JP2014023064A - Network reliability evaluation device, method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To learn how well an evaluation object communication network can maintain communication capability with an important communication node in the case where damage is large like a large scale fault and natural disaster.SOLUTION: The invention enumerates all the states of communication nodes and transmission links, calculates a probability Pi that the state S of each communication network becomes a certain state i using a probability PBthat a given communication node is in a fault state and a probability PLthat a given transmission link is in a fault state, determines whether or not a communication node is connected with a specified normal important communication node, calculates the communication scale Ei of the communication network when the state S of the communication network is the certain state i by using connection determination result between the communication node and the specified important communication node when the state S of the communication network is the certain state i, and an in advance prescribed communication scale Aof the communication node, multiplies the probability Pi by the communication scale Ei, and regards the sum of all the products as an expected value of the communication scale of the communication network.

Description

  The present invention relates to a network reliability evaluation apparatus, method, and program, and more particularly to network reliability for evaluating the reliability of communication capability of a communication network when damage is large, such as a large-scale failure or natural disaster. The present invention relates to a sex evaluation apparatus, method, and program.

  As an index to evaluate how reliable the communication network is, the communication network is regarded as a graph (communication building is a node, transmission path is a link), and all nodes specified in advance are connected with normal nodes and links. Is defined as “the communication function is normal in the communication network”, and based on this definition, it is proposed to use the probability that the communication function of the communication network is normal (defined as “reliability”). (For example, refer nonpatent literature 1).

Masahiro Hayashi and Takeo Abe, "Reliability of Communication Networks," IEICE (Corona), 2010. 5.

  The reliability evaluation index according to the prior art is based on the idea that importance is attached to ensuring the normality of the entire communication network. However, when the damage is large, such as a large-scale failure or a natural disaster (a failure of multiple nodes and multiple links is strongly assumed), it is strongly assumed that the normality of the entire communication network cannot be ensured. . Therefore, when analyzing the reliability of a communication network against large-scale damage, evaluate how much communication capability of the communication network remains in a situation where the normality of the entire communication network is not ensured. Although a viewpoint is also necessary, reliability evaluation based on remaining communication capability cannot be performed (Problem 1).

  In the prior art, as shown in FIGS. 1A and 1B, only the probability that the communication function is in a normal state is used as the evaluation index.

  As described above, conventionally, there is a problem that it is impossible to evaluate the reliability of the remaining communication capability of the communication network when the damage is large, such as a large-scale failure or a natural disaster.

  In communication networks, there are often communication buildings (nodes) that play an important role. For example, a communication building that is a connection point between layers of a communication network having a hierarchical structure, a communication building that accommodates a clock supply device, a data center, and a communication device that accommodates an important customer is set. Examples include buildings. If there is a difference in the importance of communication nodes in this way, instead of uniformly evaluating the connectivity to designated nodes including “important communication nodes”, communication is performed using an index that focuses on connectivity with important communication nodes. It is desirable to evaluate the reliability of the network (Problem 2).

  The present invention has been made in view of the above points, and to what extent can a communication network to be evaluated maintain communication capability with an important communication node in the case of a large-scale damage such as a large-scale failure or a natural disaster? It is an object of the present invention to provide a network reliability evaluation system and method capable of grasping the above.

The present invention is a network reliability evaluation apparatus for evaluating the reliability of a communication network in which damage is large, such as a large-scale failure or a natural disaster,
Network information storage means for storing information about communication nodes and transmission links;
A communication network state listing unit that lists all communication node and transmission link states from the network information storage unit, and stores the communication node and transmission link states in the communication network state information storage unit;
Reading the state of each communication network from the communication network state information storage means, using a probability PB _n that a pre-given communication node is in a failure state, and a probability PL _m that a pre-given transmission link is in a failure state, A communication network state probability calculating means for obtaining a probability Pi of the state S of the communication network being a certain state i;
Connection determination means for determining whether or not a communication node is connected to a designated normal important communication node in the state of each communication network in the communication network state information storage means;
Using the communication node when the state S of the communication network is in the state i, the determination result of the connection determination means of the communication node, and the communication scale An of the communication node given in advance, A communication scale calculating means for calculating the communication scale Ei of the communication network when the state S is in the state i;
Expectation value calculating means for multiplying the probability Pi and the communication scale Ei and adding all the multiplied values to an expected value of the communication scale of the communication network.

