CN102868572A - Path delay measuring method based on end-to-end detection - Google Patents

Abstract

The invention discloses a path delay measuring method based on end-to-end detection. The path delay measuring method comprises the following steps of: at first, establishing a link relation matrix in a network through an algebra method, and carrying out linear individual decomposition on the link relation matrix, so as to obtain a linear individual path linear independence matrix; secondly, carrying out algebra relative calculation on the basis of the path linear independence matrix, so as to obtain a link linear independence square matrix in a network; and finally, calculating to obtain a unique solution of the linear independence square matrix, and substituting the unique solution into an original link relation matrix to obtain the unique solution of the link relation matrix, so that the path delay of all paths in the network can be obtained finally. With the adoption of the path delay measuring method provided by the invention, the unique solution of all path delay in the network can be calculated; the accuracy of the path delay in the network is improved; and a better basis is provided for determining a network path fault.

Description

A kind of method of measurement of the path delay based on end-to-end detection

Technical field

The present invention relates to the network delay fields of measurement, be specifically related to a kind of method of measurement of the path delay based on end-to-end detection.

Background technology

The failure diagnosis of Internet net is all extremely important for terminal use, overlay network service provider and ISP.Such as, the Internet failure diagnosis tool has been arranged, the user can select the more excellent Internet net service provider of quality.The overlay network service provider can locate fault with such instrument in order to remedy accordingly, keep in repair; Decision-making, deployment and feedback that the information of fault also can lead service to provide.For ISP, failure diagnosis tool can be used for examining service, and these services generally comprise from the service provider, to the fault detection problem of physical network.Research must be considered the random network latency issue that Internet exists based on the network control system of Internet, adopts effective method that the Internet network delay is carried out prediction, and is most important for the design of network control system.

Network delay and uncertain depend mainly on data process jumping figure (to the number of purpose router that network passes through) and jump onto institute's time spent at each, namely the uncertainty of network delay main by the processing delay of the number of router of process and router cause.And the factor that affects route and router processing speed mainly is exactly the network congestion degree decision, therefore can say that the Congestion Level SPCC of Internet Transmission is to cause the unsettled principal element of network delay.There is unsteadiness in network delay, and this unsteadiness is at random, and this is the main cause of network delay prediction difficulty just.Can draw network delay through top analysis simultaneously and have unsteadiness, but this unsteadiness is within the specific limits, can in certain accuracy scope, predict by some algorithms or model.

Now problem is described below: in the overlay network with n terminal, now define the path that the routing path is a pair of terminal room, the IP link is the link between the route, and the path is exactly a series of link combinations.Just exist O (n at n terminal room so ²) path of the order of magnitude.And we wish to monitor the path subset of a minimum, and then can infer the time-delay that remaining path.

For understanding the state of development of prior art, to existing patent, paper is retrieved, and compares, analyzes, and filters out the higher technical information of following degree related to the present invention:

Technical scheme 1: application number is 201010116886.8,, publication number is that the Chinese patent application that CN101771585A, name are called " a kind of network delay measuring equipment and method thereof " discloses a kind of Apparatus for () and method therefor that utilizes tcp state machine passive measurement network delay.The tcp data bag occurs in client in the method through this network delay measuring equipment and between by the Internet and the webserver.This network delay measuring equipment is according to this tcp data bag linking status, sending direction, this tcp data bag linking status of flag bit information updating, and will be updated to the current time with this connection status correlation time, so that wrapping in, tcp data calculates network delay time after a transmission course finishes.But this scheme is not inject flow to network with a kind of passive monitoring technique, the advantage of this technology, increases the load of network.But in the network of actual complex, the assembly that many equipment vendors and operator provide and equipment do not have unified by interface tube, even do not possess by interface tube.Therefore this algorithm can not carry out failure diagnosis timely accurately.

