阅读说明：本技术 一种基于SDN的IPv4和IPv6互联系统 (IPv4 and IPv6 interconnection system based on SDN ) 是由 王毅 任启 高阳 王海 杨一民 陈琳羽 王锦鹏 杨沛奇 阎轶娟 于洋 于 2019-01-02 设计创作，主要内容包括：本发明提供一种基于SDN的IPv4和IPv6互联系统,利用SDN的技术手段,用控制面提供的标准控制接口编写IPv4与IPv6互联的应用软件,实现IPv4数据包与IPv6数据包的协议翻译和地址转换,然后将其安装配置到SDN控制器中。这种方式不仅配置起来简单方便而且不需要对原有网络设备做功能上的改动。当不需要IPv4与IPv6互联的需求时,只需从控制器中移除IPv4与IPv6互联的功能即可,对网络造成的影响微乎其微。本发明使网络功能的调试测试变得灵活方便,即使以后不再需要某些网络应用功能,只需将相关应用模块从控制器中移除即可,对网络造成的影响微乎其微。(The invention provides an IPv4 and IPv6 interconnection system based on an SDN, which utilizes the technical means of the SDN and uses a standard control interface provided by a control plane to write application software for interconnection of IPv4 and IPv6, realizes protocol translation and address conversion of an IPv4 data packet and an IPv6 data packet, and then installs and configures the data packet in an SDN controller. The mode is not only simple and convenient to configure, but also does not need to change the functions of the original network equipment. When the requirement of interconnection of the IPv4 and the IPv6 is not needed, only the function of interconnection of the IPv4 and the IPv6 needs to be removed from the controller, and the influence on the network is very little. The invention makes the debugging and testing of the network function flexible and convenient, even if some network application functions are not needed any more, only the relevant application modules are removed from the controller, and the influence on the network is very little.)

1. An IPv4 and IPv6 interconnection system based on SDN is characterized by comprising a routing subsystem and an interconnection subsystem;

the routing subsystem is implemented in the controller and can select a path for connecting two networks in the SDN according to the source and destination IP addresses of the received cross-network communication data packets;

after the controller receives a data packet which can not be processed by a switch, if the data packet is found to need translation and conversion, the interconnection subsystem firstly forwards the data packet to an interconnection gateway for processing by the interconnection subsystem; and after receiving the data packet, the internet gateway performs protocol translation and address conversion processing on the data packet, and then sends a new data packet after the translation and conversion is completed to the network for continuous processing by the controller.

2. The SDN-based IPv4 and IPv6 interconnection system of claim 1, wherein the routing subsystem includes three functional modules, a routing configuration module, a routing device probing module, and a routing information management module;

a route configuration module: the network administrator configures the boundary routing equipment and configures the network reachable information of the boundary routing equipment through the module, namely a routing table of the boundary routing equipment;

routing equipment detection module: the module is mainly used for detecting the specific physical information of the positioning boundary routing equipment in the SDN network;

the routing information management module: managing and maintaining known boundary routing devices in the SDN network and network reachable information in the boundary routing devices.

3. The SDN-based IPv4 and IPv6 interconnection system of claim 1, wherein the interconnection subsystem includes two functional modules, DNS-a L G and NAT-PT;

and a NAT-PT module: mainly realizes the translation conversion between the IPv4 format data packet and the IPv6 format data packet, including protocol translation and address conversion.

And the DNS-A L G module establishes the mapping between the IPv4 address and the IPv6 address through domain name resolution on the basis of the NAT-PT module.

4. The SDN-based IPv4 and IPv6 interconnection system of claim 1, wherein the routing subsystem is implemented as follows:

the routing subsystem judges whether a target host of the data packet is in the SDN according to the target IP address of the data packet, and if the target host is in the SDN, the routing subsystem can process the data packet according to the conventional processing flow of the controller; if not, the routing subsystem traverses all the border routing gateway device instances maintained and managed by the routing subsystem, queries which border routing device can reach the destination network for the data packet, obtains the SDN switch connected with the correct border routing device after finding the correct border routing device, and finally selects a path between the two switches according to the conventional processing flow of the controller and issues a flow table.

