CN102271018A - P-Cycle-based network coded optical multicast multi-fault protection method - Google Patents

Abstract

The invention discloses a p-Cycle-based network coded optical multicast multi-fault protection method which comprises the steps of: firstly establishing a multicast tree capable of carrying out network coding according to a multicast service request as the working path; and then configuring a certain number (such as p) p-Cycles for the multicast tree as the protecting paths, wherein data transmitted by the working path accords with the rule of the typical network coding technology, and the data transmitted in the p-Cycles is coded data of the original parallel information. Therefore, a destination node can rebuild the original data only by receiving p data from two paths. The protection mechanism can be used for providing protection to any multi-fault condition simultaneously caused on p end-to-end paths, avoid rerouting and detection of the fault positions, and improve the robustness of the network.

Description

A kind of network code light multicast multiple faults guard method based on p-Cycle

Technical field

The present invention proposes a kind of network code light multicast multiple faults guard method based on p-Cycle, is the method in order to realize that optical multicast network designs occurring still continuing to keep communicating by letter under a plurality of nodes or the link failure situation, belongs to the optical-fiber network technical field.

Background technology

Appearance along with point-to-multipoint bandwidth applications such as remote teaching, video conference, data distribution, online games, demand to the light multicast increases severely day by day, yet the communication network especially inefficacy of high-capacity and high-speed communication network will cause huge social influence and economic loss, therefore provide the optical multicast network with good survivability to seem particularly important and urgent.Simultaneously because network code has advantages such as the network throughput of raising, balance network load, increase utilization of network bandwidth and raising internet security, for the optical multicast network that designs highly effective and safe provides practicable solution.Therefore network coding technique is incorporated in the optical-fiber network, can improves the survivability of optical-fiber network fully in conjunction with the advantage of network code and optical-fiber network.

In the optical-fiber network, the main type of fault comprises three kinds: node failure, link failure and node and link mixed fault at present.About the research of node failure seldom, because it can be converted to the multilink fault that links to each other with node, therefore mainly pay close attention to and seek point for the node that needs protection and separate a path; And for node and link mixed fault, research also on the low side, present focus is based on the protection of tree, owing to provide protection end to end based on the protection of tree, so it not only can protect link failure can also protect node failure.Based on link failure, and 70 percent all be single link failure in the link failure in optical network fault, the frequency of occurrences is higher, all is single link failure so most relevant optical-fiber network researches of Survivability pays close attention to.But, need implement protection to the multilink fault situation usually in the application scenario higher to safety requirements.

Network code has been studied the throughput and the equally loaded that are used for increasing optical multicast network as a strong tool, and improves internet security.For the optical multicast network of coding Network Based, how to realize that the protection to the multiple faults situation is the major issue that needs to be resolved hurrily at present.

Summary of the invention

The objective of the invention is at the multiple faults situation in the optical multicast network of coding Network Based; a kind of error protection mechanism based on p-Cycle is provided; this protection mechanism is end-to-end carrying out, and can provide protection to the multiple faults situation that comprises node and link appearance.

For realizing above-mentioned goal of the invention, the technical solution used in the present invention step is as shown in Figure 1, and is specific as follows:

Step 1: the multicast in the optical-fiber network is to exist with the form of " light tree ", and its survivability mechanism is just at protection and the recovery of light tree; For new multicast service, at first set up multicast tree, set up light multicast tree according to existing algorithm with network code function.

Step 2: be the multicast tree configuration p-Cycle that sets up in the step 1, this p-Cycle is as the protection link of normal multicast active link, and wherein Chuan Shu data are the linear combination of original parallel multicast packet.

Step 3: satisfactory p-Cycle has a lot of, utilizes the multiple faults situation of required protection and the p-Cycle that p-Cycle evaluating commonly used is selected requirement.

Step 4: take the corresponding protection scheme according to the fault model of network:

1. node that occurs in the network or link failure do not have influence to operating path, and influential to the protection link, then this kind situation does not have influence to multicast service, need not to take any measure.

2. if node that occurs in the network or link failure do not have influence to the protection link; but cause active link to break down; but out of order end-to-end link number is not more than the p-Cycle number; perhaps all influential to work and protection link; but out of order end-to-end link number is not more than the p-Cycle number, then can recover multicast packet by the protection link this moment.

3. if the node or the link failure that occur in the network make affected end-to-end link number greater than the p-Cycle number, and make destination node can not normally receive data, then can reconfigure p-Cycle by the vacant resource in the network, thus the normal reception of restore data.

Describe for convenient, the linear operation that relates in the described step 2 all adopts mould two add operations.In addition, the p-Cycle for the multicast tree configuration should meet the following conditions:

1. this p-Cycle passes all sources and destination node.

2. this p-Cycle separates with the intermediate node of the multicast tree of foundation, and so-called point separates different with link disjoint, and its not only claimed path and original operating path are link disjoint, and without the intermediate node of operating path.

The evaluating that adopts in the described step 3 is a volumetric efficiency, and circle represents that with j C represents the cost of link, X _IjThe protection relation that expression circle j provides link i.

$C_{\mathrm{pj}}=\frac{{\mathrm{\ΣX}}_{\mathrm{ij}}}{{\mathrm{\ΣC}}_i}$

Wherein

C wherein _iThe cost of expression link i, volumetric efficiency have not only been considered the working capacity number that can protect of circle j, have also considered the expense of resource conservation.

