Measurement server and measurement method

Abstract

This measurement server includes: a packet generation unit which measures the quality of a plurality of logical networks and generates, for each of the logical networks, a measurement packet to be used for measuring the quality of the logical network; and an address generation unit that generates, for each of the logical networks, a MAC address to be assigned to the measurement packet.

Description

Measurement Server and Measurement Method

[0001] The present disclosure relates to a measurement server and a measurement method.

[0002] With the development of network technology, requirements such as high reliability, low latency, and low jitter are imposed on networks. To guarantee these requirements, network quality measurement is performed. For example, Patent Documents 1 and 2 propose a technique of injecting measurement packets into a network from a measurement server connected to the network. Based on the transmission and reception times of measurement packets at the measurement server, it is possible to measure the packet transfer time between nodes constituting the network (for example, edge routers that form the endpoints of the network).

[0003] International Publication No. 2021 / 166266, International Publication No. 2024 / 166372

[0004] When measuring the quality of a logical network configured between edge routers, a media access control (MAC) address assigned to a logical interface (IF) of the edge router is added to the measurement packet.

[0005] By the way, when performing quality measurement for a plurality of logical networks configured between edge routers, the plurality of logical networks correspond to the above-mentioned MAC address of the edge router. This causes a problem that, in the MAC table managed by the edge router, flapping occurs in which the setting of the logical network corresponding to the MAC address is frequently rewritten.

[0006] The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to suppress flapping that may occur when performing quality measurement on a plurality of logical networks.

[0007] One aspect of the present disclosure is a measurement server that performs quality measurement on a plurality of logical networks, comprising: a packet generation unit that generates, for each of the logical networks, a measurement packet used for quality measurement of the logical network; and an address generation unit that generates, for each of the logical networks, a MAC address to be added to the measurement packet.

[0008] One aspect of the present disclosure is a measurement method for performing quality measurements of multiple logical networks, comprising: generating a measurement packet for each logical network to be used for quality measurement of the logical network; and generating a MAC address to be assigned to the measurement packet for each logical network.

[0009] According to this disclosure, it is possible to suppress flapping that may occur when performing quality measurements on multiple logical networks.

[0010] Figure 1 shows the functional block of the measurement server. Figure 2 shows an example of the path of a measurement packet. Figure 3 shows an example of a label stack. Figure 4 shows an example of a MAC address generated by the measurement server. Figure 5 shows the transmission and reception of measurement packets in the embodiment. Figure 6 shows the label stack of the measurement packet shown in Figure 5. Figure 7 shows an example of filtering of measurement packets. Figure 8 shows a modified example of the functional block of the measurement server. Figure 9 shows a modified example of the MAC address shown in Figure 4. Figure 10 shows a comparative example in which the edge router generates a MAC address. Figure 11 shows a comparative example in which the edge router generates a MAC address. Figure 12 shows an example of a hardware configuration.

[0011] The embodiments of this disclosure will be described below with reference to the drawings.

[0012] (1) The configuration of the measurement server 100 will be described with reference to the configuration diagram 1 of the measurement server. The measurement server 100 is connected to the network (NW) 200 to be measured. The measurement server 100 can perform quality measurement of the network 200 by applying (transmitting) measurement packets to the network 200.

[0013] Network 200 may be a physical network consisting of routers, switches, lines, etc., or it may be one or more logical networks built on said physical network. Network 200 may also refer to the entirety of multiple logical networks, or to each of the logical networks.

[0014] As shown in Figure 1, the measurement server 100 includes a physical network collection unit 110, a logical network collection unit 120, a mapping unit 130, a route calculation unit 140, a packet generation unit 150, an address generation unit 160, a transmission / reception unit 170, and a measurement result DB 180.

[0015] The physical network information collection unit 110 collects information (node ​​information) from the network 200 regarding the nodes that physically constitute the network 200, and understands the physical topology of the network 200. Nodes are components of the network 200 that are connected to each other by lines, such as routers and switches. The node information includes not only information about the nodes themselves, but also information indicating the connection relationships between nodes.

[0016] The logical network collection unit 120 collects information from the network 200 regarding each logical network built on the network 200 and understands the topology of each logical network.

[0017] A logical network is, for example, a virtual private network (VPN), but may also mean a virtual local area network (VLAN). In the following explanation, unless otherwise specified, a logical network refers to a VPN, and furthermore, one or more VLANs are configured within the VPN. Information about the logical network includes VPN routing information, customer information using the VPN (VPN ID), etc.

