Background technology
Multi-service EPON (EPON) system based on Ethernet, adopt local side apparatus-optical line terminal (Optical line Terminal, be called for short OLT), connect a plurality of remote equipment-optical network units (Optical Net Unit by passive optical distribution network, be called for short ONU), constitute the tree-like benefit structure of opening up of point-to-multipoint.
Referring to Fig. 1, Fig. 2, downstream direction and upstream direction in multi-service EPON (MS-EPON) system topology are shown respectively among the figure.
Referring to Fig. 1, down direction, the same driving source of optical signals of OLT 11 side downstream signals transmission produces, as 1,2,3, link up between each signal frame, OLT 11 sends data-signal by broadcast mode to each optical network unit 13 (ONU1 to ONU3) of far-end, through splitter 12, by each optical network unit 13 (ONU1 to ONU3) of far-end, from continuous data 1,2,3, select and one or several relevant frame data, send to the user 14 of oneself.
Referring to Fig. 2, up direction, each optical network unit 13 (ONU1 to ONU3) only sends certainly user 14 Frame separately in distributing to the time slot of oneself, then be in the transmission wait state At All Other Times, the Frame of each optical network unit 13 combines to OLT 11 transmission through mixer 12 in optical fiber.
The EPON uplink is a plurality of ONU time division multiplexing upstream bandwidths, and it is very necessary therefore using appropriate allocated bandwidth mechanism.Multi-service EPON system mainly provides data service based on Ethernet service to the user, also should support the E1 business that service quality (QoS) guarantees simultaneously.
Multi-service EPON upstream bandwidth distributes the mode that can adopt the bandwidth fixed configuration, and promptly system disposes the upstream bandwidth of each ONU according to the predetermined bandwidth fixed of each ONU (static in other words).And because EPON carrying E1 (E1 Over EPON) technology is a kind of the E1 data to be adapted to the technology that Ethernet data sends at fixed time, thereby this fixed-bandwidth distribution method can organically merge EPON carrying E1 technology and supports traditional Time Division Multiplexing business.
Under the situation of bandwidth fixed configuration, if the assurance transmission performance, distribute bandwidth with the peak rate of each ONU, this moment, the data flow because of each ONU often was not to be in simultaneously under the peak rate state, to cause the whole system bandwidth not to be fully utilized, greatly reduce usage factor of system resource.And if the raising usage factor of system resource, Mean Speed with each ONU transmission data is distributed bandwidth, in the time of usually can appearing at some ONU again and will send bigger burst group data, the situation that data but can not in time send, thus the packet loss of data and time delay are increased; And the data traffic of other ONU is because of less than Mean Speed, and system resource still can not be fully utilized.This shows that because of sudden very strong Ethernet data business accounts for suitable vast scale, static bandwidth allocation will cause EPON system bandwidth utilance low.
Then to be OLT make overall arrangements according to the request to bandwidth of each ONU real-time report Dynamic Bandwidth Allocation, dynamically adjusts the bandwidth value that licenses to ONU.Because Dynamic Bandwidth Allocation can embody the real-time request of ONU, thereby can make full use of system resource, improves performances such as time delay simultaneously.
But under the Dynamic Bandwidth Allocation situation, because it is unfixing that each ONU sends the time of data, thereby can not directly use EPON carrying E1 technology to support traditional TDM business, and at present the Dynamic Bandwidth Allocation mechanism of EPON system is that request according to ONU user gives its corresponding bandwidth, can not manage bandwidth, can only do one's best to the bandwidth that user's request provides, thereby its service quality is also done one's best, telecom operators can not be satisfied to the manageable requirement of runing of synthesis business platform, actual market demand can not be satisfied.
Therefore scientific and effective upstream bandwidth dynamic assignment controlling mechanism should be able to remedy the deficiency of present MS-EPON system dynamics allocated bandwidth: can carry out upstream bandwidth in real time and distribute according to the variation of each ONU Business Stream, to improve bandwidth availability ratio; When each user's contention system bandwidth, can carry out allocated bandwidth liberally according to the contract of signing in advance between user and operator, promptly what of its paying are the bandwidth that obtains of user be proportional to, and carry out operation management to make things convenient for operator; Simultaneously, the E1 business that the technical transmission that can utilize EPON to carry E1 has QoS to guarantee satisfies the demand of client to the conventional telecommunications business.
