CN104734963A - IPv4 and IPv6 network interconnection method based on SDN - Google Patents

Abstract

The invention discloses an IPv4 and IPv6 network interconnection method based on an SDN. A domain name resolution module, an address switch module, a translation module, a map module, a topology management module, and a temporary address pool management module are referred in the process of executing the method; the domain name resolution module is a core module and used for processing a DNS request; the address switch module switches an IPv4 address to an IPv6 address and is used for being called by the domain name resolution module; the translation module is used for mutually translating an IPv4 message and an IPv6 message and comprises an IP masthead, an ICMP message and the translation of TCP/UDP messages; the map module is used for maintaining a mapping table of domain names and IP address and storing the mapping relation between the domain names and an IPv4 address and an IPv6 address; the topology management module is used for maintaining global topology of the internet; the temporary address pool management module is used for distributing and recycling the IPv4 address temporarily. By means of the method, the problems of protocol switching and address mapping are solved, and the interconnection and interworking of the internet is achieved.

Description

A method for interconnecting IPv4 and IPv6 networks based on SDN

technical field

The present invention relates to the technical field of network communication, in particular to an SDN-based IPv4 and IPv6 network interconnection method.

Background technique

The IP protocol was born in the mid-1970s. IPv4 is the fourth version of the IP protocol and is currently the most widely used IP layer protocol. IPv4 has played a key role in the development of the internet. However, due to limited address space and improper allocation, the address space of IPv4 has been exhausted. According to the statistical report of IANA, as of February 3, 2011, all IPv4 addresses have been allocated. With the depletion of IPv4, researchers pay more and more attention to the development of IPv6 technology. IPv6 is a new IP protocol proposed by IETF to completely solve the problem of insufficient IPv4 addresses. It adopts a 128-bit address space, solves the shortage of IPv4 addresses and other problems, and improves in many aspects. These improvements mainly include simplified header format, support for extended headers and options, support for automatic configuration, enhanced quality of service QoS, support for anycast, etc.

Since IPv6 was proposed, due to the incompatibility between IPv6 and IPv4, whether IPv4 can transition to IPv6 has become the key to the success of IPv6. Therefore, researchers are looking for a solution for the smooth transition from IPv4 to IPv6 from the very beginning. It's a pity that there is no good solution to completely solve this problem so far. Currently, there are three main schemes for IPv4 and IPv6 interworking: dual-stack technology, tunnel technology, and translation technology. The so-called dual-stack technology means that the terminal/host contains two protocol stacks, IPv4 and IPv6, and the host determines which IP protocol stack to use to send data packets according to the IP address. The disadvantage of this method is that old devices that cannot be upgraded cannot be used, and each node must be configured with two protocol stacks. The tunneling technology encapsulates the message and adds the IPv4 header in front of the IPv6 message. It makes IPv6 packets "look" like IPv4 packets in the IPv4 network, and after reaching the IPv6 network, they are decapsulated and restored to IPv6 packets for forwarding. There are 6rd and A+P schemes that adopt the tunnel mode. This solution only requires dual protocol stacks to be installed on the encapsulation/decapsulation nodes, which is more convenient to implement. The translation technology mainly includes the translation of IPv4 and IPv6 protocol layers, and the translation of applications. The translation of the protocol layer generally adopts NAT-PT technology, and the translation of applications is generally completed through the application proxy gateway ALG. The translation technology does not need to transform the nodes, but the translation method is more complicated, and the overhead of address conversion and protocol conversion is relatively large.

SDN originated from a campus project called clean slate at Stanford University. It is an innovative network architecture, and its core idea is to separate the forwarding plane and the control plane. The centralized SDN controller uses standard interfaces to configure and manage various network devices, making network management more centralized and refined. As the prototype implementation mode of SDN, OpenFlow fully embodies the separation of management and control of SDN. Therefore, people generally regard OpenFlow as the communication standard of SDN, just as the TCP/IP protocol is the communication standard of the Internet.

