A network resource pool congestion control framework and control method based on hybrid SDN

Abstract

The present invention discloses a network resource pool congestion control framework based on hybrid SDN, adopts hybrid routing nodes to form a hybrid SDN architecture, and uses an SDN controller to control resource pool congestion, thereby achieving centralized control of the network and monitoring of the network status. The three functional modules of the hybrid routing node include: a routing protocol control module, which is used to realize the forwarding table generation function of a traditional router; an OpenFlow switch module, which realizes the interaction with the SDN controller and the flow table forwarding function; and a data forwarding module, which forwards data according to forwarding rules. The present invention improves the utilization rate of network resources and the efficiency of congestion interface relief; at the same time, the network measurement technology in the SDN controller can provide a monitoring and management network failure function and a prevention and defense network attack behavior function for the resource pool congestion control framework based on explicit feedback, providing a guarantee for safer and more efficient congestion control.

Description

Technical Field

[0001] The present invention belongs to the technical field of network control, and in particular relates to a network resource pool congestion control framework and a control method based on hybrid SDN. Background Art

[0002] Traditional TCP end-to-end congestion control adjusts the data sending rate based on the feedback mechanism of packet loss and timeout. When there is a bottleneck link on the end-to-end path, if the sender's data sending rate is greater than the forwarding rate of the bottleneck link, packet loss will occur. At this time, according to the packet loss feedback, the sender will eventually converge the sender rate to the forwarding rate of the bottleneck link through congestion control, which cannot fully utilize the link resources, and the traditional end-to-end TCP flow cannot fully utilize the network resources through detour routing. Secondly, TCP congestion control regulates the data sending rate based on RTT (round-trip time). TCP flows with different RTTs have different sending rate growth rates, which makes it impossible to ensure the fairness of flows with different RTTs. Finally, TCP flows with longer RTTs have sending rates lower than the fair value, which prolongs the flow completion time.

[0003] In order to make full use of network resources, overcome the inefficiency of end-to-end packet loss and timeout feedback, and improve the fairness of bandwidth occupancy between different flows, there is an existing technology that considers adding additional storage space to each interface of the intermediate router, and sets upper and lower occupancy thresholds for the cache space of each interface. When the network is unobstructed, the router directly forwards the received data using the maximum link transmission rate; if the data receiving rate of the router is greater than the data output rate, the current router temporarily caches the data that cannot be forwarded in time, and finds whether there is a bypass path (a one-hop bypass path is used here), and uses the bypass path to forward the data that cannot be forwarded in time as soon as possible; when the usage rate of the router's cache space exceeds the upper threshold, the interface state is converted to a congested state, and a congestion notification is fed back to the upstream router hop by hop using a data confirmation packet (ACK data packet). After receiving the congestion notification, the upstream router caches the data packet that will arrive at the congested interface, thereby controlling the forwarding rate of the data packet. The congestion notification fed back hop by hop can eventually be transmitted to the data sending end. At this time, the data sending rate can be suppressed from the sending end, realizing the shared storage space and controllable sending rate of the upstream router. When the routing interface buffer occupancy is lower than the lower threshold, the interface is out of congestion and transmits a notification of congestion cancellation to the upstream router, so that the upstream link can resume the maximum forwarding rate.

[0004] Through the above method, the sender uses the maximum sending rate without considering the rate of the bottleneck link, achieving better fairness and flow stability; the data sending rate is no longer limited to the rate of the bottleneck link, which improves the data transmission rate and shortens the flow completion time; the storage space is shared between routers to achieve traffic detour, which improves the utilization of network resources; the use of hop-by-hop instant feedback improves the feedback efficiency compared with the feedback method based on packet loss and timeout.

[0005] Although the method of adding additional buffers to router interfaces provides many advantages over traditional congestion control algorithms, existing technologies only use one-hop detour paths and do not fully utilize multi-hop detour path resources in the network. Summary of the invention

[0006] In response to the above-mentioned problems, the present invention uses hybrid SDN technology to implement a network control center. Through the network monitoring technology in the SDN technology framework, the global network topology information and link bandwidth information can be better understood. Through the perception of the global network, multi-hop detour of data traffic can be better achieved.

