CN102238065A - Dynamic bandwidth allocation method capable of combining bandwidth utilization and fairness among optical nodes - Google Patents

Abstract

The invention discloses a dynamic bandwidth allocation method capable of combining bandwidth utilization and fairness among optical nodes. An optical line terminal (OLT) allocates the overall bandwidth to each optical network unit (ONU) according to the requested bandwidth of each optical network unit (ONU) by using the bandwidth allocation method capable of combining the bandwidth utilization and the fairness. In the method provided by the invention, a working mechanism of a counter is utilized, a priority queue and the fairness among the ONUs can be supported, and the improved ONU can be applied to a plurality of different environments such as file transfer protocol (FTP) servers and video on demand (VOD) services to greatly improve the performance of a system.

Description

Can take into account the distribution method of dynamic bandwidth of fairness between bandwidth usage and the optical node

Technical field

The present invention relates to Ethernet passive optical network (EPON) bandwidth allocation methods, particularly a kind of bandwidth allocation methods of taking into account bandwidth usage and fairness that reaches.

Background technology

Be of long duration with the notion of EPON (PON), it has the fiber resource of saving, to the transparent characteristics of procotol, is playing the part of more and more important role in optical access network.Simultaneously, Ethernet (Ethernet) technology is through vicennial development, and simple and practical with it, cheap characteristic has almost been ruled local area network (LAN) fully.And combining of Ethernet and PON just produced Ethernet passive optical network (EPON).It has possessed the advantage of Ethernet and PON simultaneously, is just becoming the hot technology in the optical access network field.

Allocated bandwidth main flow for EPON has 2 kinds of technology.A kind of is the fixed-bandwidth distribution technique, and another kind is a Dynamic Bandwidth Allocation.

The fixed-bandwidth distribution technique is that Optical Network Terminal OLT (Optical Line Termination) distributes to each optical network unit ONU (Optical Network Units) fixed-bandwidth, remains unchanged always.Another kind is a Dynamic Bandwidth Allocation.The advantage of this kind method is that algorithm is simple, is easy to realize, guarantees that simultaneously each ONU has the lowest-bandwidth of keeping basic service.Shortcoming is that bandwidth waste is bigger, often causes some ONU free time, blocks and another part is professional.

Promptly according to the request of ONU to bandwidth, OLT carries out the allocated bandwidth adjustment in each timeslice to Dynamic Bandwidth Allocation.In latter's technology, the method for main flow is that OLT adopts the mode of doing one's best to distribute to ONU.But there is certain defective in it, and it may cause the business of doing one's best not to be assigned with bandwidth, and in addition, if certain ONU constantly receives mass data, other ONU then can not get keeping the lowest-bandwidth of basic service.

Summary of the invention

Shortcoming in view of above-mentioned two kinds main bandwidth allocation techniques, proposition of the present invention is the thinking that adopts the allocated bandwidth that repeatedly circulates, and considers that simultaneously the minimal bandwidth of needed its operation of assurance of single optical network unit (ONU) and two factors of maximum bandwidth of request reach the bandwidth allocation methods of taking into account bandwidth usage and fairness.

Specific implementation method of the present invention is such.

A kind of distribution method of dynamic bandwidth of taking into account fairness between bandwidth usage and the optical node may further comprise the steps:

(1), calculates the reference bandwidth of each ONU;

(2), Optical Network Terminal (OLT) and optical network unit (ONU) are finished standards registration and discovery;

(3), Optical Network Terminal (OLT) is distributed to the reference bandwidth of each optical network unit (ONU);

(4), optical network unit (ONU) is to Optical Network Terminal (OLT) bandwidth on demand, whether the OLT inquiry has idle bandwidth;

(5), Optical Network Terminal (OLT) is according to the bandwidth on demand of each optical network unit (ONU), with the bandwidth allocation methods of taking into account bandwidth usage and fairness total bandwidth distributed to each each optical network unit (ONU).

(6), next timeslice, ONU sends bandwidth request once more, repeating step (4) and (5) are until ONU or OLT power cut-off.

The method of the invention is utilized counter works mechanism, and it can support the fairness between priority query and each ONU, and the ONU after the improvement can be applied in many different environment, such as ftp server and VOD service, can improve the performance of system greatly.

Description of drawings

According to embodiment and accompanying drawing the present invention is described in further detail below.

Fig. 1 is the flow chart that bandwidth allocation methods of the present invention realizes;

Fig. 2 be the ETRI algorithm simulating as a result figure (environment a);

Fig. 3 is the simulation result figure (environment b) after improving;

Embodiment

As shown in Figure 1, provided the realization flow figure that takes into account the distribution method of dynamic bandwidth of fairness between bandwidth usage and the optical node of the present invention, it may further comprise the steps:

(1), calculates the reference bandwidth of each ONU;

(2), Optical Network Terminal (OLT) and optical network unit (ONU) are finished standards registration and discovery;

(3), Optical Network Terminal (OLT) is distributed to the reference bandwidth of each optical network unit (ONU);

(4), optical network unit (ONU) is to Optical Network Terminal (OLT) bandwidth on demand, whether the OLT inquiry has idle bandwidth;

(5), Optical Network Terminal (OLT) is according to the bandwidth on demand of each optical network unit (ONU), with the bandwidth allocation methods of taking into account bandwidth usage and fairness total bandwidth distributed to each each optical network unit (ONU).