After searching, there is no patent application for a technical solution closer to the technical solution of this application on the website of the National Patent Office and the website of foreign patent offices, and there is no journal document that is closer to the technical solution of this application. There is only one conference document "DevOps Migration to IPv6 Powered by SDN" adopts SDN as the transition technology of IPv6. At the same time, the Chinese patent document with the publication number CN104135446A and the publication date of November 5, 2014 discloses a system and method for realizing the transition from IPv4 to IPv6 based on SDN. Involving the field of SDN, the hardware of the system includes a controller and a switch, and the software modules of the system are all developed at the application layer of the linux operating system, and the controller includes a first OpenFlow interface module, a first configuration management module, a first flow table management module and The first address management module; the switch includes a second OpenFlow interface module, a second configuration management module, a second flow table management module, a second address management module, a tunnel module and a network address translation NAT module. The invention can flexibly and simply set the transition technology of switches from IPv4 to IPv6, realize flexible control of network traffic, support traditional switches, facilitate expansion, good portability, and easy redevelopment.

However, whether it is the above-mentioned conference documents or the above-mentioned Chinese patent documents, the technical solutions realized therein are quite different from the technical solutions of the present application. It can be seen from the document that this technology does not care about protocol conversion. What SDN does is simply add flow tables, table lookup and forwarding, so it cannot support the intercommunication between non-dual protocol stack IPv4, IPv6 and SDN. It can be seen from the patent document that this method requires the switch to have two OpenFlow interface modules and two OpenFlow flow table modules, and a tunnel module needs to be added to the penFlow switch, so that hardware changes must be made on the existing OpenFlow switch to add new functions. It also complicates the SDN network workflow.

Contents of the invention

The purpose of the present invention is to solve the technical problem that the above-mentioned DevOps technology cannot realize the full intercommunication of SDN, IPv4 and IPv6 networks, and propose an SDN-based IPv4 and IPv6 network interconnection method. The method can solve the problems of protocol conversion and address mapping, and realize the interconnection and intercommunication of the whole network.

The present invention is achieved by adopting the following technical solutions:

A method for interconnecting IPv4 and IPv6 networks based on SDN, characterized in that:

Step 1, when the network is initialized, the SDN controller obtains the SDN global network topology information through detection;

Step 2, through the BGP message interaction between the topology management module and the IPv4 network or the IPv6 network, the SDN controller obtains the reachability information of the IPv6 network and the IPv4 network, and stores them in different tables respectively for use in step 5 to find routes;

Step 3, when a host in an IPv4 or IPv6 network wants to access a non-IPv4 or IPv6 network in the form of a domain name, the host first queries the local DNS cache table, and if there is a matching entry, go to step 11; otherwise, send a DNS request to the source configured by the host DNS server;

Step 4, the source DNS server resolves the domain name, if the resolution is successful, return the IP address obtained after resolution to the host, go to step 11, otherwise go to step 5;

Step 5, the source DNS server sends the DNS request of the domain name to the SDN;

Step 6, the SDN controller of the SDN network invokes the domain name resolution module for processing, and the domain name resolution module first searches whether there is a matching entry in the SDN, if so, go to step 10, otherwise go to step 7;

Step 7, the domain name resolution module judges and generates a DNS request message according to the requested IP address and sends it to the DNS server of the IPv4 or IPv6 network;

Step 8, the DNS server in the corresponding IP network is analyzed, and the resolved IP address is sent to the SDN;

Step 9, the domain name resolution module receives the DNS response message, calls the address conversion module or the temporary address pool management module to generate the entry of "domain name-IPv4-IPv6" and adds it to the mapping module;

Step 10, the domain name resolution module generates a DNS response message containing an IPv4 address or an IPv6 address and sends it to the source requesting DNS, and the source requesting DNS server forwards it to the source requesting host;

Step 11, the source requests the host to communicate with the IP address. When the data packet passes through the SDN, the domain name resolution module invokes the translation module to perform mutual translation of the IPv4 data packet and the IPv6 data packet; the translation module of the step 11 is used for header and Translation of messages.