Technical scheme 2: application number is 200810210890.3, publication number is CN101383737, name is called " a kind of method and system of carrying out the link-quality detection based on Link Layer Discovery Protocol " Chinese patent application and discloses a kind of method and system of carrying out the link-quality detection based on Link Layer Discovery Protocol, the network equipment is take unit interval T1 as the cycle in the method and the system, gather each LLDP(Link Layer Discovery Protocol) the Link Layer Discovery Protocol LLDP number-of-packet M1 that in unit interval T1, receives of stay of two nights port, and preserve the LLDP number-of-packet M1 of each LLDP stay of two nights port of current collection at management information bank MIB; When the webmaster management system is carried out quality testing to each link to be detected, MIB(management information bank from the destination interface place network equipment of this link) obtains the information of the LLDP number-of-packet M1 that this destination interface of current collection receives in unit interval T1, and the LLDP number-of-packet M2 that in unit interval T1, sends of the source port that obtains this link, calculate this link current time-delay H=(1-M1/M2) * 100%, this invention and need not to consume extra resource and be easy to and realize.This scheme has adopted Network Management Equipment that source is sent number-of-packet and egress and has accepted number-of-packet and add up, because webmaster itself can be realized this high statistical function, so need not to increase new equipment and resource, but the feature of network management statistics is that the cycle is long, need long statistical computation then to report, can't accomplish like this time-delay in the real time monitoring network, real-time is poor.

Document scheme 1: name is called " An algebraic approach to practical and scalable overlay network monitoring ", document in adopt a kind of algebraic method to realize practicality and the extensibility of overlay network.This algorithm is only measured wherein sub-fraction path, then infers remaining path delay with the path delay measurement result of these collections.Suppose to have in the network m bar link, then the time-delay in the path of the m bar Line independent of collecting by calculating now separates the equation that one group of m path and time-delay concern.In case the link delay of Line independent is known, just can be used for inferring that all n paths delay time accurately, occur unusual thereby detect which path.But this scheme can not obtain the unique solution of result of detection.Practicality at the monitoring overlay network can be measured in the algebraically active probe technology, this based on preplanned active probe algorithm compared to passive monitoring can be more timely, the state of awareness network more accurately, but shortcoming is owing to be not unique solution at the link parameter that draws, again carry it into path and link the relation equation in the time, the result who draws also is a solution in the general solution, so promote in addition the space of accuracy.

Document scheme 2: name is called have been explained in the document of " Scalable deterministic overlay network diagnosis " and can not obtain the reason of unique solution in a lot of technical schemes.Its reason has two: one, only has infinite a plurality of probes of use just can reach 100% robustness; The 2nd, supposition is under desirable multicast environment, and these systems could obtain the estimation result of high probability by some probes.Give chapter and verse the state, characteristic of link in network thus with the path fine particulate.Such as, can be with some characteristics, the on all four link of state merges.Can process the not specified situation of the link that in calculating, occurs like this.

Had now the scheme of a large amount of end-to-end measurement time-delays.Infer that by measuring end to end the performance parameter of the Internet link is called the tomography of network.Measurement result and link performance parameters are that linear relationship or Boolean calculation all can form an equation group end to end.We obtain the link performance parameters that needs by separating this equation group.Yet existing method or can not obtain unique solution, or be exactly because in solution procedure, the link granularity is divided meticulous not, causes the result accurate not.In most of Time delay measurement technology, the equation group of the state relation of algebraically measurement result and IP link does not all have unique solution.If expect unique solution, unless the row and column of the matrix of contemporary watch chain road and path relation all is Line independent.Accordingly, also should add about the information of network link and obtain immediate result, otherwise not the mating of order can cause matrix operation the time.

Summary of the invention

For the defective that exists in the prior art, the object of the present invention is to provide a kind of method of measurement of the path delay based on end-to-end detection, the method detects path delay with probe, obtains out the unique solution of All Paths time-delay by minority path delay in the Sampling network.

For achieving the above object, the technical solution used in the present invention is as follows:

A kind of method of measurement of the path delay based on end-to-end detection may further comprise the steps:

(S1) obtain the real network topology, carry out the detection of network path in the terminal of network topology to other terminal transmission traceroute packet, and generate corresponding trace file according to detective path;

(S2) according to the link of described each path process of trace file acquisition, and according to every paths the link establishment link relational matrix M of process; The delegation of described link relational matrix represents the paths in the network, data in every delegation represent the link position of link in this path that this path comprises, when certain bar link is comprised by certain paths, put 1 on the respective link position in this path in the path matrix, otherwise set to 0;

(S3) by the Line independent decomposition algorithm described link relational matrix M is carried out linearity and decomposes, obtain path linear independence matrix M '; The line number of described path linear independence matrix equals the link number in the overlay network;

(S4) by the Line independent decomposition algorithm matrix M ' carry out linearity is decomposed, obtain link linear independence square formation M ";

(S5) between the terminal of network topology, send probe, the time that the time that sends according to source and egress receive, calculate link linear independence matrix M " in the time-delay b ' in Line independent path;

(S6) according to path linear independence matrix M ', time-delay b ' and link linear independence square formation M " the path delay b in all paths in the computing network topology in Line independent path.