Summary of the invention
The dynamic assignment control method that the purpose of this invention is to provide a kind of passive optic network up bandwidth, to carry out dynamic assignment control based on the upstream bandwidth in the multi-service passive optical network of Ethernet, can not only prevent the conflict between each ONU uplink burst data of EPON system, the more important thing is can be according to the variation of each ONU Business Stream, carry out allocated bandwidth in real time, to improve bandwidth availability ratio; When each user's contention system bandwidth, the contract according to the signing of user and operator carries out allocated bandwidth liberally, and promptly what of its paying are the bandwidth that obtains of user be proportional to, and guarantees the fairness of allocated bandwidth and makes things convenient for the operation management of operator; Can utilize the technology of EPON carrying E1 business, the E1 business that transmission has QoS to guarantee satisfies the demand of client to the conventional telecommunications business.
The technical scheme that realizes the object of the invention is such: a kind of passive optic network up bandwidth dynamic assignment control method, be the dynamic assignment control of on the EPON of forming by OLT, optical distribution network and a plurality of ONU, carrying out upstream bandwidth, it is characterized in that comprising:
To each ONU based on the dynamic assignment control method of the upstream bandwidth of Ethernet service data with simultaneously to the dynamic assignment control method of the upstream bandwidth of the E1 business datum of each ONU;
Described each ONU is comprised based on the dynamic assignment control method of the upstream bandwidth of Ethernet service data:
A1. by each online ONU size that self is data cached, be encapsulated in the bandwidth request frame of the ethernet mac control frame form that contains the time tag value, and in the mandate bandwidth of distributing separately, when the Ethernet service data send end, this bandwidth request frame reported OLT by OLT;
B1.OLT is when being polled to online ONU, calculate the mandate zero-time of this ONU and authorize bandwidth length, and be encapsulated in the bandwidth authorizing frame of the ethernet mac control frame form that contains the time tag value, send to this ONU, basis comprises data cached size in the bandwidth request frame that this ONU reports and the primary bandwidth threshold value that converts according to the up user bandwidth protocol of this ONU;
The dynamic assignment control method of the upstream bandwidth of described E1 business datum to each ONU comprises:
First of each ONU E1 business datum that A2.OLT will calculate authorizes the mandate bandwidth length of transmitting time and configuration to be encapsulated in the bandwidth authorizing frame of the ethernet mac control frame form that contains the time tag value, sends to each ONU;
B2. receive each ONU of bandwidth authorizing, its ONU clock equal its first carry out the transmission of first E1 business datum when authorizing transmitting time, send an E1 business datum every a set time later on.
Technical scheme of the present invention utilizes time division multiplexing and statistic multiplexing means to realize that the EPON system is to up sharing link bandwidth dynamic assignment and control.This scheme utilizes the bandwidth request frame of ethernet mac control frame form to transmit the data cached size information of ONU; OLT requires the less ONU user of bandwidth for convention, authorize the size of the comparative result adjustment mandate bandwidth threshold value of bandwidth threshold value and maximum Ethernet frame length according to it, thereby under the situation that does not take other ONU bandwidth, guarantee to send maximum ethernet frame; The data cached size information that OLT reports according to each ONU gives each ONU and is no more than the bandwidth authorizing of its mandate bandwidth threshold value and dodges the professional sending time slots of E1; Utilize the bandwidth authorizing frame of ethernet mac control frame form to transmit the clock synchronization message and the bandwidth authorizing message of OLT side and each ONU side, the data that the time-division is controlled in the up transmission buffer memory of each ONU send; Utilize the bandwidth authorizing frame to transmit the configuration information of E1, first mandate transmitting time and the E1 that comprise each ONU authorize length, make the E1 data that are adapted to ethernet frame format of each ONU, authorize transmitting time from its first, in the fixedly up transmission in slot cycle ground.