In the described step 4,,, the utilization that step 2 and 4 relates to protection path comprises encoding operation and decode operation so recovering multicast service because the present invention is based on network code.

In sum, this guard method can provide protection to the multiple faults situation that comprises node and link, has avoided the detection of heavy-route and abort situation, has improved the robustness of network.It combines the advantage of network code and p-Cycle, at first network code can increase utilization of network bandwidth, reduce network resource consumption, p-Cycle had both had the advantage of switching fast of similar looped network in addition, also had with the close high resource utilization advantage of grid network.

Description of drawings

Accompanying drawing 1 is based on the network code light multicast multiple faults protection flow chart of p-Cycle

Accompanying drawing 2 is based on the network code light multicast multiple faults protection exemplary plot of p-Cycle

Embodiment

Network model is represented with an orientation diagram it is the directional link of D for the S destination node that link SD is described as a start node.Be without loss of generality, suppose that each node can both carry out the light multicast, a cast communication can be described as { S, D ₁D ₂... D _n, S is a source node, D _nBe destination node, source node sends a series of data to destination node.

The data that send on p-Cycle are the linear combination of raw information, and for simplicity, involved herein linear operation all adopts mould two to add form.Because p-Cycle passes each destination node; so each destination node all can be received two piece of data; portion is the data from a plurality of original operating paths; portion is from the data among a plurality of protections path p-Cycle, exists redundancy to increase the robustness of network owing to receive data like this.

Encoding operation: the minimal cut of supposing multicast network is m, and then source node is divided into independently m group with multicast traffic stream, sends to respectively on the m paths.The information that a certain moment source node sends can be with vectorial X=(d ₁, d ₂... d _m) expression, destination node is respectively D ₁D ₂... D _nWhat source node sent in operating path is initial data, will be according to realizing that the coding vector that distributes carries out encoding process when through the network code node; And source node sends in p-Cycle is data after raw information is encoded, the data of transmitting in these two paths are incoherent, and the coded data that sends in p-Cycle can be represented with following form: the data that send among j p-Cycle are

Wherein

The coefficient of representing j k information symbol among the p-Cycle; coefficient among the different p-Cycle be linearity independently; the quantity p of p-Cycle determines that according to the multiple faults situation and the p-Cycle evaluating commonly used of required protection it can provide protection to any multiple faults situation that appears at simultaneously on the p bar end-to-end path.Code coefficient can be represented with following matrix:

Be linear independence between the coefficient of different lines in the matrix, p the encoded data pit (y that is sent among p p-Cycle ₁y ₂... y _p), can be with following matrix notation:

As shown in Figure 1, be example with classical butterfly multicast network, wherein S represents source node, D1, D2 represents destination node, A, B, C, E are intermediate nodes, and the oriented solid line of black is an operating path, and red oriented dotted line is the protection path.Marked information transmitted illustration on operating path and the protection path among the figure.On operating path, node C is the network code node, in this example two-way input data is carried out simple XOR encoding operation.Protection transmit on the path to d ₁And d ₂Carry out the data after the uniform enconding.What describe among the figure is protection situation under the m=2 situation

Decoded operation: destination node can receive m the data behind network code from operating path, this m data can be regarded the linear combination of m initial data as.Can receive p data in addition from the protection path, this p data also are the linear combination of m initial data.Because the code coefficient on two paths all is a linear independence, therefore if the data number that receives from two paths more than or equal to m, then destination node just can therefrom be rebuild initial data.

Still as shown in Figure 1, S is to D1, and D2 has sent two information data d ₁, d ₂, carry out encoding process during through intermediate node Destination node just can recover d according to the signal that receives ₁, d ₂The red p-Cycle of outside chooses from network, wherein

The coefficient of representing j k information symbol among the p-Cycle.As long as each destination node can receive two data from work and protection path like this, both can recover raw information.Two p-Cycle can provide protection to any multiple faults situation that appears at simultaneously on two end-to-end paths among the figure.

Above a kind of network code light multicast multiple faults protection scheme based on p-Cycle of the present invention is had been described in detail, but concrete form of the present invention is not limited thereto.For the those skilled in the art in present technique field, the various conspicuous change of under the situation of the scope of spirit that does not deviate from the method for the invention and claim it being carried out is all within protection scope of the present invention.

Claims (3)

1. network code light multicast multiple faults guard method based on p-Cycle is characterized in that:

At first require to set up one and can carry out the multicast tree of network code as operating path according to multicast service; Then for the p-Cycle of this multicast tree configuration some (as p) as the protection path, this method can provide protection to any multiple faults situation that appears at simultaneously on the p bar end-to-end path.

2. based on claims 1 described smooth multicast multiple faults guard method, data are carried out encoding process, it is characterized in that at the source node place:

At source node when p-Cycle sends data, at first according to the network code multicast path to the initial data grouping that walks abreast, then each grouped data being carried out uniform enconding handles, the network code coefficient that carries out on code coefficient and the operating path is independently, therefore destination node needs only the data that receive sufficient amount from two paths, just can therefrom rebuild initial data.

3. 1 described smooth multicast multiple faults guard method is a kind of guard method based on tree based on claims, it is characterized in that:

Described protection mechanism provides the p bar and protects end to end, so can provide protection to any multiple faults situation that appears at simultaneously on the p bar end-to-end path.

Images