[0018] The mapping unit 130 associates the physical topology grasped by the physical network collection unit 110 with the logical topology grasped by the logical network collection unit 120. This allows the mapping unit 130 to identify the physical nodes that constitute each logical network.

[0019] The route calculation unit 140 calculates the route of measurement packets for measuring the logical network based on the information of the physical nodes constituting the logical network, which has been identified by the mapping unit 130. The route of the measurement packets is calculated by, for example, a well-known method such as Dijkstra's algorithm.

[0020] The packet generation unit 150 generates measurement packets to measure the quality of each logical network. The measurement packets are used to measure the time it takes for them to travel from the measurement server 100, through the edge routers 210 and 220 (see Figure 2), and back to the measurement server 100. The packet generation unit 150 generates measurement packets for each logical network to be measured.

[0021] The address generation unit 160 generates an address to be assigned to the measurement packet generated by the packet generation unit 150. The address includes a source MAC address and a destination MAC address. The source MAC address is used as a virtual MAC address for the edge router 210 corresponding to the starting point of the logical network. The destination MAC address is used as a virtual MAC address for the edge router 220 corresponding to the ending point of the logical network. In other words, the address generated by the address generation unit 160 is a dummy address, not the address of the edge routers 210 and 220 (assigned to the logical interface).

[0022] The address generation unit 160 generates an address to be assigned to the measurement packet for each logical network to be measured. In other words, the address generated by the address generation unit 160 is used as the originating and terminating address of the measurement packet within the logical network.

[0023] The transmitting / receiving unit 170 transmits measurement packets to the network 200 (specifically, each logical network to be measured). The transmitting / receiving unit 170 obtains the transmission time of the measurement packets using a well-known method such as a timestamp. The transmitting / receiving unit 170 also receives measurement packets from the network 200 (specifically, each logical network to be measured). The transmitting / receiving unit 170 will be described in more detail below. First, the functions related to the measurement of logical networks will be described, and then the functions related to the routing control of measurement packets will be described.

[0024] <Measurement of Logical Network> The transmitting / receiving unit 170 obtains the reception time of the measurement packet using a well-known method such as a timestamp. Based on this transmission time and reception time, the transmitting / receiving unit 170 calculates the transfer time of the measurement packet in the logical network.

[0025] This section describes a specific method for calculating the forwarding time of measurement packets in a logical network. The measurement packet includes a first measurement packet, a second measurement packet, and a third measurement packet. The first measurement packet travels back and forth between the measurement server 100 and the edge router 210. The second measurement packet travels back and forth between the measurement server 100 and the edge router 220. The third measurement packet is sent from the measurement server 100, passes through the edge routers 210 and 220, and is received by the measurement server 100.

[0026] If D is the transmission time of a measurement packet in a logical network, T1 is the difference between the transmission and reception times of the first measurement packet, T2 is the difference between the transmission and reception times of the second measurement packet, and T3 is the difference between the transmission and reception times of the third measurement packet, then D is given by the following formula: D = T3 - (T1 / 2 + T2 / 2)

[0027] As can be seen from this formula, the forwarding time (D) of a measurement packet in a logical network is calculated by subtracting the sum of the one-way time from the measurement server 100 to the edge router 210 (T1 / 2) and the one-way time from the edge router 220 to the measurement server 100 (T2 / 2) from the time (T3) from the measurement server 100 to the measurement server 100 via the edge router 210 and the edge router 220.

[0028] The transmitting / receiving unit 170 outputs the transfer time (D) of the measurement packets in the logical network to the measurement result DB 180 for each logical network. The measurement result DB 180 is a database that stores the transfer times of the measurement packets in the logical network. The transmitting / receiving unit 170 may also output the transmission time and reception time of the measurement packet, the first measurement packet, and the second measurement packet, for each logical network to the measurement result DB 180. In this case, the transfer time (D) of the measurement packets in the logical network may be measured by a measurement unit (not shown) referring to the measurement result DB 180. Furthermore, the transfer time (D) of the measurement packets in the logical network may be considered as the quality of the logical network by being compared with a predetermined threshold or the like.

[0029] <Measurement Packet Routing Control> The transmitting / receiving unit 170 generates a label stack used for forwarding measurement packets based on the routing information of the measurement packets calculated by the routing calculation unit 140. The labels are, for example, MPLS (Multi-Protocol Label Switching) labels. The transmitting / receiving unit 170 controls the transmission and reception of measurement packets between the measurement server 100 and the network 200, and the forwarding of measurement packets within the logical network, by assigning MPLS labels to the measurement packets.