The inventive method economical and effective is neatly according to the bandwidth protocol of OLT and each ONU and the real time business situation of each ONU, and the upstream bandwidth of EPON each ONU of system is controlled in management.
In the technical scheme of the present invention, each ONU is according to the Ethernet bandwidth authorizing content from OLT that receives, and the collocating uplink transmitter register is realized Ethernet data and E1 data uplink are sent control.
The present invention utilizes the bandwidth request frame of ethernet mac control frame form, realizes the reporting of data cached size information of ONU; The bandwidth request frame contains the time tag value of ONU, utilizes conventional art can realize the range finding of OLT to ONU.
The present invention utilizes the bandwidth authorizing frame of mac frame form, realizes the descending transmission of authorization messages; The bandwidth authorizing frame contains the time tag value, is used to realize that the system clock of each ONU side and OLT side is synchronous.
Technical scheme of the present invention, Bandwidth Management mode are concentrated easily control, only need just can realize configuration and management to each ONU side upstream bandwidth in the OLT side; Realize independently of one another the time-division of upstream bandwidth is controlled by each ONU side.
The upstream bandwidth control method that the present invention adopts can make full use of line resource, is providing reliable up interface channel on the EPON platform cheaply; The convention bandwidth range of supporting is wide, granularity is little, can satisfy user's demand as far as possible; Can accomplish simultaneously the flexible control of upstream bandwidth according to the service conditions of each ONU, under the situation that does not reduce all ONU service quality, provide better service for the big ONU of traffic carrying capacity; Support to have traditional TDM business of QoS assurance simultaneously, realize partly that at Access Network multi-service inserts; Also for telecom operators provide succinctly upstream bandwidth way to manage easily, guarantee to insert the reasonability of network segment operation charge, promptly the bandwidth enjoyed of user of access network can keep direct ratio with its paying.
Method of the present invention can improve the control and management capability of Access Network operator to EPON system uplink shared bandwidth, and the upstream bandwidth utilance is provided, and ensures EPON user's bandwidth rights and interests.
Embodiment
Up link of the present invention is taked time-multiplexed mode, promptly distribute one of bandwidth to take turns in the mandate for each online ONU at OLT, OLT is the situation according to the convention bandwidth of each ONU and OLT and each ONU real time business stream, up link is divided into the time slot that differs in size one by one liberally, licenses to corresponding ONU respectively; Each ONU can only send or receive data in distributing to the mandate time slot of oneself.
At the point of EPON in the system of multiple spot, definition maximum cycle T.OLT at first obtains bandwidth protocol between each ONU client and operator by network management interface, and calculate the primary bandwidth thresholding of each ONU: BTh=BW * T, wherein BW is the amount of bandwidth of agreement, the maximum bandwidth authorization value that this primary bandwidth thresholding also is ONU client.Then by the EPON management channels, the primary bandwidth thresholding BTh of each ONU is kept in field programmable logic array (FPGA) chip of OLT side.The online situation of each ONU also is kept in this fpga chip of OLT side by the EPON management channels.
The present invention program need finish that maximum bandwidth mandate (being the primary bandwidth thresholding) calculates, authorizes that zero-time calculatings, data service mandate length calculation, E1 authorize first that transmitting time is calculated, the EPON system clock synchronously, the subtasks such as time-division control of bandwidth request information transmission, the transmission of bandwidth authorizing information, metadata cache, data transmission.Be that example also further specifies each subtask among the present invention program in conjunction with the accompanying drawings in multi-service EPON system, to implement technical solution of the present invention below.
Referring to Fig. 3, the upstream bandwidth dynamic allocation procedure of MS-EPON system has been described.Express upstream data (based on the data service of Ethernet service), uplink bandwidth request and the E1 business datum of OLT reception among the figure, and OLT sends the upstream bandwidth mandate to each ONU from each ONU.The E1 business datum of each ONU be fixed on n * 500 μ s points (n=0,1,2 ...) and concentrate to send, shown in dash-dot arrows among the figure; The uplink bandwidth request frame of each ONU sends when finishing in its Ethernet service data and sends, shown in thick rare dotted arrow among the figure; OLT receives and handles immediately behind the uplink bandwidth request frame of an ONU and distribute bandwidth, notifies this ONU by the bandwidth authorizing frame, shown in fine and closely woven dotted arrow among the figure.
