Network control device and network control program

Abstract

A network control device (40) controls a network (2) having a plurality of routers (20) that are communicably connected via fibers (3), the network control device (40) comprising: a transmission information collection unit (42) that collects, from the routers (20), transmission information including link states of the routers (20) and transmission characteristics of the fibers (3) communicably connected to the routers (20); a route setting unit (43) that sets a communication route in the network (2) on the basis of the collected transmission information; and a storage unit (41) that stores transmission design information including unused margins of the fibers (3). The route setting unit (43) detects failures in the network (2) on the basis of the transmission characteristics of the fibers (3) and sets the communication route by making the unused margins usable when a failure is detected.

Description

Network control device and network control program

[0001] This invention relates to a technique for configuring communication paths within a network.

[0002] Routers equipped with DCO (Digital Coherent Optics) are emerging as nodes in carrier networks. In such carrier networks, multiple routers are connected via fiber for communication. Because signals are transmitted via fiber using the wavelength of light, the transmission section is affected by physical noise, errors, etc. The frequency of noise and errors varies depending on various factors such as the distance of the fiber, aging, curvature, and smoothness of the junction surface. The effective transmission efficiency of a fiber affected by noise and errors is called the transmission efficiency.

[0003] In carrier networks, bandwidth is designed to prevent overload under normal circumstances. Traffic engineering techniques exist to mitigate excessive traffic inflow to specific links, utilizing methods such as MPLS (Multi-Protocol Label Switching) and SR (Segment Routing) (see Non-Patent Documents 1 and 2).

[0004] Hideo Ishii, “Traffic Engineering”, [online], [Retrieved September 5, 2020], Internet <URL: https: / / www.nic.ad.jp / ja / materials / iw / 2000 / proceedings / T13-2a.PDF> Kris Michielsen, “SR Traffic-Engineering”, [online], [searched on September 5, 2020], Internet <URL: https: / / www.segment-routing.net / tutorials / 2017-03-06-segment-routing-traffic-engineering-srte /

[0005] However, in emergencies such as severe disasters, the inability to use routers can lead to an unforeseen influx of traffic into other routers. Furthermore, during large-scale disasters such as earthquakes and typhoons, overhead lines and / or underground fibers may be damaged, causing degradation in fiber quality (performance reduction). The aforementioned traffic engineering methods have the problem of being unable to address such situations.

[0006] This invention was created in view of these circumstances, and aims to provide a network control device and a network control program that can suitably secure a communication path in the event of a failure.

[0007] To solve the aforementioned problems, the present invention provides a network control device for controlling a network having a plurality of nodes that are communicated together via fiber, comprising: a transmission information collection unit that collects transmission information from the nodes, including the link state of the node and the transmission characteristics of the fiber communicated together to the node; a routing unit that sets up a communication path in the network based on the collected transmission information; and a storage unit that stores transmission design information including the unused margin of the fiber, wherein the routing unit detects a fault in the network based on the transmission characteristics of the fiber, and when a fault is detected, sets up the communication path by making the unused margin available. Here, the unused margin is a reserve value set to maintain a certain transmission quality. Each fiber is generally treated as having a lower quality than its actual transmission quality, taking the unused margin into consideration.

[0008] According to the present invention, by releasing unused margins and setting up a communication path, a communication path can be suitably secured in the event of a failure.

[0009] This is a schematic block diagram showing a network control system equipped with a network control device according to an embodiment of the present invention. This is a graph showing an example of the change in transmission quality over time. This is a block diagram for explaining an example of a network control method by the network control device according to an embodiment of the present invention. This is a hardware configuration diagram of each device in the network control system according to an embodiment of the present invention.

[0010] Embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same elements will be denoted by the same reference numerals, and redundant descriptions will be omitted.

[0011] As shown in Figure 1, the network control system 1 according to an embodiment of the present invention is a system that includes a network (carrier network) 2 for communicating between the Internet, which is a higher-level network, and the customer network, which is a lower-level network. The network control system 1 includes a host 10, a plurality of routers 20, and a plurality of transmission concentrators 30 as nodes of the network 2 which has a hierarchical structure, and also includes a network control device 40 that controls the plurality of routers 20. The host 10, routers 20 and transmission concentrators 30 are communicated with each other by fiber (optical fiber) 3. The network control device 40 is also communicated with the plurality of routers 20.