  As described above, according to the present invention, with respect to the above-mentioned problem 1, by introducing a scale of communication scale of a communication node, in the case where damage is large, such as a large-scale failure or a natural disaster, an evaluation target It is possible to grasp how much communication capacity can be maintained by the communication network.

  In addition, for the problem 2 above, by introducing the probability of each state where there is a communication node that can be connected to the important communication node, the connectivity with the important communication node when the communication function of the communication network is not normal is grasped. It becomes possible to do.

  By combining the above two means, for the first and second problems, by introducing the scale of the communication scale of the communication node and the respective probabilities of the existence of the communication node connected to the important communication node, When damage such as a scale failure or a natural disaster is large, it is possible to grasp how much the communication network to be evaluated can maintain the communication capability with the important communication node.

It is an example of the evaluation index by a prior art. It is an example of the communication network in one embodiment of this invention. It is a structural example of the network reliability evaluation apparatus in one embodiment of this invention. It is a flowchart of the network reliability evaluation process in one embodiment of this invention. It is an image of the important communication node in one embodiment of this invention. It is an example of the data stored in the communication network state information storage part in one embodiment of this invention. It is an example of the data stored in the connection information storage part in one embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the present invention, in order to simultaneously solve the above-described problems 1 and 2, the following two means are executed together.

(1) Means for solving Problem 1:
In order to quantitatively evaluate the degree of decrease in communication capability of the communication network when the communication function of the communication network is not normal, or the remaining communication capability, the amount of traffic that can be processed by the communication node, the number of accommodated users, etc. A scale representing the size of communication capability of a communication node (here, defined as “communication scale”) is introduced.

(2) Means for solving Problem 2:
When the important communication node is normal, each probability of a state in which a communication node connected to the important communication node exists is used as an index.

  By combining the above means (1) and (2), the probability that each communication node to be connected to the demand communication node when the important communication node is normal, and the connection to the important communication node are obtained. Multiply the total values of the communication scales of the communication nodes to be evaluated, add up all the multiplied values, and evaluate the reliability using the expected value of the communication scale of the communication node connected to the important communication node as an index. .

  This will be described in detail below.

  First, the definition of the state of the communication network is shown.

  -The state of the communication network is determined by a combination of normal and failure states of communication nodes and transmission links.

In the evaluation procedure shown below, for the communication node, the normal state of the n (n = 1, 2,..., N) th communication node B _n is
State (B _n ) = 1
And the failure state
State (B _n ) = 0
And

For the transmission link, the normal state of the m (m = 1, 2,..., M) th transmission link L _m is
State (L _m ) = 1
The fault condition,
State (L _m ) = 0
For the communication node B _n and the transmission link L _m constituting the communication network,
Vector S (State (B ₁ ), State (B ₂ ), ..., State (B _N ), State (L ₁ ), State (L ₂ ), ..., State (L _M ))
Is the “communication network state S” that the communication network can take.

Since there are 2 ^{(N + M)} communication network states S in total, the communication network state S can be represented by a matrix of 2 ^{(N + M)} × (N + M). Thus, the respective states S the communications network can take i (1,2, ..., 2 ( N + M)) When the state of the communication node B _n is S (i, n), the transmission link L _m state Can be represented by S (i, N + m).

・ Example of communication network:
The diagram shown in FIG. 2A and the table shown in FIG. 2B are examples of a communication network including N = 3 communication nodes and M = 3 transmission links. In this case, the state S of the communication network is 2 ^{(3 + 3)} = 64 in total.

  Therefore, when the normal state of the communication node and the transmission link is 1 and the failure state is 0, “S (3,3) = 0” indicates that the communication node B3 in the case where the communication network state S is the third is in the failure state. “S (3,5) = 1” represents that the transmission link is in a normal state when the state S of the communication network is third.

