CN102098352A

CN102098352A - Network system and method for supporting host computer mobility in Internet protocol version 4 (IPv4)-Internet protocol version 6 (IPv6) hybrid network environment

Info

Publication number: CN102098352A
Application number: CN2011100220915A
Authority: CN
Inventors: 王文东; 卢美莲; 龚向阳; 阙喜戎; 贾亦辰; 回全超; 章碧云
Original assignee: Beijing University of Posts and Telecommunications
Current assignee: Beijing University of Posts and Telecommunications
Priority date: 2011-01-19
Filing date: 2011-01-19
Publication date: 2011-06-15
Anticipated expiration: 2031-01-19
Also published as: CN102098352B

Abstract

The invention discloses a network system and a network method for supporting host computer mobility in an Internet protocol version 4 (IPv4)-Internet protocol version 6 (IPv6) hybrid network environment. The system is provided with a dynamic host configuration protocol (DHCP) server, a host computer, a mapping server and a boundary router, wherein functional modules are extended for the DHCP server and the host computer; the added mapping server is only used for storing the mapping relation between a host computer home address which belongs to a domain before movement and an intra-site automatic tunnel addressing protocol (ISATAP) care-of address after movement; the boundary router is required to support dual stacks and an ISATAP, and is used for recording an identifier (ID) and a boundary router address of the domain where the host computer is positioned in a newly-added option field of a DHCP response message; and the host computer can detect the mobility of the host computer to obtain the ID and the boundary router address of the domain, and transmits a mapping update message to the mapping server and an opposite communication end. By the system and the method, the mobility in a transition stage from the IPv4 to the IPv6 is well supported, the conventional IPv4 network equipment is fully utilized, and capitals and manpower needed by the updating of the transition stage and the deployment of new equipment are reduced. The network system has a simple structure, the mapping server has simple functions, any manual configuration is not required, and good popularization prospect is achieved.

Description

Network system and method for supporting host mobility in a hybrid network environment of IPv4 and IPv6

Technical Field

The invention relates to a network system and a method for supporting host mobility under an IPv4 and IPv6 mixed network environment, belonging to the technical field of network communication.

Background

With the rapid development of the internet, the demand for host mobility is increasing. However, the existing network environment is still in the transition phase and is likely to be in the environment of such a hybrid network of IPv4 and IPv6 for a considerable period of time in the future. Fig. 1, 2 and 3 show several mobility communication scenarios that may occur during the transition phase. Fig. 1 shows that a dual-stack host in an IPv4 environment performs IPv6 communication across an IPv6 core network, and moves within an IPv4 network domain. Fig. 2 shows that a dual-stack host in an IPv4 environment performs IPv6 communication across an IPv6 core network, and moves between IPv4 network domains. Fig. 3 shows a dual stack host in an IPv6 network communicating with a dual stack host in an IPv4 network, the dual stack host moving from an IPv6 network to an IPv4 network. In the prior art, the tunnel technology of IPv6in IPv4 can be used to complete the transmission of IPv6 data packets sent by dual-stack hosts in an IPv4 network. However, the prior art does not fully consider host mobility for such transitional scenarios.

An existing automatic tunneling technology of IPv6in IPv4 is introduced: Intra-Site Automatic Tunnel Addressing Protocol ISATAP (Intra-Site Automatic Tunnel Addressing Protocol) (rfc 5214). The ISATAP tunnel address has a specific format (see FIG. 4), when the dual stack host supports ISATAP, the prefix (FE 80:) of the local link and the 64-bit interface identifier:: 0:5EFE: w.x.y.z (wherein w.x.y.z is IPv4 unicast address) are automatically generated at the tunnel interface, thus forming an ISATAP local link address, and the host can use the address to communicate with other ISATAP hosts in the same domain for IPv 6. If communication with an ISATAP host or an IPv6 host of another network is required, a global unicast address prefix (2001:, 2002:, 3 FFE:) must be obtained by the ISATAP router and communicated with the other IPv6 host and network through the router.

