JP2003060689A - Routing unit and program and recording medium and routing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To select an economical independent route while satisfying a desired number of independent routes. SOLUTION: In the calculation of a shortest route being used at the time of searching an independent route, srlg(i, j, g) is taken into account along with the link cost COSPF(i, j).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is used for route selection in an IP network. In particular, OSPF (Open Shortest Path First) and SR are used as standards for route selection.
The present invention relates to a technology that uses both concepts of LG (Shared RiskLink Group).

[0002]

2. Description of the Related Art The control technology used in an IP network is expanded to an IP-sub layer (Wavelength, TDM,
Generalize that can control (fiber) autonomously and decentralized
d Multi-Protocol Label Sw
Investigation of etching (GMPLS) is in progress
(A.Banerjee, J.Drake, JPLang, B.Turner, K.Komplella,
and Y. Rekhter, "Generalized Multiprotocol Label Sw
itching: An Overview of Routing and Management Enhan
cements, "IEEE Commun. Mag., pp. 144-150, Jan. 2001).

In GMPLS, Open Short
IP such as st Path First (OSPF)
By extending the routing protocol and notifying each node of the link status of each layer, routing in each layer becomes possible.

In the GMPLS OSPF extension, the Shar
The information called ed Risk Link Group (SRLG) is further notified. To ensure reliability in each layer, multiple independent routes are required. For example, when multiple wavelengths belong to the same fiber,
When the fiber is cut, it is affected by those wavelengths, and therefore, the SRLG information of the lower layer must be taken into consideration also in the route selection in the upper layer.

FIG. 7 shows a conventional route selection device. The conventional route selection device illustrated in FIG. 7 includes an OSPF link cost memory 10 and an independent route calculation unit 40, and SRLG
Is not considered.

[0006]

However, ks
OSP by hortest path algorithm
There is an independent route calculation method with SRLG based on the link cost notified by F. However, when a link with a large number of members belonging to SRLG is first selected, a desired number of independent routes cannot be obtained. Occurs.

This problem will be described with reference to the network example shown in FIG. Consider setting an independent route from the source node 0 to the destination node 5. Link L for each link
The cost C _OSPF (i, j) of (i, j) is given. This link cost is notified to each node by a routing protocol called OSPF, for example. s
rlg (i, j, g) indicates SRLG information, and takes “1” if the link L (i, j) belongs to the group g, and takes “0” otherwise. In the example of FIG. 8, srlg (4,5,0) = 1, srlg (2,
5,0) = 1. This is SRLG Group #
The link L (4,5) and the link L (2,5) belong to 0. An example of SRLG is shown in FIG. In the example of FIG. 9, the link between router # 4 and router # 5 and router #
The link between 2 and router # 5 belongs to the same SRLG group # 0. That is, the link L (4,5) and the link L (2,5) use the same fiber at the wavelengths λ1 and λ2 via the optical cross connect. The SRLG group belonging to this fiber is designated as SRLG # 0.

Returning to FIG. 8, the OSPF link cost C
_When an independent route is selected based on the _OSPF (i, j), first, the shortest route is 0-1-2.
5 is selected. Next, when selecting a node independent path, L
(0,1), L (1,2), L (2,5), and S
Considering RLG, L (4,5) and nodes 1, 2
Must be deleted. When selecting the link independent route, the nodes 1 and 2 do not have to be deleted. Here, the independent route refers to a node independent route unless otherwise specified, but in the case of a link independent route, the difference is whether to delete transit nodes or not, so it applies to both node independent routes and link independent routes. it can. The network topology after the exclusion is as shown in FIG. In this case, due to the influence of SRLG, in relation to L (2,5),
Since L (4,5) is also deleted, the independent route cannot be set any more. Therefore, first the OSPF
When the route is selected by, there may occur a situation in which the desired number of independent routes cannot be satisfied.

The present invention has been made against such a background, and is capable of satisfying a desired number of independent routes and selecting an economical independent route, a program, a recording medium, and a route. The purpose is to provide a selection method.

[0010]

SUMMARY OF THE INVENTION The present invention is a shortest route calculation used in independent route search, and has a link cost C _{OSP F}
The most main feature is to consider srlg (i, j, g) together with (i, j). As a result, a desired number of independent routes can be satisfied and an economical independent route can be selected.

That is, a first aspect of the present invention is a route selection device having means for selecting a route from a source node s to a destination node d, and the feature of the present invention is that the selection is made. The means is the link cost C based on the OSPF of the link L (i, j) between the node i and the node j.
Means for holding the _OSPF (i, j) and the link L
Group identification information SR assigned to a fiber when (i, j) shares one fiber with other links
A unit for holding LG (i, j) and a unit for holding the parameter α are provided, and the link cost C _OSPF (i, j
j) and the group identification information SRLG (i, j), and means for calculating an independent route in which a plurality of routes do not pass through the same link or node, and α (0
According to the set value of ≦ α ≦ 1), the weight considering SRLG in the path calculation of the calculating means is set variably.

Thus, route selection can be performed using both the concepts of OSPF and SRLG. In addition,
The closer the value of the parameter α is to “1”, the more independent paths can be searched.

