Delay time measurement device, delay time measurement method, and delay time measurement program

Abstract

This delay time measurement device comprises: a first delay time measurement unit (11) that measures a round-trip delay time occurring between the device and a start node; a second delay time measurement unit (12) that measures a round-trip delay time occurring between the device and a destination node; a third delay time measurement unit that measures a forward delay time of a loop from the device through a measurement section back to the device; a one-way average delay time calculation unit (14) that calculates a one-way average delay time on the basis of the round-trip delay times measured by the first delay time measurement unit (11) and the second delay time measurement unit; and a delay time calculation unit (15) that subtracts the one-way average delay time from the forward delay time to calculate a forward delay time of the measurement section.

Description

[Technical Field]

[0001] The present invention relates to a delay time measuring device, a delay time measuring method, and a delay time measuring program that record the time when maintenance work is performed. [Background technology]

[0002] With the spread of services requiring real-time performance, such as 5G and e-sports, not only bandwidth but also low latency is becoming a requirement for networks. Therefore, there is a need for a method to acquire latency in a shorter time and with higher accuracy to confirm service quality.

[0003] Non-Patent Document 1 discloses a delay measurement system consisting of a hardware processing unit that stamps timestamps when probe packets are sent and received, and a software processing unit that collects network information, calculates delay measurement routes, generates probe packets, and calculates delay times. This delay measurement system uses a technology (delay measurement route control method) that measures delay times for each link by using packets (SRT packets) that travel up and down the same route to a certain device. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Hiroki Mori and four others, "Proposal of a Delay Measurement System for Highly Accurate Measurement of Network Delay," IEICE Technical Report, vol. 119, no. 460, NS2019-231, pp. 301-306, March 2020. Summary of the Invention [Problem to be solved by the invention]

[0005] The packets used in Non-Patent Document 1 specify labels for passing through arbitrary routes using a traffic engineering mechanism, so the amount of label information specified increases according to the number of forwarding nodes that are passed through. In the technology of Non-Patent Document 1, a route is specified so that measurement packets travel back and forth along the same route to measure round trip time (RTT). Therefore, if one relay point is added to the measurement section, the measurement route increases by two, one for the outbound route and one for the inbound route.

[0006] In addition, routers that relay packets generally have an upper limit on the number of relay points that can be specified in SR (Segment Routing). With the technology in Non-Patent Document 1, when the measurement section becomes long in a large-scale network, there is a high possibility that the specifications of the router will be exceeded. In particular, if the number of labels specifying the route exceeds the router's limit, it may have a negative effect on the router, inducing breakdowns or malfunctions, making it impossible to introduce the system.

[0007] The present invention has been made to solve such problems, and aims to provide a delay time measurement device, a delay time measurement method, and a delay time measurement program that can measure forward delay time or backward delay time without the packet traveling back and forth through the measurement section. [Means for solving the problem]

[0008] The present invention is a delay time measurement device for measuring packet delay time occurring in a measurement section between a start node and an end node, comprising: a first delay time measurement unit for measuring a round-trip delay time occurring between the device itself and the start node without passing through the measurement section; a second delay time measurement unit for measuring a round-trip delay time occurring between the device itself and the end node without passing through the measurement section; a third delay time measurement unit for measuring either a forward delay time of a loop returning from the device itself via the measurement section to the device itself or a backward delay time until returning in the reverse direction through the loop; and the first delay time measurement unit. a one-way average delay time calculation unit that calculates a one-way average delay time occurring in a section that passes through the device between the start node and the end node, based on a first round-trip delay time measured by the third delay time measurement unit and a second round-trip delay time measured by the second delay time measurement unit; and a delay time calculation unit that, when the third delay time measurement unit measures the forward delay time, subtracts the one-way average delay time from the forward delay time to calculate a forward delay time of the measurement section, and, when the third delay time measurement unit measures the backward delay time, subtracts the one-way average delay time from the backward delay time to calculate a backward delay time of the measurement section. a label embedding unit that embeds multiple labels into a packet, omitting the labels of nodes that make the shortest path unique; The present invention is characterized by having the following. [Effects of the Invention]