Although the ISATAP tunnel technology solves the problem of transmission of IPv6 data packets sent by a dual-stack host in an IPv4 network, when the dual-stack host moves into a pure IPv4 domain and needs to communicate with an opposite-end host using an ISATAP tunnel, the technology cannot support the host to automatically form a new ISATAP tunnel address, that is, it does not support mobility of the dual-stack host in such a scenario.

Another prior art is mobile IP technology: the working process of the mobile IPv4 mainly comprises a proxy search and mobility detection process, a registration process and a routing process. After the mobile host changes its Internet connection point, the mobile host can judge whether it is on the home network or the foreign network through the received agent notification message. If it finds itself has moved to a foreign network, it will obtain a care-of address on the foreign network, and the mobile host registers its care-of address with the home agent. The home agent intercepts packets destined to the mobile host's home address and sends the packets to the mobile host via the foreign agent. Thereafter, the packet sent by the mobile host is sent directly to the correspondent without going through the home agent. The mobile IPv4 technology can keep communication with the correspondent terminal under the condition of keeping the IP address unchanged, so that the original communication can be kept by the IP address before the mobile host leaves the home network after the mobile host leaves the home network.

Compared with the IPv4, the IPv6 has a larger address space, and due to advantages in terms of automatic address configuration and neighbor discovery mechanisms, the address configuration of the mobile host after the mobile host moves and the working process of the mobile IPv6 are simpler. The mobile IPv6 protocol removes foreign agents, the mobile host completes the mobile detection process through a neighbor discovery mechanism, and forms a care-of address according to the network prefix in the received router advertisement message RA (RouterAdvertisement) from a new router; then sending binding update message to home agent and communication opposite host, establishing binding relation between home address and care-of address at home agent and communication opposite host, then two hosts communication process no longer need passing home agent, avoiding triangle route problem in mobile IPv 4.

However, both the mobile IPv4 technology and the mobile IPv6 technology consider only the mobility of hosts in the communication between IPv 4-only environments and the communication between IPv 6-only environments, and ignore the mobility in the transition phase, so that it has the following two disadvantages: when the dual-stack host in the pure IPv4 network traverses the pure IPv6 network or communicates with the IPv6 host in the pure IPv6 network, the dual-stack host moves in or among the pure IPv4 network or moves between the pure IPv4 network and the IPv6 network.

The third prior art is support of host mobility by HIP, which designs a sink server rvs (rendezvous server) for node mobility, and stores mapping relationship of host HIT-IP for querying current IP address of mobile node. For initial communication, the host registers its own HIT-IP mapping with the RVS, and then the I1 message sent by the communication initiator is forwarded to the destination node via the RVS. All subsequent packets are then sent by both parties and the RVS is no longer involved.

When the host detects that the host moves, an update message is sent to the RVS to update the mapping information of the HIT-IP of the host, then data packets are continuously sent to the communication opposite terminal to complete the new HIP basic exchange, the address information of the communication opposite terminal is informed, and the previous session connection is continued.

HIP relies on modifications to the conventional protocol hierarchy to better support mobility of hosts, but the following problems also exist: as with the mobile IP technology, the host mobility scenario and the communication procedure thereof that may occur in the transition phase are not fully considered, and only the host mobility in the case of communication between IPv 4-only environments and IPv 6-only environments is considered. When the host moves, the process of detecting the movement of the mobile host and forming a new address is not deeply considered.

Disclosure of Invention

In view of this, an object of the present invention is to provide a network system and method for supporting host mobility in a mixed network environment of IPv4 and IPv6 for a mobility communication scenario that may occur in several transition phases as shown in fig. 1, fig. 2, and fig. 3, so that a dual-stack host moves from an IPv4 network domain or an IPv6 network domain to an IPv4 network domain, and when an IPv6in IPv4 tunnel is needed for communication, the mobile host can automatically acquire an address of a border router and an identifier of the domain, and form an ISATAP tunnel address by using an ISATAP tunnel technology according to whether intra-domain movement or inter-domain movement occurs, and then send an update message to a mapping server and a correspondent node, so that the original communication can continue after the host moves.