Further, the method for measurement of aforesaid a kind of path delay based on end-to-end detection, in the step (S2), the concrete mode of setting up link relational matrix M is:

Suppose total s bar link in network, use column vector v ∈ { 0,1} ^sRepresent a paths, if link j is the part in path, so v _j=1, otherwise v _j=0; The time-delay of supposing link j is l _j, the time-delay p in path uses v to be expressed as so:

$p=\underset{j=1}{\overset{s}{\mathrm{\Σ}}}{l}_j^{v_j}---\left(1\right)$

Taken the logarithm in equation (1) both sides, and definition x _j=logl _j, the transposition of column vector v is written as v ^TCan get $\log p=\underset{j=1}{\overset{n_s}{\mathrm{\Σ}}}\log l_j{v}_j=\underset{j=1}{\overset{n_s}{\mathrm{\Σ}}}{x}_j{v}_j=x{v}^T---\left(2\right)$

When the terminal number in the network is n, a total r=O (n in overlay network ²) paths, just there is the equation of r (2) form to exist, obtain relational matrix M ∈ { 0, the 1} of link that every paths passes through according to the equation of r (2) form ^{R * s}, the paths of every row representative in network of M: comprise link j, then M if work as path i _Ij=1, otherwise M _Ij=0.

Further, the method for measurement of aforesaid a kind of path delay based on end-to-end detection, in the step (S3), by the Line independent decomposition algorithm obtain path linear independence matrix M ' concrete mode be:

If p _iRepresent the time-delay of i bar end-to-end path, b _i=logp _i, then link relational matrix M and the formula (2) by link that every paths passes through obtains

Mx=b （3）

Wherein, b represents the path delay matrix in all paths in the network topology;

If the order of matrix M is k, from matrix M, select k bar Line independent path according to the Line independent decomposition method, obtain path linear independence matrix M ' concrete mode as follows:

Step 301: take out the first row of M, be made as v;

Step 302: set up one according to the distortion of QR Standard Decomposition method and decompose M ' ^T=QR;

Wherein, M ' ^TFor matrix M ' transposed matrix, Q is M ' ^TAccording to the matrix of the row quadrature after the decomposition of QR Standard Decomposition method, R is the upper triangular matrix after decomposing; R ₁₂And R ₂₂To form the ever-increasing part of upper triangular matrix R, R ₁₂=R ^-TM ' v ^T, R wherein ^-TTransposed matrix for the inverse matrix of triangular matrix R;

R ₂₂=||v|| ²-||R ₁₂|| ²

Step 303: check whether satisfy R ₂₂≠ 0, if then enter step 304, otherwise execution in step 306;

Step 304: with v add path linear independence matrix M ' in;

Step 305: the basis at original R is expanded, with it as new upper triangular matrix R ₁Upper left corner matrix-block, and with R ₁₂And R ₂₂Be placed on its right side and bottom right, its lower benefit 0 forms new upper triangular matrix R ₁, $R_1=\left[\begin{array}{cc}R& R_{12}\\ 0& R_{22}\end{array}\right];$

Step 306: judge whether v is last column of matrix M, if then enter step 307, the next line that then takes out if not M is made as v and returns step 302;

Step 307: finish, with path linear independence matrix M ' return.

Further, the method for measurement of aforesaid a kind of path delay based on end-to-end detection, in the step (S4), by the Line independent decomposition algorithm with described matrix M ' carrying out linearity decomposes, and obtains the link linear independence square formation M of k * k " mode be:

Matrix M ' order be k, ", then M " satisfies described matrix M ' carry out linearity is decomposed, to obtain link linear independence square formation M by the Line independent decomposition algorithm:

M″x＝b′（4）

Wherein, the path delay matrix that comprises the path among the b " expression link linear independence matrix M ";

Matrix M ' carry out is obtained link linear independence square formation M linear the decomposition " concrete mode as follows:

Step 401: matrix M ' transposition is obtained M ' ^T

Step 402: with M ' ^TAs the M in step 301～step 307, the M ' in step 301～step 307 is designated as M ", the processing procedure by step 301～step 307 obtains link linear independence square formation M ' again, is designated as M ".

Further, the method for measurement of aforesaid a kind of path delay based on end-to-end detection, in the step (S6), the concrete mode of the path delay in all paths is in the computing network topology:

Step 601: with link linear independence matrix M " in the path delay matrix b ' substitution formula (4) in Line independent path in calculate x;

Step 602: x brought into calculate all path delay b in the formula (3).