More specifically, the calculating means takes "1" for srlg (i, j, g) if the link L (i, j) belongs to the group g, and "0" otherwise. , G is the number of SRLG groups, and the sum D of the costs of all independent routes between the source node s and the destination node d.
_path (s, d)

[Equation 5] , C _comp (i, j) = (1−α) C _OSPF (i,
j) + α _max {SRLG (i, j), 1}

[Equation 6] And the initial value is k = 1, and the source node s and the destination node d
The shortest route of the k-th path between
_source node s and destination node d obtained as _comp (i, j)
If there is no route between the group and the number of independent routes requested by k, the first step is terminated, and all groups for the via links L (i, j) of the path obtained in this first step are terminated. srlg (i, j, g) = 1 for g
Then, the second step of deleting all the links belonging to the group g to which the link L (i, j) belongs from the topology used in the path calculation and the transit node thereof, and k = k + 1 and the above first step It is desirable to provide means for repeatedly executing the returning third step until the route between the source node s and the destination node d is exhausted or the required number of independent routes is satisfied.

Alternatively, a first aspect of the present invention is that
From the destination node d to the destination node d.
The route selecting device, which is a feature of the present invention, is
The means for selecting is the link between node i and node j.
Link cost C based on OSPF of L (i, j)
_OSPFMeans for holding (i, j) and the link L
If (i, j) shares one fiber with other links
Group identification information SR assigned to the fiber
Means to hold LG (i, j) and set parameter α
And a link cost C_OSPF(I,
j) and the group identification information SRLG (i, j)
Based on multiple routes based on the same link or node
A means for calculating an independent path that does not pass through is provided, and the α (0
≦ α ≦ 1) according to the set value
The weights that take SRLGs into account
And a required independent path between the source node s and the destination node d.
Number of paths is D_{c omp}(S, d), and the minimum value of α is α
_minAnd the maximum value of α is α_maxAnd as the initial value
α_min= 0.0, α_max= 1.0 and the convergence of α
The determination value is ε, and between the source node s and the destination node d
The number of independent routes required for the path is D _req(S, d) and
However, the means for setting the parameter α is α = α_min+ Α_max And the fourth step, k-shorttest pa
The number of independent routes D by the th calculation algorithm
_{nu m}A fifth step of finding (s, d), D_num(S, d) <D_req(S, d) Then α_min= Α and α otherwise_max= And
The sixth step to do, α_max-Α_min> Ε If so, go back to the fourth step α = α_max+ Α_min And the seventh step of setting the value of parameter α as
A means for performing, the means for calculating, D_num(S, d) -D_req(S, d) D among the set of independent paths that minimize_path(S,
d) the set of independent paths that minimizes the selected path
Means for performing an eighth step of
As a hortest path calculation algorithm,
srlg (i, j, g) is a link L (i, j)
If it belongs to Pg, "1" otherwise "0"
, G is the number of SRLG groups, and
Sum D of the costs of all independent paths to and from card d_path
When defining (s, d) as [Equation 5],   C_comp(I, j) =   (1-α) C_OSPF(I, j) + α_max{SRLG (i, j), 1} [Equation 6] And the initial value is k = 1, and the source node s and the destination node d
The shortest route of the k-th path between
_compSource node s and destination node d obtained as (i, j)
Or there is no route between and the independent route requested by k
If it is a number, finish with the ninth step and this ninth step
About the via link L (i, j) of the path found in
Srlg (i, j, g) = 1 for all groups g
Then belongs to group g to which link L (i, j) belongs
Remove all links from the topology used for path calculation.
Tenth step of deleting the transit node
Then, set k = k + 1 and return to the ninth step.
There is no route between the source node s and the destination node d.
Until the required number of independent routes is satisfied
There is a means to execute repeatedly.

As a result, the optimum value of α can be obtained by calculation instead of setting the value of α by trial and error.

Also, C _OSPF (i, j) and SRL
The value of G (i, j)

[Equation 7] As the maximum value for the link L (i, j), respectively, or _COSPF (i, j) and S
The value of RLG (i, j)

[Equation 8] Can be standardized by the sum of the links L (i, j).

For example, C _OSPF (i, j) and SRLG
If there is an extreme difference in value between (i, j), α
Even if the value of is changed, one of the elements is always large, and it may be difficult to find the optimum value of α by changing the value of α by trial and error. By doing so, such a situation can be avoided.

A second aspect of the present invention is that when installed in an information processing device, the information processing device has a function corresponding to a route selection device for selecting a route from a source node s to a destination node d. Link cost C based on OSPF of link L (i, j) between i and node j
_The function to hold the _OSPF (i, j) and the link L
Group identification information SR assigned to a fiber when (i, j) shares one fiber with other links
The function of holding LG (i, j) and the function of holding the parameter α are realized, and the link cost C
_OSPF (i, j) and the group identification information SRL
Based on G (i, j), a function of calculating an independent route in which a plurality of routes do not pass through the same link or node with each other is realized, and the calculation is performed according to the set value of α (0 ≦ α ≦ 1). The program is characterized in that the weight considering SRLG in the path calculation is variably set.