[0009] According to the present invention, it is possible to measure the forward delay time or the backward delay time without the packet traveling back and forth through the measurement section. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a configuration diagram of a delay time measuring device according to a first embodiment of the present invention. [Figure 2] 1 is a flowchart (1) executed by the control unit of the delay time measuring device. [Figure 3] 10 is a flowchart (2) executed by the control unit of the delay time measuring device. [Figure 4] This is a conceptual diagram (1) for understanding network topology. [Figure 5]10 is a flowchart (3) executed by the control unit of the delay time measuring device. [Figure 6] This is a conceptual diagram (2) for understanding network topology. [Figure 7] FIG. 1 illustrates a return measurement path to a start node and an end node. [Figure 8] FIG. 1 illustrates a loop measurement path passing through a start node and an end node. [Figure 9] FIG. 10 is a conceptual diagram illustrating a case where the number of labels embedded in a measurement packet is reduced. [Figure 10] FIG. 10 is a diagram showing a label embedded in a measurement packet. [Figure 11] FIG. 10 is a conceptual diagram illustrating the process of deleting labels on a route when the label upper limit is exceeded. [Figure 12] FIG. 10 is a conceptual diagram illustrating how to measure the delay time of a return measurement path. [Figure 13] FIG. 1 is a conceptual diagram illustrating how to measure the delay time of a loop measurement path. [Figure 14] FIG. 10 is a conceptual diagram showing a case where packet loss occurs in a measurement section. [Figure 15] FIG. 10 is a conceptual diagram illustrating a case where packet loss occurs on a measurement path other than the measurement section. [Figure 16] FIG. 10 is a diagram showing an example of a measurement route when the second embodiment of the present invention is applied to a large-scale network. [Figure 17] FIG. 10 is a diagram showing a label embedded in a measurement packet. [Figure 18] FIG. 10 is a diagram illustrating an example of a measurement path when the comparative example is applied to a large-scale network. [Figure 19] FIG. 10 is a diagram showing a label embedded in a measurement packet in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings. Note that each drawing is merely a schematic illustration to allow a sufficient understanding of the present invention. In addition, in each drawing, common or similar components are given the same reference numerals, and redundant explanations thereof will be omitted.

[0012] (First embodiment) FIG. 1 is a diagram showing the configuration of a delay time measuring device according to a first embodiment of the present invention. The measurement device 100 is a delay time measurement device that sends a measurement packet to a network NW, measures the delay time until the sent measurement packet returns, and calculates the delay time in the measurement section from the start router (start node) to the end router (end node). The measurement device 100 is configured with the following hardware resources: a control unit 10, a communication unit 30, a clock 40, a memory unit 50, and an operation / display unit 60. The communication unit 30 is an interface that communicates packets via multiple routers (routers A to F (Figure 4)) installed in the network NW. The clock 40 measures the reference time for the timestamp to be added to the measurement packet. The memory unit 50 is configured with a non-volatile memory unit such as a ROM (Read On Memory) or HDD (Hard Disk Drive) and a volatile memory unit such as a RAM (Random Access Memory). The operation / display unit 60 is a touch-panel light-emitting diode (LED) display.

[0013] The control unit 10 is a CPU (central processing unit) that executes a delay time measurement program stored in the storage unit 50 to realize the functions of a first delay time measurement unit 11, a second delay time measurement unit 12, a third delay time measurement unit 13, a one-way average delay time calculation unit 14, a delay time calculation unit 15, a packet loss determination unit 16, a measurement path derivation unit 20, and a display control unit 25. The display control unit 25 controls the operation display unit 60.

[0014] The first delay time measurement unit 11 measures the round-trip delay time that occurs between the device itself and a start node without passing through the measurement section from the start node to the end node. The second delay time measurement unit 12 measures the round-trip delay time that occurs between the device itself and an end node without passing through the measurement section from the start node to the end node. The third delay time measurement unit 13 includes a forward delay time measurement unit 13a and a backward delay time measurement unit 13b. The forward delay time measurement unit 13a measures the forward delay time of a looped path (section measurement path) that returns from the device itself via the measurement section. The backward delay time measurement unit 13b measures the backward delay time until returning in the reverse direction along the looped path (section measurement path).