[0012] <Host> Host 10 is the highest-level server in the network control system 1. Host 10 is connected to the Internet for communication. Examples of Host 10 include a content server and an Internet Exchange (IX) as an interconnection point that enables the exchange of Internet traffic.

[0013] <Router> Router 20 is equipped with a DCO (Digital Coherent Optics) transceiver and is configured to communicate with devices outside the network control system 1 (relay devices, client terminals, etc.). Router 20 is connected to the customer network in a communicative manner. Router 20 generates an LSDB (Link-State Data Base) representing the link state (connection information) of the fiber 3 and the transmission concentrator 30 (or host 10) that are connected to Router 20 in a communicative manner, and periodically transmits the generated LSDB to the network control device 40.

[0014] Furthermore, the router 20 collects the optical characteristics, i.e., transmission characteristics, of the fiber 3 that is communicably connected to the router 20, and transmits the collected transmission characteristics to the network control device 40. Here, the router 20 can collect the transmission quality (bit error rate) as an example of the transmission characteristics of the fiber 3, for example, using Pre / Post-FEC BER (Bit Error Rate).

[0015] <Transmission and Concentration Device> The transmission and concentration device 30 is a device that enables communication between one upper-level router 20 and multiple lower-level routers 20.

[0016] <Oversubscription Hierarchical Structure> The network in the network control system 1 exhibits an oversubscription hierarchical structure. Oversubscription refers to setting the line speed of the upper-level fiber 3 to a value smaller than the sum of the line speeds of the lower-level fiber 3, based on the premise that not all of the lower-level fiber 3 are used to their full capacity. Such oversubscription is applied to the hosts 10 and routers 20 at each level.

[0017] Furthermore, the network 2 in the network control system 1 is configured such that each router 20 has a redundant path and there is no single point of failure. In other words, if one router 20 fails, the network is configured to allow communication to be established through other routers 20 at the same level.

[0018] <Network Control Device> The network control device 40 is a server that is connected to multiple routers 20 in a communicative manner. The network control device 40 includes, as functional units, a storage unit 41, a transmission information collection unit 42, and a route setting unit 43.

[0019] <<Storage Unit>> The storage unit 41 comprises a transmission design information database 41a and a transmission information database 41b.

[0020] ≪Transmission Design Information Database≫ The transmission design information database 41a stores the ID of fiber 3 and the transmission design information of fiber 3 in association with each other. As shown in Figure 2, the transmission design information of fiber 3 is the transmission quality (traffic limit) of fiber 3 which changes over time, and is information that associates the transmission quality of fiber 3 with the start date and time of operation and the operation period of fiber 3.

[0021] Fiber 3 is provided with a margin M to prevent excessive degradation of transmission characteristics due to signal (optical signal) deterioration during the design of Network 2. The transmission quality of Fiber 3 deteriorates over time, and the margin M also fluctuates (attenuates) over time.

[0022] Margin M stands for design margins. Ｄ And, System margins M Ｓ And, unallocated margins M Ｕ It is equipped with the following.

[0023] Design margin M Ｄ This is the difference between the Quality of Transmission (QoT) estimated by the estimation tool and the measured QoT, i.e., the margin based on the error of the estimation tool. This error is based on the error of the estimation tool's QoT model and the error of the parameters input to the QoT model.

[0024] System margin M ＳThis is a margin that fluctuates depending on time and operating conditions. Examples of margins that fluctuate depending on time include distortions that fluctuate in the short term (polarization fluctuations) and distortions that fluctuate in the long term (aging degradation, increase in wavelength). Examples of margins that fluctuate depending on operating conditions include the margin secured by the operator.

[0025] Unused margin M Ｕ This is a margin set up as a buffer in case the signal degrades beyond other margins. Unused margin M Ｕ This value is maintained at a constant level regardless of the operating period.

[0026] In this embodiment, the transmission design information stored in the transmission design information database 41a includes the ID of fiber 3 and the unused margin M of fiber 3. Ｕ and FEC limit FC, and at least the above.