In order to achieve the above object, the present invention provides a network system supporting host mobility in a mixed network environment of IPv4 and IPv6, which is provided with a dynamic host configuration protocol dhcp (dynamic host configuration protocol) server, a host, and a border router; the method is characterized in that: in order to support mobility of a mixed scene of IPv4 and IPv6, the system expands functional modules for both a DHCP server and a host, and is additionally provided with a mapping server; wherein,

the DHCP server is positioned in the pure IPv4 domain and is used for distributing an IPv4 address to the host, recording the pure IPv4 domain identification ID where the host is positioned and the address of the domain boundary router, adding the information into a DHCP response message of the newly added option field and sending the DHCP response message to the host;

the host is a dual-stack host which simultaneously supports an IPv4 protocol and an IPv6 protocol, has an ISATAP interface and can use an ISATAP tunnel to complete communication; the host supports a link state detection function to detect the movement behavior of the host; the host also supports a DHCP client and expands the function of the traditional DHCP client, after receiving the DHCP response message of the newly added option field, the host analyzes the newly distributed IPv4 address information and also analyzes the field to obtain the ID of the domain and the address of the boundary router of the domain, and then compares the domain ID field to judge whether inter-domain movement or intra-domain movement occurs so as to execute the subsequent operation of forming an ISATAP care-of address; after moving and forming a new address, the host sends a mapping update message to a mapping server and a communication opposite terminal so as to update the mapping information of home addresses and ISATAP care-of addresses before and after the host moves, and processes an update response message returned by the mapping server and the communication opposite terminal;

the mapping server is provided with three modules: the mapping information receiving/sending module, the mapping information storage management module and the mapping information query module; each domain is provided with a mapping server which is responsible for maintaining the mapping information of the home address of the mobile host belonging to the domain and the ISATAP care-of address before moving; the mapping server in the pure IPv4 domain is a dual-stack host with an ISATAP interface and supporting an ISATAP tunnel, and the mapping server in the pure IPv6 domain supports an IPv6 protocol;

and the boundary router is positioned at the edge of the pure IPv4 domain or the pure IPv6 domain respectively and is a dual-stack router supporting ISATAP.

In order to achieve the above object, the present invention further provides an operating method of a network system supporting host mobility in a hybrid network environment of IPv4 and IPv6, where the host mobility includes two types: the host moves in the domain of site migration in the same border router administrative range, and the host moves from one border router administrative range to another border router administrative range; the method is characterized in that: the method comprises the following operation steps:

(1) movement detection and new address formation after movement of the host: the host judges whether the host moves by adopting a link state detection method; if the mobile host moves, the mobile host immediately sends a DHCP request message to a DHCP server, then the mobile host analyzes relevant information from a replied extended DHCP response message, and a new address is formed by utilizing an ISATAP tunnel technology: the ISATAP care-of address after moving;

(2) the mobile host updates mapping information to the mapping server: the mobile host updates the mapping information of the home address and the ISATAP care-of address to a mapping server by adopting an ISATAP tunnel technology and a standard routing mechanism, so that other hosts only knowing the home address of the mobile host can communicate with the mobile host;

(3) the mobile host updates mapping information to the correspondent node: the mobile host updates the mapping information of the home address and the ISATAP care-of address to the communication opposite end by adopting an ISATAP tunnel technology and a standard routing mechanism so that a data packet sent by the communication opposite end can be directly sent to the mobile host;

(4) establishing a communication link to realize conversation: after the steps are completed, the mobile host can continue to carry out conversation with the communication opposite terminal, and the communication process is the same as that before the host moves.