[0015] The one-way average delay time calculation unit 14 includes a first calculation unit 14a and a second calculation unit 14b, and executes either one of them. The first calculation unit 14a calculates the one-way average delay time by adding together the one-way average delay time obtained by dividing the round-trip delay time measured by the first delay time measurement unit 11 by 2 and the one-way average delay time obtained by dividing the round-trip delay time measured by the second delay time measurement unit 12 by 2. The second calculation unit 14b adds together the round-trip delay time measured by the first delay time measurement unit 11 and the round-trip delay time measured by the second delay time measurement unit 12 and divides the summed round-trip delay time by 2 to calculate the one-way average delay time.

[0016] When the third delay time measurement unit 13 (forward delay time measurement unit 13a) measures a forward delay time, the delay time calculation unit 15 subtracts the one-way average delay time from the forward delay time to calculate the forward delay time of the measurement section. Also, when the third delay time measurement unit 13 (backward delay time measurement unit 13b) measures a backward delay time, the delay time calculation unit 15 subtracts the one-way average delay time from the backward delay time to calculate the backward delay time of the measurement section.

[0017] When measuring the round trip delay time by the first delay time measurement unit 11 or the second delay time measurement unit 12, or the forward delay time or backward delay time by the third delay time measurement unit 13, the packet loss determination unit 16 determines that a packet loss has occurred if the measurement packet does not return.

[0018] The measurement path derivation unit 20 derives a measurement path before sending a measurement packet and embeds a label indicating the measurement path in the measurement packet. The measurement path derivation unit 20 includes an information collection unit 21, a topology understanding unit 22, a path derivation unit 23, and a label embedding unit 24.

[0019] The information collection unit 21 collects information about routers (nodes) present in the network. The topology understanding unit 22 understands the configuration (topology) in which routers to be measured in the network are connected. At this time, the information collection unit 21 records information about adjacent routers and link costs (IGP costs). The route derivation unit 23 derives a communication route based on the link costs. The communication route may be, for example, the shortest route from the device itself to the start router (start node), the shortest route from the device itself to the end router (end router), or a looped route connecting the two shortest routes and the measurement section. The label embedding unit 24 embeds a label indicating the route derived by the route derivation unit 23 into the measurement packet.

[0020] (Operation of the measuring device 100) The operation of the measurement path derivation unit 20 will be described below with reference to the flowcharts of FIGS. 2 is a flowchart for explaining the operation of the information collecting unit 21. This flow (SP10) is started at the same time as power is turned on, and is configured to repeat predetermined processing at regular time intervals (SP11 to SP14). The information collection unit 21 collects network information from the routers to be measured (routers A to F (FIG. 4)) and the control device (not shown) (SP12). After SP12, the information collection unit 21 determines whether there is a difference from the previous acquisition (SP13). If there is no difference from the previous acquisition ("No" in S13), the process returns to SP11 via SP14 and the processes of SP12 and SP13 are repeated. On the other hand, if there is a difference from the previous acquisition ("Yes" in S13), the information collection unit 21 causes the topology understanding unit 22 to perform the topology understanding process (SP20). Note that when the power is turned on, there is no previously acquired information, so the determination in S13 is "Yes."

[0021] FIG. 3 is a flowchart for explaining the operation of the topology grasping unit 22. As shown in FIG. This flow (SP20) is started when SP13 (Figure 2) determines that there is a difference from the previous acquisition ("Yes" in SP13), and is configured to be repeated for the number of routers included in the collected information (SP21 to SP24). The topology grasping unit 22 records information about each router in the storage unit 50 (FIG. 1) (SP22). After SP22, the topology grasping unit 22 records information about adjacent routers and link costs (IGP (Interior Gateway Protocol) costs) (SP23). After processing SP23, the topology grasping unit 22 returns the processing to SP21 via SP24, and repeats the processing of SP22 and SP23 for the number of routers.

[0022] FIG. 4 is a conceptual diagram for understanding the network topology. The delay time measurement system S1 is, for example, a system in which multiple (six) routers (routers A to F) are connected to the measurement device 100. Only router B is connected to router B. Routers A, C, and E are connected to router B. Here, the route between router B and router A is route BA, the route between router B and router C is route BC, and the route between router B and router E is route BE. Router F is connected to router A, and router D is connected to router C. Here, the route between router A and router F is route AF, and the route between router C and router D is route CD. Routers F and D are connected to router E. Here, the route between router D and router E is route DE, and the route between router E and router F is route EF. The measurement section in which the delay time of the measurement packet is measured has router D as the start node and router F as the end node. In other words, the measurement section is the section that combines routes DE and EF. Moreover, the nodes from the start node to the end node (routers D, E, and F) are called measurement endpoints.