The "detection" in step 1 means that the SDN controller periodically sends LLDP data packets to detect the active status of nodes in the SDN network, thereby maintaining the active topology of the SDN network.

The reachability information in step 2 is obtained through the interaction of the BGP protocol.

The domain name request sending process of described step 5 is specifically that the source DNS server sets the source IP address as its own IP address, sets the destination IP address as the IP address of the SDN controller, and uses the DNS request content of the source request host as the new DNS Request content; the entire processing process of DNS requests is transparent to the source requesting host.

The "finding" of said step 6 includes two parts: the search of the domain name table of SDN and the search of the mapping module. The former represents that the requested domain name is in the SDN network, and the latter represents that the requested domain name is in other IP networks, but Already cached.

Said step 7 further includes:

If it is in a system interconnected by multiple SDN networks, multiple IPv4 networks, and multiple IPv6 networks, the domain name resolution module needs to send DNS requests to other networks other than its own network and the network where the source DNS request is located, until a certain network DNS server resolves successfully.

The address conversion module of described step 9 is used for converting IPv4 address into IPv6 address according to rules, and the rule that address conversion adopts is to form a new IPv6 address with IPv4 address as a part of IPv6 address, and this IPv6 address consists of prefix, IPv4 address, Suffix composition; for specific rules, refer to the RFC document "IPv6 Addressing of IPv4/IPv6 Translators" (RFC6052).

The temporary address pool management module of the step 9 is used to manage the allocation and reclaim of the temporary address, when the domain name resolution needs to use the temporary IPv4 address, take out an unallocated IPv4 address from the temporary address pool, and according to the expiration mechanism of the mapping module The reclamation of the allocated IPv4 address; the mapping module of the step 9 is used to maintain the mapping table of domain name and IP address, store the mapping relationship of domain name and IPv4 address, IPv6 address, and provide an expiration mechanism; the expiration mechanism of the mapping module Specifically, when a certain mapping relationship has not been used for a period of time, the mapping relationship is deleted, and the temporary address management module is notified to reclaim the temporary IPv4 address of the mapping relationship.

Said step 11 further comprises: the mutual translation of IPv4 data packet and IPv6 data packet, mainly adopt SIIT (Stateless IP/ICMP Translation) technology, carry out the translation of IP header between the two, if it is ICMP message, carry out ICMP-ICMPv6 The translation, if it is TCP/UDP, recalculates the checksum.

Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

1. This technical solution can realize the full intercommunication of SDN, IPv4 and IPv6. Whether it is IPv4 accessing IPv4, IPv6 accessing IPv6, IPv4 accessing IPv6, or IPv6 accessing IPv4, or SDN accessing IP network, this technical solution can ensure mixed network normal communication between hosts.

2. This technical solution has few changes to the traditional network, and only needs to add a routing table entry to the SDN controller of the SDN network on the DNS server. No changes are made to other nodes such as hosts, routers, and switches in the network, which makes this solution well applicable to the current network through simple configuration.

3. The technical solution has strong transparency. For hosts on an IPv4 or IPv6 network, they do not care whether the address corresponding to the domain name is IPv4 or IPv6, and they only need to enter the domain name to access the service. For the complex conversion link in the middle, the host does not know and does not need to know at all. This feature is very important for smooth transition.

4. Compared with the conference document "DevOps Migration to IPv6 Powered by SDN", the special technical effect of this application focuses on the protocol conversion of IPv4-IPv6 from IP layer to application layer, and supports non-dual protocol stack IP network and SDN network interoperability.

5. Compared with the Chinese patent document with the publication number CN104135446A, the special technical effect of this application is that there are few changes to the original network equipment, and the changes are concentrated on the software-programmable controller, which is beneficial to The method is implemented and deployed in a specific network environment.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments of the description, wherein:

Fig. 1 is a block diagram of the SDN-based IPv4 and IPv6 network interconnection method of the present invention.