[0007] The technical solution of the present invention is as follows:

[0008] A network resource pool congestion control framework based on hybrid SDN adopts hybrid routing nodes to form a hybrid SDN architecture, and uses an SDN controller to control resource pool congestion, thereby achieving centralized control of the network and monitoring of the network status. The three functional modules of the hybrid routing node include:

[0009] Routing protocol control module, used to realize the forwarding table generation function of traditional routers;

[0010] OpenFlow switch module, which realizes the interaction with SDN controller and flow table forwarding function;

[0011] The data forwarding module forwards data according to the forwarding rules.

[0012] Furthermore, the hybrid SDN architecture control rules include:

[0013] When data is input, the data is first input into the OpenFlow switch module, and the flow table is matched against the input data; if the data flow successfully matches the flow table entry, the data forwarding module is used directly to forward the data; if the data flow does not match the flow table entry, the data will flow to the routing protocol control module, and the traditional routing protocol will be used to generate a routing forwarding table, and the data will be forwarded according to the routing forwarding table.

[0014] A control method for a network resource pool congestion control framework based on a hybrid SDN, the control method comprising the following steps:

[0015] (1) The SDN controller establishes a connection with the routing node to obtain network topology information and link bandwidth information;

[0016] (2) Determine whether the routing interface is congested. If the routing interface is not congested, forward data at the maximum link transmission rate. If the routing interface is congested, the router sends an asynchronous message to the SDN controller to request a detour path. At the same time, the congested router feeds back congestion information to the upstream router.

[0017] (3) The SDN controller generates a detour path based on the network topology information and link bandwidth information, while the upstream router caches the data traffic flowing to the downstream node;

[0018] (4) The SDN controller generates a flow table and sends it to each route on the detour path. At the same time, the sender reduces the sending rate.

[0019] (5) Congestion routing uses detour routing to forward data in the buffer;

[0020] (6) After the routing interface exits the congestion state, it notifies the SDN controller, and the SDN controller deletes the bypass flow entry;

[0021] (7) The upstream router cancels the cache and continues to forward data at the maximum rate.

[0022] Furthermore, in step (1),

[0023] Use the LLDP protocol to take active measurements to obtain network topology information. The SDN controller periodically sends LLDP packets and calculates the current network topology based on the packets returned by the router port.

[0024] The link bandwidth information obtained is the remaining bandwidth information of the network link. The passive measurement method is adopted. The SDN controller queries the counter statistics of the route through the OpenFlow protocol. The route returns the forwarding bytes (bytes) of the data flow flowing through the port. Through n and n+1 detections in the same time period T, the data throughput rate Through per unit time can be obtained. The calculation formula of the data throughput rate is as follows:

[0025]

[0026] Furthermore, in the step (2), whether there is congestion in the routing interface is determined based on the interface cache occupancy of the router. When the interface cache occupancy of the router does not reach the upper threshold, it indicates that there is no congestion in the data transmission process; when the cache occupancy of the router interface exceeds the upper threshold, it indicates that there is congestion in the data transmission process, and the current routing interface state becomes a congested state.

[0027] Furthermore, in step (3), the calculation of the detour path uses the obtained network topology information and link bandwidth information, and the current network is set to G = (V, E), V is the set of all nodes in the network, E is the set of all links in the topology, and the link utilization θ is used to represent the weight of the link in the topology. Bandwidth represents the bandwidth size of the link. The link calculation formula is as follows:

[0028]

[0029] According to the network topology and the weight information on the corresponding links, the SDN controller uses the single-source shortest path algorithm to calculate the detour path.

[0030] Compared with the prior art, the present invention has the following technical effects:

[0031] By sensing the global network topology information through the SDN controller, the network congestion situation can be better judged, and a more reasonable multi-hop detour path can be specified for the congested interface, which not only improves the network resource utilization but also improves the efficiency of congested interface relief. At the same time, the network measurement technology in the SDN controller can provide the monitoring and management of network faults and the prevention and defense of network attack behaviors for the resource pool congestion control framework based on explicit feedback, providing a guarantee for safer and more efficient congestion control. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the routing interface congestion control process of the present invention;

[0033] Figure 2 It is the framework model of the hybrid routing node of the present invention. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0035] The present invention combines resource pool congestion control with hybrid SDN architecture to achieve centralized control of the network and monitoring of network status. Different from traditional networks and complete SDN architectures, hybrid SDN architectures can control forwarding traffic based on both traditional IP and SDN control, and different forwarding methods can be used according to different traffic types. Resource pool congestion control can effectively reduce flow completion time and improve network transmission efficiency. Hybrid SDN architecture can provide high-granularity regulation and control for network traffic. Combining the two will form a more efficient network data transmission model.