The MS-EPON systems soft ware calculates the up primary bandwidth thresholding (maximum bandwidth mandate) of each ONU according to bandwidth protocol, calculate the bandwidth authorizing of the every transmission period T of each ONU then by FPGA, comprise and authorize zero-time ST and authorize the length G (broadcast frame that each ONU of up direction sends voluntarily, as some management information, still take this ONU data channel, i.e. occupied bandwidth).The mode of MS-EPON system by bandwidth request-bandwidth authorizing, for the sub data transmission of each ONU be you can well imagine for logical links passage independently, and the size that ensures this logical links passage is not less than the bandwidth protocol with the user.
Among Fig. 3, the MS-EPON system, will be fixed on the transmission of E1 business datum n * 500 μ s (n=0,1,2 ...) and set time point place, promptly per set time the point place mandate is provided, be used to transmit the E1 packet of ethernet frame format.The MS-EPON system by increase level and smooth shake measure (buffer memory different cycles data) at receiving terminal, just can fully ensure the quality of service (QOS) of E1 business again.Whenever, take turns mandate and provide n mandate, be used for the individual common ethernet data frame of the corresponding n of transmission for the transmission of common Ethernet data ONU1DATA1 to the ONUn DATAn of n online ONU.Among Fig. 3, the OLT side to ONU1, the ONU2 of ONU side different distance position ..., ONUn, independently carrying out up common Ethernet data transmission in the logical transport passage mutually, shown in solid arrow among the figure.
The subtask is calculated in maximum bandwidth mandate (being the primary bandwidth threshold value): the EPON system is called maximum bandwidth mandate computational process with the process that the ONU user bandwidth protocol is converted to the maximum bandwidth mandate.The present invention by systems soft ware, utilizes the maximum bandwidth allocation table (BW) of formulating each ONU in agreement to calculate the up maximum bandwidth mandate of each ONU: BTh=T * BW in OLT side CPU.
Authorize zero-time to calculate the subtask: the EPON system determines each ONU to authorize the process of time started to be called at every turn and authorizes zero-time computational process.The present invention by hardware, utilizes the value of authorizing in the time register, the loop time delay of ONU, the mandate time starting point of E1 packet in OLT side FPGA, and present clock determines the mandate zero-time (concrete computational process is seen accompanying drawing 6 explanations) of ONU.
Data service mandate length calculation subtask: the process that the EPON system determines the next transmission cycle to give ONU data service bandwidth authorizing size is called data service mandate length computation process.The present invention is in the FPGA of OLT side, pass through hardware, relatively the difference of maximum bandwidth allocation table, ONU bandwidth request table and mandate zero-time and next E1 transmitting time determines ONU and sends the data service bandwidth authorizing (concrete computational process is seen accompanying drawing 6 explanations) in cycle at next.
E1 authorizes transmitting time to calculate the subtask first: the EPON system determines the E1 data of each ONU to authorize the process of transmitting time to be called E1 first and authorizes transmitting time computational process first.In OLT side FPGA of the present invention, by hardware, begin to continue counting from 0 of system counter, add the value of system successively for each E1 mandate length (register) of each ONU configuration, just can calculate the zero-time of each ONU E1 bandwidth authorizing successively; The zero-time of each ONU E1 bandwidth authorizing and the loop time delay of each ONU subtract each other, and just can obtain the transmitting time of each ONU E1 bandwidth authorizing.
The last behavior multiple spot of the synchronous subtask of EPON system clock: EPON is to the topological structure mode of a bit, each ONU sending time slots is consistent with the OLT distributed time slot to be the basis that prevents that each ONU upstream data from bumping, therefore, the clock of ONU side should with the clock synchronization of OLT side.It is the Clock Synchronization Technology (utilize the time tag value to carry out the clock synchronization of each ONU side and OLT side, the application number that its realization technology can be submitted on December 6th, 2002 referring to the applicant is 02153928.6, name is called the patent application document of " method of two-way bandwidth control in the Ethernet passive optical network system ") of core that this programme has adopted with the time tag value.