FIG. 2 is a flowchart of an IPv4 host accessing an IPv6 server according to an embodiment of the present invention.

FIG. 3 is a flowchart of an IPv6 host accessing an IPv4 server according to an embodiment of the present invention.

Detailed ways

Example 1

As the best implementation of this method, referring to Figure 1 and Figure 2, this example takes the IPv4 host H1 accessing the IPv6 server Server (www.aaa6.com) as an example, and briefly describes its communication process, the specific steps are as follows:

Step 1, when a host H1 in the IPv4 network wants to access the domain name www.aaa6.com, and its default DNS server DNS-IPv4 cannot resolve the domain name, it will forward the DNS request to the SDN network;

Step 2: After receiving the domain name resolution request, the SDN controller of the SDN network hands it over to the domain name resolution module for processing. It will first look for relevant modules to see whether there is a matching entry to exist, if there is, directly generate a DNS response message according to the matching entry, and turn to step 6; if not, send a DNS request to the DNS-IPv6 server of the IPv6 network; the step 2 Related modules include SDN domain name table and mapping module;

Step 3: After the DNS-IPv6 server performs resolution, it returns the IPv6 address corresponding to the domain name;

Step 4, the domain name resolution module calls the temporary address pool management module to take an unused IPv4 address from the temporary IPv4 address pool for H1 communication, calls the address conversion module to convert the IPv4 address of H1 into a corresponding IPv6 address, and calls the mapping The module records the mapping relationship; there are two mapping relationships added here, one is the mapping relationship about the IP address of H1, namely "domain name-IPv4 _H1 -IPv6 _H1 ", and the other is the mapping relationship about the IP address of the IPv6 server, namely "Domain-IPv4 _Server -IPv6 _Server ";

Step 5, the domain name resolution module generates a DNS response message according to the newly allocated IPv4 address and forwards it to the DNS server DNS-IPv4 server, and the DNS-IPv4 server slightly modifies the response message and returns it to the host H1;

Step 6, H1 uses the returned IPv4 address as the destination IP address to access the server Server; the message reaches the SDN network;

Step 7, the domain name resolution module of the SDN controller of the SDN network calls the mapping module and the translation module to translate the IPv4 message into an IPv6 message;

Step 8, the IPv6 message enters the IPv6 network from the SDN, the Server returns the result to H1 after processing, and the message passes through the SDN network;

Step 9, the domain name resolution module of the SDN controller of the SDN network calls the mapping module and the translation module to translate the IPv6 message into an IPv4 message;

Step 10, the IPv4 message reaches H1 of the IPv4 network through the SDN network.

Said step 1 further includes: H1 first searches the local DNS cache, if there is no matching item, sends a DNS request message to the DNS server configured on the machine, and if the DNS server cannot find it, it will modify the source address and forward The DNS request is sent to the SDN controller of the SDN network.

Example 2

As the best implementation of this method, referring to Figure 3, this example takes an IPv6 host accessing an IPv4 server Server2 (www.aaa4.com) as an example to briefly describe its communication process, and the specific steps are as follows:

Step 1, when a host H2 in the IPv6 network wants to access the domain name www.aaa4.com, its default DNS server DNS-IPv6 cannot resolve the domain name, and will forward the DNS request to the SDN;

Step 2: After receiving the domain name resolution request, the SDN controller of the SDN network hands it over to the domain name resolution module for processing. It will first call the SDN domain name table and mapping module to find out whether there is a matching entry, if so, directly generate a DNS response message according to the mapping entry, and go to step 6; if not, send a DNS request to the DNS-IPv4 server of the IPv6 network;

Step 3: After the DNS-IPv4 server performs resolution, it returns the IPv4 address corresponding to the domain name;