5. The SDN-based IPv4 and IPv6 interconnection system of claim 1, wherein to implement three-tier routing between different networks, a routing subsystem needs to manage and maintain logic information of border routing gateway devices and network reachability information of border routing gateway devices, and a network administrator can configure both information through a configuration module pair of the routing subsystem; after the configuration module obtains the configuration information parameters, determining the configuration type according to the specific parameter details; if the routing gateway equipment needs to be configured, a detection module constructs equipment detection information and broadcasts the detection information in an SDN network, and for the IPv4 routing gateway equipment, the detection information is an ARP address request message; for the IPv6 routing gateway device, the detection message is an ICMPv6 neighbor address request message; when the basic function module of the controller receives the reply of the detection message, the registration information including the specific position of the equipment in the network is recorded for the equipment. Then, after receiving the reply of the detection message, the management module of the routing subsystem creates a logic instance for the equipment, including a routing table and a routing method of the equipment, and the like; the configuration of the routing gateway equipment is completed; if network reachable information is to be configured for a certain routing gateway device, the management module of the routing subsystem finds a corresponding routing gateway instance according to the specific parameters, and then adds a routing table entry in the routing table.

6. The SDN-based IPv4 and IPv6 interconnection system of claim 1, wherein the interconnection subsystem implementation method is as follows:

the interconnection subsystem firstly filters and classifies received data packets, if the destination IP address of the data packet is the IP address of the interconnection gateway and the source port number or the destination port number of a transmission layer is 53, the data packet is put into a DNS message queue to wait for the processing of a DNS-A L G module, and if the destination IP address of the data packet is an IPv4 address in a temporary IPv4 address pool or an IPv6 address with a specific 96-bit address prefix, the data packet is put into the IP message queue to wait for the processing of the NAT-PT module.

7. The SDN-based IPv4 and IPv6 interconnection system of claim 6, wherein the NAT-PT module obtains messages from an IP message queue, then performs translation conversion processing according to specific message types, performs different processing according to message types, and describes in four steps:

(1) acquiring an original data packet from a message;

(2) inquiring an address translation table according to the IPv4/IPv6 address of the data packet to carry out address mapping translation;

(3) translating and converting the header fields of IPv4/IPv6, ICMPv4/ICMPv6, UDP and TCP according to the actual condition of the data packet;

(4) and directly sending out a new data packet obtained after translation from a link layer, and sending the data packet to a controller by the controller after the data packet reaches a switch of the SDN network because the switch has no flow table item which can be matched.

8. The SDN-based IPv4 and IPv6 interconnection system of claim 6, wherein the DNS-A L G module obtains messages from DNS message queues, then performs corresponding processing according to specific message types, and executes different processing modes according to message types:

(1) DNSv 4: for the DNS request in the IPv4 format, the request type 'A' is changed into 'AAAA', then the destination address is changed into the DNS server address of the IPv6 network, and the source address is changed into the IPv6 address of the device where the interconnection subsystem is located; for the DNS reply in IPv4 format, the request type "a" is changed to "AAAA", and a 96-bit prefix is added to the IPv4 address in the resolution result, as 64 used by the interconnect subsystem: ff9 b: : and/96, and then changing the destination address to the DNS address of the IPv6 network. Finally, the data packet after translation conversion is sent to the SDN network and is continuously processed by the controller;

(2) DNSv 6: for the DNS request, changing the request type 'AAAA' into 'A', then changing the destination address into the DNS server address of the IPv4 network, and changing the source address into the IPv4 address of the device where the interconnection subsystem is located; for the DNS response in the IPv6 format, the request type 'AAAA' is changed into 'A', a temporarily available IPv4 address is allocated from the address pool for the IPv6 in the resolution result, the IPv4 address and the IPv6 address in the resolution result are recorded into an address mapping conversion table as an address mapping pair, and then the destination address is changed into the DNS address of the IPv6 network. And finally, sending the data packet after translation conversion to the SDN network for continuous processing by the controller.

