Communication system, route control device, and route control method

Abstract

This communication system, in which are formed a plurality of networks having an end-to-end detour, comprises: a plurality of section control units that perform path control for each of sections divided by the networks having the detours; and an integrated control unit that controls the plurality of section control units. The integrated control unit comprises an optimization unit that determines an optimal guaranteed delay time for each of the sections so as to satisfy an end-to-end guaranteed delay time provided by a service, and a reporting unit that reports, to the plurality of section control units, the optimal guaranteed delay time for each of the sections determined by the optimization unit. The plurality of section control units each comprise a switching-destination designation unit that designates a switching destination so as to switch to a path that satisfies the optimal guaranteed delay time reported by the integrated control unit.　

Description

[Technical Field]

[0001] The present invention relates to a communication system, a route control device, and a route control method. [Background technology]

[0002] In a typical communication network, when a packet reaches its destination, it is transferred via multiple communication devices that relay the packet. When packets are transferred via multiple communication devices, the delay until the packet reaches its destination increases. Therefore, a technique for guaranteeing end-to-end delay has been proposed (see, for example, Patent Document 1). Patent Document 1 proposes a technique for prioritizing reads within a specified route, and keeping the delay time below the end-to-end guaranteed delay time (SLA (Service Level Agreement) value) provided by the service. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-118072 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if delays increase due to congestion or other reasons in the communication devices through which packets pass, the guaranteed delay time may not be met by read priority alone, which can make it difficult to provide services that meet the guaranteed delay time.

[0005] In view of the above circumstances, the present invention aims to provide a technology that can provide a service that satisfies a guaranteed delay time even when delay increases in a communication device through which packets pass between end-to-end. [Means for solving the problem]

[0006] One aspect of the present invention is a communication system in which multiple networks with detour routes between end-to-end nodes are formed, the communication system including multiple section control units that perform route control for each section divided by the networks with detour routes, and an integrated control unit that controls the multiple section control units, the integrated control unit including an optimization unit that determines an optimal guaranteed delay time for each section so as to satisfy the end-to-end guaranteed delay time provided by the service, and a notification unit that notifies the multiple section control units of the optimal guaranteed delay time for each section determined by the optimization unit, and the multiple section control units including a switching destination instruction unit that instructs a switching destination to switch to a route that satisfies the optimal guaranteed delay time notified by the integrated control unit.

[0007] One aspect of the present invention is a route control device in a communication system in which multiple networks with detour routes are formed between end-to-end routes, wherein the communication system is divided into multiple sections by the networks with detour routes, and the route control device comprises: an optimization unit that determines an optimal guaranteed delay time for each section so as to satisfy the end-to-end guaranteed delay time provided by the service; and a switching destination instruction unit that instructs, for each section, a switching destination to switch to a route that satisfies the optimal guaranteed delay time determined by the optimization unit.

[0008] One aspect of the present invention is a route control method in a communication system in which multiple networks with detour routes are formed between end-to-end nodes, wherein the communication system is divided into multiple sections by the networks with detour routes, and the route control method determines an optimal guaranteed delay time for each section so as to satisfy the end-to-end guaranteed delay time provided by the service, and instructs the switching destination for each section to switch to a route that satisfies the determined optimal guaranteed delay time. [Effects of the Invention]

[0009] According to the present invention, even if delay increases in a communication device through which a packet passes between end-to-end, it is possible to provide a service that satisfies the guaranteed delay time. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of the configuration of a communication system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of a functional configuration of an integrated control unit according to the present embodiment. [Figure 3] 10 is a diagram for explaining a method for determining an optimal section SLA value performed by a section SLA optimization unit in this embodiment. FIG. [Figure 4] FIG. 2 is a diagram illustrating an example of the functional configuration of a section control unit according to the present embodiment. [Figure 5] FIG. 2 is a sequence diagram showing a processing flow of the communication system according to the present embodiment. [Figure 6] FIG. 2 is a sequence diagram showing a processing flow of the communication system according to the present embodiment. [Figure 7] FIG. 10 is a diagram illustrating an example of the configuration of a communication system according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of the configuration of a communication system 100 according to this embodiment. The communication system 100 includes a plurality of terminating devices 10-1 to 10-2, a plurality of communication devices 20-1 to 20-10, an integrated control unit 30, and a plurality of section control units 40-1 to 40-3. As shown in Fig. 1, in the communication system 100 of this embodiment, a plurality of networks having detour routes are formed between end-to-end. The networks having detour routes are, for example, mesh networks or ring networks.

[0012] 1 shows an example in which one ring network (hereinafter referred to as "first NW") is formed by communication devices 20-1 to 20-4, one ring network (hereinafter referred to as "second NW") is formed by communication devices 20-4 to 20-7, and one ring network (hereinafter referred to as "third NW") is formed by communication devices 20-7 to 20-10. That is, the communication system 100 shown in FIG. 1 shows an example in which the first NW is connected to termination device 10-1, the second NW is connected to the first NW, the third NW is connected to the second NW, and termination device 10-2 is connected to the third NW.