Step 4, the domain name resolution module calls the temporary address pool management module to take an unused IPv4 address from the temporary IPv4 address pool for H2 communication, calls the address conversion module to convert the IPv4 address of the domain name into a corresponding IPv6 address, and calls the mapping The module records the mapping relationship; there are two mapping relationships added here, one is the mapping relationship about the IP address of H1, namely "domain name-IPv4 _H2 -IPv6 _H2 ", and the other is the mapping relationship about the IP address of the IPv6 server, namely "Domain Name-IPv4 _Server2 -IPv6 _Server2 ";

Step 5, the domain name resolution module generates a DNS response message according to the IPv6 address obtained by the address translation module and forwards it to the DNS server DNS-IPv6, and the DNS-IPv6 slightly modifies the response message and returns it to the host H2;

Step 6, H2 uses the returned IPv6 address as the destination IP address to access the server; the message reaches the SDN;

Step 7, the domain name resolution module of the SDN controller calls the mapping module and the translation module to translate the IPv6 message into an IPv4 message;

Step 8, the IPv4 message enters the IPv4 network from the SDN, Server2 returns the result to H2 after processing, and the message passes through the SDN;

Step 9, the domain name resolution module of the SDN controller invokes the mapping module and the translation module to translate the IPv4 message into an IPv6 message, and delivers the corresponding flow entry;

Step 10, the IPv6 packet reaches H2 through the SDN.

Example 3

As another best implementation of this method, this example takes an SDN host (assumed to be an IPv4 address) accessing an IPv4/IPv6 server Server3 as an example, and briefly describes its communication process. The specific steps are as follows:

Step 1, when a host H3 in the SDN network wants to access the domain name www.aaa4.com, its default DNS server DNS-SDN cannot resolve the domain name, and will forward the DNS request to the SDN controller;

Step 2: After receiving the domain name resolution request, the SDN controller of the SDN network invokes the domain name resolution module for processing. It will first call the mapping module to find out whether there is a matching entry, if so, directly generate a DNS response message based on the mapping entry, and go to step 7; if not, generate a DNS request message and send it to the DNS-IPv4 of the IPv4 network, go to step 3;

Step 3, if the DNS-IPv4 can resolve the domain name, return the corresponding IPv4 address to the domain name resolution module of the SDN, and turn to step 6; otherwise, the SDN controller generates a DNS request message and sends it to the DNS-IPv6 of the IPv6 network; turn to step 4;

Step 4, DNS-IPv6 resolves the domain name, returns the IPv6 address obtained after resolution to the domain name resolution module of SDN, and turns to 5;

Step 5, the domain name resolution module calls the temporary address pool management module to take out a temporary IPv4 address for H3 communication to use;

Step 6, the domain name resolution module calls the mapping module to add the corresponding mapping relationship; there are two mapping relationships added here, one is the mapping relationship about the IP address of H3, that is, "domain name-IPv4H3-IPv6H3", and the other is about the IP address of the server The mapping relationship of addresses, that is, "domain name-IPv4Server3-IPv6Server3";

Step 7, the domain name resolution module of the SDN controller generates a DNS response message according to the IPv4/IPv6 address and returns it to the host H3;

Step 8, H3 uses the returned IPv4/IPv6 address as the destination IP address to access the server.

Claims (9)

1., based on an IPv4 and IPv6 network interconnecting method of SDN, it is characterized in that:

Step 1, during netinit, SDN controller obtains SDN global network topology information by detection;

Step 2, mutual by the BGP message of Topology Management module and IPv4 network or IPV6 network, SDN controller obtains the reachability information of IPv6 network and IPv4 network, respectively stored in different tables, finds route for step 5;

Step 3, when the main frame in IPv4 or IPv6 network will access non-IPv4 or IPv6 network in domain name mode, first main frame inquires about local dns cache table, if there is the entry of coupling, goes to step 11; Otherwise send DNS request to the source dns server of host configuration;

Step 4, source dns server resolves this domain name, if successfully resolved, the IP address obtained after returning parsing, to main frame, goes to step 11, otherwise goes to step 5;

Step 5, source dns server sends the DNS request of this domain name to SDN;