The technical innovation of the invention is as follows: the DHCP protocol is firstly expanded, and fields are added in the DHCP response message to carry the ID of the domain where the domain is and the address of the router at the boundary of the domain. A network system architecture for supporting host mobility in IPv4 and IPv6 mixed network environment is proposed, in which the function of a mapping server is to maintain the mapping information of the home address and ISATAP care-of address of the mobile host belonging to the domain, and only one mapping server is needed in each domain. The function of the DHCP server, in addition to assigning IPv4 addresses to the host, is to record the ID of the domain in which it is located and the address of the domain border router. The mobile host is used as a DHCP client, after the ID of the domain where the mobile host is located is obtained, the domain ID fields are compared, and whether inter-domain movement or intra-domain movement occurs is judged. The border router in the system must be a dual stack router that supports ISATAP tunnels. In addition, a method for supporting mobility of a host in a hybrid network environment of IPv4 and IPv6 is also provided.

The invention has the advantages and effects that: the method of the invention can well support the mobility from IPv4 to IPv6in the transition stage, still adopts an IPv4 router in a pure IPv4 domain, does not need any change, and only needs to upgrade the boundary router into a dual-stack router supporting an ISATAP tunnel, thus fully utilizing and protecting the existing IPv4 network equipment and reducing the fund and manpower for upgrading and deploying the equipment in the transition stage. The additional mapping server of the invention has the functions of: the mapping relation between the home address of the mobile host belonging to the domain and the ISATAP care-of address is stored; meanwhile, the number of the mapping servers is obviously reduced compared with that of the home agents, the mapping servers are not limited to the home link of the host, and each domain is guaranteed to have one mapping server. The method of the invention does not need any manual configuration, and compared with the mobile IPv4, the method saves the expense of the foreign agent network element, when the routers in the domain are completely upgraded to the IPv6, the data packets forwarded by the domain can be directly forwarded by adopting the IPv6, and only the process of starting the ISATAP tunnel is not needed, thereby realizing the smooth transition capability of the network equipment from the IPv4 to the IPv 6. Therefore, the invention has good popularization and application prospect.

Drawings

Fig. 1 is a diagram of a scenario in which a dual stack host moves within an IPv4 domain.

Fig. 2 is a scene diagram of the movement of dual-stack hosts between IPv4 domains.

Fig. 3 is a scene diagram of a dual stack host moving from an IPv6 domain to an IPv4 domain.

Fig. 4 is a schematic diagram of the format of the ISATAP tunnel address.

Fig. 5 is a schematic diagram of a network system in which dual-stack hosts move in IPv4 domain.

Fig. 6 is a schematic diagram of a network system in which dual-stack hosts move between IPv4 domains.

FIG. 7 is a diagram of a network system in which dual stack hosts move from IPv6 domain to IPv4 domain.

Fig. 8 is a format diagram of the new option field of the DHCP reply message of the present invention.

Fig. 9 is a block diagram of a network system supporting mobility of hosts in a hybrid network environment of IPv4 and IPv6 according to the present invention.

FIG. 10 is a timing diagram of the complete operation of the dual stack host of the present invention moving within a domain.

FIG. 11 is a timing diagram of the complete operation process of the dual stack host of the present invention moving between domains.

Fig. 12 is a timing diagram of the movement detection and new address formation process of the method of the present invention moving within a domain.

Fig. 13 is a timing diagram of the movement detection and new address formation process of the method of the present invention moving between domains.

Fig. 14 is a block diagram illustrating a network system in which hosts move in a hybrid network environment of IPv4 and IPv6in an ID/Locator separated network architecture according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the accompanying drawings.

Referring to fig. 1, 2 and 3, several host movement scenarios that may occur during the transition phase to which the present invention is applicable will be described. When a dual-stack host in an IPv4 network environment needs to communicate across an IPv6 network environment, the tunneling technique of IPv6in IPv4 must be used, that is, the host must form a tunnel address in an IPv6 address format (as shown in fig. 4), where a prefix of the tunnel address must be applied to a border router for acquisition. In the existing mobile IPv4 technology, when a Host moves into a new IPv4 domain, the Host may obtain a new IPv4 address through foreign agent allocation or dynamic Host Configuration protocol (dhcp), but cannot automatically obtain a tunnel address prefix in the IPv6 format, so that a new tunnel address cannot be formed, and communication may be interrupted.