[0013] In the communication system 100 of this embodiment, the end-to-end path (between the terminal device 10-1 and the terminal device 10-2) is divided into multiple sections at any point, and route control is performed for each section, thereby providing a service that satisfies the guaranteed delay time. As a method of dividing the end-to-end path into multiple sections at any point, for example, it is possible to divide the end-to-end path into multiple sections at a hub location on the end-to-end path or at the boundary of a network. More specifically, it is possible to divide the end-to-end path into multiple sections at the junction of rings in the case of a ring-type network, or at the boundary of an AS (Autonomous System) in the case of a BGP (Border Gateway Protocol) network.

[0014] In this embodiment, the end-to-end path is divided into multiple sections at the junction between the first NW and the second NW (for example, the position of communication device 20-4) and the junction between the second NW and the third NW (for example, the position of communication device 20-7). In the following description, the first NW belongs to section 1, the second NW belongs to section 2, and the third NW belongs to section 3.

[0015] In the following description, termination devices 10-1 to 10-2 will be referred to as termination device 10 when no distinction is made, communication devices 20-1 to 20-10 will be referred to as communication device 20 when no distinction is made, and section control devices 40-1 to 40-3 will be referred to as section control device 40 when no distinction is made. The number of termination devices 10, communication devices 20, and section control devices 40 provided in communication system 100 may be plural and is not limited to the number shown in Fig. 1. For example, the number of section control devices 40 provided may be equal to the number of sections.

[0016] The terminating devices 10-1 and 10-2 are devices that perform end-to-end communication and are devices that are the source or destination of packets.

[0017] The communication device 20 forwards a packet transmitted from the termination device 10 to the destination termination device 10. When the communication device 20 receives a route switching instruction from the section control unit 40, it forwards the packet to the communication device 20 on the specified route. When the communication device 20 does not receive a route switching instruction from the section control unit 40, it forwards the packet to the communication device 20 on a predetermined route.

[0018] The central control unit 30 controls the section control units 40-1 to 40-3 so as to satisfy the end-to-end guaranteed delay time (SLA value) provided by the service. Specifically, the central control unit 30 divides the SLA value into minimum required section SLA values ​​(hereinafter referred to as "minimum section SLA values") for each section, and notifies the section control units 40-1 to 40-3 of the minimum section SLA values. Here, the minimum section SLA value is the delay time that is allowable in each section.

[0019] The section control units 40-1 to 40-3 are provided for each section and control the packet forwarding path to guarantee the minimum section SLA value assigned by the integrated control unit 30. In this embodiment, the section control unit 40-1 controls the packet forwarding path in section 1, the section control unit 40-2 controls the packet forwarding path in section 2, and the section control unit 40-3 controls the packet forwarding path in section 3.

[0020] Specifically, the section control unit 40 measures the delay time of packets in the section, and if the delay time exceeds the minimum section SLA value, controls the transfer route to detour. The section control unit 40 checks the congestion state or total low delay time of the detour destination and switches the route, and then confirms that the packet delay time is within the time indicated by the minimum section SLA value before switching. Note that if there are multiple detour routes, the section control unit 40 selects one of the routes that satisfies the minimum section SLA value and switches.

[0021] FIG. 2 is a diagram showing an example of the functional configuration of the integrated control unit 30 in this embodiment. The central control unit 30 has an SLA value storage unit 31, NW configuration collection units 32-1 to 32-N, section SLA calculation units 33-1 to 33-N, a section SLA optimization unit 34, and a section SLA notification unit 35. N is an integer equal to or greater than 2, and corresponds to the number of section control units 40 (in FIG. 1, the number of section control units is 3). In the following explanation, a case where N is 3 will be described as an example.

[0022] The SLA value storage unit 31 stores an SLA value, which is an end-to-end guaranteed delay time provided by a service. The SLA value storage unit 31 may acquire and store an SLA value from an external functional unit. In response to a request from the section SLA optimization unit 34, the SLA value storage unit 31 outputs the stored SLA value to the section SLA optimization unit 34.

[0023] The NW configuration collector 32-n (1≦n≦N) acquires configuration information (distance, number of devices, bandwidth, etc.) of the section managed by the section controller 40-n from the section controller 40-n. For example, the NW configuration collector 32-1 acquires configuration information of section 1 from the section controller 40-1 that manages section 1.

[0024] The section SLA calculation unit 33-n calculates the minimum section SLA value for the section based on the configuration information acquired by the NW configuration collection unit 32-n. For example, the section SLA calculation unit 33-1 acquires the configuration information for section 1 from the NW configuration collection unit 32-1, and calculates the minimum section SLA value for section 1 based on the acquired configuration information for section 1.