Technical Field

The invention relates to an IPv4 and IPv6 interconnection system based on SDN

Background

With the expansion of network size and the generation of various new applications, IPv4 networks are exposed to more and more problems, such as IPv4 address exhaustion, security problems, QoS (quality of service) problems, insufficient simplicity of configuration, and the like. These problems have severely hampered the current internet development, and therefore a new IPv6 protocol was devised. The cost for completely upgrading the current IPv4 network into the IPv6 network is huge, so that the IPv4 and the IPv6 can exist simultaneously in the future for a long time. In order to ensure the continuity of network traffic, an IPv6 transition technology must be introduced in the stage of coexistence of IPv4 and IPv 6. Each of the transition techniques currently used is only specific to a particular application requirement and is not universal. Therefore, in actual deployment, devices with corresponding functions are added to the network according to specific application requirements, which not only increases the complexity of network functions, but also causes resource waste due to complex configuration.

Sdn (software Defined networking) is a novel network architecture proposed by the university of stanford clean slate research group, and the core idea is to decouple network control and network forwarding in a traditional network into a control plane and a data plane, where the control plane opens standard control interfaces to the outside, and a network administrator can use these control interfaces to write specific network applications to achieve control of specific requirements of the network. And the data plane only carries out processing such as forwarding and the like on data communication in the network according to commands from the control plane. SDN has since its advent enabled the implementation of more flexible, open, fine-grained management and control of networks through software programming with attention from both academic and business circles. At present, OpenFlow is the most approved implementation mode as SDN, and has been widely researched and developed in academia and business circles. SDN is likely to be the direction of next generation internet architectures.

After the emergence of the SDN, much attention and application have been paid to the SDN, but how to introduce the SDN technology into the conventional IPv6 transition technology to solve the complexity of the network and the sustainability of the service in the coexistence phase of IPv4 and IPv6 has not been studied intensively at present.

Disclosure of Invention

Aiming at the defects of the prior art, the invention avoids customizing various complex-configuration network equipment for realizing a certain function in a network, and leads the debugging and the testing of the network function to be flexible and convenient.

In order to achieve the purpose, the invention is realized by the following technical scheme:

the invention relates to an IPv4 and IPv6 interconnection system based on SDN, which consists of a routing subsystem and an interconnection subsystem;

the routing subsystem is implemented in the controller and can select a path for connecting two networks in the SDN according to the source and destination IP addresses of the received cross-network communication data packets;

after the controller receives a data packet which can not be processed by a switch, if the data packet is found to need translation and conversion, the interconnection subsystem firstly forwards the data packet to an interconnection gateway for processing by the interconnection subsystem; and after receiving the data packet, the internet gateway performs protocol translation and address conversion processing on the data packet, and then sends a new data packet after the translation and conversion is completed to the network for continuous processing by the controller.

Furthermore, the routing subsystem comprises three functional modules, namely a routing configuration module, a routing equipment detection module and a routing information management module;

a route configuration module: the network administrator configures the boundary routing equipment and configures the network reachable information of the boundary routing equipment through the module, namely a routing table of the boundary routing equipment;

routing equipment detection module: the module is mainly used for detecting the specific physical information of the positioning boundary routing equipment in the SDN network;

the routing information management module: managing and maintaining known boundary routing devices in the SDN network and network reachable information in the boundary routing devices.

Further, the interconnection subsystem comprises two functional modules, namely a DNS-A L G module and a NAT-PT module;

and a NAT-PT module: mainly realizes the translation conversion between the IPv4 format data packet and the IPv6 format data packet, including protocol translation and address conversion.