Step 6, the SDN controller of SDN calls domain name mapping module and processes, and first domain name mapping module searches the entry whether SDN has coupling, if go to step 10, otherwise goes to step 7;

Step 7, domain name mapping module judges to generate the dns server that DNS request message is sent to IPv4 or IPv6 network according to the IP address of request;

Step 8, the dns server in corresponding IP network is resolved, and SDN is issued in the IP address after resolving;

Step 9, domain name mapping module receives DNS response message, and the entry that call address modular converter or pond, temporary address administration module produce " domain name-IPv4-IPv6 " adds mapping block to;

Step 10, domain name mapping module produces the DNS response message comprising IPv4 address or IPv6 address and sends to source request DNS, and request dns server in source is transmitted to source requesting host main frame again;

Step 11, source requesting host main frame communicates with this IP address, and packet is through SDN time, and domain name mapping module calls the mutual translation that translation module carries out IPv4 packet and IPv6 packet; The translation module of described step 11 is used for carrying out the translation of header and message.

2. a kind of IPv4 and IPv6 network interconnecting method based on SDN according to claim 1, it is characterized in that: " detection " of described step 1 refers to that SDN controller detects the active state of SDN interior joint by periodically sending LLDP packet, and then maintain the active topology of SDN.

3. a kind of IPv4 and IPv6 network interconnecting method based on SDN according to claim 1, is characterized in that: the reachability information of described step 2 is by the mutual acquisition of bgp protocol.

4. a kind of IPv4 and IPv6 network interconnecting method based on SDN according to claim 1, it is characterized in that: the domain name request process of transmitting of described step 5 specifically source dns server is set to source IP address oneself IP address, object IP address is set to the IP address of SDN controller, using the DNS request content of source requesting host as new DNS request content; The whole processing procedure of DNS request is transparent for the requesting host of source.

5. a kind of IPv4 and IPv6 network interconnecting method based on SDN according to claim 1, it is characterized in that: described step 6 " searching " comprise the domain name table of SDN search with mapping block search two parts, the domain name that the former represents request is in SDN, the domain name of latter representative request in other IP network, but has buffer memory.

6. a kind of IPv4 and IPv6 network interconnecting method based on SDN according to claim 1, is characterized in that: described step 7 comprises further:

If in the system of multiple SDN, multiple IPv4 network and multiple IPv6 network interconnection, domain name mapping module will send a DNS request to other networks of non-network own and DNS request place, source network respectively, until the dns server successfully resolved of some networks.

7. a kind of IPv4 and IPv6 network interconnecting method based on SDN according to claim 1, it is characterized in that: the address conversion module of described step 9 is used for, according to rule, IPv4 address transition is become IPv6 address, the rule that address transition adopts is that IPv4 address is formed a new IPv6 address as the part of IPv6 address, and this IPv6 address is made up of prefix, IPv4 address, suffix.

8. a kind of IPv4 and IPv6 network interconnecting method based on SDN according to claim 1, it is characterized in that: pond, the temporary address administration module of described step 9 is used for managing distribution and the recovery of temporary address, when domain name mapping needs to use temporary IP v4 address, a unappropriated IPv4 address is taken out from pond, temporary address, and according to the expiration mechanism of mapping block to the recovery of the IPv4 address dispensed; The mapping block of described step 9 is used for maintaining the mapping table of domain name and IP address, stores the mapping relations of domain name and IPv4 address, IPv6 address, and provides expiration mechanism; The expiration mechanism of mapping block specifically refers to, when some mapping relations a period of times do not use, delete this mapping relations, and notifies that temporary address administration module reclaims the temporary IP v4 address of these mapping relations.

9. a kind of IPv4 and IPv6 network interconnecting method based on SDN according to claim 1, it is characterized in that: described step 11 comprises further: the mutual translation of IPv4 packet and IPv6 packet, main employing SIIT(Stateless IP/ICMP Translation) technology, carry out the translation of IP header between the two, if icmp packet, carry out the translation of ICMP-ICMPv6, if TCP/UDP, recalculate School Affairs.