[0023] The link cost (IGP cost) of a route is defined as {100Mbps / link bandwidth (bps)}; for example, if the bandwidth is 100Mbps, the link cost = 1. In Figure 4, the link costs (IGP costs) of all routes BA, BC, CD, BE, AF, DE, and EF are set to "1." It is assumed that the link cost between the measuring device 100 and router B is extremely small.

[0024] FIG. 5 is a flowchart executed by the control unit of the delay time measuring device. This flow is started independently of Figures 2 and 3 before the measurement packet is released to the network NW (Figure 1), and is configured to repeat the specified processing for the number of measurement endpoints between SP31 and SP40 (SP31 to SP40). After SP31, the route derivation unit 23 (FIG. 1) derives routes between the measurement endpoints (SP32). That is, the route derivation unit 23 derives routes DE and EF between the measurement endpoints (router D, router E, router F). After SP32, the route derivation unit 23 derives a route from the measurement device 100 to the measurement start point (router D) (SP33).

[0025] FIG. 6 is a conceptual diagram for understanding the network topology. The topology grasping unit 22 changes the link costs of the measurement sections, routes DE and EF, from "1" to an extremely large value (for example, 100), and derives the route with the smallest link cost from the measurement device 100 to the measurement start point (router D). As a result, the route derivation unit 23 derives the route (route BC + route CD) without selecting (route BE + route DE). 5, after SP33, the route derivation unit 23 derives a route from the measurement device 100 to the measurement end point (router F) (SP34). That is, the route derivation unit 23 derives a route of (route BA+route AF).

[0026] After SP34, the route derivation unit 23 derives the pre-section turn-back measurement route and the section measurement route based on the results of SP32 to SP34 (SP35). The shortest route to the measurement start point is (route BC + route CD) derived in SP33, and the shortest route to the measurement end point is (route BA + route AF) derived in SP34. Therefore, the route derivation unit 23 derives the round-trip route of (route BC + route CD) (solid line α in FIG. 7) and the round-trip route of (route BA + route AF) (dashed line β in FIG. 7) as the pre-section turn-back measurement route. Note that the pre-section turn-back measurement route is both the shortest round-trip route to the measurement start point and the shortest round-trip route to the measurement end point, and does not include the route between the measurement end points (SP32).

[0027] The section measurement route is a combination of the pre-section turn-back measurement route and the measurement section. That is, the section measurement route is a looped route that combines route BC, route CD, route DE, route EF, route AF, and route BA. The dashed-dotted line δ in Figure 8 represents the forward section measurement route, and the dashed-two-dotted line γ represents the reverse section measurement route.

[0028] The label embedding unit 24 (Fig. 1) embeds labels that identify the measurement route into the measurement packet. For example, a measurement packet for the forward loop route (section measurement route δ) is embedded with a total of seven labels: "Router B" - "Router C" - "Router D" - "Router E" - "Router F" - "Router A" - "Router B" (see Fig. 10 (before reduction)).

[0029] After SP35, the route derivation unit 23 determines whether there is a section where the route is unique even if the label is omitted (SP36). If there is a section where the route is unique even if the label is omitted ("Yes" in S36), the route derivation unit 23 deletes the label of the device (router) in that section from the measured route (SP37), and proceeds to S38.

[0030] FIG. 9 is a conceptual diagram showing how the number of labels embedded in a measurement packet is reduced. There are two shortest routes from router B to router D: (route BC + route CD) and (route BE + route DE), and there are two shortest routes from router B to router F: (route BA + route AF) and (route BE + route EF). Therefore, if the label is omitted, the route will not be unique.

[0031] On the other hand, the route from router D to router F (route DE+route EF) always passes through router E as the shortest route, so the route remains unique even if the label "router E" is omitted.

[0032] FIG. 10 is a diagram showing labels embedded in the measurement packets. For example, in the forward section measurement route δ, before the deletion, a total of seven labels were embedded in the order of "Router B" - "Router C" - "Router D" - "Router E" - "Router F" - "Router A" - "Router B". However, after "Router E" is deleted, six labels are embedded in the order of "Router B" - "Router C" - "Router D" - "Router F" - "Router A" - "Router B".