And the DNS-A L G module establishes the mapping between the IPv4 address and the IPv6 address through domain name resolution on the basis of the NAT-PT module.

Further, the routing subsystem implementation method is as follows:

the routing subsystem judges whether a target host of the data packet is in the SDN according to the target IP address of the data packet, and if the target host is in the SDN, the routing subsystem can process the data packet according to the conventional processing flow of the controller; if not, the routing subsystem traverses all the border routing gateway device instances maintained and managed by the routing subsystem, queries which border routing device can reach the destination network for the data packet, obtains the SDN switch connected with the correct border routing device after finding the correct border routing device, and finally selects a path between the two switches according to the conventional processing flow of the controller and issues a flow table.

Furthermore, to implement three-layer routing between different networks, the routing subsystem needs to manage and maintain the logic information of the border routing gateway device and the network reachable information of the border routing gateway device, and a network administrator can configure two kinds of information through the configuration module of the routing subsystem; after the configuration module obtains the configuration information parameters, determining the configuration type according to the specific parameter details; if the routing gateway equipment needs to be configured, a detection module constructs equipment detection information and broadcasts the detection information in an SDN network, and for the IPv4 routing gateway equipment, the detection information is an ARP address request message; for the IPv6 routing gateway device, the detection message is an ICMPv6 neighbor address request message; when the basic function module of the controller receives the reply of the detection message, the registration information including the specific position of the equipment in the network is recorded for the equipment. Then, after receiving the reply of the detection message, the management module of the routing subsystem creates a logic instance for the equipment, including a routing table and a routing method of the equipment, and the like; the configuration of the routing gateway equipment is completed; if network reachable information is to be configured for a certain routing gateway device, the management module of the routing subsystem finds a corresponding routing gateway instance according to the specific parameters, and then adds a routing table entry in the routing table.

Further, the implementation method of the interconnection subsystem is as follows:

the interconnection subsystem firstly filters and classifies received data packets, if the destination IP address of the data packet is the IP address of the interconnection gateway and the source port number or the destination port number of a transmission layer is 53, the data packet is put into a DNS message queue to wait for the processing of a DNS-A L G module, and if the destination IP address of the data packet is an IPv4 address in a temporary IPv4 address pool or an IPv6 address with a specific 96-bit address prefix, the data packet is put into the IP message queue to wait for the processing of the NAT-PT module.

7. The SDN-based IPv4 and IPv6 interconnection system of claim 6, wherein the NAT-PT module obtains messages from an IP message queue, then performs translation conversion processing according to specific message types, performs different processing according to message types, and describes in four steps:

(1) acquiring an original data packet from a message;

(2) inquiring an address translation table according to the IPv4/IPv6 address of the data packet to carry out address mapping translation;

(3) translating and converting the header fields of IPv4/IPv6, ICMPv4/ICMPv6, UDP and TCP according to the actual condition of the data packet;

(4) and directly sending out a new data packet obtained after translation from a link layer, and sending the data packet to a controller by the controller after the data packet reaches a switch of the SDN network because the switch has no flow table item which can be matched.

Further, the DNS-a L G module obtains the message from the DNS message queue, performs corresponding processing according to the specific message type, and executes different processing modes according to the type of the message:

(1) DNSv 4: for the DNS request in the IPv4 format, the request type 'A' is changed into 'AAAA', then the destination address is changed into the DNS server address of the IPv6 network, and the source address is changed into the IPv6 address of the device where the interconnection subsystem is located; for the DNS reply in IPv4 format, the request type "a" is changed to "AAAA", and a 96-bit prefix is added to the IPv4 address in the resolution result, as 64 used by the interconnect subsystem: ff9 b: : and/96, and then changing the destination address to the DNS address of the IPv6 network. Finally, the data packet after translation conversion is sent to the SDN network and is continuously processed by the controller;