In order to solve the problems, the idea of the invention is as follows: when the dual-stack host moves into a pure IPv4 domain, the mobile host can automatically acquire the address of the boundary router of the accessed network and the domain identification by expanding the DHCP protocol and the dual-stack host function and setting a mapping server, a DHCP server and a boundary router supporting the ISATAP tunnel technology in the network, and judge whether the mobile host moves in the domain or between the domains according to the domain identification. If the mobile host moves in the domain, automatically forming an ISATAP care-of address for the mobile host by utilizing an ISATAP tunnel technology; if the mobile terminal moves between domains, a neighbor discovery mechanism supported by an ISATAP tunnel technology is used for automatically acquiring a tunnel address prefix for the mobile host, and then the ISATAP care-of address is automatically formed locally by the mobile host. After acquiring the new ISATAP care-of address, the mobile host needs to update the mapping information between the home address of the mobile host and the newly formed ISATAP care-of address to the mapping server and the correspondent host, and then continue the communication with the correspondent host by using the ISATAP care-of address.

In order to make the host automatically obtain new ISATAP tunnel address prefix after moving to a pure IPv4 domain, the invention expands DHCP protocol, when the mobile host applies for new IPv4 address to the DHCP server of the domain where the mobile host is located, an option field is added in the DHCP response message replied by the DHCP server to inform the host of the ID of the domain and the address of the boundary router of the domain.

Referring to fig. 8, 4 parts of the format of the new option field in the DHCP reply message are described: type (Type), Length (Length), Domain identification (Domain ID) and border router address (Edge RouterAddresses).

The Type is the mark of the newly added option field, is formed by specific numbers, characters or a mixture of the numbers and the characters, and is used for indicating that the storage content of the field is the domain mark and the address of the border router, so that the host can quickly and definitely find the field after receiving the DHCP response message.

The Length is the Length of the option field.

The Domain identification Domain ID is an ID of a Domain for distinguishing different domains; when the host moves in the domain, the ISATAP tunnel address prefix does not need to be acquired again; however, during inter-domain movement, because ISATAP tunnel address prefixes of all IPv4 domains are different, the mobile host acquires a new ISATAP tunnel address prefix from the boundary router, so that the option field is newly added; the field contents of different DHCP servers in the same IPv4 domain are the same, and the field contents of the DHCP servers in different IPv4 domains are different;

the Edge Router Addresses are IPv4 Addresses of Edge routers, and since there may be more than 1 Edge Router of the domain, the address of the field is 1 or more.

Referring to fig. 9, a network system composition structure supporting host mobility in the mixed network environment of IPv4 and IPv6 according to the present invention is described (the network system composition structure of the present invention supporting three mobility scenarios at the transition stage as shown in fig. 1, fig. 2, and fig. 3 is respectively shown in fig. 5, fig. 6, and fig. 7). In order to support host mobility in the mixed scenario of IPv4 and IPv6, a DHCP server, a host, a mapping server, and a border router supporting ISATAP tunneling are provided in each IPv4 network domain. The network system of the present invention expands the functions of the DHCP server and the host in the existing network, and adds a mapping server, and the specific functions of each network element in the network system of the present invention are specifically described as follows:

the DHCP server is located in the IPv 4-only domain, and besides being able to allocate an IPv4 address to the host, the DHCP server needs to record the ID information of the domain where the DHCP server is located and the address of the IPv4 domain border router, and add these information to the DHCP reply message and send the DHCP reply message to the host. In order to complete the extended function, besides the existing DHCP request message receiving/processing module, IPv4 address information setting module and DHCP response message sending module, the DHCP server adds a module: and the domain ID and boundary router information storage and setting module is responsible for storing the ID of the domain where the DHCP server is located and the boundary router address in the DHCP server and setting the ID and the boundary router address in a newly-added option field in the DHCP response message.