[0033] Returning to the explanation of the flowchart in FIG. 5, on the other hand, if there is no section where the route is unique even if the label is omitted (“No” in S36 (FIG. 5)), the route derivation unit 23 advances the process to S38.

[0034] In SP38, it is determined whether the number of labels on the measurement route exceeds the device's upper limit. If a measurement packet that exceeds the device's upper limit is sent to the router, it may cause a malfunction or other problem. If the number of labels exceeds the device's upper limit ("Yes" in SP38), the labels are reduced until the number is below the device's upper limit (SP39), and the process between SP40 and SP31 is repeated. On the other hand, if the number of labels does not exceed the device's upper limit ("No" in SP38), the process between SP40 and SP31 is repeated.

[0035] FIG. 11 is a conceptual diagram showing how labels on the route are deleted when the label limit is exceeded. In the forward section measurement route δ, seven labels should be embedded, but when the upper limit of the number of labels per router is five, omitting the label of router E is not enough. In this case, the label embedding unit 24 (Fig. 1) omits embedding of labels for routers A and C, for example. In this case, the measurement packet may pass through the route of router B → router E → router D → router E → router F → router E → router B. In other words, label reduction causes the route to become non-unique, resulting in route duplication. As a result, although the accuracy of delay time measurement decreases, it becomes possible to measure even large-scale networks.

[0036] FIG. 12 is a conceptual diagram showing how to measure the delay time of a return measurement path. The first delay time measurement unit 11 (Fig. 1) emits a measurement packet embedded with the label of the measurement route α leading to the start node (router D) and measures the time it takes for the packet to return (start point round trip delay time Tα). The second delay time measurement unit 12 (Fig. 1) emits a measurement packet embedded with the label of the measurement route β leading to the end node (router F) and measures the time it takes for the packet to return (end point round trip delay time Tβ). Furthermore, the one-way average delay time calculation unit 14 (Fig. 1) calculates the one-way average delay time (Tα + Tβ) / 2.

[0037] FIG. 13 is a conceptual diagram showing how to measure the delay time of a loop measurement path. The forward delay time measurement unit 13a (Fig. 1) of the third delay time measurement unit 13 emits a measurement packet (measurement packet passing through the measurement section) with an embedded label of the forward section measurement path δ, and measures the time it takes for the packet to return (forward delay time Tδ). The backward delay time measurement unit 13b (Fig. 1) emits a measurement packet (measurement packet passing through the measurement section) with an embedded label of the backward section measurement path γ, and measures the time it takes for the packet to return (backward delay time Tγ).

[0038] When the forward delay time measurement unit 13a measures a forward delay time Tδ, the delay time calculation unit 15 (Fig. 1) subtracts the one-way average delay time (Tα+Tβ) / 2 from the forward delay time Tδ to calculate the forward delay time {Tδ-(Tα+Tβ) / 2} of the measurement section. Also, when the backward delay time measurement unit 13b measures a backward delay time Tγ, the delay time calculation unit 15 subtracts the one-way average delay time (Tα+Tβ) / 2 from the backward delay time Tγ to calculate the backward delay time {Tγ-(Tα+Tβ) / 2} of the measurement section.

[0039] For example, if the starting point round trip delay time Tα = 100 μSec and the destination point round trip delay time Tβ = 50 μSec, the one-way average delay time is (Tα + Tβ) / 2 = 75 μSec. If the measured forward delay time Tδ = 125 μSec, the forward delay time of the measurement section is {Tδ - (Tα + Tβ) / 2} = 50 μSec. Also, if the measured backward delay time Tγ = 145 μSec, the backward delay time of the measurement section is {Tγ - (Tα + Tβ) / 2} = 70 μSec.

[0040] FIG. 14 is a conceptual diagram when packet loss occurs in the measurement section. The packet loss determination unit 16 (Figure 1) can measure the round-trip delay time Tα to the start point of the measurement path α that returns before the section from the measurement device 100 to the measurement start point (router D) and the round-trip delay time Tβ to the end point of the measurement path β that returns before the section to the measurement end point (router F).When a measurement packet that passes through the measurement section does not return to the measurement device 100, it determines that packet loss has occurred in the measurement section (path DE + path EF).