More specifically, as a function of the calculation, srlg (i, j, g) is a link L (i, j).
But take a long as "1", otherwise "0" belong to the group g, G is the number of groups of SRLG, the sum D _path of the cost of all of the independent path between the source node s and the destination node d When (s, d) is defined as [Equation 5], C _comp (i, j) = (1−α) C _OSPF (i, j) + α _max {SRLG (i, j), 1} [Equation] 6], the initial value is k = 1, and the source node s and the destination node d are
The shortest route of the k-th path between
_source node s and destination node d obtained as _comp (i, j)
If there is no route between the group and the number of independent routes requested by k, the first step is terminated, and all groups for the via links L (i, j) of the path obtained in this first step are terminated. srlg (i, j, g) = 1 for g
Then, the second step of deleting all the links belonging to the group g to which the link L (i, j) belongs from the topology used in the path calculation and the transit node thereof, and k = k + 1 and the above first step It is desirable to realize a function of repeatedly executing the returning third step until the route between the source node s and the destination node d is exhausted or the required number of independent routes is satisfied.

Alternatively, a second aspect of the present invention is that the information processing
By installing it on the processing device,
In addition, the route from the source node s to the destination node d is selected.
Nodes i and j have functions corresponding to the route selection device.
Link based on OSPF of link L (i, j) between and
Cost C_OSPFThe function of holding (i, j)
Link L (i, j) shares one fiber with other links
Group identification information assigned to the fiber when
The function of holding the report SRLG (i, j) and the parameter α
And the function of setting the link cost C
_OSPF(I, j) and the group identification information SRL
Multiple links based on G (i, j)
Or, it implements a function to calculate an independent route that does not pass through a node.
And according to the set value of α (0 ≦ α ≦ 1)
Consider SRLG in path calculation of calculation function
Between the source node s and the destination node d whose weights are variably set
The number of independent routes required for_comp(S, d),
The minimum value of α is α_minAnd the maximum value of α is α_maxWhen
And α as the initial value_min= 0.0, α_max= 1.0
Let ε be the value that determines the convergence of α, and
D is the number of independent paths required for the path to node d
_req(S, d) and set the parameter α
As Noh α = α_min+ Α_max And the fourth step, k-shorttest pa
The number of independent routes D by the th calculation algorithm
_numA fifth step of finding (s, d), D_num(S, d) <D_req(S, d) Then α_min= Α and α otherwise_max= And
The sixth step to do, α_max-Α_min> Ε If so, go back to the fourth step α = α_max+ Α_min And the seventh step of setting the value of parameter α as
As a function to be realized and to select, D_num(S, d) -D_req(S, d) D among the set of independent paths that minimize_path(S,
d) the set of independent paths that minimizes the selected path
To realize the function of executing the eighth step,
-As a shortest path calculation algorithm
Srlg (i, j, g) has link L (i, j)
"1" if it belongs to loop g, otherwise "0"
Let G be the number of SRLG groups, and
Sum D of costs of all independent paths to node d
_pathWhen defining (s, d) as [Equation 5],   C_comp(I, j) =   (1-α) C_OSPF(I, j) + α_max{SRLG (i, j), 1} [Equation 6] And the initial value is k = 1, and the source node s and the destination node d
The link cost of the shortest route of the k-th path between
source node s and destination node d obtained as omp (i, j)
The number of independent routes that there is no route between or
If so, the ninth step to end and this ninth step
All about the via link L (i, j) of the path found in
Srlg (i, j, g) = 1 for all groups g
It belongs to the group g to which the Raba link L (i, j) belongs.
Remove all links from the topology used for path calculation
And the tenth step of deleting its transit node as well,
Set k = k + 1 and return to the ninth step. Eleventh step
There is no route between the source node s and the destination node d.
Until the required number of independent routes is satisfied.
A program characterized by realizing the function of returning and executing
It's lamb.

A third aspect of the present invention is a recording medium readable by the information processing device, in which the program of the present invention is recorded. The program of the present invention can be installed in the information processing apparatus using the recording medium of the present invention. The information processing apparatus can also install the program of the present invention by the information processing apparatus downloading the program of the present invention from a server holding the program of the present invention via a network.

A fourth aspect of the present invention is a route selection method for selecting a route from a source node s to a destination node d, which is a feature of the present invention. Link cost C _OSPF (i, j) based on the OSPF of the link L (i, j) and the group assigned to the fiber when the link L (i, j) shares one fiber with other links. Identification information SRLG (i, j)
And the parameter α, the link cost C
_OSPF (i, j) and the group identification information SRL
When calculating an independent route in which a plurality of routes do not pass through the same link or node based on G (i, j), when calculating the independent route according to the set value of α (0 ≦ α ≦ 1) The weight for considering SRLG in the path calculation is set variably.

More specifically, srlg (i,
j, g) is “1” if the link L (i, j) belongs to the group g, and “0” otherwise, and G is SRLG.
And the sum of costs D _{p ath} (s, d) of all independent paths between the _source node s and the destination node d is defined as [ _Equation 5], C _comp (i, j) = (1-α) _COSPF (i, j) + α _max {SRLG (i, j), 1} [Equation 6], the initial value is k = 1, and the source node s and the destination node d
The shortest route of the k-th path between
_source node s and destination node d obtained as _comp (i, j)
If there is no route between the group and the number of independent routes requested by k, the first step is terminated, and all groups for the via links L (i, j) of the path obtained in this first step are terminated. srlg (i, j, g) = 1 for g
Then, the second step of deleting all the links belonging to the group g to which the link L (i, j) belongs from the topology used in the path calculation and the transit node thereof, and k = k + 1 and the above first step It is desirable to repeatedly execute the returning third step until the route between the source node s and the destination node d is exhausted or the required number of independent routes is satisfied.