[0036] Please refer to the attached Figure 1-2The present invention discloses a network resource pool congestion control framework based on hybrid SDN, adopts hybrid routing nodes to form a hybrid SDN architecture, and uses an SDN controller to control resource pool congestion, thereby achieving centralized control of the network and monitoring of the network status.

[0037] like Figure 2 As shown in the figure, the framework module of the hybrid routing node is shown. The hybrid routing node is divided into three functional modules, namely the routing protocol control module, which is used to realize the forwarding table generation function of the traditional router; the OpenFlow switch module, which realizes the interaction with the SDN controller and the flow table forwarding function; and the data forwarding module, which forwards data according to the forwarding rules.

[0038] The working mode of the hybrid routing node is that when data is input, the data is first input into the OpenFlow switch module, and the flow table is matched for the input data; if the data flow successfully matches the flow table entry, the data forwarding module is directly used to forward the data; if the data flow does not match the flow table entry, the data will flow to the routing protocol control module, and the traditional routing protocol will be used to generate a routing forwarding table, and the data will be forwarded according to the routing forwarding table.

[0039] By adopting this framework module, the router can forward data using traditional routing protocols as well as according to the OpenFlow flow table generated by the SDN controller, thus realizing network control based on a hybrid SDN architecture.

[0040] Based on the above control framework, the present invention also discloses a control method for a network resource pool congestion control framework based on a hybrid SDN, such as Figure 1 As shown, the control method includes the following steps:

[0041] Step (1), the SDN controller establishes a connection with the routing node to obtain network topology information and link bandwidth information. The LLDP protocol is used to take active measurement methods to obtain network topology information. The SDN controller periodically sends LLDP data packets, and calculates the current network topology based on the data packets returned by the router port; the link bandwidth information obtained is the remaining bandwidth information of the network link. The passive measurement method is used. The SDN controller queries the counter statistics of the route through the OpenFlow protocol (OFPT_MULTIPART_REQUEST information), and the route returns the forwarding bytes (number of bytes) of the data flow flowing through the port (through OFPT_MULTIPART_REPLY information). Through n and n+1 detections in the same time period T, the data throughput rate Through per unit time can be obtained. The calculation formula of the data throughput rate is as follows:

[0042]

[0043] Step (2) can determine whether the routing interface is congested based on the data throughput rate and the interface cache occupancy of the router. When the interface cache occupancy of the router is used for judgment, when the interface cache occupancy of the router does not reach the upper threshold, it indicates that there is no congestion during the data transmission process; when the cache occupancy of the router interface exceeds the upper threshold, it indicates that there is congestion during the data transmission process, and the current routing interface state changes to a congested state. When there is no congestion on the routing interface, data is forwarded at the maximum transmission rate of the link; when the routing interface is congested, the routing sends an asynchronous message to the SDN controller to request a detour path, and the congested routing feeds back congestion information to the upstream routing. After receiving the information, the upstream routing caches the data that will pass through the congestion window, thereby controlling the data transmission rate. When the interface cache occupancy in the congested state is lower than the lower threshold, the interface state changes to a push state, and the upstream router no longer caches the traffic of the current interface. The routing node continues to forward data at the maximum transmission rate. At this time, the router sends an asynchronous message to the SDN controller to notify the SDN controller of the status change of the routing port.

[0044] Step (3), the SDN controller generates a detour path based on the network topology information and link bandwidth information, and the upstream router caches the data traffic flowing to the downstream node. The calculation of the detour path uses the obtained network topology information and link bandwidth information, and sets the current network to G = (V, E), where V is the set of all nodes in the network, and E is the set of all links in the topology. The link utilization θ is used to represent the weight of the link in the topology, and Bandwidth represents the bandwidth size of the link. The link calculation formula is as follows:

[0045]

[0046] According to the network topology and the weight information on the corresponding links, the SDN controller uses the Dijkstra algorithm (single-source shortest path algorithm) to calculate the detour path.

[0047] Step (4): The SDN controller generates a flow table and sends it to each route on the detour path, while the sender reduces the sending rate.

[0048] Step (5), the congested routing uses a detour route to forward the data in the buffer.