[0041] FIG. 15 is a conceptual diagram showing a case where packet loss occurs on a measurement path other than the measurement section. When the packet loss determination unit 16 (Figure 1) is unable to measure the delay times Tα and Tβ of the pre-section return measurement path α to the measurement start point (router D) and the pre-section return measurement path β to the measurement end point (router F), it determines that there is an abnormality in the path from the measurement device 100 to the measurement section (router D or router F).

[0042] As described above, the measurement device 100 of this embodiment is configured to measure and calculate the delay time of a measurement section (from the start node to the end node) in the network NW (FIG. 1). The measurement device 100 measures the start-point round-trip delay time Tα, the end-point round-trip delay time Tβ, and either or both of the forward delay time Tδ and the backward delay time Tγ of the measurement section, and can determine the delay time of the measurement section by calculating either or both of {Tδ - (Tα + Tβ) / 2} and {Tγ ​​- (Tα + Tβ) / 2}.

[0043] The measurement device 100 embeds labels indicating the section pre-turn measurement route α to the measurement start point (router D), the section pre-turn measurement route β to the measurement end point (router F), the forward section measurement route δ, and the reverse section measurement route γ in the measurement packet. Furthermore, the measurement device 100 omits labels from the measurement packet when the route can be uniquely identified even if some of the labels indicating the routers in the measurement route are omitted. This avoids exceeding the upper limit on the number of labels for a router by omitting the labels. Furthermore, when the measurement device 100 is unable to measure the start point round trip delay time Tα or the end point round trip delay time Tβ, it determines that an abnormality has occurred on the route from the measurement device 100 to the measurement section (router D or router F).

[0044] (Second embodiment) FIG. 16 is a diagram showing an example of a measurement route when a measurement device is applied to a large-scale network according to the second embodiment of the present invention. The delay time measurement system S2 is configured with a measurement device 100 and multiple routers A to J. The measurement device 100 is connected to router A, router A is connected to routers C, D, E, and F, router C is connected to routers B, H, etc., router D is connected to routers B, H, etc., router E is connected to routers B, J, etc., and router F is connected to routers B, J, etc.

[0045] The measurement section is router J → router E → router A → router D → router H. In other words, the start node of the measurement section is router J and the end node is router H. In this case, the pre-section turn-back measurement route α is Router A → Router F → Router J → Router F → Router A. The pre-section turn-back measurement route β is Router A → Router C → Router H → Router C → Router A. The forward loop δ is Router A → Router F → Router J → Router E → Router A → Router D → Router H → Router C → Router A. The reverse loop γ is Router A → Router C → Router H → Router D → Router A → Router E → Router J → Router F → Router A. The pre-section turn-back measurement routes α and β include a node (router A) that identifies the measurement section.

[0046] FIG. 17 is a diagram showing a label embedded in a measurement packet. In the forward loop δ, a total of nine labels are embedded in the order of "Router A" - "Router F" - "Router J" - "Router E" - "Router A" - "Router D" - "Router H" - "Router C" - "Router A".

[0047] (Comparative Example) FIG. 18 is a diagram showing an example of a measurement route when the comparative example is applied to a large-scale network. The configuration of the delay time measurement system S2 is the same as that of the delay time measurement system S2 (FIG. 16) of the previous embodiment, but the route that the measurement device 100 passes the measurement packet through and the delay time calculation method are different. Specifically, the measurement device 100 measures the round-trip delay time TE of the measurement path ε from the device itself to the end node (router H) and the round-trip delay time TS of the measurement path α from the device itself to the start node (router J), and calculates the one-way average delay time Ta of the measurement section by Ta = (TE - TS) / 2. As a result, the measurement section (router J - router E - router A) is included in the measurement path α.

[0048] However, in the second embodiment (FIG. 16), the measurement route α does not include the measurement section (router J-router E-router A-router D-router H).

[0049] FIG. 19 is a diagram showing a label embedded in a measurement packet in a comparative example. In the round-trip delay time measurement route ε to the destination node, a total of 13 labels are embedded in the following order: "Router A" - "Router E" - "Router J" - "Router E" - "Router A" - "Router D" - "Router H" - [Router D] - "Router A" - "Router E" - "Router J" - "Router E" - "Router A".