Alternatively, a fourth aspect of the present invention is that
In the route selection method that selects the route from the destination s to the destination node d
The feature of the present invention is that node i and node
Link L (i, j) with the gateway j based on OSPF.
Link cost C_OSPF(I, j) and the link L
If (i, j) shares one fiber with other links
Group identification information SR assigned to the fiber
Using LG (i, j), the link cost C_OSPF
(I, j) and the group identification information SRLG (i,
j), multiple routes have the same link or
When calculating an independent route that does not pass through a node, α (0 ≤ α
When calculating the independent route according to the setting value of ≦ 1)
The weight that considers SRLG in the path calculation of
And is required between the source node s and the destination node d.
Number of vertical paths is D_comp(S, d), and the minimum value of α is α
_minAnd the maximum value of α is α_maxAnd as the initial value
α_{mi n}= 0.0, α_max= 1.0 and the convergence of α
The determination value is ε, and between the source node s and the destination node d
The number of independent routes required for the path is D_req(S, d) and
Then α = α_min+ Α_max And the fourth step, k-shorttest pa
The number of independent routes D by the th calculation algorithm
_numA fifth step of finding (s, d), D_num(S, d) <D_req(S, d) Then α_min= Α and α otherwise_max= And
The sixth step to do, α_max-Α_min> Ε If so, go back to the fourth step α = α_max+ Α_min And the seventh step of setting the value of parameter α as
Run and set the parameter α, D_num(S, d) -D_req(S, d) D among the set of independent paths that minimize_path(S,
d) the set of independent paths that minimizes the selected path
The eighth step of performing the k-shortes
As the t path calculation algorithm, srlg
(I, j, g) has link L (i, j) belonging to group g
If so, "1" otherwise "0", G is S
The number of RLG groups is defined as the number of source nodes s and destination nodes d.
Sum of costs of all independent paths between_path(S, d)
When is defined as [Equation 5],   C_comp(I, j) =   (1-α) C_OSPF(I, j) + α_max{SRLG (i, j), 1} [Equation 6] And the initial value is k = 1, and the source node s and the destination node d
The shortest route of the k-th path between
_compSource node s and destination node d obtained as (i, j)
Or there is no route between and the independent route requested by k
If it is a number, finish with the ninth step and this ninth step
About the via link L (i, j) of the path found in
Srlg (i, j, g) = 1 for all groups g
Then belongs to group g to which link L (i, j) belongs
Remove all links from the topology used for path calculation.
Tenth step of deleting the transit node
Then, set k = k + 1 and return to the ninth step.
There is no route between the source node s and the destination node d.
Until the required number of independent routes is satisfied
It is about to be executed repeatedly.

In addition, C _OSPF (i, j) and SRL
Link L (i, j) with the value of G (i, j) as [Equation 7]
The maximum value for each, or C
The values of _OSPF (i, j) and SRLG (i, j) can be set to [Equation 8] and standardized by the sum regarding the link L (i, j).

[0026]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of the route selection device of the first embodiment of the present invention. FIG. 2 is a flowchart showing the k-shortest path algorithm of the first embodiment of the present invention. FIG. 3 is a block diagram of the route selection device of the second embodiment of the present invention. FIG. 4 is a block diagram of the route selection device of the third embodiment of the present invention. FIG. 5 is a flowchart showing the α setting algorithm of the third embodiment of the present invention. FIG. 6 is a diagram for explaining the effect of the route selection device according to the embodiment of the present invention, in which the value of α is plotted on the horizontal axis and the average number of unconnected links and the standard average link cost are plotted on the vertical axis.

According to the present invention, as shown in FIG.
Independent route calculation unit 40 for selecting a route from the destination node to the destination node d
A route selection device provided with a feature of the present invention is that a link L (i,
j) the link cost _COSPF (i,
j), and the group identification information SRLG (i, j) assigned to the fiber when the link L (i, j) shares one fiber with another link. SRLG memory 2
0 and a parameter α memory 30 holding the parameter α
And the independent path calculation unit 40 includes the link cost C
_OSPF (i, j) and the group identification information SRL
An independent route in which a plurality of routes do not pass through the same link or node is calculated based on G (i, j), and α
The independent path calculation unit 4 according to the set value of (0 ≦ α ≦ 1)
The weight for considering SRLG in the 0 path calculation is set variably.

Alternatively, the present invention, as shown in FIG.
A route selection device having an independent route calculation unit 40 for selecting a route from a source node s to a destination node d, which is a feature of the present invention is that a link L (i , J) the link cost C based on OSPF
_OSPF (i, j) and OSPF link cost memory 10 for holding the link L (i, j) is group identification information SRLG (i allocated to the fiber when sharing the other links and one fiber, j that holds j)
The RLG memory 20 and the parameter α setting unit 70 for setting the parameter α are provided, and the independent route calculation unit 40 makes a plurality of independent routes based on the link cost C _OSPF (i, j) and the group identification information SRLG (i, j). Independent routes that do not pass through the same link or node as each other, and SRLG (Shared Ri) in the path calculation of the independent route calculation unit 40 according to the set value of α (0 ≦ α ≦ 1).
The sk link group) weight is set variably.

Further, as shown in FIG. 3 or 4, C
The values of _OSPF (i, j) and SRLG (i, j) are each set to [Equation 7] and standardized by the maximum value for the link L (i, j), or _COSPF (i, j).
It is also possible to use the values of SRLG (i, j) as [Equation 8] and standardize the sum with respect to the link L (i, j).