(6), next timeslice, ONU sends bandwidth request once more, repeating step (4) and (5) are until ONU or OLT power cut-off.

Wherein the method for step (5) is described below:

At up direction, EPON uses the TDMA technology, uses request/acknowledgement mechanism to avoid conflict.ONUs can report their quene state to OLT (Optical Line Termination), and OLT accepts quene state and distributes upstream bandwidth.ETRI ' s is popular a kind of in the dynamic bandwidth allocation algorithm, and it develops on IPCAT algorithm basis.But there is certain defective in it, and it may cause the business of doing one's best not to be assigned with bandwidth, and in addition, if certain ONU constantly receives mass data, other ONU then can not get bandwidth.We adopt a kind of improved DBA algorithm, utilize counter works mechanism, and it can support the fairness between priority query and each ONUs.

1) ETRI ' s DBA algorithm

Be the DBA algorithm that ETRI proposes below, suppose that the ONU number of having found automatically is n, Btotal is total bandwidth, and Btarget is the target bandwidth, and Bbetc is the bandwidth of Best-Effort service.

One, the mandate bandwidth GHi of high-priority service, expression, fixing allocated bandwidth is given high-priority service and is not considered whether it has Frame to need to send.

Two, the business of medium priority has precedence over the professional processed of high low priority, so medium priority mandate broadband is distributed by following formula:

If $\mathrm{RMi}\≤\mathrm{Bt}\arg \mathrm{et}-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{GH}$

Otherwise

$\mathrm{RMi}\≥\mathrm{Bt}\arg \mathrm{et}-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{GH}$

$\mathrm{GMi}=\frac{\mathrm{RMi}}{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{RMi}}(\mathrm{Bt}\arg \mathrm{et}-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{GH})$

Three, low priority mandate bandwidth GLi distributes to the business of doing one's best, and Bbetc can obtain by following formula:

$\mathrm{Bbetc}=\mathrm{Bt}\arg \mathrm{et}-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}(\mathrm{GH}+\mathrm{GM})$

GLi can obtain by following formula:

$\mathrm{GLi}=\frac{\mathrm{RLi}}{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{RLi}}\mathrm{Bbetc}$

This algorithm looks like a kind of effective algorithm, but has certain defective.If

$\mathrm{Bt}\arg \mathrm{er}\≤\underset{i=1}{\overset{n}{\mathrm{\Σ}}}(\mathrm{GHi}+\mathrm{GMi})$

Value is 0 so, and therefore the business of doing one's best is not implemented, and in addition, if certain ONU constantly receives mass data, other ONU then can not get bandwidth substantially.

2) improved DBA algorithm

Therefore, we make further improvement to algorithm, to address the above problem, obtain good allocated bandwidth.The acquisition of high priority mandate bandwidth is identical with ETRI ' s, comes bandwidth authorizing for medium priority so we propose following formula.Allow Bassur guarantee bandwidth, in a polling cycle, if total bandwidth is enough big, Bassur just can not be 0.

$\mathrm{Bassur}=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{RMi}}{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{RMi}+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{RLi}}(\mathrm{Bt}\arg \mathrm{et}-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{GHi})$

Our usage counter mechanism is controlled the quene state of each ONU ' s, and CMi represents the accumulated value of i ONU middle rank priority report queue length.When algorithm began, CMi was zero.At first each ONU of poll obtains maximum that ONU of medium priority in the formation, when distributing bandwidth, earlier to its distribution, other is distributed again.Distribute to bandwidth on demand less than Bassur, Bassur deducts RMi then, other is distributed again, and less than RMi, remaining wait lower whorl is handled up to Bassur.

Step 4: low priority mandate bandwidth GLi distributes to the business of doing one's best, and Bbetc can get by following mode

$\mathrm{Bbetc}=\mathrm{Bt}\arg \mathrm{et}-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}(\mathrm{GHi}+\mathrm{GMi})$

GLi can obtain by same mode.When the value of CMi and CLi was very little, i ONU be not its distribution or distribute very little time slot, but because the value of RMi or RLi increases very soon, be its distribution time slot at next polling cycle.

Under general traffic environment, two kinds of algorithms can effectively carry out allocated bandwidth, so we do requirement, are designated as environment a, at first allow the flow of the 17th to 32 ONU greater than the 1st to 16 ONU.Adopt two kinds of methods to carry out emulation relatively, its result respectively as shown in Figures 2 and 3.

By and the emulation of ETRI ' s relatively, the algorithm after the improvement has improved the performance of system greatly.

Claims (1)

1. the distribution method of dynamic bandwidth that can take into account fairness between bandwidth usage and the optical node is characterized in that may further comprise the steps:

(1), calculates the reference bandwidth of each ONU;

(2), Optical Network Terminal (OLT) and optical network unit (ONU) are finished standards registration and discovery;

(3), Optical Network Terminal (OLT) is distributed to the reference bandwidth of each optical network unit (ONU);

(4), optical network unit (ONU) is to Optical Network Terminal (OLT) bandwidth on demand, whether the OLT inquiry has idle bandwidth;

(5), Optical Network Terminal (OLT) is according to the bandwidth on demand of each optical network unit (ONU), with the bandwidth allocation methods of taking into account bandwidth usage and fairness total bandwidth distributed to each each optical network unit (ONU).

(6), next timeslice, ONU sends bandwidth request once more, repeating step (4) and (5) are until ONU or OLT power cut-off.

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