[0050] In this comparative example, the number of labels is 13, whereas in the second embodiment, the number of labels is reduced to 9. In other words, in this comparative example, the measurement route is specified so that the measurement packet travels back and forth along the same route. Therefore, when one relay point is added to the measurement section, the measurement route adds two labels, one for the outbound route and one for the inbound route. However, in the first and second embodiments, when one relay point is added to the measurement section, the number of labels indicating the section measurement routes δ and γ only increases by one.

[0051] Furthermore, in this comparative example, when quality degradation such as packet loss occurs in a measurement section, for example, between router E and router J, measurement packets are not returned from either the round-trip delay time measurement route α to the start node or the round-trip delay time measurement route ε to the end node. On the other hand, according to the delay time measurement method of the second embodiment, even if packet loss occurs between router E and router J, the measurement packets of loops δ and γ do not return, but the measurement packets of the measurement routes α and β that return before the section return, so it can be determined that packet loss has occurred in the measurement section including router E and router J.

[0052] <Effects> The effects of the delay time measuring device of the present invention will be described below. The delay time measurement device 100 according to the embodiment of the present invention is a delay time measurement device 100 that measures packet delay time occurring in a measurement section (section DE+section EF) between a start node and an end node, and includes a first delay time measurement unit (11) that measures a round-trip delay time (Tα) occurring between the device itself and the start node (router D) without passing through the measurement section, a second delay time measurement unit (12) that measures a round-trip delay time (Tβ) occurring between the device itself and the end node (router F) without passing through the measurement section, a third delay time measurement unit (13) that measures either a forward delay time (Tδ) of a loop (δ) returning from the device itself via the measurement section to the device itself, or a backward delay time (Tγ) until returning in the reverse direction through the loop, and a first round-trip delay time (Tα) occurring between the device itself and the end node (router F) without passing through the measurement section. The device is characterized by having a one-way average delay time calculation unit (14) that calculates a one-way average delay time {(Tα+Tβ) / 2} that occurs in a section that passes through the device between the start node (router D) and the end node (router F) based on the delay time (Tα) and the second round-trip delay time (Tβ) measured by the second delay time measurement unit, and a delay time calculation unit (15) that, when the third delay time measurement unit (13) measures the forward delay time (Tδ), subtracts the one-way average delay time {(Tα+Tβ) / 2} from the forward delay time (Tδ) to calculate a forward delay time of the measurement section, and, when the third delay time measurement unit (13) measures the backward delay time (Tγ), subtracts the one-way average delay time {(Tα+Tβ) / 2} from the backward delay time (Tγ) to calculate a backward delay time of the measurement section.

[0053] This allows the measurement of either or both of the forward delay time and the backward delay time in the measurement section without the packet traveling back and forth through the measurement section. Therefore, even if one relay node that relays the measurement section is added, the number of relay nodes along the measurement path along which the third delay time measurement unit measures the delay time is also added by one.

[0054] Furthermore, when measuring the first round-trip delay time (Tα) or the second round-trip delay time (Tβ), the first delay time measurement unit (11) and the second delay time measurement unit (12) may pass through a node that specifies the measurement section (for example, router A connected to the device itself). In other words, the path from the device itself to the start node and the path from the device itself to the end node must be different from the measurement section, but the nodes may be the same. This allows the node connected to the device itself to be included in the measurement section.

[0055] The device is also characterized by further comprising a label embedding unit (24) that embeds multiple labels into the packet, omitting labels of nodes that make the shortest path unique. As a result, the number of labels indicating the measurement path is reduced because labels of nodes that make the shortest path unique are omitted.

[0056] The device further comprises a packet loss determination unit (16) that determines that a packet loss has occurred when the first delay time measurement unit (11) or the second delay time measurement unit (12) is unable to measure the round trip delay time (Tα, Tβ). This makes it possible to determine whether a packet loss has occurred between the device itself and a start node or between the device itself and a destination node. In other words, if the forward delay time (Tδ) or the backward delay time (Tγ) can be measured, it means that a packet loss has occurred outside the measurement section.