In the embodiment of the present invention, the route selection device of the present invention is realized by using a computer device. However, in order to realize the mobile communication system of the present invention by using the computer device, a computer device which is an information processing device is used. The program of the present invention is used by causing the computer device to realize a function corresponding to the route selection device of the present invention by installing the program in the computer.

The computer-readable recording medium in which the program of the present invention is recorded can be used as the recording medium of the present invention, and the program of the present invention can be installed in the computer apparatus using the recording medium of the present invention. You can The computer device can also install the program of the present invention by the computer device downloading the program of the present invention from a server holding the program of the present invention via a network.

The embodiments of the present invention will be described in more detail below.

(First Embodiment) The first embodiment of the present invention is shown in FIG.
This will be described with reference to FIGS. In the first embodiment, k-
When the shortest path is searched by the shortest path algorithm, the next link cost C _comp (i,
j) is used. C _comp (i, j) = (1−α) C _OSPF (i, j) + α _max {SRLG (i, j), 1} [Equation 6] where C _OSPF (i, j): Advertised by OSPF Link L (i, j) cost, srlg (i,
j, g): 1 if the link L (i, j) belongs to the group g, 0 otherwise α: 0 ≤ α ≤ 1, a weight that considers SRLG in the path calculation, G: SRLG Is the number of groups in. Also, the sum D _path (s, d) of the costs of all the independent paths between the originating and terminating nodes s and d is defined as [Equation 5].

The larger the value of α is, SRLG (i, j)
It makes it easier to find an independent route. But,
On the other hand, the contribution of _COSPF (i, j) is reduced, so that D _path (s, d) is increased. When giving priority to the number of independent routes, the value of α is brought close to 1.

K-shorttest considering SRLG
The path calculation algorithm uses the following.
As an initial value, k = 1.

Step 1: k-th path between nodes s and d
The shortest path of the link, the link cost is C _comp(I, j)
Ask as. However, if there is a route between nodes s and d
No or k = D_regIf (s, d), end
To do.

Step 2: With respect to the via link L (i, j) of the path obtained in Step 1, for all g,
If srlg (i, j, g) = 1, link L
All the links belonging to the group g to which (i, j) belong are deleted from the topology used in the path calculation, and their transit nodes are also deleted.

Step 3: Set k = k + 1 and set Step 1
Go to. FIG. 2 shows the k-shorttest of the first embodiment.
The path algorithm is shown.

FIG. 1 shows the route selection device of the first embodiment. The route selection device is provided in each node. Further, it may be arranged in an operation device that centrally manages each node.

An example of route selection will be described with reference to FIG. For simplicity, α = 1. C _{c omp} (i, j) since the link cost of the calculation of the independent paths, 0-
Two routes, 1-3-5 and 0-4-5, can be obtained.

In the conventional method, the network of FIG. 8 can obtain only one route of 0-1-2-5, whereas the first embodiment can obtain two routes.

As described above, in the first embodiment, when α is set to 1 or a large value close to 1, more independent routes can be searched.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. In the first embodiment, _COSPF (i,
j) the SRLG (i, j), compared two values, since it has no relevance, for example, generally _C OSPF (i, j)
When the value of C is extremely larger than that of SRLG (i, j), the element of _COSPF (i, j) is always large even if the value of α is changed. Therefore, in _the second _embodiment, to normalize the value of _C OSPF (i, j) and SRLG (i, j). FIG. 3 shows the route selection device of the second embodiment.

[Equation 7] This is for each C
(I, j) of _OSPF (i, j) and SRLG (i, j)
Is standardized with the maximum value of. Also, [Equation 8] This is the respective _C OSPF (i, j) and SRLG (i,
j) is standardized by the sum of (i, j). In _the second _{embodiment, C} OSPF _(i, j) and SRLG (i, j)
Since it is possible to reduce the extreme difference between the values of and, it is effective to change the value of α by trial and error and select an appropriate α.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIGS. In the first and second embodiments, the value of α is given as a parameter. In the third embodiment, the number D of independent paths required between the originating and terminating nodes s and d
While satisfying _comp (s, d), D _{patch h} (s,
A path that minimizes d) is obtained using the binary search.

FIG. 4 shows the route selecting device of the third embodiment.
FIG. 5 shows the α setting algorithm of the third embodiment. The α setting algorithm of the third embodiment is as follows. As initial values, α _min = 0.0 and α _max = 1.0. The value for determining the convergence of α is ε.

Step 4: α = α_min+ Α_max Step 5: k-shortest path calculation
The number of independent routes D_numFind (s, d)
It Step6: D_num(S, d) <D_req(S, d)
Then α_min= Α, otherwise α_max= Α
And Step7: α_max-Α_minIf> ε, Step
Go to 1, otherwise go to Step 5. Step8: D_num(S, d) -D_req(S, d)
Of the set of independent paths that minimize
_pathSolve a set of independent paths that minimizes (s, d)
And However, D_req(S, d): Between nodes s and d
Is the number of independent routes required for the path.

K-shorttest considering SRLG
As the path calculation algorithm, the algorithm already described with reference to FIG. 2 is used.