[0027] ≪Transmission Information Database≫ Returning to Figure 1, the transmission information database 41b stores the ID of router 20 and the transmission information of router 20 in association with each other. The transmission information includes the LSDB of router 20 and the transmission characteristics of fiber 3 which is communicably connected to router 20.

[0028] ≪Transmission Information Collection Unit≫ The transmission information collection unit 42 collects transmission information from multiple routers 20 and stores the collected transmission information in the transmission information database 41b.

[0029] ≪Routing Unit≫ The routing unit 43 identifies the overall structure of the network 2 based on the collected transmission information. The routing unit 43 also sets communication paths within the network control system 1 based on the LSDB for each router 20 stored in the transmission information database 41b and the transmission design information of fiber 3 stored in the transmission design information database 41a, and transmits the set communication paths to the lower routers 20, which are the network edges. Here, the routing unit 43 calculates the traffic limit for fiber 3 based on the transmission characteristics of fiber 3 and sets the calculated traffic limit for fiber 3. In other words, the routing unit 43 can set communication paths, which are Layer 3 information, by considering the transmission design information, which is Layer 1 information. The routing unit 43 also adjusts the Layer 1 power for the lower routers 20, which are the edges, and sets TE (Traffic Engineering) (for example, an SR (Segment Routing) policy) based on the set communication paths.

[0030] The routing unit 43 sets the transmission mode (communication speed setting, for example, 400G, 200G, etc.) and communication method (UDP communication, TCP communication, etc.) for each fiber 3, and stores the setting results in the transmission information database 41b.

[0031] ≪Normal Communication Path Setting Method≫ The path setting unit 43 sets the communication path from the lower router 20 to the upper router 20 so as not to exceed the traffic limit. The path setting unit 43 also sets the transmission mode (400G, 200G, etc.) for each fiber 3 based on the traffic limit of the fiber 3.

[0032] <<Communication Path Setting Method at the Time of Failure>> When a failure occurs in the network due to a severe disaster or the like, the path setting unit 43 detects the failure based on the transmission characteristics of the fiber 3. For example, when the bit error rate as the transmission characteristic of the fiber 3 exceeds a predetermined value, the path setting unit 43 can determine that a failure has occurred in the fiber 3. Further, when the bit error rates of the fibers 3 on the upper side and the lower side of the router 20 exceed a predetermined value, the path setting unit 43 can determine that a failure has occurred in the router 20.

[0033] Further, when a failure is detected, the path setting unit 43 sets the communication path to use the unused margin M. Here, the situation when a failure occurs shown in FIG. 3 will be described. In FIG. 3, the reference numeral 3 indicating the fiber is omitted. Further, the numbers surrounded by squares attached to the fiber 3 are the values of the traffic upper limit (set maximum communication speed) set for the fiber 3. Ｕ The top router 20 in the middle (third tier) has failed and is unable to communicate, and the fibers 3 on the upper side and the lower side of the router 20 have become unable to communicate due to such a failure. Further, the fiber 3 on the lower side of the middle router 20 in the middle (third tier) has failed and the transmission quality has deteriorated. Further, the fiber 3 on the upper side of the bottom router 20 in the middle (third tier) has failed and the transmission quality has deteriorated.

[0034] When a failure occurs, the path setting unit 43 resets the traffic upper limit of the fiber 3 of the path where the failure has occurred according to the collected transmission characteristics (for example, bit error rate) as described above. For example, the path setting unit 43 resets the traffic upper limits of the fibers 3 on the upper side and the lower side of the top router 20 in the middle (third tier) to zero. Further, the path setting unit 43 resets the traffic upper limit of the fiber 3 on the lower side of the middle router 20 in the middle (third tier) to a lower value (10×4 [Gbps] → 8×4 [Gbps]). Further, the path setting unit 43 resets the traffic upper limit of the fiber 3 on the upper side of the bottom router 20 in the middle (third tier) to a lower value (20 [Gbps] → 15 [Gbps]).

[0035]

[0036] Furthermore, the route setting unit 43 sets the unused margin M of the fiber 3 of the route where no fault has occurred. Ｕ To ensure sufficient traffic volume by freeing up resources, the traffic limit for Fiber 3 will be reset to a higher value.