[0049] Step (6): After the routing interface exits the congestion state, the SDN controller is notified, and the SDN controller deletes the bypass flow table entry to avoid a large amount of bypass traffic causing the flow table to be too large and excessive bypass traffic occupying bandwidth resources, resulting in unfair allocation of network resources.

[0050] Step (7), the upstream router cancels the cache and continues to forward data at the maximum rate.

[0051] The present invention can also utilize the hybrid SDN architecture to perform fine-grained processing on the data flow in the network, dynamically implement traffic scheduling according to the network status, and implement multi-path transmission according to the data flow of different business attributes, thereby further improving the utilization rate of network resources. The SDN controller can utilize OF-Config (OpenFlow management and configuration protocol) to realize the unified configuration of the upper and lower thresholds of different interfaces in the routing node, avoiding the cumbersome maintenance of network nodes.

[0052] Compared with the prior art, the present invention has the following technical effects:

[0053] By sensing the global network topology information through the SDN controller, the network congestion situation can be better judged, and a more reasonable multi-hop detour path can be specified for the congested interface, which not only improves the network resource utilization but also improves the efficiency of congested interface relief. At the same time, the network measurement technology in the SDN controller can provide the monitoring and management of network faults and the prevention and defense of network attack behaviors for the resource pool congestion control framework based on explicit feedback, providing a guarantee for safer and more efficient congestion control.

Claims

1. A control method for a network resource pool congestion control framework based on a hybrid SDN, characterized by: The network resource pool congestion control framework of the hybrid SDN adopts hybrid routing nodes to form a hybrid SDN architecture, and uses the SDN controller to control the resource pool congestion, thereby achieving centralized control of the network and monitoring of the network status. The three functional modules of the hybrid routing node include: a routing protocol control module for realizing the forwarding table generation function of the traditional router; an OpenFlow switch module for realizing the interaction with the SDN controller and the flow table forwarding function; and a data forwarding module for forwarding data according to the forwarding rules. The control method comprises the following steps: (1) The SDN controller establishes a connection with the routing node to obtain network topology information and link bandwidth information; (2) Based on the routing protocol control module, the SDN controller determines whether the routing interface is congested. When the routing interface is not congested, the data forwarding module forwards data at the maximum transmission rate of the link. When the routing interface is congested, the router sends an asynchronous message to the SDN controller to request a detour path. At the same time, the congested router feeds back congestion information to the upstream router. (3) The SDN controller generates a detour path based on the network topology and link bandwidth information, while the upstream router caches the data traffic flowing to the downstream node; (4) Based on the OpenFlow switch module, the SDN controller generates a flow table and sends it to each route on the detour path, while the sending end reduces the sending rate; (5) Congestion routing uses detour routing to forward data in the buffer; (6) After the routing interface exits the congestion state, it notifies the SDN controller, which then deletes the bypass flow entry. (7) The upstream router cancels the cache and continues to forward data at the maximum rate.

2. The control method according to claim 1, wherein: In the step (1), Use the LLDP protocol to actively measure and obtain network topology information. The SDN controller periodically sends LLDP packets and calculates the current network topology based on the packets returned by the router port. The link bandwidth information obtained is the remaining bandwidth of the network link. Using the passive measurement method, the SDN controller queries the routing counter statistics through the OpenFlow protocol. The routing returns the forwarding bytes of the data flow passing through the port. Through n and n+1 detections in the same time period T, the data throughput rate per unit time can be obtained. The calculation formula for the data throughput rate is as follows:

3. The control method according to claim 2, wherein: In the step (2), whether the routing interface is congested is determined based on the interface buffer occupancy of the router. When the interface buffer occupancy of the router does not reach the upper threshold, it indicates that no congestion occurs during the data transmission process. When the buffer usage of a router interface exceeds the upper threshold, it indicates that data transmission is congested and the current routing interface status changes to congested.

4. The control method according to claim 3, wherein: In step (3), the detour path is calculated using the obtained network topology information and link bandwidth information. The current network is set to G = (V, E), where V is the set of all nodes in the network, and E is the set of all links in the topology. The link utilization θ is used to represent the weight of the link in the topology, and Bandwidth represents the bandwidth of the link. The link calculation formula is as follows: According to the network topology and the weight information on the corresponding links, the SDN controller uses the single-source shortest path algorithm to calculate the detour path.

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