[0030] The routing of measurement packets will be explained with reference to Figures 2 and 3. Figure 2 shows the path of the measurement packet. Figure 3 shows the label stack. The path numbers shown in Figure 2 correspond to the path numbers shown in Figure 3. First, the measurement packet departing from the measurement server 100 has the label numbered (1) removed at the edge router 210, which corresponds to the starting point of the logical network. Next, the measurement packet arriving at router 241 has the label numbered (2)-1 removed. Furthermore, the measurement packet arriving at the edge router 220, which corresponds to the ending point of the logical network, has the label numbered (2)-2 removed. Finally, the label numbered (3) is removed at the measurement server 100, which is the destination of the measurement packet.

[0031] Furthermore, the transmitting / receiving unit 170 assigns the address generated by the address generation unit 160 to the measurement packet. The address generated by the address generation unit 160 is used as a dummy address (source MAC address) for the edge router 210 and as a dummy address (destination MAC address) for the edge router 220, respectively.

[0032] (2) The network 200 (the nodes that make up the network 200) will be described with reference to the network configuration diagram 2. As shown in Figure 2, the network 200 comprises edge router 210, edge router 220, router 241, and router 242.

[0033] The edge router 210 is a provider edge router corresponding to the origin of the logical network. The edge router 210 receives measurement packets from the measurement server 100 via router 241. The edge router 210 routes the measurement packets within the logical network based on the MPLS label assigned to the measurement packets. Routers 241 (and 242) are provider routers.

[0034] The edge router 210 corresponds to the starting point of multiple logical networks in network 200. In the example in Figure 2, three logical networks are configured in network 200, and the edge router 210 corresponds to the starting point of these three logical networks.

[0035] Edge router 220 is a provider edge router corresponding to the endpoint of the logical network. Edge router 220 receives measurement packets from edge router 210 via router 241. Based on the MPLS label assigned to the measurement packet, edge router 220 sends the measurement packet to measurement server 100 via router 241. In this case, edge router 220 uses the dummy address (destination MAC address) assigned to the measurement packet to perform Layer 2 forwarding to measurement server 100 via router 241. Note that StaticPW in the figure indicates a logical pseudowire (PW) on the physical line between edge router 220 and router 241.

[0036] The edge router 220 corresponds to the endpoint of multiple logical networks in network 200. In the example in Figure 2, three logical networks are configured in network 200, and the edge router 220 corresponds to the endpoint of these three logical networks. The following describes the test VPN settings used for sending and receiving measurement packets, the MAC table of the edge router 210, and the dummy address generation rules.

[0037] <Test VPN Settings> This section describes the test VPN settings used for sending and receiving measurement packets. The logical network to be measured is the logical network between CE router 310 and CE router 320 used by the user (User VPN #1 setting, User VPN #2 setting, User VPN #3 setting in the figure). Therefore, measurement packets sent from the measurement server 100 cannot pass through the logical network. To address this, the test VPN settings allow measurement packets sent from the measurement server 100 to pass through each logical network via switches 315 and 325 (see arrows in Figure 2). This enables quality measurement using measurement packets in each logical network. Note that the test VPN settings may be performed by the measurement server 100 or by the edge routers 210 and 220.

[0038] <MAC Table> This section describes the MAC table managed by the edge router 210. The MAC table managed by the edge router 210 does not record the MAC addresses assigned to the logical interface of the edge router 210, but rather dummy addresses (source MAC addresses) generated by the address generation unit 160 for each logical network (MAC#1, MAC#2, MAC#3 in the figure). These dummy addresses are attached to the measurement packets sent from the measurement server 100. The right column of the MAC table records the MAC addresses of nodes adjacent to the edge router 210 in each logical network (Next hop in the figure).

[0039] <Dummy Address Generation Rules> The rules for generating dummy addresses generated by the address generation unit 160 are explained below. As shown in Figure 4, the dummy address includes fields indicating the identifier of the measurement server 100 (measurement server identifier in the figure), the identifier of the edge router 210 (PE router identifier in the figure), the identifier of the test VPN setting (test VPN identifier in the figure), and the VLAN identifier. The 7th bit from the beginning of the dummy address is fixed to 1 to avoid duplication with the user's MAC address. The VLAN identifier is set to identify each VLAN when multiple VLANs are configured within each logical network (VPN).

[0040] (3) The transmission and reception of measurement packets will be explained with reference to the examples Figures 5 to 7. In Figures 5 and 7, only one logical network through which the measurement packets pass is shown for the sake of simplicity of explanation, but in reality, multiple logical networks are set up as in Figure 2, and quality measurements are performed for each logical network.