[0037] For example, the routing unit 43 sets the traffic limit of the fiber 3 on the upper side of the router 20 in the middle (third tier) by the unused margin M of the fiber 3. Ｕ The speed is increased by adding part or all of it (20 [Gbps] → 20 + a [Gbps], 20 [Gbps] → 20 + b [Gbps]). In addition, the routing unit 43 sets the traffic limit of the fiber 3 on the lower side of the lowest router 20 in the middle (third tier) by the unused margin M of the fiber 3. Ｕ It can be increased by adding part or all of it (10 × 4 [Gbps] → (10 + c) × 4 [Gbps]).

[0038] Furthermore, the routing unit 43 sets the traffic limit of fiber 3, which is connected to the top router 20 of the intermediate (third tier) in a communicative manner, to zero. Also, the routing unit 43 maintains the traffic limit of fiber 3 on the upper side of the bottom router 20 of the intermediate (third tier) in the normal value (20 [Gbps] → 20 [Gbps]). Note that the routing unit 43 sets the traffic limit of fiber 3 on the upper side of the bottom router 20 of the intermediate (third tier) in the unused margin M of said fiber 3. Ｕ The configuration may be one in which the increase is achieved by adding some or all of the elements.

[0039] Furthermore, the routing unit 43 may be configured to change the traffic limit of fiber 3 between the third-tier transmission concentrator 30 and the fourth-tier router 20 in accordance with the change in the traffic limit of fiber 3 as described above.

[0040] Note: Unused margin M Ｕ If this is used for communication, the margin M may decrease and fall below the FEC limit FC. The network control device 40 can ensure sufficient traffic volume in emergencies by bearing this risk.

[0041] Furthermore, the routing unit 43 readjusts the transmission mode for fiber 3 whose traffic limit has changed. For example, if the routing unit 43 cannot maintain the existing transmission mode for fiber 3 whose traffic limit has decreased due to a failure, it readjusts the transmission mode to a lower quality (lower speed) mode. Also, for fiber 3 whose traffic limit has increased due to a failure, the routing unit 43 readjusts the transmission mode to a higher quality (higher speed) mode. This setting method can effectively deal with packet corruption due to noise.

[0042] Furthermore, the routing unit 43 detects the recovery of a fault based on the transmission characteristics of fiber 3, and if recovery is detected, the unused margin M of fiber 3 Ｕ The release can be canceled, or the transmission mode of fiber 3 can be returned to its original mode (as in the example of power adjustment of layer 1 described above).

[0043] In this way, the routing unit 43, in the event of a failure in the network 2, uses the unused margin M of the fiber 3 that is not experiencing a failure. Ｕ To release the unused margin M for fiber 3, which is experiencing a failure Ｕ It assigns TCP communication without releasing the port.

[0044] As a variation, the routers 20 may perform route configuration in the event of a failure instead of the network control device 40. In this case, the routers 20 can obtain transmission design information for fiber 3 and the LSDB for the entire network from the network control device 40, and reconfigure the communication paths based on the obtained transmission design information and LSDB.

[0045] <<Reconfiguring Communication Method>> The routing unit 43 sets the communication method of fiber 3 to TCP communication when the traffic limit of fiber 3 is less than or equal to a predetermined value set for each fiber 3. In this embodiment, the routing unit 43 compares the traffic limit of fiber 3 with the FEC (forward Error Correction) limit FC, and sets the communication method of fiber 3 to TCP communication when the difference between them ([traffic limit] - [FEC limit]) is less than or equal to a predetermined difference.

[0046] <Hardware Configuration> Figure 4 is a hardware configuration diagram of each device in the network control system 1. As shown in Figure 4, each device in the network control system 1 (host 10, router 20, transmission concentrator 30, network control device 40) is configured as a computer 900 having a CPU 901, RAM 902, ROM 903, HDD 904, communication I / F 905, input / output I / F 906, and media I / F 907, respectively.

[0047] The communication interface 905 is connected to an external communication device 915. The input / output interface 906 is connected to an input / output device 916. The media interface 907 reads and writes data to the recording medium 917. Furthermore, the CPU 901 controls each part by executing a program (system call collection program) loaded into the RAM 902. This program (application, also called an app) can be distributed via a communication line or by recording it on a recording medium 917 such as a USB memory stick and distributing it there.