(2) DNSv 6: for the DNS request, changing the request type 'AAAA' into 'A', then changing the destination address into the DNS server address of the IPv4 network, and changing the source address into the IPv4 address of the device where the interconnection subsystem is located; for the DNS response in the IPv6 format, the request type 'AAAA' is changed into 'A', a temporarily available IPv4 address is allocated from the address pool for the IPv6 in the resolution result, the IPv4 address and the IPv6 address in the resolution result are recorded into an address mapping conversion table as an address mapping pair, and then the destination address is changed into the DNS address of the IPv6 network. And finally, sending the data packet after translation conversion to the SDN network for continuous processing by the controller.

The invention has the following beneficial effects:

the invention uses SDN technical means, uses standard control interface provided by control surface to compile IPv4 and IPv6 interconnected application software, then installs and adds the software into SDN controller in form of plug-in, when the controller receives data packet communicated between IPv4 host and IPv6 host, the data packet is handed to IPv4 and IPv6 interconnected application module to process, then sets corresponding forwarding rule in the switch according to the processing result. And finally, the switch completes transmission and switching on the data packet according to the forwarding rule data issued by the controller. It can be seen that after the SDN is adopted, not only is it avoided to customize various network devices with complex configurations for implementing a certain function in a network, but also the debugging and testing of network functions becomes flexible and convenient. Even if some network application functions are not needed any more in the future, only the relevant application modules need to be removed from the controller, and the influence on the network is very little.

Drawings

Fig. 1 is a schematic diagram of an SDN-based IPv4 and IPv6 interconnection system of the present invention.

Fig. 2 is a flow chart of controller routing according to the present invention.

FIG. 3 is a detailed architecture diagram of an interconnect subsystem of the present invention.

Fig. 4 is a flow chart of the NAT-PT module processing of the present invention.

Fig. 5 is a diagram of the experimental environment of the present invention.

Fig. 6 is a schematic configuration diagram of a border routing gateway of the present invention.

Fig. 7 is a diagram of switch flow table information.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

The research of the interconnection technology of IPv4 and IPv6 is carried out on the basis of an SDN framework, and an SDN-based IPv4 and IPv6 interconnection system is designed. In the system, an SDN technical means is utilized, a standard control interface provided by a control plane is used for writing application software interconnected by IPv4 and IPv6, the application software is installed and added into an SDN controller in a plug-in mode, after the controller receives a data packet communicated between an IPv4 host and an IPv6 host, the data packet is handed to an application module interconnected by IPv4 and IPv6 for processing, and then a corresponding forwarding rule is set in a switch according to a processing result. And finally, the switch completes transmission and switching on the data packet according to the forwarding rule data issued by the controller. It can be seen that after the SDN is adopted, not only is it avoided to customize various network devices with complex configurations for implementing a certain function in a network, but also the debugging and testing of network functions becomes flexible and convenient. Even if some network application functions are not needed any more in the future, only the relevant application modules need to be removed from the controller, and the influence on the network is very little.

The model of the interconnection system of the IPv4 and IPv6 based on SDN is shown in fig. 1, and the whole system is composed of two subsystems, namely a routing subsystem and an interconnection subsystem. The routing subsystem is designed and implemented in the controller, and the routing subsystem selects a path for connecting two networks in the SDN according to the source and destination IP addresses of the received cross-network communication data packets. This is equivalent to connecting to a central router for IPv4 and IPv6 networks connected to an SDN network. If the interconnection subsystem is also designed to be implemented in the controller, all communication data packets between the IPv4 and the IPv6 network need to be processed by the controller, which occupies a large amount of computing resources of the controller. Not only can the communication efficiency between the IPv4 network and the IPv6 network be low, but also the processing of other network services by the controller can be affected. The interconnect system is thus implemented in a stand-alone device, i.e. the interconnect gateway in the figure. The controller may select a path through the inter-connected gateway device in the SDN network for data communications between the IPv4 and the IPv6 networks.