Bandwidth request information is transmitted the subtask: this process is the process that is delivered to OLT side FPGA from the FPGA of ONU side.In this programme, this process is to utilize the EPON mac frame (the data cached size information that the carrying of frame type identifier=0x8808) ONU side sends is a bandwidth request information.
Bandwidth authorizing information is transmitted the subtask: this process is the upstream bandwidth authorization message is delivered to ONU side FPGA from OLT side FPGA a process.In this programme, this process is to utilize the EPON mac frame (carrying of frame type identifier=0x8808) upstream bandwidth authorization message.
The metadata cache subtask: owing to adopt the time-division control strategy, each ONU can only send or receive data in the mandate time slot of oneself, and therefore, up direction EPON system need be data cached in the ONU side.
The time-division that data send is controlled the subtask: this task is the core of EPON system bandwidth control strategy.Up direction after each ONU receives the bandwidth authorizing frame, according to bandwidth authorizing collocating uplink authority register, and utilizes the up transmission start time point of this register controlled and sends duration.
The mandate time of E1 fixes, and all E1 that disposed the ONU of E1 link to authorize be continuous, authorize since 0 E1 first ONU, finish until last E1 that has disposed the ONU of E1 link authorized.Can obtain the length of the E1 of each ONU configuration by network management interface, be kept among the FPGA.Next, by FPGA from OLT counter 0, calculate first mandate zero-time of each ONU E1 continuously, first that calculates each ONU E1 more continuously authorized transmitting time, first authorized the E1 of transmitting time and configuration to authorize length to be encapsulated in the bandwidth authorizing frame of mac frame form again and sends to ONU.
Calculate first mandate zero-time of each ONU E1, be from OLT counter 0, first mandate zero-time for first ONU, add that with first mandate zero-time of this ONU the E1 of this ONU authorizes length promptly to calculate the mandate zero-time of the next ONU E1 of this ONU, so finishes up to first mandate zero-time of having calculated last ONU E1 that has disposed the E1 link.
Calculating first mandate transmitting time of each ONU E1, is from calculating first mandate transmitting time of first ONU, up to first mandate transmitting time end of calculating last ONU E1 that has disposed the E1 link.Its process is: the loop time delay of reading each ONU, first mandate zero-time and its loop time delay of ONU are subtracted each other, if difference is a negative, then add the cycle of counter, be first mandate transmitting time of this ONU transmission E1 business datum, if difference is a positive number, then this difference is first mandate transmitting time that this ONU sends the E1 business datum.
First bandwidth authorizing frame of authorizing transmitting time and corresponding mandate length to be packaged into the mac frame form of each ONU E1 is sent to ONU, and promptly OLT sends E1 band width configuration information by the bandwidth authorizing frame to each ONU.After ONU received bandwidth authorizing to E1, first authorized transmitting time and E1 to authorize amount of bandwidth to isolate E1.When the clock of ONU equals its first E1 mandate transmitting time, carry out the transmission of E1 data, later ONU sends the E1 data once automatically every 500us.
As long as the E1 configuration change (comprising the ONU user's that configuration E1 links the increase or the variation of minimizing and configuration thereof) of an ONU is arranged, system all recomputates transmission once to the E1 configuration of all ONU.
In addition,, need the clock of each ONU synchronously, make it consistent with the OLT clock in order to guarantee acting in agreement of each ONU.
The EPON system is by above-mentioned bandwidth control flow, come down on PON platform based on gigabit Ethernet, for each ONU provide separate, had bandwidth safeguard, can be according to the data transmission channel of the busy not busy flexible allocation bandwidth of business, and the bandwidth authorizing of utilizing time-division control and distributing, guaranteed not disturbing mutually of each ONU data channel, send the E1 business simultaneously on fixed time ground dot cycle, and guarantee the QoS of E1 business.
Fig. 4, Fig. 5 have shown the frame format of bandwidth request frame and bandwidth authorizing frame respectively.Fig. 4 is the frame format of bandwidth request frame, and Fig. 5 is the frame format of bandwidth authorizing frame.