Because hosts in the IPv4 domain use ISATAP tunnel communication, whether under the traditional TCP/IP network architecture or the novel ID/Locator separation network architecture or under the pure IPv4 domain or the pure IPv6 domain before moving, the hosts must be dual-stack hosts which have ISATAP interfaces to support ISATAP tunnel completion communication. In addition, the host needs to support the DHCP client and perform function extension on the conventional DHCP client, so that after receiving the DHCP response message of the newly added option field of the present invention, the host can analyze the field, obtain the ID of the domain in which the host is located and the address of the border router, and determine whether inter-domain movement or intra-domain movement occurs by analyzing the domain ID field, so as to perform the next operation of forming an ISATAP address. The host needs to have a function of sending mapping update messages to the mapping server and the correspondent node to update the mapping information of the home address and the ISATAP care-of address of the host, and can process the update response messages returned by the mapping server and the correspondent node.

In order to detect whether the host moves so as to acquire the ID of a domain and the address of a boundary router, form a globally routable ISATAP tunnel address, and respectively send mapping update messages to a mapping server and a communication opposite end, the following five modules are additionally arranged: the device comprises a link state detection module, a newly added field analysis module, a domain ID comparison and storage module, a global ISATAP tunnel address forming module and an update mapping information sending/receiving module. Wherein,

the link state detection module is responsible for monitoring the connection condition of a host link so as to judge whether the host moves; if the movement occurs, the host is triggered to send a DHCP request message.

And the newly added field analysis module is responsible for analyzing the newly added option field in the DHCP response message and acquiring the ID of the domain where the host is located and the address of the boundary router.

The domain ID comparison and storage module is responsible for comparing a new domain ID obtained by analyzing the DHCP message with a domain ID stored in the local host computer and judging whether the host computer moves in the domain or between the domains; if the two are the same, the host is moved in the domain, and the domain ID stored in the local host does not need to be changed; if the two are different, it is indicated that the host is inter-domain mobile, and the domain ID stored locally in the host needs to be changed into a new domain ID obtained through analysis.

The global ISATAP tunnel address forming module is used for forming a global ISATAP tunnel address according to the comparison result of the domain ID comparison and storage module; if the mobile terminal moves in the domain, directly forming a global ISATAP tunnel address locally; if the inter-domain movement is carried out, a new ISATAP tunnel address prefix is applied to the boundary router, and after the prefix is obtained, a global ISATAP tunnel address is formed locally.

And the update mapping information sending/receiving module is responsible for constructing and sending update mapping information which is respectively sent to the mapping server and the communication opposite terminal, and receiving and processing update response information returned by the mapping server and the communication opposite terminal.

The mapping servers are located in the domain where the hosts are located before movement, and each mapping server can manage the hosts of one domain. Whether the mapping server is located in the IPv 4-only domain or the IPv 6-only domain, the only function of the mapping server of the present invention is to maintain mapping information of the home address of the mobile host and the ISATAP care-of address. The mapping server in IPv 4-only domain must support double stacks, the ISATAP interface supports ISATAP tunnel, and the mapping server in IPv 6-only domain is IPv6 host. To accomplish this, the mapping server is provided with the following three modules: the device comprises a mapping information receiving/sending module, a mapping information storage management module and a mapping information query module.

The mapping information receiving/sending module is responsible for receiving the updating information of the mapping information sent by the host computer and constructing and sending an updating response message to the host computer.

The mapping information storage management module is responsible for storing the received mapping information in a local database, and can maintain a plurality of pieces of mapping information of one host, wherein the maintained mapping information is the mapping between two addresses with the length of 128 bits.

The mapping information query module is responsible for querying mapping information from a local database storing the mapping information. When the host of the opposite communication terminal only knows the home address of the mobile host, the mapping server intercepts the data packet sent to the home address of the mobile host, calls the module to inquire the mapping information, and returns the inquired mapping information to the mapping information receiving/sending module for processing.

The border router is located at the edge of an IPv4 domain or an IPv6 domain and is a dual-stack router supporting ISATAP.