[0025] The section SLA optimization unit 34 determines an optimal section SLA value for each section based on the SLA value stored in the SLA value storage unit 31 and the minimum section SLA value for each section calculated by each of the section SLA calculation units 33-1 to 33-N. Specifically, the section SLA optimization unit 34 compares the sum of the minimum section SLA values ​​for each section with the SLA value, and determines an optimal section SLA value for each section based on the comparison result. The section SLA optimization unit 34 is one aspect of the optimization unit.

[0026] If the sum of the minimum section SLA values ​​of each section is the same as the SLA value, the section SLA optimization unit 34 determines the minimum section SLA value of each section as the optimum section SLA value of each section.

[0027] If the sum of the minimum section SLA values ​​for each section falls below the SLA value, the section SLA optimization unit 34 determines the optimal section SLA value for each section by adding a proportionally divided surplus to the minimum section SLA value for each section. The surplus here is the value obtained by subtracting the SLA value from the sum of the minimum section SLA values ​​for each section. The proportional division method can be an equal division method, a weighting method, or a method calculated from configuration information.

[0028] The equal allocation method allocates the surplus equally to each section. The weighted method allocates the surplus according to the ratio of the minimum section SLA value of each section. The calculation method based on configuration information allocates a larger surplus to sections estimated to have a high probability of network status fluctuations by referencing the configuration information than to sections estimated to have a low probability of network status fluctuations. Sections estimated to have a high probability of network status fluctuations are estimated based on conditions such as a greater number of devices than other sections, a longer section distance than other sections, or a narrower bandwidth than other sections.

[0029] If the sum of the minimum section SLA values ​​of the sections exceeds the SLA value, the section SLA optimization unit 34 determines that the situation is such that the service cannot be provided, and ends the process.

[0030] The section SLA notification unit 35 notifies each of the section control units 40-1 to 40-3 of the optimum section SLA value for each section determined by the section SLA optimization unit 34. The section SLA notification unit 35 is one aspect of a notification unit.

[0031] Next, a method for determining the optimal section SLA value performed by the section SLA optimization unit 34 will be described. Fig. 3 is a diagram for explaining a method for determining the optimal section SLA value performed by the section SLA optimization unit 34 in this embodiment. Note that if the sum of the minimum section SLA values ​​for each section is the same as the SLA value, the minimum section SLA value for each section will be determined as the optimal section SLA value for each section. Therefore, Fig. 3 describes a method for calculating the optimal section SLA value for each section when the sum of the minimum section SLA values ​​for each section is lower than the SLA value.

[0032] 3, an example will be described in which the SLA value held by the SLA value holding unit 31 is "180 ms," the minimum section SLA value of section 1 is "20 ms," the minimum section SLA value of section 2 is "30 ms," and the minimum section SLA value of section 3 is "40 ms." In this case, the sum of the minimum section SLA values ​​of each section is "20 ms" + "30 ms" + "40 ms" = "90 ms."

[0033] As described above, if the sum of the minimum section SLA values ​​for each section falls below the SLA value, the section SLA optimization unit 34 determines the optimal section SLA value for each section by adding a proportionally divided value of the surplus to the minimum section SLA value for each section. Fig. 3 shows the optimal section SLA values ​​for each section obtained using the equal allocation method, the weighting method, and the method determined from configuration information.

[0034] First, a method for determining the optimal section SLA value for each section using the equal allocation method will be described. First, the section SLA optimization unit 34 subtracts the sum of the minimum section SLA values ​​for each section, "90 ms," from the SLA value "180 ms." This calculates a surplus of "90 ms." Next, the section SLA optimization unit 34 apportions the surplus of "90 ms" proportionally so that it is allocated equally among the three sections. As a result, a value of "30 ms" is assigned to each of the three sections. Then, the section SLA optimization unit 34 determines the optimal section SLA value for each section by adding the value "30 ms" to the minimum section SLA value for each section.

[0035] For example, since the minimum section SLA value for section 1 is "20 ms," the section SLA optimization unit 34 determines "50 ms" ("20 ms" + "30 ms") as the optimal section SLA value for section 1. Similarly, since the minimum section SLA value for section 2 is "30 ms," the section SLA optimization unit 34 determines "60 ms" ("30 ms" + "30 ms") as the optimal section SLA value for section 2. Similarly, since the minimum section SLA value for section 3 is "40 ms," the section SLA optimization unit 34 determines "70 ms" ("40 ms" + "30 ms") as the optimal section SLA value for section 3.

[0036] Next, a method for determining the optimal section SLA value for each section using the weighting method will be described. First, the section SLA optimization unit 34 subtracts the sum of the minimum section SLA values ​​for each section, "90 ms," from the SLA value "180 ms." This calculates a surplus of "90 ms." Next, the section SLA optimization unit 34 apportions the surplus "90 ms" proportionally according to the ratio of the minimum section SLA values ​​for each section. Since the minimum section SLA value for section 1 is "20 ms," the minimum section SLA value for section 2 is "30 ms," and the minimum section SLA value for section 3 is "40 ms," a value of "20 ms" is assigned to section 1, a value of "30 ms" is assigned to section 2, and a value of "40 ms" is assigned to section 3. The section SLA optimization unit 34 then determines the optimal section SLA value for each section by adding the apportioned value to the minimum section SLA value for each section.