The bandwidth request frame is produced and is sent by ONU side FPGA, is received and ended in the fpga chip of OLT end by the OLT termination.The bandwidth request frame is the approach that OLT obtains the data cached size information of ONU, and it has adopted the structure of mac frame, has comprised territories all in the general ethernet frame format.
The bandwidth request frame contains following information among Fig. 4: the lead code of 8 bytes, contain broadcasting LLID (LogicalLink Identification, being LLID, is the sign of the point-to-point logical links passage set up on the EPON platform by the bandwidth control strategy); The purpose MAC of 6 bytes (DA, media access control layer are sublayers of ethernet data link layer) is the OLT MAC Address; The source MAC (SA) of 6 bytes is ONU MAC Address; Unique type identifier 0x8808 of 2 bytes is used to carry out frame type sign (EPON OAM mac frame); 2 byte MAC are controlled code 0x0003, are used to distinguish different EPONMAC control frames; The time tag of 4 bytes (timestamp can be used for the OLT end to the range finding of ONU end) is the time tag value that the bandwidth request frame sends.
The request content that contains in the bandwidth request frame comprises: the LLID of 2 bytes; The request of 3 bytes is used for the data cached size to OLT end report ONU, calculates the mandate bandwidth of next transmission cycle to this ONU for the OLT end.
The bandwidth authorizing frame is produced and is sent by OLT side fpga chip, receives and end in ONU end fpga chip by the ONU termination.The bandwidth authorizing frame is the approach that ONU obtains the upstream bandwidth authorization message, and it adopts the structure of mac frame, has comprised territories all in the general ethernet frame format.
The bandwidth authorizing frame contains following message among Fig. 5: the lead code of 8 bytes, contain broadcasting LLID or ONULLID (ONUID+0x00), establish the correspondence table of ONU Ethernet target MAC (Media Access Control) address and purpose ONU_ID in the OLT side, can obtain LLID number of corresponding ONU by the mode of hardware consulting table, and write in the lead code; The purpose MAC of 6 bytes (DA) is broadcast address or purpose ONU MAC Address; Source MAC (SA) address of 6 bytes is OLT MAC Address; Unique type identifier 0x8808 of 2 bytes is used to carry out frame type sign (EPON OAM mac frame); 2 byte MAC are controlled code 0x0002, are used to distinguish different EPON mac frames; The time tag (timestamp) of 4 bytes is the time tag values of authorizing frame to send, and it is synchronous to be used for the EPON system clock.
The authorized content that contains in the bandwidth authorizing frame comprises: the mandate number of 1 byte/flag territory (MSG), and the pon port flag comprising 1 bit represents corresponding OLT port; The discovery flag bit of 1 bit, whether expression is the sign of initialization mandate; Preceding 2 backs 4 reserved of totally 6 bits are reserved places; The LLID of 2 bytes, the LLID under expression is authorized (be used to distinguish ONU is sent be the bandwidth authorizing frame of E1 band width configuration or the bandwidth authorizing frame of Ethernet service data bandwidth configuration); The StartTime of 4 bytes (being labeled as ST in the present invention), zero-time is authorized in expression; The Length of 3 bytes, length (being labeled as G in the present invention) is authorized in expression.
Utilize bandwidth request frame, the bandwidth authorizing frame of above-mentioned mac frame form, realize system clock synchronously, range finding, the up transmission of bandwidth request information and the descending transmission of authorization messages.
In sum, whenever the mandate that relates to E1 configuration more during kainogenesis, the MS-EPON system all can send the bandwidth authorizing frame of a relevant E1 configuration respectively for each online ONU by OLT; After OLT receives bandwidth request frame from ONU, send a bandwidth authorizing frame to this ONU; When ONU closes to an end in each upstream data transmission, send a bandwidth request frame to OLT.
Referring to Fig. 6, for OLT generates the computational process that ONU authorizes content frame.