Routing subsystem

The controller selects a path for data communication between the IPv4 network and the IPv6 network, whether a data packet needs to be processed by an internet gateway or an exit boundary route of the data packet is judged according to an IP address, the SDN controller only realizes a basic management control function of the SDN network, the SDN controller actually manages a two-layer link network, and the three-layer routing function between different networks is not supported. The routing subsystem is thus designed and implemented on the basis of the basic functional architecture of the controller, which for other networks connected to the SDN network amounts to a central router. The routing subsystem comprises three functional modules, namely a routing configuration module, a routing equipment detection module and a routing information management module.

1. A route configuration module: the network administrator configures the boundary routing device and configures the network reachable information of the boundary routing device, namely the routing table of the boundary routing device through the module.

2. Routing equipment detection module: the module is mainly used for detecting specific physical information of the positioning boundary routing equipment in the SDN network.

3. The routing information management module: managing and maintaining known boundary routing devices in the SDN network and network reachable information in the boundary routing devices.

Interconnection subsystem

After the controller receives a data packet which can not be processed by the switch, if the data packet needs to be translated and converted, the data packet is firstly forwarded to the internet Gateway to be processed by the internet subsystem, the internet Gateway performs Protocol Translation and Address conversion processing on the data packet after receiving the data packet, and then sends a new data packet after the Translation and conversion is completed to a Network to be processed by the controller continuously, wherein the internet subsystem comprises two functional modules, namely a DNS-A L G (Domain Name System-Application L eye Gateway) module and a NAT-PT (Network Address Translation-Protocol Translation) module.

NAT-PT module: mainly realizes the translation conversion between the IPv4 format data packet and the IPv6 format data packet, including protocol translation and address conversion.

And 2, a DNS-A L G module, which is used for establishing the mapping between the IPv4 address and the IPv6 address through domain name resolution on the basis of the NAT-PT module.

Routing subsystem

The processing flow after the controller added into the routing subsystem receives the data packet which the switch cannot process is shown in fig. 2. The routing subsystem judges whether a target host of the data packet is in the SDN according to the target IP address of the data packet, and if the target host is in the SDN, the routing subsystem can process the data packet according to the conventional processing flow of the controller; if not, the routing subsystem traverses all the border routing gateway device instances maintained and managed by the routing subsystem, queries which border routing device can reach the destination network for the data packet, obtains the SDN switch connected with the correct border routing device after finding the correct border routing device, and finally selects a path between the two switches according to the conventional processing flow of the controller and issues a flow table.

The inter-gateway device is also a border routing device and the networks it reaches include an IPv4 network representing all IPv6 networks and an IPv6 network representing all IPv4 networks. For a packet from an IPv4 network host and a destination host in an IPv6 network, the routing subsystem would consider the packet to be able to reach the destination network through the inter-gateway device, and the controller would forward the packet to the inter-gateway device. The interconnection gateway device translates and converts the received IPv4 data packet into an IPv6 data packet and sends the IPv6 data packet back to the SDN network, similar to the previous processing flow, the routing subsystem finds an exit boundary routing device for the new IPv6 data packet, and then the controller selects a forwarding path and sends a flow table to a switch on the path.

To implement three-layer routing between different networks, the routing subsystem needs to manage and maintain the logic information of the border routing gateway device and the network reachable information of the border routing gateway device. A network administrator may configure both types of information through a configuration module pair of the routing subsystem. And after the configuration module obtains the configuration information parameters, determining the configuration type according to the specific parameter details. If the routing gateway equipment needs to be configured, a detection module constructs equipment detection information and broadcasts the detection information in an SDN network, and for the IPv4 routing gateway equipment, the detection information is an ARP address request message; for the IPv6 routing gateway device, the probe message is an ICMPv6 neighbor address request message. When the basic function module of the controller receives the reply of the detection message, the registration information including the specific position of the equipment in the network is recorded for the equipment. Then, after receiving the reply of the probe message, the management module of the routing subsystem creates a logic instance for the device, including a routing table and a routing method of the device. And the configuration of the routing gateway equipment is completed. If network reachable information is to be configured for a certain routing gateway device, the management module of the routing subsystem finds a corresponding routing gateway instance according to the specific parameters, and then adds a routing table entry in the routing table.