[0057] The one-way average delay time calculation unit (14) is characterized in that it performs either a first calculation (a calculation by a first calculation unit 14a) of adding together a one-way average delay time (Tα / 2) obtained by dividing the round-trip delay time (Tα) measured by the first delay time measurement unit (11) by 2 and a one-way average delay time (Tβ / 2) obtained by dividing the round-trip delay time (Tβ) measured by the second delay time measurement unit (12) by 2, or a second calculation of adding together the round-trip delay time (Tα) measured by the first delay time measurement unit (12) and the round-trip delay time (Tβ) measured by the second delay time measurement unit (12) and dividing the summed round-trip delay time by 2 to calculate a one-way average delay time {(Tα+Tβ) / 2}. This makes it possible to calculate the one-way average delay time {(Tα+Tβ) / 2} from the round-trip delay times (Tα, Tβ). [Explanation of symbols]

[0058] 10 Control Unit 11 First delay time measurement unit 12 Second delay time measurement unit 13 Third delay time measurement unit 13a Forward delay time measurement unit 13b Reverse delay time measurement section 14 One-way average delay time calculation unit 14a 1st calculation section 14b 2nd calculation section 15 Delay time calculation section 16 Packet loss determination unit 20 Measurement path derivation unit 23 Route derivation unit 24 Label embedding section 100 Measuring device (delay time measuring device)

Claims

1. A delay time measurement device for measuring packet delay time occurring in a measurement section between a start node and an end node, a first delay time measurement unit that measures a round-trip delay time occurring between the device itself and the source node without passing through the measurement section; a second delay time measurement unit that measures a round-trip delay time occurring between the device itself and the end node without passing through the measurement section; a third delay time measurement unit that measures either a forward delay time of a loop returning to the own device via the measurement section or a backward delay time of the loop returning in the reverse direction; a one-way average delay time calculation unit that calculates a one-way average delay time occurring in a section that passes through the device between the start node and the end node based on the first round-trip delay time measured by the first delay time measurement unit and the second round-trip delay time measured by the second delay time measurement unit; When the third delay time measurement unit measures the forward delay time, the one-way average delay time is subtracted from the forward delay time to calculate the forward delay time of the measurement section, and when the third delay time measurement unit measures the backward delay time, the one-way average delay time is subtracted from the backward delay time to calculate the backward delay time of the measurement section; a label embedding unit that embeds multiple labels into a packet, omitting the labels of nodes that make the shortest path unique; A delay time measuring device comprising:

2. 2. The delay time measuring device according to claim 1, The first delay time measurement unit and the second delay time measurement unit may pass through a node that specifies the measurement section when measuring the round-trip delay time. A delay time measuring device characterized by:

3. 2. The delay time measuring device according to claim 1, The apparatus further includes a packet loss determination unit that determines that a packet has been lost when the first delay time measurement unit or the second delay time measurement unit cannot measure the round-trip delay time. A delay time measuring device characterized by:

4. 2. The delay time measuring device according to claim 1, The one-way average delay time calculation unit A first calculation of calculating a one-way average delay time by adding a one-way average delay time obtained by dividing the round-trip delay time measured by the first delay time measurement unit by 2 and a one-way average delay time obtained by dividing the round-trip delay time measured by the second delay time measurement unit by 2; A second calculation is performed to calculate an average one-way delay time by adding the round-trip delay time measured by the first delay time measurement unit and the round-trip delay time measured by the second delay time measurement unit and dividing the added round-trip delay time by 2; Execute either one of the following operations: A delay time measuring device characterized by:

5. A delay time measurement method executed by a delay time measurement device that measures packet delay time occurring in a measurement section between a start node and an end node, The delay time measuring device a first delay time measurement step of measuring a round trip delay time occurring between the device itself and the source node without passing through the measurement section; a second delay time measurement step of measuring a round-trip delay time occurring between the own device and the end node without passing through the measurement section; a third delay time measurement step of measuring either a forward delay time of a loop returning to the own device via the measurement section or a backward delay time of the loop returning in the reverse direction; a one-way average delay time calculation step of calculating a one-way average delay time occurring in a section passing through the device between the start node and the end node based on the first round-trip delay time measured in the first delay time measurement step and the second round-trip delay time measured in the second delay time measurement step; When the forward delay time is measured in the third delay time measurement step, the one-way average delay time is subtracted from the forward delay time to calculate the forward delay time of the measurement section, and when the backward delay time is measured in the third delay time measurement step, the one-way average delay time is subtracted from the backward delay time to calculate the backward delay time of the measurement section; Embedding multiple labels into a packet, omitting the labels of nodes that make the shortest path unique; A delay time measuring method comprising:

6. A delay time measuring program that causes a computer to execute the delay time measuring method according to claim 5.

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