[0037] For example, since the minimum section SLA value for section 1 is "20 ms," the section SLA optimization unit 34 determines "40 ms" ("20 ms" + "20 ms") as the optimal section SLA value for section 1. Similarly, since the minimum section SLA value for section 2 is "30 ms," the section SLA optimization unit 34 determines "60 ms" ("30 ms" + "30 ms") as the optimal section SLA value for section 2. Similarly, since the minimum section SLA value for section 3 is "40 ms," the section SLA optimization unit 34 determines "80 ms" ("40 ms" + "40 ms") as the optimal section SLA value for section 3.

[0038] Next, a method for determining the optimal section SLA value for each section using a method for determining it from configuration information will be described. First, the section SLA optimization unit 34 subtracts the sum of the minimum section SLA values ​​for each section, "90 ms," from the SLA value "180 ms." This calculates a surplus of "90 ms." Next, the section SLA optimization unit 34 apportions the surplus of "90 ms" based on the configuration information for each section. Here, it is assumed that sections 1 and 3 are sections estimated to be prone to fluctuations in network conditions. In this case, the section SLA optimization unit 34 apportions the surplus of "90 ms" so that it allocates more to sections 1 and 3 than to section 2. For example, the section SLA optimization unit 34 apportions the surplus of "90 ms" so that it allocates "40 ms" to sections 1 and 3, respectively, and "10 ms" to section 2. Then, the section SLA optimization unit 34 determines the optimum section SLA value for each section by adding the proportionally divided value to the minimum section SLA value for each section.

[0039] For example, since the minimum section SLA value for section 1 is "20 ms," the section SLA optimization unit 34 determines "60 ms" ("20 ms" + "40 ms") as the optimal section SLA value for section 1. Similarly, since the minimum section SLA value for section 2 is "30 ms," the section SLA optimization unit 34 determines "40 ms" ("30 ms" + "10 ms") as the optimal section SLA value for section 2. Similarly, since the minimum section SLA value for section 3 is "40 ms," the section SLA optimization unit 34 determines "80 ms" ("40 ms" + "40 ms") as the optimal section SLA value for section 3.

[0040] 4 is a diagram showing an example of the functional configuration of the section control unit 40 in this embodiment. Note that each section control unit 40 has the same configuration. When describing the functional units of a certain section control unit 40, they are distinguished by adding a sub-number. For example, when describing the functional unit of section control unit 40-1, the sub-number "-1" is added after the number of the functional unit to distinguish it.

[0041] The section control unit 40 has a section SLA value acquisition unit 41, a configuration information acquisition unit 42, a delay information acquisition unit 43, a switching determination unit 44, a NW information acquisition unit 45, a switching destination selection unit 46, a switching destination determination unit 47, and a switching destination instruction unit 48.

[0042] The section SLA value acquisition unit 41 acquires the optimum section SLA value notified by the integrated control unit 30. The section SLA value acquisition unit 41 notifies the switching determination unit 44 and the switching destination determination unit 47 of the acquired optimum section SLA value.

[0043] The configuration information acquisition unit 42 holds configuration information of the sections managed by the section control unit 40. The configuration information acquisition unit 42 may also acquire and hold the section configuration information from an external functional unit. The configuration information acquisition unit 42 notifies the integrated control unit 30 of the section configuration information it holds.

[0044] The delay information acquisition unit 43 acquires information (hereinafter referred to as "delay information") relating to the delay time of a route through which a packet passes, among routes in a section managed by the section control unit 40. The delay information acquisition unit 43 may acquire the delay information by measuring the delay within the section of the route through which the packet passes, among routes in a section managed by the section control unit 40, or may acquire the delay information from an external function.

[0045] The switching determination unit 44 determines whether or not route switching is necessary based on the optimal section SLA value notified by the section SLA value acquisition unit 41 and the delay time indicated in the delay information output by the delay information acquisition unit 43. Specifically, the switching determination unit 44 determines that route switching is necessary when the delay time indicated in the delay information exceeds the optimal section SLA value. On the other hand, the switching determination unit 44 determines that route switching is unnecessary when the delay time indicated in the delay information is the same as or shorter than the optimal section SLA value. When the switching determination unit 44 determines that route switching is necessary, it outputs a notification to the switching destination determination unit 47 that route switching is necessary.

[0046] The NW information acquisition unit 45 acquires NW information of routes that packets are not currently passing through in the sections managed by the section control unit 40. The NW information is information that indicates the connection relationships and the like of the communication devices 20 on routes that packets are not currently passing through.