  Next, symbols used in the description of the evaluation procedure are defined.

i: Status number of the communication network (i = 1, 2,..., 2 ^{(N + M)} )
n: Communication node number (n = 1, 2,..., N)
S (i, n): n th state of the communication node B _n in the state S of the communication network i (a normal state 1, a fault condition 0)
PB _n : Probability that the _nth communication node B _n is in a failure state
A _n : Communication scale of the _nth communication node B _n m: Transmission link number (m = 1, 2,..., M)
S (i, N + m): The state of the mth transmission link L _m when the communication network state S is i
PL _m : Probability that the m-th transmission link L _m is in a failure state
C (i, n): Whether or not the n-th communication node and the important communication node B _n when the communication network state S is i is connected (the connected state is 1 and the unconnected state is 0) To do)
Pi: Probability that the communication network state S is in state i
Ei: Communication network communication scale when communication network state S is in state i
R: Expected value of communication scale of communication network FIG. 3 shows a configuration of a network reliability evaluation apparatus according to an embodiment of the present invention.

  The network reliability evaluation apparatus shown in FIG. 1 includes a network information storage unit 1, a communication network state information storage unit 2, a state probability storage unit 3, a connection information storage unit 4, a communication scale storage unit 5, a communication network state listing unit 10, The communication network state probability calculation unit 20, the connection determination unit 30, the communication scale calculation unit 40, and the expected value calculation unit 50 are configured.

  Each of the storage units 1 to 5 is a storage medium such as a hard disk or a memory.

  The network information storage unit 1 is connected to an external input device and stores information related to communication nodes and transmission links input from the input device. The network information storage unit 1 may be external to the network reliability evaluation apparatus.

  The expected value calculation unit 50 is connected to an external display device and outputs the calculated expected value.

  FIG. 4 is a flowchart of network reliability evaluation processing according to an embodiment of the present invention.

  The operation of the network reliability evaluation apparatus will be described below with reference to FIGS.

  Step 100) Obtain information about the communication node and the transmission link from an input device external to the network reliability evaluation device, and store it in the network information storage unit 1. The information stored is as follows.

-Number and number of communication nodes-Number and number of transmission links-Connection information of each communication node and each transmission link (which communication node is connected to each transmission link)
Probability PB _n that the _nth communication node B _n is in a failure state
-Communication scale A _{n of the nth} communication node B _n
Probability PL _m that the m-th transmission link L _m is in a failure state
Step 110) The communication network state listing unit 10 acquires information of an important communication node designated by the user (operator) via the input device, and stores it in a memory (not shown). It is assumed that the operator designates an important communication node from among the communication nodes input in step 100. An example of the designated important communication node is shown in FIG. FIG. 2A shows an important communication node in a loop network having a hierarchical structure, and FIG. 2B shows an image of the important communication node in a mesh communication network. In the present embodiment, there is only one important communication node, but the present invention is not limited to this example, and a plurality of important communication nodes may exist.

Step 120) The communication network state listing unit 10 reads information on each communication node and each transmission link from the network information storage unit 1, lists all the communication network states S, and stores them in the communication network information storage unit 2. An example of information stored in the communication network state information storage unit 2 is shown in FIG. From the network information, the communication network state listing unit 10 determines whether the communication buildings (communication nodes) B _{1 to} B _N in each state are normal or in a function stop state, and the transmission path L in each state. ₁ ~L _M extracts information indicating which one of normal or disconnected.

Step 130) Next, the communication network state probability calculating unit 20 reads the state S from the communication network state information storage unit 2, and stored in the network information storage unit 1, the probability PB that the communication node B _n is in a failure state PB Using the probability PL _m that _n and the transmission link L _m are in the failure state, the probability Pi that the state S of the communication network is in the state i is calculated by the following equation (1).

上記で求められた確率Piを状態確率記憶部３に格納する。

The probability Pi determined above is stored in the state probability storage unit 3.

Step 140) The connection determination unit 30 connects the communication node _Bn to the important communication node designated by the operator in Step 110 for each state Si of the communication network listed in Step 120 from the communication network state information storage unit 2. It is determined whether or not it is connected, and “1” is set as C (i, n) if it is connected, and “0” is set if it is not connected, and is stored in the connection information storage unit 4. A storage example of the connection information storage unit 4 is shown in FIG. In the figure, in the state S ₁ , the communication building (communication node) B ₁ is connected to the important communication node, and the node B _N is not connected.

Step 150) The communication scale calculating unit 40 stores information C on whether or not the communication node B _n and the important communication node are connected when the communication network state S of the connection information storage unit 4 stored in Step 140 is i. (i, n) and acquires the communication-scale a _n communication node B _n from the network information storage unit 1, the following equation (2) of the communication network of the state i in the state S of the network using The communication scale Ei is calculated and stored in the communication scale storage unit 5.