(Summary of Embodiments) The number of nodes is 20 and the SRLG is considered using random numbers, and the average noded is used.
Topology that satisfies egree = 6 (10 samples)
0) _{generates, C co mp (i, j} ) as the link cost, alpha, mean independent paths number between destination nodes, normalized path cost _D path (s, d) (conventional method, i.e., alpha
The link cost when = 0 is set to "1") is shown in FIG. 6 according to the method of the second embodiment. The number of groups of SRLG is G = 16, and the number of members per group is 14,
The value of srlg (i, j, g) was given using a random number. From FIG. 6, it is understood that economical path setting can be performed by obtaining α satisfying the requirement.

[0050]

As described above, according to the present invention,
It is possible to satisfy the desired number of independent routes and select an economical independent route.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a route selection device according to a first embodiment of the present invention.

FIG. 2 is a k-shortest p of the first embodiment of the present invention.
The flowchart which shows an ath algorithm.

FIG. 3 is a block configuration diagram of a route selection device according to a second embodiment of the present invention.

FIG. 4 is a block configuration diagram of a route selection device according to a third embodiment of the present invention.

FIG. 5 is a flowchart showing an α setting algorithm of the third embodiment of the present invention.

FIG. 6 is a diagram for explaining effects of the route selection device according to the embodiment of the present invention.

FIG. 7 is a block configuration diagram of a conventional route selection device.

FIG. 8 is a diagram showing an example of a network configuration involving SRLG.

FIG. 9 is a diagram showing an example of SRLG.

FIG. 10 is a diagram showing a topology after links and nodes involved are excluded.

[Explanation of symbols]

10 OSPF link cost memory 20 SRLG memory 30 parameter α memory 40 Independent route calculator 50, 60 Standardization department 70 Parameter α setting section

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kohei Shiomoto             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F-term (reference) 5K030 LB05

Claims (14)