The invention also provides a working method of the network system supporting host mobility under the mixed network environment of IPv4 and IPv6, and host mobility in the mixed scene of IPv4 and IPv6 has two types: the intra-domain movement of a host in the migration of a location within the same border router jurisdiction (see fig. 5, the complete working process of its movement detection and new address formation is shown in fig. 12), and the inter-domain movement of a host from within one border router jurisdiction to within another border router jurisdiction (see fig. 6 or 7, the complete working process of its movement detection and new address formation is shown in fig. 13).

Under the mixed scene, no matter the movement in the domain or the movement between the domains, the method of the invention comprises the following four steps:

step 1, mobile detection and new address formation are carried out after the host moves: the host judges whether the host moves by adopting a link state detection method; if the mobile host moves, the mobile host immediately sends a DHCP request message to a DHCP server, then the mobile host analyzes relevant information from a replied extended DHCP response message, and a new address is formed by utilizing an ISATAP tunnel technology: the moved ISATAP care-of address.

The step 1 comprises the following operations:

(11) the host computer adopts a link state detection method to carry out mobility detection, and is used for monitoring the connection condition of host computer links and judging whether the host computer links move or not; if the movement occurs, triggering the host to execute the subsequent step (12); otherwise, the host does not perform any operation;

(12) the mobile host sends a DHCP request message to a DHCP server of a domain where the mobile host is located after moving, requests to allocate a new IPv4 address, and requires to reply and inform an identification ID of the domain where the host is located and an address of a boundary router;

(13) after receiving the request, the DHCP server replies the constructed extended DHCP response message to the mobile host, and the response message adds the identification ID of the domain where the DHCP server is located and the address of the boundary router in the newly added option field;

(14) the mobile host analyzes the received DHCP response message to obtain a new IPv4 address, the identification ID of the domain where the mobile host is located and the address of the domain boundary router; then, the mobile host starts an ISATAP tunnel, and forms an ISATAP local link address in the moved domain;

(15) the mobile host compares the ID of the domain with the stored domain ID before the movement, if the two are the same, the mobile host judges that the domain moves in the domain, and the step (18) of jumping execution is carried out; if not, judging the domain is moved, firstly storing the ID of the new domain in the local and then sequentially executing the step (16);

(16) the mobile host sends a unicast router request message RS to the boundary router through the ISATAP tunnel, and after receiving the RS, the boundary router returns a unicast router announcement RA containing prefix information of the ISATAP address of the local domain to the mobile host through the ISATAP tunnel;

(17) after receiving RA, the mobile host analyzes prefix information of an ISATAP address of the local domain;

(18) the mobile host automatically forms a globally routable ISATAP care-of address locally by using ISATAP tunneling technology.

Step 2, the mobile host updates mapping information to the mapping server: the mobile host adopts ISATAP tunnel technology and standard routing mechanism to update the mapping information of the home address and the ISATAP care-of address to the mapping server, so that other hosts only knowing the home address of the mobile host can communicate with the mobile host.

The step 2 comprises the following operations:

(21) the mobile host judges whether the destination address of the updated mapping message, namely the address of the mapping server, is positioned in the local domain or not at an ISATAP interface by utilizing an ISATAP tunnel technology; if yes, sequentially executing the step (22); otherwise, jumping to execute step (24);

(22) the mobile host directly establishes an ISATAP tunnel with the mapping server and sends an update mapping message to the mapping server;

(23) after receiving and processing the message, the mapping server updates the mapping information of the home address of the mobile host and the ISATAP care-of address in a local database; then, returning an updating response message to the mobile host through the established direct connection ISATAP tunnel; ending the operation of the step (2);

(24) the mobile host sends the updating mapping message to the boundary router of the moved domain in an ISATAP tunnel mode;

(25) after receiving the encapsulated update mapping message, the border router carries out de-encapsulation and routes the update mapping message to the border router of the domain where the mapping server is located; if the mobile host is located in the IPv4 domain before moving, that is, the mapping server corresponding to the mobile host is located in the IPv4 domain, then sequentially performing step (26); if the mobile host is located in the IPv6 domain before the movement, namely the mapping server corresponding to the mobile host is located in the IPv6 domain, jumping to execute step (27);

(26) the boundary router of the IPv4 domain where the mapping server is located sends the updating mapping message to the mapping server in an ISATAP tunnel mode; a jump execution step (28);

(27) the boundary router of the IPv6 domain where the mapping server is located sends the updated mapping message to the mapping server through a standard routing mechanism;

(28) after receiving and processing the mapping updating message, the mapping server updates the mapping information of the home address of the mobile host and the ISATAP care-of address in a local database; then, an update response message is returned to the mobile host according to the same path.