Step 600, each ONU presence is read in the FPGA circulation of OLT side, if find that current ONU is not online, then reads the presence of next ONU; If find that some ONU (i) are online, then stop to read the operation of next ONU (i+1) presence, read out ONU (i) simultaneously and authorized concluding time T_end (i-1) last time, when authorizing the concluding time consistent in the last time of reading with the OLT system time, read the bandwidth request information of this ONU, be data cached size, be expressed as Re (i) and utilize the loop time delay RTT (i) of this ONU that the time tag value in the bandwidth request frame calculates by the FPGA of OLT end;
Step 601, relatively (system time is calculated in the back that powers on by OLT the mandate concluding time T_end (i-1) of the last ONU of this ONU (i-1) automatically with system time T_sys, by Counter Value reflection) between difference whether greater than loop time delay RTT (i), if difference is greater than the loop time delay RTT (i) of ONU (i), execution in step 603, otherwise execution in step 602;
Step 602, the difference of T_end (i-1) and T_sys be less than RTT (i), and then the mandate initial starting point time IT_begin (i) of ONU (i) equals T_sys and adds RTT (i);
Step 603, the difference of T_end (i-1) and T_sys is more than or equal to RTT (i), and then the mandate initial starting point time IT_begin (i) of ONU (i) equals T_end (i-1).
By above-mentioned steps 601 to 603, obtain the mandate initial starting point time IT_begin (i) of this online ONU (i).Step 601 also can be described as to 603: OLT gets big value as the initial authorization zero-time with the addition of loop time delay value and value and the last mandate of this ONU concluding time comparison of system time and this ONU.
Step 609, relatively whether the difference of last E1 data transmitting time T_E1 of this ONU (i) and IT_begin (i) is more than or equal to the up minimum bandwidth mandate of this ONU (i), if difference is more than or equal to up minimum bandwidth mandate, execution in step 610, if difference is less than up minimum bandwidth mandate, execution in step 611 (protecting the size of amount of bandwidth and mac frame to sue for peace the front and back that webmaster is provided with, obtain up minimum bandwidth mandate, is a fixed value);
Step 610, difference authorize zero-time T_begin (i) for authorizing initial starting point time IT_begin (i) during more than or equal to up minimum bandwidth mandate;
Step 611, difference be during less than up minimum bandwidth mandate, after the mandate zero-time T_begin (i) of ONU (i) is postponed till its E1 data and sends.
To 611, obtained the mandate zero-time T_begin (i) of this ONU (i) by step 609.
Step 612, calculate the byte number that can send in mandate zero-time T_begin (i) interval of E1 transmitting time point T_E1 and ONU (i), be designated as the mandate limited value, and zero-time authorized in record, the mandate limited value of calculating is sent step 613, be used to calculate ultimate authority value G (i), authorize zero-time T_begin (i) to send step 614, be used for generating the mandate frame.
Step 604, with step 601 while, relatively the size of the bandwidth request information Re (i) of ONU (i) and its threshold T h (i) is (during initial authorization, this threshold value equals primary bandwidth thresholding BTh), if Re (i) is smaller or equal to Th (i), then execution in step 605, otherwise execution in step 606;
Step 605, smaller or equal to Th (i), the initial authorization bandwidth IG (i) that OLT distributes to ONU (i) equals its bandwidth request value Re (i), simultaneously the threshold value size is returned to initial value, promptly returns to primary bandwidth thresholding BTh as if Re (i);
Step 606, if Re (i) is greater than threshold T h (i), the size that then compares Th (i) and maximum Ethernet frame length MF, Th (i) execution in step 607 during more than or equal to MF, Th (i) execution in step 608 during less than MF is provided with step 606, be in order to prevent when ONU side buffer memory frame length is bigger than its primary bandwidth thresholding, can send this frame by oneself the primary bandwidth thresholding of adding up, and not need to take other OUN bandwidth, also avoid not send out the generation of this frame;
Step 607, Th (i) is during more than or equal to MF, and initial authorization bandwidth IG (i) equals Th (i), and the recovery threshold value is an initial value, and promptly threshold value returns to primary bandwidth thresholding BTh;
Step 608, Th (i) is during less than MF, and initial authorization bandwidth IG (i) equals the bandwidth request frame length, is that granularity increases threshold value with primary bandwidth threshold value B Th simultaneously.
