CN101217459A - An Ethernet passive optical network dynamic bandwidth distribution method based on bandwidth credit - Google Patents

Abstract

The invention provides an Ethernet passive optical network bandwidth distribution method based on bandwidth borrowing, comprising: OLT receives a bandwidth distribution request reported by the ONU and distributes the bandwidth according the load of the ONU. Therefore, by borrowing the bandwidth to the heavy load ONU through the light load ONU or by withdrawing the borrowed bandwidth through the heavy load ONU to satisfy the bandwidth authorization of every ONU that every ONU fairly receives the bandwidth authorization is realized.

Description

Ethernet passive optical network distribution method of dynamic bandwidth based on the bandwidth debt-credit

Technical field

The present invention relates to optical communication field, relate in particular to a kind of Ethernet passive optical network distribution method of dynamic bandwidth based on the bandwidth debt-credit.

Background technology

Passive optical network technique is considered in the broadband light Access Network technology of tool application prospect always, and it has been broken traditional point-to-point optical fiber and has inserted solution, for the network user provides a kind of economy, that face the future, multi-service broadband access scheme.PON firmly gets the approval of communications industry expert and vast operator as the developing direction of broadband access network technology.Since the eighties in 20th century by standardization and come into operation up to now, passive optical network technique has been gone through several developing stage, international telecommunication standardization body and equipment manufacturers have developed various protocols and technology, so that make the PON solution can better satisfy the Access Network market demands, formed series of standards standards such as APON/BPON, EPON, GPON.Wherein, the EPON technology was owing to both had being extensive use of and low-cost advantage of Ethernet, therefore the easy easy care, the high bandwidth advantage that have EPON are again compared with the PON technology of other types and are had better cost performance, and are more and more paid close attention to and use.

Fig. 1 is a typical EPON Ethernet passive optical network access network, it is by local side apparatus optical line terminal (OLT) 101, optical branching device passive optical splitter (POS) 102 and remote equipment optical network unit (ONU) 103-n (n=1,2,3,4......), terminal use 104-n (n=1,2,3,4......) and some optical fiber composition, constitute the tree topology of a point, realize that a local side apparatus (OLT) carries out bidirectional high speed by an optical fiber with a plurality of remote equipments (ONU) and communicates by letter to multiple spot.Its downlink communication is a continuation mode, LLID (the Logic Link Identifier that has each ONU in the ethernet data frame that OLT sends, LLID), send to each ONU by the ODN Web broadcast, in ONU equipment, come selectivity to receive and wherein issue the Frame of oneself, and abandon not one's own Frame according to LLID; Uplink communication is a burst mode, each ONU adopts TDMA Time Division Multiple Access (TimeDivision Multiple Access, TDMA) mode is transmitted, and each ONU sends Frame in by the unified scheduling of OLT distributed time slot, thereby has avoided the data collision between each ONU.For example, down direction in Fig. 1, ONU103-1 receive have LLID=1, the Frames of 2,3 signs, but only the Frame of LLID=1 is sent to terminal use 104-1; Otherwise at up direction, ONU103-1 is according to the scheduling of OLT101, is arranged in the Frame that sends its LLID=1 in certain time slot, and the Frame of ONU103-2 and ONU103-3 can only be waited for after its transmission finishes and sending.

OLT passes through the control to the uplink time slot of ONU, has realized effective transmission of EPON network uplink, and this mechanism is called bandwidth allocation methods.In the upstream bandwidth assigning process of EPON system, for effectively utilizing system bandwidth, (Dynamic Bandwidth Allocation DBA) carries out dynamic time gap adjustment and distribution, to improve the utilization ratio of bandwidth often to take Dynamic Bandwidth Allocation.In the Dynamic Bandwidth Allocation process, each ONU needs the state information reports such as data volume of uplink to give OLT it, OLT carries out DBA according to these state informations and calculates, and arranges concrete transmission time and the transmission duration of each ONU, sends downstream grants information for then each ONU.Each ONU carries out the transmission of upstream data in the moment of OLT appointment according to the transmission duration that distributes according to the authorization message of receiving.

In actual application, each ONU can report its purchase bandwidth (guaranteeing bandwidth) when OLT registers, but because the relation of Dynamic Bandwidth Allocation, the bandwidth that the ONU actual request obtains in each cycle might be bought bandwidth greater than it.Therefore in real network,, may cause other ONU can't guarantee its purchase bandwidth, bring fairness problem if certain ONU always asks to surpass the bandwidth of its actual purchase.