Further, the method for measurement of aforesaid a kind of path delay based on end-to-end detection, in the step (S5), when sending probe between the terminal of network topology, each terminal sends 100 TCP probes that size is 100 bits to the another one terminal.

Further again, the method for measurement of aforesaid a kind of path delay based on end-to-end detection, in the step (5), it is 0.2 exponential distribution that the time interval that at every turn sends probe is set to obey mean value.

Further, the method for measurement of aforesaid a kind of path delay based on end-to-end detection, described method is further comprising the steps of:

(S7) with the threshold value of the path delay of the path delay b in all paths and setting relatively, judge the path of breaking down.

Beneficial effect of the present invention is:

The minority path delay is inferred the time-delay of All Paths in the monitoring network, rather than monitors the time-delay in all paths.Utilize algebraic process to carry out modeling real network, this model is conducive to the relation between definite network link and the path, mathematical theory according to model, choosing few path of trying one's best surveys, go to infer all path delay with the result who monitors, prevent that meaningless network fault diagnosis from causing unnecessary overhead.But because the result of prior art is not unique, be in the general solution, we propose to try to achieve the technology of unique solution, and namely all links can replace with the link of Line independent.Show as the relation that linear combination substitutes between them.We obtained obtaining the scheme of unique solution in conjunction with former algorithm.

Description of drawings

Fig. 1 is the flow chart of the method for measurement of a kind of path delay based on end-to-end detection of the present invention;

Fig. 2 is the flow chart of embodiment neutral line independence decomposition algorithm;

Fig. 3 is the flow chart that calculates the path delay unique solution in the concrete real-time mode;

Fig. 4 is the network topology schematic diagram in the specific embodiment.

Embodiment

The present invention is described in further detail below in conjunction with Figure of description and embodiment.

Fig. 1 shows the flow chart of the method for measurement of a kind of path delay based on end-to-end detection of the present invention, and as can be seen from Figure, the method mainly may further comprise the steps:

Step S101: obtain network topology, send traceroute in some terminals and finish the path detection, generate the trace file according to detective path;

Use SNMP(Simple Network Management Protocol in the present embodiment, Simple Network Management Protocol) instrument is found the real network topology, terminal in network topology sends traceroute packet, the link of finding out each path process to other terminal.In this case, can guarantee that every link is all detected fully, some some link occurs fault of some paths can not occur, and can not reach the situation of last terminal, so that the path of record data bag transmission, the terminal of network refers to that the number of degrees are 1 node.

After finishing above-mentioned steps, can produce corresponding trace file.The trace file is the file of record data bag jump procedure.We can obtain according to the trace file relational matrix of the link of every paths process.The delegation of matrix is just representing a certain paths.If certain bar link is comprised by certain paths, so respective link position set on those paths, otherwise reset.

Step S102: the link relational matrix M that gets outbound path according to the trace file;

According to the link of each path process of trace file acquisition that produces among the step S101, and according to every paths the link establishment link relational matrix M of process; The delegation of link relational matrix represents the paths in the network, data in every delegation represent the link position of link in this path that this path comprises, when certain bar link is comprised by certain paths, put 1 on the respective link position in this path in the path matrix, otherwise set to 0.

According to every paths the link of process, set up link relational matrix M in conjunction with the related operation in the algebraically and belong to existing technical scheme, its concrete mode is:

Suppose total s bar link in network, use column vector v ∈ { 0,1} ^sRepresent a paths, if link j is the part in path, so v _j=1, otherwise v _j=0; The time-delay of supposing link j is l _j, the time-delay p in path uses v to be expressed as so:

$p=\underset{j=1}{\overset{s}{\mathrm{\Σ}}}{l}_j^{v_j}---\left(1\right)$

Taken the logarithm in equation (1) both sides, and definition x _j=logl _j, the transposition of column vector v is written as v ^TCan get $\log p=\underset{j=1}{\overset{n_s}{\mathrm{\Σ}}}\log l_j{v}_j=\underset{j=1}{\overset{n_s}{\mathrm{\Σ}}}{x}_j{v}_j=x{v}^T---\left(2\right)$

When the terminal number in the network is n, a total r=O (n in overlay network ²) paths, just there is the equation of r (2) form to exist, obtain relational matrix M ∈ { 0, the 1} of link that every paths passes through according to the equation of r (2) form ^{R * s}, the paths of every row representative in network of M: comprise link j, then M if work as path i _Ij=1, otherwise M _Ij=0.