[0047] The switching destination selection unit 46 selects candidate routes (hereinafter referred to as "candidate routes") that can be switched to, based on the NW information notified from the NW information acquisition unit 45. Furthermore, the switching destination selection unit 46 estimates the delay on each selected candidate route. The switching destination selection unit 46 may estimate the delay on the candidate route by measuring the delay time by transmitting and receiving a control frame on the candidate route and calculating the delay time before and after switching. Hereinafter, the delay estimated by the switching destination selection unit 46 is referred to as the estimated delay time.

[0048] The switching destination determination unit 47 determines a route to be used as a switching destination when notified by the switching determination unit 44 that switching is necessary. Specifically, the switching destination determination unit 47 determines, as a switching destination route, a candidate route, among the candidate routes notified by the switching destination selection unit 46, whose estimated delay time is less than the section SLA value notified by the section SLA value acquisition unit 41. Note that, when there are multiple candidate routes whose estimated delay time is less than the section SLA value notified by the section SLA value acquisition unit 41, the switching destination determination unit 47 determines, as a switching destination route, the candidate route with the smallest estimated delay time.

[0049] The switching destination instruction unit 48 generates a switching instruction including information about the switching destination route notified by the switching destination determination unit 47. The switching destination instruction unit 48 transmits the generated switching instruction to the communication devices 20 in the section managed by the section control unit 40. In this way, the switching destination instruction unit 48 switches the communication NW by instructing the communication devices 20 to switch the packet forwarding route to the switching destination route notified by the switching destination determination unit 47.

[0050] 5 and 6 are sequence diagrams showing the flow of processing in the communication system 100 in this embodiment. The configuration information acquisition unit 42-1 of the section control unit 40-1 notifies the integrated control unit 30 of the configuration information of section 1 (step S101). The delay information acquisition unit 43-1 of the section control unit 40-1 periodically acquires delay information of the route through which the packet is routed among the routes in section 1 (step S102). Every time the delay information acquisition unit 43-1 acquires delay information, it outputs the acquired delay information to the switching determination unit 44-1.

[0051] The NW information acquisition unit 45-1 of the section control unit 40-1 periodically acquires NW information of routes in section 1 that packets are not currently passing through (step S103). Every time the NW information acquisition unit 45-1 acquires NW information, it outputs the acquired NW information to the switching destination selection unit 46-1. The switching destination selection unit 46-1 selects a switching destination route every time it acquires NW information from the NW information acquisition unit 45-1.

[0052] Similarly, the configuration information acquisition unit 42-2 of the section control unit 40-2 notifies the integrated control unit 30 of the configuration information of section 2 (step S104). The delay information acquisition unit 43-2 of the section control unit 40-2 periodically acquires delay information of the route through which the packet is routed among the routes in section 2 (step S105). Every time the delay information acquisition unit 43-2 acquires delay information, it outputs the acquired delay information to the switching determination unit 44-2.

[0053] The NW information acquisition unit 45-2 of the section control unit 40-2 periodically acquires NW information of routes in section 2 that packets are not currently passing through (step S106). Every time the NW information acquisition unit 45-2 acquires NW information, it outputs the acquired NW information to the switching destination selection unit 46-2. Every time the switching destination selection unit 46-2 acquires NW information from the NW information acquisition unit 45-2, it selects a switching destination route.

[0054] Similarly, the configuration information acquisition unit 42-3 of the section control unit 40-3 notifies the integrated control unit 30 of the configuration information of section 3 (step S107). The delay information acquisition unit 43-3 of the section control unit 40-3 periodically acquires delay information of the route through which the packet is routed among the routes in section 3 (step S108). Every time the delay information acquisition unit 43-3 acquires delay information, it outputs the acquired delay information to the switching determination unit 44-3.

[0055] The NW information acquisition unit 45-3 of the section control unit 40-3 periodically acquires NW information of a route in section 3 that is not currently being taken by packets (step S109). Every time the NW information acquisition unit 45-3 acquires NW information, it outputs the acquired NW information to the switching destination selection unit 46-3. The switching destination selection unit 46-3 selects a switching destination route every time it acquires NW information from the NW information acquisition unit 45-3.

[0056] The NW configuration collectors 32-1 to 32-3 of the integrated control unit 30 acquire the configuration information of each section transmitted from each section control unit 40-1 to 40-3 (step S110). For example, the NW configuration collector 32-n acquires the configuration information of section n transmitted from the section control unit 40-n. The NW configuration collector 32-n outputs the acquired configuration information of section n to the section SLA calculation unit 33-n. The section SLA calculation unit 33-n calculates the minimum section SLA value of section n based on the configuration information output from the NW configuration collector 32-n (step S111). The section SLA calculation unit 33-n outputs the calculated minimum section SLA value of section n to the section SLA optimization unit 34.