Summary of the invention

Can ask to cause other ONU can't guarantee the problem of its purchase bandwidth in order to solve the ONU that exists in the prior art above the bandwidth of its actual purchase, the invention provides a kind of Ethernet passive optical network distribution method of dynamic bandwidth based on the bandwidth debt-credit, thereby realize the mutual debt-credit of bandwidth, what guarantee that ONU can both be fair obtains buying bandwidth.

To achieve these goals, the invention provides a kind of Ethernet passive optical network bandwidth allocation methods based on the bandwidth debt-credit, this method comprises:

OLT receives the bandwidth allocation request that ONU reports, and when the load of determining described ONU is underloading and historical debt-credit amount greater than zero the time, carries out first allocated bandwidth; When the load of determining described ONU is heavy duty, carry out second allocated bandwidth.

Further, the load of described ONU is that underloading is that bandwidth that the bandwidth allocation request that reports according to described ONU and described ONU buy compares the result for smaller or equal to determining.

Further, the load of described ONU is that heavy duty is that bandwidth that the bandwidth allocation request that reports according to described ONU and described ONU buy compares the result for greater than determining.

Further, described execution first allocated bandwidth is that described OLT sends bandwidth authorizing to described ONU.

Further, described execution second allocated bandwidth is:

Described OLT borrows or lends money described ONU to heavy duty with the Jieed bandwidth of the ONU of underloading, and adds up and upgrade Jieed bandwidth and the historical debt-credit amount of each ONU respectively.

Further, statistics and upgrade the Jieed bandwidth of each ONU and historical debt-credit amount after also comprise:

Determine also to have heavily loaded ONU, and the history debt-credit amount of described ONU is greater than zero the time, described OLT will arrange the described ONU of debt will repay bandwidth;

Described OLT issues bandwidth authorizing in proper order each described ONU.

Further, described OLT give to arrange repays bandwidth authorizing that the described ONU of the debt of bandwidth issues for ensureing the bandwidth of amount of bandwidth.

Therefore, by underloading ONU bandwidth is borrowed or lent money to heavily loaded ONU or by heavily loaded ONU and will regain the bandwidth authorizing that the bandwidth of borrowing or lending money satisfies each ONU, thereby realize the fair bandwidth authorizing that receives of each ONU.

Description of drawings

Fig. 1 is basic EPON network topological diagram;

Fig. 2 is the flow chart that the present invention is based on the Ethernet passive optical network bandwidth allocation methods of bandwidth debt-credit.

Embodiment

Below by drawings and Examples, the technical scheme of the embodiment of the invention is described in further detail.

The invention provides the up distribution method of dynamic bandwidth that uses in a kind of Ethernet passive optical network, based on the fairness distribution method of dynamic bandwidth of bandwidth debt-credit.The bandwidth allocation request that OLT reports according to each ONU is divided into underloading ONU with ONU, and wherein underloading is that the actual request bandwidth is bought bandwidth and heavily loaded ONU smaller or equal to it, and wherein heavy duty is that the actual request bandwidth is bought bandwidth two classes greater than it.In each polling cycle (Cycle Time), OLT gives the unnecessary bandwidth " debt-credit " of underloading ONU with the heavily loaded ONU in one-period.OLT carries out record to the debt-credit situation of each ONU, and the history debt-credit amount of adding up each ONU, promptly this ONU lends bandwidth and deducts the difference of borrowing bandwidth, is that positive ONU is designated as credits ONU with the debt-credit amount, the debt-credit amount is designated as debt ONU for negative ONU, and the debt-credit amount is that zero ONU is designated as normal ONU.If in some polling cycles, the unnecessary bandwidth of underloading ONU is not enough to satisfy the bandwidth demand of heavily loaded ONU, and then OLT will arrange debt ONU to repay bandwidth and give credits ONU, to guarantee the bandwidth request of credits ONU.When the debt-credit amount vanishing of debt ONU, this ONU becomes normal ONU.

To introduce the detailed process of Ethernet passive optical network bandwidth allocation methods in detail below, as shown in Figure 2, be the flow chart of the Ethernet passive optical network bandwidth allocation methods that the present invention is based on bandwidth debt-credit.As shown in the figure, this method comprises:

Step 201, OLT receives the bandwidth allocation request R that ONU reports ⁱ

Step 202 is determined the loading condition of described ONU, when the load of determining described ONU is that underloading can be borrowed bandwidth $B_{\mathrm{exess}}^i=B^i-R^i=B_{\mathrm{exess}}^i\&GreaterEqual;0,$ And historical debt-credit amount L ⁱGreater than zero the time, execution in step 203 first allocated bandwidth; When the load of determining described ONU is heavy duty $B_{\mathrm{exess}}^i<0$ The time, execution in step 204 second allocated bandwidth;