[0048] <Effects> The effects of the network control device 40, etc. will be described below. The network control device 40 according to the embodiment of the present invention is a device for controlling a network 2 having a plurality of nodes that are communicated to each other via fiber 3, and includes a transmission information collection unit 42 that collects transmission information from the nodes, including the link state of the node and the transmission characteristics of the fiber 3 that is communicated to the node, a route setting unit 43 that sets a communication path in the network 2 based on the collected transmission information, and an unused margin M of the fiber 3 ＵThe system includes a storage unit 41 which stores transmission design information including the above, and the routing unit 43 detects a fault in the network 2 based on the transmission characteristics of the fiber 3, and if a fault is detected, the unused margin M Ｕ The communication path is set to enable use. Therefore, the network control device 40 has an unused margin M Ｕ By releasing the connection and appropriately configuring the communication path, the communication path can be appropriately secured in the event of a failure.

[0049] Furthermore, in the network control device 40, the route setting unit 43 has the unused margin M that has been determined to be available. Ｕ Based on the unused margin M, Ｕ The transmission mode of the fiber 3, which has been deemed usable, is set. Therefore, the network control device 40 sets the unused margin M Ｕ This allows for increased communication speeds while taking these factors into consideration.

[0050] Furthermore, in the network control device 40, the routing unit 43 sets TCP communication for the fiber 3 when the transmission characteristics of the fiber 3 fall below a predetermined value. Therefore, the network control device 40 can retransmit data through the fiber 3 with degraded transmission characteristics, thereby achieving optimal communication.

[0051] Furthermore, the network control program according to the embodiment of the present invention includes a computer acting as a network control device 40 that controls a network 2 having a plurality of nodes communicated via fiber 3, a transmission information collection means that collects transmission information from the nodes, including the link state of the node and the transmission characteristics of the fiber 3 communicated to the node, and a system that sets a communication path in the network 2 based on the collected transmission information, and detects a fault in the network 2 based on the transmission characteristics of the fiber 3, and if a fault is detected, the unused margin M of the fiber 3 included in the transmission design information stored in the storage unit 41. ＵThe network control program is configured to function as a routing means for setting the communication path by making it available. Ｕ By releasing the connection and appropriately configuring the communication path, the communication path can be appropriately secured in the event of a failure.

[0052] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and can be modified as appropriate without departing from the spirit of the invention. For example, the method of collecting transmission information by the transmission information collection unit 42 is not limited to those described above. The transmission information collection unit 42 may be configured to periodically and / or based on the results of operations performed by the operator on the operation unit to send a transmission information request signal to the router 20. In this case, when the router 20 receives a transmission information request signal, it sends transmission information to the transmission information collection unit 42.

[0053] 1 Network control system 2 Network 3 Fiber 10 Host (node) 20 Router (node) 30 Transmission concentrator (node) 40 Communication control device 41 Storage unit 42 Transmission information collection unit 43 Route setting unit

Claims

1. A network control device for controlling a network having a plurality of nodes that are communicated together via fiber, comprising: a transmission information collection unit that collects transmission information from the nodes, including the link state of the nodes and the transmission characteristics of the fiber that is communicated together with the nodes; a routing unit that sets up communication paths in the network based on the collected transmission information; and a storage unit that stores transmission design information including unused margins of the fiber, wherein the routing unit detects a fault in the network based on the transmission characteristics of the fiber, and when a fault is detected, sets up the communication path by making the unused margin available.

2. The network control device according to claim 1, characterized in that the routing unit sets the transmission mode of the fiber for which the unused margin has been deemed available, based on the unused margin that has been deemed available.

3. The network control device according to claim 1, characterized in that the routing unit sets TCP communication for the fiber when the transmission characteristics of the fiber fall below a predetermined value.

4. A network control program that causes a computer, which acts as a network control device for controlling a network having multiple nodes connected communicably via fiber, to function as: a transmission information collection means for collecting transmission information from the nodes, including the link status of the nodes and the transmission characteristics of the fiber connected communicably to the nodes; and a path setting means for setting communication paths in the network based on the collected transmission information, detecting network failures based on the transmission characteristics of the fiber, and, if a failure is detected, setting the communication path by making available the unused margin of the fiber included in the transmission design information stored in the memory unit.

Images