Step S103: use the Line independent decomposition algorithm to carry out linearity decomposition to matrix M, obtain path linear independence matrix M ';

Among the present invention by algorithm 1(Line independent decomposition algorithm) link relational matrix M carried out linearity decompose, obtain path linear independence matrix M ', the line linearity of this matrix is independent, i.e. the path Line independent; The line number of path linear independence matrix equals the link number in the overlay network, like this, just can cover all links.Algorithm 1 is a distortion of QR Standard Decomposition algorithm, is progressively to set up one to decompose M ' ^T=QR, wherein Q is the matrix of row quadrature, R is upper triangular matrix.By algorithm 1 obtain path linear independence matrix M ' concrete mode shown in:

If p _iRepresent the time-delay of i bar end-to-end path, b _i=logp _i, then link relational matrix M and the formula (2) by link that every paths passes through obtains

Mx=b （3）

In the ordinary course of things, M is not full rank, establishes k=rank (M) and is the order of M.This just points out us, can only monitor the path of k bar Line independent, and all links all cover in the energy ensuring coverage network like this, can also reduce as much as possible simultaneously to inject unnecessary load in network.Formula above so just using is inferred to all paths.Here, we come to select the k paths with algorithm 1 and monitor from path matrix.From matrix M, select K bar Line independent path according to the Line independent decomposition method, obtain path linear independence matrix M ' concrete mode as shown in Figure 2:

Step 301: take out the first row of M, be made as v;

Step 302: set up one according to the distortion of QR Standard Decomposition method and decompose M ' ^T=QR;

Wherein, M ' ^TFor matrix M ' transposed matrix, Q is M ' ^TAccording to the matrix of the row quadrature after the decomposition of QR Standard Decomposition method, R is the upper triangular matrix after decomposing; R ₁₂And R ₂₂To form the ever-increasing part of upper triangular matrix R, R ₁₂=R ^-TM ' v ^T

R ₂₂=||v|| ²-||R ₁₂|| ²

Step 303: check whether satisfy R ₂₂≠ 0, if then enter step 304, otherwise execution in step 306; If R ₂₂≠ 0, represent that then v satisfies the condition of linear independence;

Step 304: with v add path linear independence matrix M ' in;

Step 305: the basis at original R is expanded, with it as new upper triangular matrix R ₁Upper left corner matrix-block, and with R ₁₂And R ₂₂Be placed on its right side and bottom right, its lower benefit 0 forms new upper triangular matrix R ₁, $R_1=\left[\begin{array}{cc}R& R_{12}\\ 0& R_{22}\end{array}\right];$

Step 306: judge whether v is last column of matrix M, if then enter step 307, then will take out if not the next line assignment of M to v, return step 302;

Step 307: finish, with path linear independence matrix M ' return.

In the implementation process of reality, at first with v, initialization R ₁₂And R ₂₂, then carry out above-mentioned steps 310～307.

Step S104: by the Line independent decomposition algorithm matrix M ' carry out linearity is decomposed, obtain link linear independence square formation M ";

Key point of the present invention is exactly the unique solution how way to acquire is delayed time.Discussion by the front knows, to only have when M ' is square formation according to the principle of matrix operation, just can obtain unique solution.Problem is exactly the square formation that how to obtain M ' so.Matrix M that and if only if " when being square formation; we can obtain unique solution from (3) formula; obtain unique solution by following algorithm (algorithm 2) in the present embodiment; namely again by Line independent decomposition algorithm (algorithm) matrix M ' carry out linearity is decomposed; obtain link linear independence square formation M ", its concrete mode is as follows:

Matrix M ' order be k, ", then M " satisfies described matrix M ' carry out linearity is decomposed, to obtain link linear independence square formation M by the Line independent decomposition algorithm:

M″x＝b″（5）

Wherein, the path delay that comprises the path among the b " expression path linear independence matrix M ";

Matrix M ' carry out is obtained link linear independence square formation M linear the decomposition " concrete mode as follows:

Step 401: matrix M ' transposition is obtained M ' ^T

Step 402: with M ' ^TAs the M in step 301～step 307, the M ' in step 301～step 307 is designated as M ", obtain link linear independence square formation M ' by step 301～step 307, be designated as M ", specific as follows:

Take out M ' ^TThe first row, be made as v;