[0057] The section SLA optimization unit 34 determines an optimal section SLA value for each section based on the minimum section SLA value for section n output from each section SLA calculation unit 33-n and the SLA value held by the SLA value holding unit 31 (step S112). Specifically, if the sum of the minimum section SLA values ​​for each section is the same as the SLA value held by the SLA value holding unit 31, the section SLA optimization unit 34 determines the minimum section SLA value for each section as the optimal section SLA value for each section. On the other hand, if the sum of the minimum section SLA values ​​for each section is lower than the SLA value, the section SLA optimization unit 34 determines the optimal section SLA value for each section by adding a value obtained by proportionally dividing the surplus to the minimum section SLA value for each section. The section SLA optimization unit 34 outputs information on the optimal section SLA value for each section to the section SLA notification unit 35.

[0058] The section SLA notification unit 35 notifies the section control units 40-1 to 40-3 of information on the optimal section SLA value for each section output from the section SLA optimization unit 34. The section SLA notification unit 35 notifies the section control unit 40-1 of information on the optimal section SLA value for section 1 output from the section SLA optimization unit 34 (step S113). Similarly, the section SLA notification unit 35 notifies the section control unit 40-2 of information on the optimal section SLA value for section 2 output from the section SLA optimization unit 34 (step S114). Similarly, the section SLA notification unit 35 notifies the section control unit 40-3 of information on the optimal section SLA value for section 3 output from the section SLA optimization unit 34 (step S115).

[0059] The section SLA value acquisition unit 41-1 of the section control unit 40-1 acquires the optimal section SLA value for section 1 notified by the integrated control unit 30 (step S116). The section SLA value acquisition unit 41-1 notifies the switching determination unit 44-1 and the switching destination determination unit 47-1 of the acquired optimal section SLA value for section 1. The switching determination unit 44-1 determines whether or not route switching is necessary based on the optimal section SLA value for section 1 notified by the section SLA value acquisition unit 41-1 and the delay value indicated by the latest delay information obtained from the delay information acquisition unit 43-1 (step S117). Here, it is assumed that it is determined that route switching for section 1 is necessary. The switching determination unit 44-1 outputs a notification that route switching is necessary to the switching destination determination unit 47-1.

[0060] In response to the notification output from the switching determination unit 44-1, the switching destination determination unit 47-1 determines one candidate route from the latest candidate routes notified by the switching destination selection unit 46-1 as the switching destination route (step S118). The switching destination determination unit 47-1 notifies the switching destination instruction unit 48-1 of information on the determined switching destination route. The switching destination instruction unit 48-1 generates a switching instruction including the information on the switching destination route notified by the switching destination determination unit 47-1. The switching destination instruction unit 48-1 transmits the generated switching instruction to the communication devices 20 in the sections managed by the section control unit 40, thereby instructing them to switch the packet forwarding route in section 1 (step S119).

[0061] The switching instruction sent from the switching destination instruction unit 48-1 is received by the communication devices 20-1 and 20-4 belonging to section 1. The communication devices 20-1 and 20-4 transfer the packet via the route included in the switching instruction.

[0062] Similarly, the section SLA value acquisition unit 41-2 of the section control unit 40-2 acquires the optimal section SLA value for section 2 notified by the integrated control unit 30 (step S120). The section SLA value acquisition unit 41-2 notifies the switching determination unit 44-2 and the switching destination determination unit 47-2 of the acquired optimal section SLA value for section 2. The switching determination unit 44-2 determines whether or not route switching is necessary based on the optimal section SLA value for section 2 notified by the section SLA value acquisition unit 41-2 and the delay value indicated by the latest delay information obtained from the delay information acquisition unit 43-2 (step S121). Here, it is assumed that it is determined that route switching for section 2 is necessary. The switching determination unit 44-2 outputs a notification that route switching is necessary to the switching destination determination unit 47-2.

[0063] In response to the notification output from the switching determination unit 44-2, the switching destination determination unit 47-2 determines one candidate route from the latest candidate routes notified by the switching destination selection unit 46-2 as the switching destination route (step S122). The switching destination determination unit 47-2 notifies the switching destination instruction unit 48-2 of information on the determined switching destination route. The switching destination instruction unit 48-2 generates a switching instruction including the information on the switching destination route notified by the switching destination determination unit 47-2. The switching destination instruction unit 48-2 transmits the generated switching instruction to the communication device 20 in the section managed by the section control unit 40, thereby instructing the switching of the packet forwarding route in section 2 (step S123).

[0064] The switching instruction sent from the switching destination instruction unit 48-2 is received by the communication devices 20-4 and 20-7 that belong to section 2. The communication devices 20-4 and 20-7 transfer the packet via the route included in the switching instruction.

[0065] Similarly, the section SLA value acquisition unit 41-3 of the section control unit 40-3 acquires the optimal section SLA value for section 3 notified by the integrated control unit 30 (step S124). The section SLA value acquisition unit 41-3 notifies the switching determination unit 44-3 and the switching destination determination unit 47-3 of the acquired optimal section SLA value for section 3. The switching determination unit 44-3 determines whether or not route switching is necessary based on the optimal section SLA value for section 3 notified by the section SLA value acquisition unit 41-3 and the delay value indicated by the latest delay information obtained from the delay information acquisition unit 43-3 (step S125). Here, it is assumed that it is determined that route switching for section 3 is unnecessary. In this case, the section control unit 40-3 does not control route switching for section 3.