Step 203, described OLT sends bandwidth authorizing G to described ONU ⁱ=R ⁱWherein, also comprise and work as bandwidth allocation request $R^i{\&le;B}_{\mathrm{safe}}^i$ The time, B wherein _Safe ⁱFor ONU ensures bandwidth, satisfy $B_{\mathrm{safe}}^i<B^i;$ Execution in step 203;

Step 204, described OLT is with underloading $B_{\mathrm{exess}}^i>0$ The Jieed bandwidth of ONU borrow or lend money to heavy duty $B_{\mathrm{exess}}^i<0$ Described ONU, and add up and upgrade the Jieed bandwidth B of each ONU respectively _Exess ⁱWith history debt-credit amount L ⁱ

Step 205 determines also to exist heavy duty $B_{\mathrm{exess}}^i<0$ ONU, and the history debt-credit amount L of described ONU ⁱGreater than zero the time, promptly this ONU is credits ONU, and described OLT will arrange debt L ⁱ＜0 described ONU will repay bandwidth;

Step 206 can calculate the bandwidth authorizing G of all ONU according to above-mentioned two steps ⁱ, issue bandwidth authorizing G for one by one from small to large each ONU according to sequence number i then ⁱWherein note, be arranged to repay the bandwidth authorizing of the debt ONU of bandwidth $G^i=B_{\mathrm{safe}}^i.$

The present invention provides a kind of distribution method of dynamic bandwidth for the EPON network, based on the Ethernet passive optical network distribution method of dynamic bandwidth of bandwidth debt-credit.This EPON network comprises a local side apparatus OLT (optical line terminal) and is connected to a plurality of ONU (optical network unit) of OLT via ODN (Optical Distribution Network) that the ultimate range between OLT and the ONU is 20Km.Method of the present invention is used for controlling OLT and carries out allocated bandwidth for each ONU according to purchase bandwidth and the actual request bandwidth of ONU, realizes effective transmitting uplink data.

Therefore, the invention provides a kind of Ethernet passive optical network distribution method of dynamic bandwidth based on the bandwidth debt-credit, this method can effectively solve the above-mentioned fair share of bandwidth problem of mentioning, and is the very strong dynamic bandwidth allocation algorithm of a kind of practicality.

It should be noted last that, above embodiment is only unrestricted in order to the technical scheme of the explanation embodiment of the invention, although the embodiment of the invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can make amendment or be equal to replacement the technical scheme of the embodiment of the invention, and not break away from the spirit and scope of embodiment of the invention technical scheme.

Claims (9)

1. Ethernet passive optical network bandwidth allocation methods based on bandwidth debt-credit, it is characterized in that comprising: OLT receives the bandwidth allocation request that ONU reports, and carries out allocated bandwidth according to the loading condition of ONU.

2. method according to claim 1, it is characterized in that described loading condition according to ONU carry out allocated bandwidth be specially when the load of determining described ONU be underloading and historical debt-credit amount greater than zero the time, carry out first allocated bandwidth; When the load of determining described ONU is heavy duty, carry out second allocated bandwidth.

3. method according to claim 2, the load that it is characterized in that described ONU are that underloading is that bandwidth that the bandwidth allocation request that reports according to described ONU and described ONU buy compares the result for smaller or equal to determining.

4. method according to claim 2, the load that it is characterized in that described ONU are that heavy duty is that bandwidth that the bandwidth allocation request that reports according to described ONU and described ONU buy compares the result for greater than determining.

5. according to claim 1 or 2 or 3 described methods, it is characterized in that described execution first allocated bandwidth is that described OLT sends bandwidth authorizing to described ONU.

6. according to claim 1 or 2 or 4 described methods, it is characterized in that described execution second allocated bandwidth is:

Described OLT borrows or lends money described ONU to heavy duty with the Jieed bandwidth of the ONU of underloading, and adds up and upgrade Jieed bandwidth and the historical debt-credit amount of each ONU respectively.

7. method according to claim 6, it is characterized in that statistics and upgrade the Jieed bandwidth of each ONU and historical debt-credit amount after also comprise:

Determine also to have heavily loaded ONU, and the history debt-credit amount of described ONU is greater than zero the time, described OLT will arrange the described ONU of debt will repay bandwidth;

Described OLT issues bandwidth authorizing in proper order each described ONU.

8. method according to claim 7 is characterized in that the bandwidth authorizing that described OLT issues for the described ONU of the debt of arranging the repayment bandwidth is the bandwidth that ensures amount of bandwidth.

9. method according to claim 8 is characterized in that described historical debt-credit amount is that the bandwidth that lends of described ONU deducts the difference of borrowing bandwidth.

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