Set up one according to the distortion of QR Standard Decomposition method and decompose M ^T=QR;

Wherein, M ^TBe matrix M " transposed matrix, Q is M ^TAccording to the matrix of the row quadrature after the decomposition of QR Standard Decomposition method, R is the upper triangular matrix after decomposing; R ₁₂And R ₂₂To form the ever-increasing part of upper triangular matrix R, R ₁₂=R ^-TM ' v ^T

R ₂₂=||v|| ²-||R ₁₂|| ²

Check and whether satisfy R ₂₂≠ 0, if then enter step 304, otherwise execution in step 306; If R ₂₂≠ 0, represent that then v satisfies the condition of linear independence;

V is added path linear independence matrix M " in;

Basis at original R is expanded, with it as new upper triangular matrix R ₁Upper left corner matrix-block, and with R ₁₂And R ₂₂Be placed on its right side and bottom right, its lower benefit 0 forms new upper triangular matrix R ₁, $R_1=\left[\begin{array}{cc}R& R_{12}\\ 0& R_{22}\end{array}\right];$

Judge v whether be matrix M ' ^TLast column, if then enter step 307, then will take out M ' if not ^TThe next line assignment to v, return step 302;

Finish, path linear independence matrix M " is returned.

Step S103 neutral line independence decomposition algorithm and step S104 neutral line independence decomposition algorithm are easy to realize by MATLAB.

Step S105: the time difference of monitoring from the source to the egress, calculate M " in the time-delay b ' in Line independent path;

Between the terminal of network topology, send probe, the time that the time that sends according to source and egress receive, calculate link linear independence matrix M " in the time-delay b ' in Line independent path.Here be that 1 leaf node is called terminal with the number of degrees in the network topology.At random a certain number of base station of selection in terminal, base station are exactly the terminal that sends probe to other-end.Guarantee that per two base stations have probe to survey.Can guarantee like this physical network of the required bottom of overlay network is all covered.We are on host-host protocol, and the udp protocol before having abandoned has been selected Transmission Control Protocol.Because can prevent like this among the UDP because transmission environment changes, and the path also changes, so that the matrix of front has lost meaning.Each terminal sends 100 TCP probes that size is 100 bits.It is 0.2 exponential distribution that the time interval that at every turn sends probe is set to obey mean value.

Step S106: the path delay in all paths in the computing network topology;

According to path linear independence matrix M ', time-delay b ' and link linear independence square formation M " the path delay b in all paths in the computing network topology in Line independent path.

Illustrated among Fig. 3 and utilized the final flow chart (algorithm 2 comprises step S104～step S106) of realizing obtaining the path delay unique solution of said method of the present invention, specific implementation is as follows:

At first, according to the path delay b ' that comprises the path in the link linear independence matrix M " the time-delay b ' of link independent pathway determines link linear independence matrix M ";

Then, b ' is brought in the formula (4) and calculate x;

At last, x is brought into calculate all path delay b in the formula (3).

Step S107: according to the path threshold value, judge which path breaks down.

After obtaining all path delay vector b, according to the threshold value of path delay, judge that fault has appearred in which path.

Key point of the present invention is:

1. only monitor the minority path and infer all paths;

Method of the present invention is only monitored a small amount of path, and the path delay that then uses monitoring to detect is calculated the path delay that all are remaining.Suppose to have in network m bar link, then the path that this just might measure m bar Line independent solves the equation in m path.In case independent link delay is known, they just can be used for accurately inferring the time-delay of n bar network path, and with respect to n, Time delay measurement only need to be measured m time.Obviously, m has been howed than n is little, can greatly reduce the monitoring flow like this.

2. by by link relational matrix M, decompose except network path being carried out linearity, also the linearity decomposition is carried out in the link of network;

Every delegation correspondence of M the paths in the overlay network, each row corresponding a link, algorithm standard rules order decomposition algorithm (Line independent decomposition algorithm), the line linearity Independent Factorization of advancing to M, can obtain the path of Line independent, can only monitor the time-delay in these paths, use again the generally formula of applicable any network topology of this patent, so release the time-delay in path.Row to M carry out the linear independence decomposition, can obtain the set of the row of Line independent, thereby can with the linear combination of these links, express whole links.

3. obtain the rationale of unique solution according to us, finally obtained unique solution.