[Claims] 1. A route selection device comprising means for selecting a route from a source node s to a destination node d, wherein the means for selecting is a link L (i, j) between a node i and a node j. OS
Means for holding a link cost _COSPF (i, j) based on PF (Open Shortest Path First), and the link L (i, j) is assigned to the fiber when sharing one fiber with other links. And a means for holding the group identification information SRLG (i, j), and a means for holding the parameter α, and a plurality of means are provided based on the link cost _COSPF (i, j) and the group identification information SRLG (i, j). Is provided with means for calculating independent paths that do not pass through the same link or node, and SRLG (Shared Risk Link) in the path calculation of the means for calculating according to the set value of α (0 ≦ α ≦ 1).
A route selection device characterized in that a weight considering Group) is variably set. 2. The means for calculating is srlg (i, j, g) is a link L (i, j)
If it belongs to Pg, "1" otherwise "0"
G is a group of SRLG (Shared Risk Link Group)
And all independent paths between the source node s and the destination node d.
Sum of road costs D _path(S, d) [Equation 1] When you define C_comp(I, j) = (1-α) C_OSPF(I,
j) + α_max{SRLG (i, j), 1} [Equation 2] And the initial value is k = 1, Shortest path of k-th path between source node s and destination node d
Link cost C _compDerived from (i, j)
There is no route between node s and destination node d, or
If k is the required number of independent routes, the first step
And Via link L (i, i) of the path obtained in the first step
srlg for all groups g for j)
If (i, j, g) = 1, the link L (i, j) belongs
Use all links belonging to group g in path calculation
Delete it from the topology and delete its transit node.
The second step, Set k = k + 1 and return to the first step.
There is no route between the source node s and the destination node d.
Or until the required number of independent routes is satisfied
2. The route selection device according to claim 1, further comprising means for executing. 3. A route from a source node s to a destination node d is selected.
In the route selection device having means for selecting, The means for selecting is OS of link L (i, j) between node i and node j
Link cost based on PF (Open Shortest Path First)
C_OSPFMeans for holding (i, j), The link L (i, j) is one fiber together with the other link.
Group assigned to the fiber when sharing
Means for holding the identification information SRLG (i, j), And means for setting the parameter α, Link cost C_OSPF(I, j) and the guru
Based on the loop identification information SRLG (i, j)
Independent routes that do not pass through the same links or nodes
With means for calculating The calculation is performed according to the set value of α (0 ≦ α ≦ 1).
SRLG (Shared Risk Link)
Group) weight is set variably, Number of independent routes required between source node s and destination node d
To D_comp(S, d), and the minimum value of α is α_minWhen
And the maximum value of α is α_maxAnd α as the initial value_min
= 0.0, α_max= 1.0 and determine the convergence of α
The value is ε, and the path between the source node s and the destination node d is required.
D is the number of required independent paths_req(S, d), The means for setting the parameter α is α = α_min+ Α_max And the fourth step, According to the k-shortest path calculation algorithm
, The number of independent routes D_{nu m}The fifth step to find (s, d)
And D_num(S, d) <D_req(S, d) Then α_min= Α and α otherwise_max= And
The sixth step to do, α_max-Α_min> Ε If so, go back to the fourth step α = α_max+ Α_min And the seventh step of setting the value of parameter α as
Equipped with means to perform, The means for calculating is D_num(S, d) -D_req(S, d) D among the set of independent paths that minimize_path(S,
d) the set of independent paths that minimizes the selected path
Comprising means for performing the eighth step The k-shortest path calculation algorithm
as, srlg (i, j, g) is a link L (i, j)
If it belongs to Pg, "1" otherwise "0"
G is a group of SRLG (Shared Risk Link Group)
And all independent paths between the source node s and the destination node d.
Sum of road costs D _path(S, d) is defined as [Equation 1]
When   C_comp(I, j) =   (1-α) C_OSPF(I, j) + α_max{SRLG (i, j), 1} [Equation 2] And the initial value is k = 1, Shortest path of k-th path between source node s and destination node d
Link cost C _compDerived from (i, j)
There is no route between node s and destination node d, or
If k is the number of required independent paths, the ninth step is completed.
And The via link L (i,
srlg for all groups g for j)
If (i, j, g) = 1, the link L (i, j) belongs
Use all links belonging to group g in path calculation
Delete it from the topology and delete its transit node.
The tenth step Set k = k + 1 and return to the ninth step. Eleventh step
There is no route between the source node s and the destination node d.
Until the required number of independent routes is satisfied.
A route selection device having means for returning and executing
Place 4. _COSPF (i, j) and SRLG
The value of (i, j) is given by The route selection device according to any one of claims 1 to 3, which is standardized by a maximum value relating to the link L (i, j). 5. _COSPF (i, j) and SRLG
The value of (i, j) is given by The route selection device according to any one of claims 1 to 3, wherein each of the routes is standardized by a sum regarding the link L (i, j). 6. When the information processing apparatus is installed, the information processing apparatus is installed in the source node s to the destination node d.
As a function corresponding to the route selection device for selecting the route to the node, the OS of the link L (i, j) between the node i and the node j
A function of holding a link cost _COSPF (i, j) based on PF (Open Shortest Path First), and the link L (i, j) is assigned to the fiber when sharing one fiber with other links. A function of holding the group identification information SRLG (i, j) and a function of holding the parameter α, and based on the link cost _COSPF (i, j) and the group identification information SRLG (i, j). SRLG (Shared Risk Link) in the path calculation of the function that realizes the function of calculating independent paths in which a plurality of routes do not pass through the same link or node, according to the set value of α (0 ≦ α ≦ 1)
A program that is characterized in that the weight considering Group) is variably set. 7. The function of the calculation includes: srlg (i, j, g) is a link L (i, j)
If it belongs to Pg, "1" otherwise "0"
G is a group of SRLG (Shared Risk Link Group)
And all independent paths between the source node s and the destination node d.
Sum of road costs D _path(S, d) is defined as [Equation 1]
When   C_comp(I, j) =   (1-α) C_OSPF(I, j) + α_max{SRLG (i, j), 1} [Equation 2] And the initial value is k = 1, Shortest path of k-th path between source node s and destination node d
Link cost C _compDerived from (i, j)
There is no route between node s and destination node d, or
If k is the required number of independent routes, the first step
And Via link L (i, i) of the path obtained in the first step
srlg for all groups g for j)
If (i, j, g) = 1, the link L (i, j) belongs
Use all links belonging to group g in path calculation
Delete it from the topology and delete its transit node.
The second step, Set k = k + 1 and return to the first step.
There is no route between the source node s and the destination node d.
Or until the required number of independent routes is satisfied
The program according to claim 6, which realizes a function of executing the program.
Mu. 8. The method of installing in an information processing device
From the source node s to the destination node d,
The function corresponding to the route selection device that selects the route to
hand, OS of link L (i, j) between node i and node j
Link cost based on PF (Open Shortest Path First)
C_OSPFThe function of holding (i, j), The link L (i, j) is one fiber together with the other link.