[0066] 5 and 6, the section control units 40-1 to 40-3 acquire delay information and network information, and then the integrated control unit 30 determines an optimal section SLA value for each section. The section control units 40-1 to 40-3 acquire the optimal section SLA value for each section, determine whether route switching is necessary, and switch the route if route switching is necessary. The processing flow shown in FIGS. 5 and 6 is an example, and the processing does not necessarily have to be performed in the order shown in FIGS. 5 and 6. For example, in the section control units 40-1 to 40-3, the cycle for acquiring the optimal section SLA value and the cycle for switching in response to acquisition of delay information do not necessarily have to be synchronized. The section control units 40-1 to 40-3 acquire delay information and network information at regular intervals, and acquire information on the optimal section SLA value by transmission from the integrated control unit 30. In this way, the cycle for acquiring the optimal section SLA value and the cycle for acquiring the delay information and network information are independent of each other in the section control units 40-1 to 40-3, and therefore do not necessarily have to be synchronized. The section control units 40-1 to 40-3 may determine whether or not route switching is necessary based on the latest optimum section SLA value and the latest delay time that they hold. Note that the section control units 40-1 to 40-3 do not need to acquire delay information and NW information at the same intervals.

[0067] The communication system 100 configured as described above enables provision of services that satisfy guaranteed delay times even when delays increase in communication devices through which packets pass. Specifically, the communication system 100 includes multiple section control units 40 that perform route control for each section divided by a network having detours, and an integrated control unit 30 that controls the multiple section control units 40. The integrated control unit 30 includes a section SLA optimization unit 34 that determines an optimal guaranteed delay time for each section so as to satisfy the end-to-end guaranteed delay time provided by the service, and a section SLA notification unit 35 that notifies the multiple section control units of the determined optimal guaranteed delay time for each section. The multiple section control units 40 also include a switching destination instruction unit 48 that instructs a switching destination to switch to a route that satisfies the optimal guaranteed delay time notified by the integrated control unit 30. This enables route control for each section, allowing for more immediate switching to a route with a shorter delay time. Therefore, it becomes possible to provide services that satisfy guaranteed delay times even when delays increase in communication devices through which packets pass.

[0068] A modification of the communication system 100 will now be described. (Variation 1) In the above-described embodiment, the central control unit 30 is configured to calculate an optimal section SLA value for each section by using the results of calculation of the minimum section SLA value for each section by the section SLA calculation units 33-1 to 33-N. The central control unit 30 may be configured to calculate an optimal section SLA value for each section without calculating the minimum section SLA value for each section. In such a configuration, the central control unit 30 does not need to include the section SLA calculation units 33-1 to 33-N or the NW configuration collection units 32-1 to 32-N and the section SLA calculation units 33-1 to 33-N. When the central control unit 30 does not include the section SLA calculation units 33-1 to 33-N, the section SLA optimization unit 34 of the central control unit 30 determines an optimal section SLA value for each section based on the configuration information for each section obtained from the NW configuration collection units 32-1 to 32-N and the SLA value stored in the SLA value storage unit 31. For example, the section SLA optimization unit 34 determines the optimal section SLA value for each section by referring to the configuration information and allocating more SLA values ​​held by the SLA value holding unit 31 to sections where it is estimated that the network situation is more likely to fluctuate than to sections where the network situation is less likely to fluctuate.

[0069] If the integrated control unit 30 does not include the network configuration collection units 32-1 to 32-N and the section SLA calculation units 33-1 to 33-N, the section SLA optimization unit 34 of the integrated control unit 30 determines the optimum section SLA value for each section by equally allocating to each section the SLA values ​​held by the SLA value holding unit 31. For example, if the sections are divided into three with an SLA value of "180 ms," the section SLA optimization unit 34 determines "60 ms" as the optimum section SLA value for each section.

[0070] (Variation 2) Each section control unit 40 may be included in the configuration of the integrated control unit 30 and configured as a route control device.

[0071] (Variation 3) When there are multiple section control units 40, a hierarchical configuration may be adopted by providing an area control unit 50 between the central control unit 30 and the multiple section control units 40, as shown in FIG. 7. FIG. 7 is a diagram showing an example of the configuration of a communication system 100a according to a modified example. The communication system 100a includes multiple termination devices 10-1 to 10-2, multiple communication devices 20-1 to 20-10, a central control unit 30a, multiple section control units 40-1 to 40-3, and an area control unit 50. The area control unit 50 collects information from the multiple section control units 40 (section control units 40-1 and 40-2 in FIG. 7) and transmits the collected information to the central control unit 30a. The operation of the central control unit 30a is basically the same as that of the central control unit 30. The operation of the central control unit 30a differs from that of the central control unit 30 in that the central control unit 30a controls the section control units 40 via the area control unit 50. The configuration is otherwise the same as that of the communication system 100.

