaining authorization length is not enough to send the next frame and the bandwidth request frame, stop sending the OAM frame or Ethernet data, query the size of the OAM memory and the size of the Ethernet memory, and use the sum of the two items as the bandwidth request information Then assemble the bandwidth request frame into the MAC control frame format and send it to the OLT.

The uplink bandwidth dynamic allocation control mechanism involved in the present invention makes up for the deficiency of dynamic bandwidth allocation in the current EPON system. It can allocate in real time according to the change of each ONU business flow to improve the bandwidth utilization; when each user competes for the system bandwidth, the bandwidth is allocated fairly according to the contract signed between the user and the operator, that is, the bandwidth obtained by the user is proportional to its payment How much, which is convenient for operators to operate and manage; at the same time, E1 Over EPON technology is used to transmit E1 services with QoS guarantee.

Referring to Fig. 7, the figure shows the principle of uplink bandwidth control. The uplink bandwidth authorization message of OLT side 71, by OLT bandwidth authorization generator 54, according to the bandwidth request length that separates from the bandwidth request frame 532 that receives, and the maximum bandwidth authorization table that is produced by CPU 51 and generates by Ethernet switch 52 531 is calculated and generated, and the uplink bandwidth grant message enters the bandwidth grant frame generator 45 . The bandwidth authorization frame generator 45 produces the upstream bandwidth authorization frame, and after entering the management queue 44, inserts the time stamp value generated by the OLT clock counter 42 in step 43, and then sends the bandwidth authorization frame containing the time stamp value to the ONU end 72. The OLT clock counter 42 counts under the drive of the OLT local clock source 41 .

The ONU terminal 72 receives the bandwidth authorization frame through step 461, and extracts the time stamp value from the received bandwidth authorization frame through step 462, and modifies the local ONU clock counter 47 according to the time stamp value. Step 461 also saves the grant information (grant start time and grant length) extracted from the received bandwidth grant frame in the uplink grant register of the uplink transmission controller 60 . On the other hand, the local data on the ONU side is encapsulated into a standard MAC frame in the Ethernet interface 55, and then in step 56, add the LLID of this ONU, then cache in the upstream sending buffer 59, and send it in the upstream sending controller 59. Under control, the uplink data can be sent when the value of the local clock counter 47 is equal to the authorization start time (ST) of this ONU in the uplink bandwidth authorization, and when the authorization period is about to end, the bandwidth request frame generator 57 generates a bandwidth authorization frame , insert the time stamp generated by the local clock source 48 at step 58 and send it to the OLT side 71.

In a word, adopting the method of the present invention can effectively improve the utilization rate of lines, ensure the reliability of transmission in PON, enhance the flexibility of bandwidth control and allocation, and provide traditional TDM services with QoS, providing truly safe and reliable services for telecom operators. Controlled bandwidth management control scheme.

The method of the present invention is mainly applied in the multi-service EPON system based on gigabit Ethernet, but the scheme design of the present invention can also be applied in any network that can provide point-to-multipoint application based on Ethernet.

Claims (12)