In the formula of generally applicable any network topology of the present invention, it is matrix operation that a link is arranged.According to the linear algebra principle, only have when matrix M is square formation, the solution x that draws is only unique solution.Yet be that the possibility of square formation is very little under normal circumstances.We only have by M is out of shape, and the x that obtains equating just can reach this purpose.Carry out respectively linearity by the row and column to M and decompose, the M that obtains at last " is k * k (k is the order of M).Thereby obtain x by M ' x=b ', x at this moment is exactly unique value.Among the substitution Mx=b, obtain all path delay b of unique solution again.

For a better understanding of the present invention, below in conjunction with specific embodiment the present invention is further detailed:

Embodiment

Fig. 4 is the network topology structure in the present embodiment, this embodiment selects the topological structure of a mininet, use BRITE to generate one and comprise 4 nodes (the node here comprises interior nodes and the terminal in the network), the network topology of route layer super power type of law has wherein comprised 3 terminals.

On the overlay network of terminal, can both cover in order to guarantee all relevant links, at first send lightweight ping probe, obtain the link relational matrix according to the trace file of corresponding generation $M=\left[\begin{array}{ccc}1& 1& 0\\ 0& 0& 1\\ 1& 1& 1\end{array}\right]$ Bring M into algorithm 1, obtain path linear independence matrix $M^{\′}=\left[\begin{array}{ccc}1& 1& 0\\ 0& 0& 1\end{array}\right].$

Next, making has probe to send between every a pair of terminal, and every pair sends altogether 100 probes.Choosing of probe, we use the packet based on TCP, rather than UDP.Can guarantee that like this path can not change when probe is surveyed.

We repeat this experiment 5 times, then only monitor M ' corresponding to the mean value of the time-delay of M respective paths $b^{\′}=\left[\begin{array}{c}0.014213\\ 0.011698\end{array}\right],$ Bring M ' into algorithm 2(Fig. 3) in, at first obtain $M^{\′\′}=\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right],$ And then obtain $x_M=\left[\begin{array}{c}-0.0143\\ -0.0118\end{array}\right],$ The time-delay that draws at last all paths is $b=\left[\begin{array}{c}0.014213\\ 0.011698\\ 0.006745\end{array}\right].$ With respect to real time-delay $\stackrel{\‾}{b}=\left[\begin{array}{c}0.014213\\ 0.011698\\ 0.005901\end{array}\right],$ The accuracy of the path delay that this algorithm is inferred is still very high.

Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technology thereof, then the present invention also is intended to comprise these changes and modification interior.

Claims (8)

1. method of measurement based on the path delay of end-to-end detection may further comprise the steps:

(S1) obtain the real network topology, carry out the detection of network path in the terminal of network topology to other terminal transmission traceroute packet, and generate corresponding trace file according to detective path;

(S2) according to the link of described each path process of trace file acquisition, and according to every paths the link establishment link relational matrix M of process; The delegation of described link relational matrix represents the paths in the network, data in every delegation represent the link position of link in this path that this path comprises, when certain bar link is comprised by certain paths, put 1 on the respective link position in this path in the path matrix, otherwise set to 0;

(S3) by the Line independent decomposition algorithm described link relational matrix M is carried out linearity and decomposes, obtain path linear independence matrix M '; The line number of described path linear independence matrix equals the link number in the overlay network;

(S4) by the Line independent decomposition algorithm matrix M ' carry out linearity is decomposed, obtain link linear independence square formation M ";

(S5) between the terminal of network topology, send probe, the time that the time that sends according to source and egress receive, calculate link linear independence matrix M " in the time-delay b ' in Line independent path;

(S6) according to path linear independence matrix M ', time-delay b ' and link linear independence square formation M " the path delay b in all paths in the computing network topology in Line independent path.

2. the method for measurement of a kind of path delay based on end-to-end detection as claimed in claim 1, it is characterized in that: in the step (S2), the concrete mode of setting up link relational matrix M is:

Suppose total s bar link in network, use column vector v ∈ { 0,1} ^sRepresent a paths, if link j is the part in path, so v _j=1, otherwise v _j=0; The time-delay of supposing link j is l _j, the time-delay p in path uses v to be expressed as so:

$p=\underset{j=1}{\overset{s}{\mathrm{\Σ}}}{l}_j^{v_j}---\left(1\right)$

Taken the logarithm in equation (1) both sides, and definition x _j=logl _j, the transposition of column vector v is written as v ^TCan get $\log p=\underset{j=1}{\overset{n_s}{\mathrm{\Σ}}}\log l_j{v}_j=\underset{j=1}{\overset{n_s}{\mathrm{\Σ}}}{x}_j{v}_j=x{v}^T---\left(2\right)$

When the terminal number in the network is n, a total r=O (n in overlay network ²) paths, just there is the equation of r (2) form to exist, obtain relational matrix M ∈ { 0, the 1} of link that every paths passes through according to the equation of r (2) form ^{R * s}, the paths of every row representative in network of M: comprise link j, then M if work as path i _Ij=1, otherwise M _Ij=0.