Group assigned to the fiber when sharing
A function of holding the identification information SRLG (i, j), Realize the function to set the parameter α, Link cost C_OSPF(I, j) and the guru
Based on the loop identification information SRLG (i, j)
Independent routes that do not pass through the same links or nodes
Realize the function to calculate The calculation is performed according to the set value of α (0 ≦ α ≦ 1).
SRLG (Shared Risk Link)
Group) weight is set variably, Number of independent routes required between source node s and destination node d
To D_comp(S, d), and the minimum value of α is α_minWhen
And the maximum value of α is α_maxAnd α as the initial value_min
= 0.0, α_max= 1.0 and determine the convergence of α
The value is ε, and the path between the source node s and the destination node d is required.
D is the number of required independent paths_req(S, d), As a function of setting the parameter α, α = α_min+ Α_max And the fourth step, According to the k-shortest path calculation algorithm
, The number of independent routes D_{nu m}The fifth step to find (s, d)
And D_num(S, d) <D_req(S, d) Then α_min= Α and α otherwise_max= And
The sixth step to do, α_max-Α_min> Ε If so, go back to the fourth step α = α_max+ Α_min And the seventh step of setting the value of parameter α as
Make it happen, As the function to be selected, D_num(S, d) -D_req(S, d) D among the set of independent paths that minimize_path(S,
d) the set of independent paths that minimizes the selected path
To realize the function of executing the eighth step,
-As a shortest path calculation algorithm
Is srlg (i, j, g) is a link L (i, j)
If it belongs to Pg, "1" otherwise "0"
G is a group of SRLG (Shared Risk Link Group)
And all independent paths between the source node s and the destination node d.
Sum of road costs D _path(S, d) is defined as [Equation 1]
When   C_comp(I, j) =   (1-α) C_OSPF(I, j) + α_max{SRLG (i, j), 1} [Equation 2] And the initial value is k = 1, Shortest path of k-th path between source node s and destination node d
Derived from the road with the link cost as Ccomp (i, j)
There is no route between node s and destination node d, or
If k is the number of required independent paths, the ninth step is completed.
And the via link L of the path obtained in this ninth step
Srl for all groups g for (i, j)
If g (i, j, g) = 1, the link L (i, j) belongs
Use all links belonging to group g in the path calculation
Node that has been deleted from the topology as well as its transit node
The tenth step to do, Set k = k + 1 and return to the ninth step. Eleventh step
There is no route between the source node s and the destination node d.
Until the required number of independent routes is satisfied.
A program characterized by realizing the function of returning and executing
Lamb. 9. A recording medium readable by the information processing device, in which the program according to claim 6 is recorded. 10. A route selection method for selecting a route from a source node s to a destination node d, the OS of a link L (i, j) between a node i and a node j.
Link cost _COSPF (i, j) based on PF (Open Shortest Path First) and group identification information assigned to the fiber when the link L (i, j) shares one fiber with other links Using SRLG (i, j) and the parameter α, a plurality of routes do not pass through the same link or node based on the link cost C _OSPF (i, j) and the group identification information SRLG (i, j). When calculating an independent route, SRLG (Shared Ri) in the path calculation when calculating the independent route according to the set value of α (0 ≦ α ≦ 1) is calculated.
A method for selecting a route characterized in that the weight considering sk link group) is variably set. 11. srlg (i, j, g) is a link L
If (i, j) belongs to group g, it would be "1".
If it is “0”, G is SRLG (Shared RiskLink G
roup) and the number of groups of the source node s and the destination node d
Sum of costs of all independent paths between_path(S, d)
When is defined as [Equation 1],   C_comp(I, j) =   (1-α) C_OSPF(I, j) + α_max{SRLG (i, j), 1} [Equation 2] And the initial value is k = 1, Shortest path of k-th path between source node s and destination node d
Link cost C _compDerived from (i, j)
There is no route between node s and destination node d, or
If k is the required number of independent routes, the first step
And Via link L (i, i) of the path obtained in the first step
srlg for all groups g for j)
If (i, j, g) = 1, the link L (i, j) belongs
Use all links belonging to group g in path calculation
Delete it from the topology and delete its transit node.
The second step, Set k = k + 1 and return to the first step.
There is no route between the source node s and the destination node d.
Or until the required number of independent routes is satisfied
The route selection method according to claim 10, which is executed. 12. A route from a source node s to a destination node d
In the route selection method to select, OS of link L (i, j) between node i and node j
Link cost based on PF (Open Shortest Path First)
C_OSPF(I, j), The link L (i, j) is one fiber together with the other link.
Group assigned to the fiber when sharing
Using the identification information SRLG (i, j), Link cost C_OSPF(I, j) and the guru
Based on the loop identification information SRLG (i, j)
Independent routes that do not pass through the same links or nodes
When calculating According to the set value of α (0 ≦ α ≦ 1), the independent path
SRLG (Shared Risk L) in the path calculation when calculating
The weight considering ink group) is variably set, Number of independent routes required between source node s and destination node d
To D_comp(S, d), and the minimum value of α is α_minWhen
And the maximum value of α is α_maxAnd α as the initial value_min
= 0.0, α_max= 1.0 and determine the convergence of α
The value is ε, and the path between the source node s and the destination node d is required.
D is the number of required independent paths_req(S, d), α = α_min+ Α_max And the fourth step, According to the k-shortest path calculation algorithm
, The number of independent routes D_{nu m}The fifth step to find (s, d)
And D_num(S, d) <D_req(S, d) Then α_min= Α and α otherwise_max= And
The sixth step to do, α_max-Α_min> Ε Then, if it is unlikely to return to the fourth step, α = α
_max+ Α_minTo set the value of parameter α as
Execute the seven steps and to set the parameter α, D_num(S, d) -D_req(S, d) D among the set of independent paths that minimize_path(S,
d) the set of independent paths that minimizes the selected path
Perform the eighth step to The k-shortest path calculation algorithm
as, srlg (i, j, g) is a link L (i, j)
If it belongs to Pg, "1" otherwise "0"
G is a group of SRLG (Shared Risk Link Group)
And all independent paths between the source node s and the destination node d.
Sum of road costs D _path(S, d) is defined as [Equation 1]
When   C_comp(I, j) =   (1-α) C_OSPF(I, j) + α_max{SRLG (i, j), 1} [Equation 2] And the initial value is k = 1, Shortest path of k-th path between source node s and destination node d
Link cost C _compDerived from (i, j)
There is no route between node s and destination node d, or
If k is the number of required independent paths, the ninth step is completed.
And The via link L (i,
srlg for all groups g for j)
If (i, j, g) = 1, the link L (i, j) belongs
Use all links belonging to group g in path calculation
Delete it from the topology and delete its transit node.
The tenth step Set k = k + 1 and return to the ninth step. Eleventh step
There is no route between the source node s and the destination node d.
Until the required number of independent routes is satisfied.
A route selection method characterized by being executed by returning. 13. C _OSPF (i, j) and SRLG
The value of (i, j) is set to [Equation 3] and standardized by the maximum value for the link L (i, j).
2. The route selection method according to any one of 2 above. 14. _COSPF (i, j) and SRLG
13. The route selection method according to claim 10, wherein the value of (i, j) is set to [Equation 4] and standardized by the sum of the links L (i, j).