1. A passive optical network upstream bandwidth dynamic distribution control method is to carry out the dynamic distribution control of upstream bandwidth on the passive optical network formed by OLT, optical distribution network and a plurality of ONUs, it is characterized in that comprising: A method for dynamically allocating and controlling the uplink bandwidth of each ONU based on Ethernet service data, and a method for dynamically allocating and controlling the uplink bandwidth of E1 service data for each E1 link ONU configured at the same time; The described method for dynamically allocating and controlling each ONU based on the upstream bandwidth of Ethernet service data includes: A1. Each online ONU encapsulates the size of its cached data in the bandwidth request frame of the Ethernet MAC control frame format containing the time tag value, and sends it to the Ethernet service data within the respective authorized bandwidth allocated by the OLT Report the bandwidth request frame to the OLT at the end of sending; B1.OLT calculates the authorized start time and authorized bandwidth length of the ONU when polling the online ONU, and encapsulates it in the bandwidth authorization frame of the Ethernet MAC control frame format containing the time tag value, and sends it to the ONU. The calculation basis includes the cached data size reported by the ONU and the basic bandwidth threshold converted according to the ONU's upstream user bandwidth protocol; The described method for dynamically allocating and controlling the uplink bandwidth of the E1 service data of each configured E1 link ONU includes: A2. The OLT encapsulates the calculated first authorized sending time of each ONU E1 service data and the configured authorized bandwidth length in the bandwidth authorization frame of the Ethernet MAC control frame format containing the time tag value, and sends it to each ONU ; B2. Each ONU that receives the bandwidth authorization, when its ONU clock is equal to its first authorized sending time, sends the first E1 service data within the configured authorized bandwidth length, and then sends E1 once every fixed time business data. 2. The passive optical network uplink bandwidth dynamic allocation control method according to claim 1, characterized in that: in the step A1, the size of the self buffer data includes the size of the OAM memory and the size of the Ethernet service data buffer The sum of the sizes; when the remaining authorized bandwidth length of the ONU is not enough to send the next frame of Ethernet service data and bandwidth request frame, stop sending the Ethernet service data and bandwidth request frame to the OLT. 3. the passive optical network uplink bandwidth dynamic distribution control method according to claim 1, is characterized in that: in described step A1, described bandwidth request frame is produced and sent by the Field Programmable Logic Array chip of each ONU, Includes all fields in the Common Ethernet Frame Format. 4. The passive optical network uplink bandwidth dynamic distribution control method according to claim 1, characterized in that: in the step A1, the Ethernet service data of the ONU is sent in the local clock and bandwidth authorization frame of the ONU start sending when the authorization start times in the . 5. The passive optical network uplink bandwidth dynamic allocation control method according to claim 1, characterized in that: in the step B1, it also includes recording the bandwidth authorization end time of the ONU when encapsulating the bandwidth authorization frame. 6. The passive optical network uplink bandwidth dynamic allocation control method according to claim 1, characterized in that: In the step B1, the authorization start time of the calculation ONU further includes: B11.OLT adds the system time to the loop delay value of the ONU, compares the sum value with the last authorization end time of the ONU, and takes the larger value as the initial authorization start time; B12. After calculating the initial authorization start time of the ONU, the difference between a group of E1 service data transmission time and the initial authorization start time, when the difference is judged to be less than the upstream minimum bandwidth authorization value, change the authorization start time of the ONU is the sending end time of the E1 service data, otherwise the authorization start time of the ONU is the initial authorization start time. 7. The passive optical network uplink bandwidth dynamic allocation control method according to claim 6, characterized in that: Taking a large value in the step B11 further includes: When the last authorization end time of the ONU is less than the sum of the system time and the loop delay value of the ONU, the sum of the system time and the loop delay value of the ONU is taken as the initial authorization start time; When the last authorization end time of the ONU is greater than the sum of the system time and the loop delay value of the ONU, the last authorization end time of the ONU is taken as the initial authorization start time. 8. The passive optical network uplink bandwidth dynamic allocation control method according to claim 1, characterized in that: In the step B1, the authorized bandwidth length of the calculation ONU further includes: B13.OLT compares the buffered data size value and the threshold value of the ONU request, wherein the threshold value is the cumulative value of the basic bandwidth threshold value of the ONU; B14. When the threshold value is greater than the requested cache data size value, take the requested cache data size value as the initial authorized bandwidth value, and restore the threshold value to the basic bandwidth threshold value; B15. When the threshold value is less than the requested buffer data size value, compare the threshold value and the maximum Ethernet frame length; B16. When the threshold value is greater than the maximum Ethernet frame length, get the threshold value as the initial authorized bandwidth value of the ONU, and restore the threshold value to the basic bandwidth threshold value; B17. When the threshold value is less than the maximum Ethernet frame length, the upstream minimum bandwidth authorization of the ONU is taken as the initial authorized bandwidth value, and the threshold value is increased at the granularity of the basic bandwidth threshold value; B18. Compare the initial authorized bandwidth value obtained in step B14 or step B16 or step B17 with the authorized limited value, and take the smaller value as the authorized bandwidth length of the ONU. 9. The passive optical network uplink bandwidth dynamic allocation control method according to claim 8, characterized in that: in the step B18, the authorized limit value is after the initial authorization start time of the ONU, a group of E1 The service data sending time and the number of bytes that can be sent within the ONU authorization starting time interval. 10. The passive optical network uplink bandwidth dynamic allocation control method according to claim 1, characterized in that: in the steps B1 and A2, the bandwidth authorization frame is generated and sent by the Field Programmable Logic Array chip of the OLT , including all fields in the general Ethernet frame format. 11. The passive optical network uplink bandwidth dynamic allocation control method according to claim 1, characterized in that: the bandwidth authorization frame in the step A2 is sent when the ONU updates the E1 service data authorization bandwidth configuration. 12. the passive optical network uplink bandwidth dynamic distribution control method according to claim 1, is characterized in that in the step A2, the first authorized sending time of each ONU E1 service data, its calculation comprises: Starting from the value of the system counter 0, add the authorized bandwidth length configured by the network management system for each ONU in turn, and obtain the first authorized start time of each ONU E1 business data in turn; Read out the loop delay of each ONU, and subtract its first authorized start time from its loop delay; When the difference is a positive number, the difference is the first authorized sending time of the ONU E1 business data; When the difference is negative, plus the period of the counter, it is the first authorized sending time of the ONU E1 business data.

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