Above-mentioned steps 604 to 608 obtains the initial authorization bandwidth IG (i) under the different situations.
Step 613, will from the initial authorization bandwidth IG (i) of step 605 or 607 or 608 with carry out size from the mandate limited value of step 612 relatively, get lessly as ultimate authority value G (i), and send step 614, be used for generating the mandate frame;
Step 614, the bandwidth authorizing frame that to authorize zero-time T_begin (i) (being the StartTime among Fig. 5) and ultimate authority value G (i) (being the Length among Fig. 5) to be assembled into the mac frame form sends to ONU, write down this simultaneously and authorize concluding time T_end (i), use when authorizing next time in order to this ONU.
ONU isolates mandate zero-time and ultimate authority value G (i) (mandate length) after receiving the bandwidth authorizing frame, and when the clock of ONU equated with the mandate zero-time, ONU is transmit operation and management (Operation﹠amp successively; Manage:OAM) frame and Ethernet data.When finding that remaining mandate length sends next frame and bandwidth request frame inadequately, stop the transmission of OAM frame or Ethernet data, the size of inquiry OAM memory and the size of Ethernet memory are with two refill the bandwidth request frame that is made into the mac frame form with value as bandwidth request information and send to OLT.
Involved in the present invention to upstream bandwidth dynamic assignment controlling mechanism remedied the deficiency of present EPON system dynamics allocated bandwidth.It can divide in real time according to the variation of each ONU Business Stream and is equipped with the raising bandwidth availability ratio; Contract according to the signing of user and operator when each user's contention system bandwidth carries out allocated bandwidth liberally, and promptly what of its paying are the bandwidth that obtains of user be proportional to, and make things convenient for operator's operation management like this; The E1 business of utilizing E1 Over EPON technical transmission to have QoS to guarantee simultaneously.
Referring to Fig. 7, the control principle of upstream bandwidth shown in the figure.The upstream bandwidth authorization messages of OLT side 71, by OLT bandwidth authorizing maker 54, according to the bandwidth request length of from the bandwidth request frame 532 that receives, separating, with the maximum bandwidth authorization list 531 calculating generations that produced and pass through Ethernet switch 52 generations by CPU 51, the upstream bandwidth authorization messages enters bandwidth authorizing frame maker 45.Bandwidth authorizing frame maker 45 produces upstream bandwidth mandate frames, go into administration queue 44 after, insert the time tag value that produces by OLT clock counter 42 in step 43, the bandwidth authorizing frame that will contain this time tag value then sends to ONU end 72.OLT clock counter 42 is counted under the driving in OLT local clock source 41.
ONU end 72 receives the bandwidth authorizing frame by step 461, and extracts the time tag value by step 462 from the bandwidth authorizing frame that receives, and revises local ONU clock counter 47 according to this time tag value.The authorization message that step 461 also will extract from the bandwidth authorizing frame that receives simultaneously (authorize zero-time and authorize length) is kept in the uplink authorization register of up transmit control device 60.On the other hand, the local data of ONU side is packaged into the standard mac frame in Ethernet interface 55, in step 56, add the LLID of this ONU then, buffer memory in up transmit buffer 59 again, under the control of up transmit control device 59, upstream data can send when the value of local clock counter 47 equals the initial moment of mandate (ST) of this ONU in the upstream bandwidth mandate, when authorizing duration to close to an end, generate the bandwidth authorizing frame by bandwidth request frame maker 57, send to OLT side 71 behind the time tag that insertion local clock source 48 produces when step 58.
In a word, adopt method of the present invention, can effectively improve the utilance of circuit, ensure the reliability of transmission in the PON, the flexibility that strengthens bandwidth control and distribute, and the traditional TDM business that provides QoS are for telecom operators provide real safety controlled Bandwidth Management controlling schemes.
Method of the present invention is mainly used in the multi-service EPON system based on gigabit Ethernet, but can provide in any network of using based on the Ethernet point-to-multipoint at other, also can use the solution of the present invention design.