Interconnection subsystem

The interconnection subsystem firstly filters and classifies the received data packet, if the destination IP address of the data packet is the IP address of the interconnection gateway and the source port number or the destination port number of the transmission layer is 53, the data packet is put into the DNS message queue to wait for the DNS-A L G module to process, and if the destination IP address of the data packet is the IPv4 address in the temporary IPv4 address pool or the IPv6 address of a specific 96-bit address prefix, the data packet is put into the IP message queue to wait for the PT-module to process.

The NAT-PT module mainly obtains a message from the IP message queue, then performs translation and conversion processing according to a specific message type, and performs different processing according to the message type, and a specific processing flow is shown in fig. 4, and can be roughly described in four steps:

(1) the original data packet is obtained from the message.

(2) And inquiring an address translation table according to the IPv4/IPv6 address of the data packet to perform address mapping translation.

(3) And translating and converting the header fields of IPv4/IPv6, ICMPv4/ICMPv6, UDP and TCP according to the actual condition of the data packet.

(4) And directly sending out a new data packet obtained after translation from a link layer, and sending the data packet to a controller by the controller after the data packet reaches a switch of the SDN network because the switch has no flow table item which can be matched.

The DNS-A L G module mainly obtains the message from the DNS message queue, and then performs corresponding processing according to the specific message type.

(1) DNSv 4: for the DNS request in the IPv4 format, the request type 'A' is changed into 'AAAA', then the destination address is changed into the DNS server address of the IPv6 network, and the source address is changed into the IPv6 address of the device where the interconnection subsystem is located; for the DNS reply in IPv4 format, the request type "a" is changed to "AAAA", and a 96-bit prefix is added to the IPv4 address in the resolution result, as 64 used by the interconnect subsystem: ff9 b: : and/96, and then changing the destination address to the DNS address of the IPv6 network. And finally, sending the data packet after translation conversion to the SDN network for continuous processing by the controller.

(2) DNSv 6: for the DNS request, changing the request type 'AAAA' into 'A', then changing the destination address into the DNS server address of the IPv4 network, and changing the source address into the IPv4 address of the device where the interconnection subsystem is located; for the DNS response in the IPv6 format, the request type 'AAAA' is changed into 'A', a temporarily available IPv4 address is allocated from the address pool for the IPv6 in the resolution result, the IPv4 address and the IPv6 address in the resolution result are recorded into an address mapping conversion table as an address mapping pair, and then the destination address is changed into the DNS address of the IPv6 network. And finally, sending the data packet after translation conversion to the SDN network for continuous processing by the controller.

Simulation environment construction

The equipment and tools required for system simulation are shown in fig. 1, and in the simulation experiment environment of the present disclosure, a physical PC host is used for simulation of an SDN network. As used herein, an SDN controller is flodlight, which is an open source controller, and a routing subsystem is added to the above implementations herein. The method comprises the steps of selecting an OpenvSwitch simulation SDN switch, and simulating and building an SDN network topology. Two virtual machines are created using a VirtualBox, detailed with reference to figure 1. The constructed experimental simulation network is shown in fig. 5.