[0041] In the embodiment shown in Figure 5, for redundancy, a router 243 is provided between the measurement server 100 and the network 200 in addition to router 241. Before sending measurement packets, the measurement server 100 sends a health check packet to routers 241 and 243 to determine a more appropriate route for the measurement packets. The health check packet may be assigned a dummy address (MAC address) as shown in the figure. This dummy address includes the measurement server identifier described above, and may also be distinguished by a last 1 bit to avoid the source MAC and destination MAC being the same. This last 1 bit can reduce the risk of the packet being dropped by routers 241 and 243.

[0042] Assume that it is determined that the measurement packet passes through the router 241 as a route. In this case, in order to identify the return route from the edge router 220 to the measurement server 100, an identifier corresponding to a pseudo line configured between the edge router 220 and the router 241, and between the router 243 may be used. This identifier may be, for example, a VLAN ID, and may be embedded in a label stack for forwarding the measurement packet as shown in FIG. 6. Accordingly, the measurement packet can pass through the route (pseudo line) determined by the measurement server 100 based on the alive monitoring packet. Note that although it is assumed here that a pseudo line, which is a logical line, is configured between the edge router 220 and the router 241, and between the edge router 220 and the router 243, the edge router 220, the router 241, and the router 243 may each be connected via a physical line.

[0043] In the embodiment shown in FIG. 7, it is assumed that an edge router 230 is provided as an end point of the logical network in addition to the edge router 220. Further, it is assumed that the user uses two VLANs in one logical network (user VPN#1 setting in the figure). That is, it is assumed that the user uses a VLAN (VLAN#2) between the CE router 310 and the CE router 330 in addition to the VLAN (VLAN#1) between the CE router 310 and the CE router 320 in one logical network.

[0044] Here, consider a case where quality measurement is performed for each of the two VLANs. As a premise for transmitting and receiving measurement packets, the above-described test VPN settings are performed for each VLAN (VLAN#1, VLAN#2). For the switch 335 through which the measurement packet passes in VLAN#2, refer to the above description of the switch 315 and the switch 325.

[0045] As shown in Figure 7, it is assumed that measurement packets are first sent and received in VLAN #1. However, if the edge router 220 goes down for any reason before the measurement packets arrive at the edge router 220, the measurement packets may be flooded and returned to the measurement server 100 via the edge router 230. To solve this problem, the edge router 230 can be configured to filter (for example, configure ACL (Access Control List) settings). That is, the edge router 230 can filter and discard measurement packets that are not addressed to it (addressed to other edge routers 220).

[0046] To determine whether a measurement packet is addressed to itself, the test VPN identifier included in the dummy address assigned to the measurement packet can be used (see Figure 4). That is, if the edge router 230 finds that the measurement packet is addressed to it, it can determine that the measurement packet is addressed to it. Conversely, if the test VPN identifier does not find that it is addressed to it, the edge router 230 can determine that the measurement packet is not addressed to it. Based on this determination, the edge router 230 can filter the measurement packet. Note that this determination is performed not only by the edge router 230, but also by the edge routers 210 and 220.

[0047] (4) Modified Figure 8 shows a modified version of the measurement server 100. The difference from Figure 1 is that the address generation unit 160 is located outside the measurement server 100, rather than inside it.

[0048] FIG. 9 shows a modification of the dummy address generated by the address generation unit 160. The order of the fields of the dummy address described in FIG. 4 may be changed. For example, as shown in FIG. 9, the dummy address may be configured in the order of a VLAN identifier, an identifier of an edge router 210 (PE router identifier in the figure), an identifier of a test VPN configuration (test VPN identifier in the figure), and an identifier of a measurement server 100 (measurement server identifier in the figure). Also in FIG. 9, the 7th bit from the head of the dummy address is fixed to 1 to avoid overlapping with a user's MAC address.

[0049] The measurement packet according to the above-described embodiment is transmitted from the edge router 210 to the edge router 220, but may be transmitted in the reverse direction. Measurement accuracy can be improved by measuring the quality of the logical network in both directions. When the measurement packet is transmitted in the reverse direction, the description of the embodiment shall be appropriately read as replaced (for example, the description of the edge router 210 and the description of the edge router 220 shall be read as replaced with each other).

[0050] (5) Effects The measurement server 100 of the present embodiment is a measurement server 100 that measures the quality of a plurality of logical networks, and includes: a packet generation unit 150 that generates, for each logical network, a measurement packet used for quality measurement of the logical network; and an address generation unit 160 that generates, for each logical network, a MAC address to be added to the measurement packet.