3. the method for measurement of a kind of path delay based on end-to-end detection as claimed in claim 2 is characterized in that: in the step (S3), by the Line independent decomposition algorithm obtain path linear independence matrix M ' concrete mode be:

If p _iRepresent the time-delay of i bar end-to-end path, b _i=logp _i, then link relational matrix M and the formula (2) by link that every paths passes through obtains

Mx=b （3）

Wherein, b represents the path delay matrix in all paths in the network topology;

If the order of matrix M is k, from matrix M, select k bar Line independent path according to the Line independent decomposition method, obtain path linear independence matrix M ' concrete mode as follows:

Step 301: take out the first row of M, be made as v;

Step 302: set up one according to the distortion of QR Standard Decomposition method and decompose M ' ^T=QR;

Wherein, M ' ^TFor matrix M ' transposed matrix, Q is M ' ^TAccording to the matrix of the row quadrature after the decomposition of QR Standard Decomposition method, R is the upper triangular matrix after decomposing; R ₁₂And R ₂₂To form the ever-increasing part of upper triangular matrix R, R ₁₂=R ^-TM ' v ^T, R wherein ^-TTransposed matrix for the inverse matrix of triangular matrix R;

R ₂₂=||v|| ²-||R ₁₂|| ²

Step 303: check whether satisfy R ₂₂≠ 0, if then enter step 304, otherwise execution in step 306;

Step 304: with v add path linear independence matrix M ' in;

Step 305: the basis at original R is expanded, with it as new upper triangular matrix R ₁Upper left corner matrix-block, and with R ₁₂And R ₂₂Be placed on its right side and bottom right, its lower benefit 0 forms new upper triangular matrix R ₁, $R_1=\left[\begin{array}{cc}R& R_{12}\\ 0& R_{22}\end{array}\right];$

Step 306: judge whether v is last column of matrix M, if then enter step 307, the next line that then takes out if not M is made as v and returns step 302;

Step 307: finish, with path linear independence matrix M ' return.

4. the method for measurement of a kind of path delay based on end-to-end detection as claimed in claim 3, it is characterized in that: in the step (S4), by the Line independent decomposition algorithm described matrix M ' carry out linearity is decomposed, obtains link linear independence square formation M " mode be:

Matrix M ' order be k, ", then M " satisfies described matrix M ' carry out linearity is decomposed, to obtain the link linear independence square formation M of k * k by the Line independent decomposition algorithm:

M″x＝b′（4）

Wherein, b ' expression link linear independence matrix M " the middle path delay matrix that comprises the path;

Matrix M ' carry out is obtained link linear independence square formation M linear the decomposition " concrete mode as follows:

Step 401: matrix M ' transposition is obtained M ' ^T

Step 402: with M ' ^TAs the M in step 301～step 307, the M ' in step 301～step 307 is designated as M ", the processing procedure by step 301～step 307 obtains link linear independence square formation M ' again, is designated as M ".

5. the method for measurement of a kind of path delay based on end-to-end detection as claimed in claim 4, it is characterized in that: in the step (S6), the concrete mode of the path delay in all paths is in the computing network topology:

Step 601: with link linear independence matrix M " in the path delay matrix b ' substitution formula (4) in Line independent path in calculate x;

Step 602: x brought into calculate all path delay b in the formula (3).

6. the method for measurement of a kind of path delay based on end-to-end detection as claimed in claim 1, it is characterized in that: in the step (S5), when sending probe between the terminal of network topology, each terminal sends 100 TCP probes that size is 100 bits to the another one terminal.

7. the method for measurement of a kind of path delay based on end-to-end detection as claimed in claim 6 is characterized in that: in the step (5), it is 0.2 exponential distribution that the time interval that at every turn sends probe is set to obey mean value.

8. the method for measurement of a kind of path delay based on end-to-end detection as claimed in claim 1, it is characterized in that: described method is further comprising the steps of:

(S7) with the threshold value of the path delay of the path delay b in all paths and setting relatively, judge the path of breaking down.

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