Functional testing

The method includes the steps that before the whole interconnection system is tested, an SDN network boundary routing gateway is configured in a Floodlight controller, and routing information of a network where the SDN network boundary routing gateway is added is configured, and the method is also used for testing a routing subsystem. In the experimental simulation, although the IPv4 host1 and the IPv6 host2 represent the IPv4 network and the IPv6 network actually connected to the SDN network, respectively, they are also ordinary hosts under the SDN network, and thus, they are not required to be border routing gateways. But the internet gateway acts as a special border routing device whose reachable networks are 222.205.38.0/24 and 64: ff9 b: : 0/96, it needs to be set up in the routing subsystem. Thus, in the experiment, the interconnection gateway was configured as an IPv4 border routing gateway and an IPv6 border routing gateway, and then configured with routing information for the networks to which the two border routing gateways reach. Fig. 6(a) shows the configuration of IPv4 network border routing gateways and IPv6 network border routing gateways, and fig. 6(b) shows the configuration of routing tables for two border routing gateways. Now, the connectivity between the IPv4 host1 and the IPv6 host2 is tested, and the connectivity between the host1 and the host2 is tested by using the domain name "www.zyt.com" of the host2, and as can be seen from the test result, the domain name "www.zyt.com" of the IPv6 host2 is resolved into 222.205.38.1, which is an address in a temporary address pool in the interconnect subsystem, and it is described that the interconnect gateway allocates a temporary IPv4 address to the IPv6 address of the host2 from the temporary address pool when processing a domain name resolution packet, and address mapping is completed.

The overall progress of the communication between host1host2 can be seen by looking at the flow entries in bridges br0, br1, and br 2. First, bridge br1, which has only flow table entries of IPv4 protocol, as shown in fig. 7(a), can see UDP type message communication between host1 and the internet gateway, which is the domain name resolution request and domain name resolution reply between them according to the port number. There are also communication messages between host1 and host with address 222.205.38.1, and the sending and receiving of these messages are still between host1 and the internet gateway, which is the IPv4 part of the whole communication process of host1 and host 2. The second is bridge br0, whose flow table entry includes both the flow table entry of IPv6 protocol and the flow table entry of IPv4 protocol, from which the translation and conversion process of the packet can be seen, as shown in fig. 7(b), according to the packet type and port number, not only the interaction of the domain name resolution packet between the internet gateway and host1, but also the interaction of the domain name resolution packet between the internet gateway and host2 can be seen. Also, the conversion of host1 and host2 communication messages, it can be seen that in the IPv4 portion of host1 communicating with host2, host2 maps address 222.205.38.1 using IPv6, while in the IPv6 portion of host1 communicating with host2, host1 maps address 64 using IPv 4: ff9 b: : c0a 8: 3802 the two parts of the communication message must pass through the internet gateway, which is responsible for translation. Finally bridge br2, which has only flow entries of the IPv6 protocol, is similar to br1, but it exhibits the IPv6 part of the overall communication process of host1 and host 2.

The expected test results can also be obtained by testing connectivity with host1 on IPv6 host2 using the domain name "www.zql.com" of IPv4 host 1.

The advent of SDN has brought about a software and driver approach to managing control networks, which has great advantages over the problems that are difficult to solve in traditional networks through a new network architecture formed by decoupling the control logic and data logic of traditional networks. The SDN is introduced on the basis of the traditional IPv6 transition technology, an SDN-based IPv4 and IPv6 interconnection system is researched and designed by utilizing the technology of control and forwarding separation, and the whole interconnection system consists of a routing subsystem and an interconnection subsystem. The routing subsystem mainly realizes the maintenance and management of configuration, detection, routing tables and other information of the border routing gateway equipment, and the controller can search a path for connecting an IPv4 network and an IPv6 network in the SDN network topology according to the maintained routing tables. The interconnection subsystem realizes the establishment of the mapping relation between the IPv4 address and the IPv6 address in the domain name resolution stage and the protocol translation and address conversion between the IPv4 data packet and the IPv6 data packet in the data communication process in the communication process of the IPv4 host and the IPv6 host. Finally, an SDN simulation network based on an OpenFlow technology is built by using tools such as a Floodlight controller, an Openvswitch and the like to test an interconnection system and analyze a test result.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.