[0072] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention. [Industrial Applicability]

[0073] The present invention can be applied to a communication system that transfers packets end-to-end. [Explanation of symbols]

[0074] 10, 10-1 to 10-2... Termination devices, 20, 20-1 to 20-10... Communication devices, 30... Integrated control unit, 40, 40-1 to 40-3... Section control unit, 31... SLA value storage unit, 32, 32-1 to 32-N... Network configuration collection unit, 33, 33-1 to 33-N... Section SLA calculation unit, 34... Section SLA optimization unit, 35... Section SLA notification unit, 41... Section SLA value acquisition unit, 42... Configuration information acquisition unit, 43... Delay information acquisition unit, 44... Switching determination unit, 45... Network information acquisition unit, 46... Switching destination selection unit, 47... Switching destination determination unit, 48... Switching destination instruction unit

Claims

1. A communication system in which a plurality of networks having detour routes between end-to-end nodes are formed, the communication system includes a plurality of section control units that perform route control for each section divided by a network having a detour route, and an integrated control unit that controls the plurality of section control units; The integrated control unit an optimization unit that determines an optimal guaranteed delay time for each section so as to satisfy the end-to-end guaranteed delay time provided by the service; a notification unit that notifies the plurality of section control units of the optimal guaranteed delay time for each section determined by the optimization unit; Equipped with The plurality of section control units include: a switching destination instruction unit that instructs a switching destination to switch to a route that satisfies the optimal guaranteed delay time notified by the integrated control unit; Equipped with The plurality of section control units include: a delay information acquisition unit that acquires information about delay times of routes through which packets pass among routes in a section that the unit manages; a switching determination unit that determines whether or not a route switching is necessary based on the optimal guaranteed delay time notified from the integrated control unit and the delay time, the switching destination instruction unit instructs the switching destination to switch to a route that satisfies the optimal guaranteed delay time when the switching determination unit determines that route switching is necessary. Communication system.

2. The integrated control unit a collection unit that collects configuration information relating to the configuration of each section from each of the plurality of section control units; a calculation unit that calculates a minimum required guaranteed delay time for each section based on the collected configuration information; Furthermore, The optimization unit determines the optimal guaranteed delay time for each section using the guaranteed delay time and the minimum required guaranteed delay time for each section. The communication system of claim 1 .

3. When the sum of the minimum required guaranteed delay times for each section is the same as the guaranteed delay time, the optimization unit determines the minimum required guaranteed delay time for each section as the optimal guaranteed delay time for each section. The communication system according to claim 2 .

4. When the sum of the minimum required guaranteed delay times for each section is less than the guaranteed delay time, the optimization unit determines the optimal guaranteed delay time for each section by adding a value obtained by proportionally dividing the surplus to the minimum required guaranteed delay time for each section. The communication system according to claim 2 .

5. The optimization unit determines the optimal guaranteed delay time for each section by adding one of the following to the minimum required guaranteed delay time for each section: a value in which the surplus is allocated equally to each section; a value in which the surplus is allocated in accordance with the ratio of the minimum required guaranteed delay time for each section; and a value in which the surplus is allocated in accordance with the degree of possibility that the network status of each section will fluctuate. The communication system according to claim 4.

6. A route control device in a communication system in which a plurality of networks having detour routes between end-to-end nodes are formed, the communication system is divided into a plurality of sections by a network having a detour route; an optimization unit that determines an optimal guaranteed delay time for each section so as to satisfy the end-to-end guaranteed delay time provided by the service; a switching destination instruction unit that instructs a switching destination for each section so as to switch to a route that satisfies the optimal guaranteed delay time determined by the optimization unit; a plurality of section control units that perform route control for each section divided by a network having a detour route; Equipped with The plurality of section control units include: a delay information acquisition unit that acquires information about delay times of routes through which packets pass among routes in a section that the unit manages; a switching determination unit that determines whether or not a route switching is necessary based on the determined optimal guaranteed delay time and the delay time, The switching destination instruction unit instructs the switching destination to switch to a route that satisfies the optimal guaranteed delay time when the switching determination unit determines that route switching is necessary.

7. A route control method in a communication system in which a plurality of networks having detour routes between end-to-end nodes are formed, comprising: the communication system is divided into a plurality of sections by a network having a detour route; Determine the optimal guaranteed delay time for each section so as to satisfy the end-to-end guaranteed delay time provided by the service, Instructing a switching destination for each section so as to switch to a route that satisfies the determined optimal guaranteed delay time; Acquire information about delay times of routes through which packets pass among routes in sections managed by each of a plurality of section control units that perform route control for each section divided by a network having a detour route; determining whether or not a route change is necessary based on the determined optimum guaranteed delay time and the delay time; When it is determined that a route switching is necessary, instruct a route destination to switch to a route that satisfies the optimal guaranteed delay time. Routing methods.

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