[0051] In the comparative example shown in FIG. 10, an edge router 210 corresponding to the start point of a logical network allocates a MAC address corresponding to its own logical interface, and the MAC address is added to a measurement packet. However, in the MAC table managed by the edge router 210, a plurality of logical networks correspond to one source MAC address, so there is a risk that flapping occurs. Flapping imposes a load on the edge router 210, which may degrade the quality of the logical network.

[0052] In contrast, the measurement server 100 of this embodiment can generate a MAC address to be assigned to the measurement packet for each logical network to be measured. As a result, in the MAC table managed by the edge router 210, there is a one-to-one correspondence between the source MAC address and the logical network, which can suppress the occurrence of flapping.

[0053] Furthermore, in the comparative example shown in Figure 11, the edge router 210 can assign the same number of MAC addresses as the number of logical networks, thereby suppressing the occurrence of the flapping described above. However, there is an upper limit to the number of logical interfaces of the edge router 210, and therefore an upper limit to the number of MAC addresses that can be assigned. Also, even if the number of MAC addresses does not reach the upper limit, if there are many logical networks to be measured, a large load will be placed on the edge router 210, which may degrade the quality of the logical networks.

[0054] In contrast, in this embodiment, the MAC address assigned to the measurement packet is generated not by the edge router 210, but by a measurement server 100 (address generation unit 160) configured separately from the network 200. This avoids placing a load on the edge router 210, thus stabilizing the quality of the logical network.

[0055] Furthermore, in this embodiment, the logical network includes multiple lines between the edge router 220 corresponding to the endpoint (destination point) of the logical network and the measurement server 100, and the MAC address includes an identifier (VLAN identifier) ​​that indicates the line among the multiple lines corresponding to the route of the measurement packet. As a result, the measurement server 100 can change the route of the measurement packet in consideration of the status of the nodes or lines constituting the network 200.

[0056] Furthermore, in this embodiment, the MAC address includes an identifier (test VPN identifier) ​​indicating that the measurement packet is destined for the edge router 220. This ensures that even if the edge router 220 goes down during logical network quality measurement and the measurement packet ends up at another edge router 230 via an unintended route, the measurement packet will be discarded at the edge router 230, thus reducing the risk of the measurement packet returning to the measurement server 100 via an unintended route.

[0057] The measurement server 100 described above can use, for example, a general-purpose computer system as shown in Figure 12. The illustrated computer system comprises a processor (CPU: Central Processing Unit) 901, memory 902, storage 903 (HDD: Hard Disk Drive, SSD: Solid State Drive), communication device 904, input device 905, and output device 906. The memory 902 and storage 903 are storage devices. In this computer system, the processor 901 executes a predetermined program loaded onto the memory 902, thereby realizing each function of the measurement server 100.

[0058] Furthermore, the measurement server 100 may be implemented on a single computer or on multiple computers. The measurement server 100 may also be a virtual machine implemented on a computer. The program of the measurement server 100 can be stored on a computer-readable recording medium such as an HDD, SSD, USB (Universal Serial Bus) memory, CD (Compact Disc), or DVD (Digital Versatile Disc), or distributed over a network. A computer-readable recording medium is, for example, a non-transitory recording medium.

[0059] This disclosure is not limited to the embodiments described above, and numerous modifications are possible within the scope of its essence.

[0060] 100 Measurement Server 110 Physical Network Data Collection Unit 120 Logical Network Data Collection Unit 130 Mapping Unit 140 Route Calculation Unit 150 Packet Generation Unit 160 Address Generation Unit 170 Transmit / Receive Unit 180 Measurement Result DB 200 Network (NW) 210, 220, 230 Edge Routers 241, 242, 243 Routers 310, 320, 330 CE Routers 315, 325, 335 Switches

Claims

1. A measurement server for performing quality measurements of multiple logical networks, comprising: a packet generation unit for each logical network that generates measurement packets used for quality measurement of the logical network; and an address generation unit for each logical network that generates MAC addresses to be assigned to the measurement packets.

2. The measurement server according to claim 1, wherein the logical network includes a plurality of lines between an edge router corresponding to an endpoint of the logical network and the measurement server, and the MAC address includes an identifier indicating the line among the plurality of lines that corresponds to the route of the measurement packet.

3. The measurement server according to claim 2, wherein the MAC address includes an identifier indicating that the measurement packet is destined for the edge router.

4. A measurement method for measuring the quality of multiple logical networks, comprising: generating a measurement packet for each logical network to be used for measuring the quality of the logical network; and generating a MAC address to be assigned to the measurement packet for each logical network.

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