ステップ１６０） 期待値算出部５０は、状態確率記憶部３からステップ１３０で算出された通信ネットワークにおいて、状態Siとなる確率Piを読み出し、通信規模記憶部５からステップ１５０で算出された通信規模Eiを読み出して、式（３）によってPiとEiを乗算し、これらの乗算した値を全て積算して通信ネットワークの通信規模の期待値Ｒを計算する。

Step 160) The expected value calculation unit 50 reads the probability Pi of the state Si in the communication network calculated in Step 130 from the state probability storage unit 3, and the communication scale Ei calculated in Step 150 from the communication scale storage unit 5. Is multiplied by Pi and Ei by equation (3), and all these multiplied values are added up to calculate the expected value R of the communication scale of the communication network.

上記で求められた期待値Ｒを表示装置に出力する。

The expected value R obtained above is output to the display device.

  As described above, in the present invention, each probability that there is a communication node connected to the important communication node when the important communication node is normal, and the total value of the communication scale of the communication node connected to the important communication node Based on the above, the reliability is evaluated using the expected value of the communication scale of the communication node connected to the important communication node as an index.

  The operation of each component of the network reliability evaluation apparatus shown in FIG. 3 can be constructed as a program, installed and executed on a computer used as the network reliability evaluation apparatus, or distributed via a network. Is possible.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims.

DESCRIPTION OF SYMBOLS 1 Network information storage part 2 Communication network state information storage part 3 State probability storage part 4 Connection information storage part 5 Communication scale storage part 10 Communication network state enumeration part 20 Communication network state probability calculation part 30 Connection determination part 40 Communication scale calculation part 50 Expected value calculator

Claims (3)

A network reliability evaluation device for evaluating the reliability of a large-scale communication network such as a large-scale failure or natural disaster,
Network information storage means for storing information about communication nodes and transmission links;
A communication network state listing unit that lists all communication node and transmission link states with reference to the network information storage unit, and stores the communication node and transmission link states in the communication network state information storage unit;
Reading the state of each communication network from the communication network state information storage means, using a probability PB _n that a pre-given communication node is in a failure state, and a probability PL _m that a pre-given transmission link is in a failure state, A communication network state probability calculating means for obtaining a probability Pi of the state S of the communication network being a certain state i;
Connection determination means for determining whether or not a communication node is connected to a designated normal important communication node in the state of each communication network in the communication network state information storage means;
Using the communication node when the state S of the communication network is in the state i, the determination result of the connection determination means of the communication node, and the communication scale An of the communication node given in advance, A communication scale calculating means for calculating the communication scale Ei of the communication network when the state S is in the state i;
An expected value calculation means for multiplying the probability Pi and the communication scale Ei, and multiplying all the multiplied values as an expected value of the communication scale of the communication network;
A network reliability evaluation apparatus comprising: A network reliability evaluation method for evaluating the reliability of a large-scale communication network such as a large-scale failure or natural disaster,
Network information storage means for storing information on communication nodes and transmission links, communication network state listing means, communication network state probability calculation means, connection determination means, communication scale calculation means, and expected value calculation means In the device
The communication network state listing unit refers to the network information storage unit, lists all communication nodes and transmission link states, and stores in the communication network state information storage unit;
The communication network state probability calculating means reads out the state of each communication network from the communication network state information storage means, and a probability PB _n that a predetermined communication node is in a failure state, and a predetermined transmission link is in a failure state. A communication network state probability calculation step for obtaining a probability Pi of a state S of each communication network using a certain probability PL _m ;
A connection determination step for determining whether or not the communication node is connected to a designated normal important communication node in the state of each communication network in the communication network state information storage unit;
The communication scale calculation means calculates a communication node when the communication network state S is in a state i, a determination result of the connection determination step of the communication node, and a communication scale An of the communication node given in advance. A communication scale calculating step for calculating a communication scale Ei of the communication network when the communication network state S is in a state i;
The expected value calculation means multiplies the probability Pi and the communication scale Ei, and an expected value calculation step of setting a value obtained by accumulating all the multiplied values as an expected value of the communication scale of the communication network;
A network reliability evaluation method characterized by: Computer
The network reliability evaluation program for functioning as each means of the network reliability evaluation apparatus of Claim 1.

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