Step 3, the mobile host updates mapping information to the communication opposite terminal: the mobile host adopts ISATAP tunnel technology and standard routing mechanism to update the mapping information of the home address and the ISATAP care-of address of the communication opposite terminal, so that the data packet sent by the communication opposite terminal can be directly sent to the mobile host.

The step 3 comprises the following operations:

(31) the mobile host judges whether a destination address of the updated mapping message, namely an address of a communication opposite end is located in a local domain or not at an ISATAP interface by utilizing an ISATAP tunnel technology; if yes, sequentially executing the step (32); otherwise, jumping to execute step (34);

(32) the mobile host directly establishes an ISATAP tunnel with a communication opposite terminal and sends an update mapping message to the communication opposite terminal;

(33) after receiving and processing the message, the correspondent node returns an update response message to the mobile host through the established direct-connection ISATAP tunnel; ending the operation of the step (3);

(34) the mobile host sends the updating mapping message to the boundary router of the moved domain in an ISATAP tunnel mode;

(35) after receiving the encapsulated update mapping message, the boundary router carries out de-encapsulation and routes the update mapping message to the boundary router of the domain where the communication opposite end is located; if the correspondent node is located in the IPv4 domain, sequentially executing the step (36); if the correspondent node is located in the IPv6 domain, skipping to execute the step (37);

(36) the boundary router of the IPv4 domain where the communication opposite end is located sends the updating mapping message to the communication opposite end in an ISATAP tunnel mode; a jump execution step (38);

(37) the boundary router of the IPv6 domain where the communication opposite end is located sends the update mapping message to the communication opposite end through a standard routing mechanism;

(38) and after receiving and confirming the updating mapping message, the communication opposite end returns an updating response message to the mobile host according to the same path.

Step 4, establishing a communication link to realize communication: after the steps are completed, the mobile host can continue to carry out conversation with the communication opposite terminal, and the communication process is the same as that before the host moves.

The invention carries out a plurality of tests, and the updating process of the mapping information in the test is briefly introduced as follows:

the present invention supports not only host mobility in a hybrid scenario of IPv4 and IPv6 (as shown in fig. 5, 6, and 7) under a conventional TCP/IP network architecture, but also host mobility in a hybrid scenario of IPv4 and IPv6 under an ID/Locator separated network architecture (as shown in fig. 14).

The new network architecture with separated ID/Locator is to insert a new protocol Layer-Host label Layer (Host Identity Layer) between the transport Layer and the network Layer of the current network. The host mark is used for identifying the host Identity, all IP addresses are replaced by HIT (host Identity tag) in a transmission layer and an application layer, and the HIT cannot be changed no matter how the position of the host in a network is changed. The IP address is no longer used for marking two communication parties, but only plays the roles of host positioning and data routing in the network layer.

The following describes the working process of the method supporting host mobility in a network environment at a transition stage under a network architecture with ID/Locator separated in conjunction with the scenario shown in fig. 14.

Referring to fig. 14, host 1 is initially in an IPv 4-only domain LD1, host 2 and ID/Locator mapping server are both in an IPv 6-only domain LD2, and host 2 and ID/Locator mapping server may form a globally routable IPv6 address, i.e., the Locator of host 2, using neighbor discovery and address autoconfiguration mechanisms of IPv 6. When two hosts need to communicate, the host 1 needs to use an ISATAP tunnel, and the host 1 needs to form an ISATAP address, namely the Locator of the host 1. The specific process is as follows:

(1) after the host 1 is started, a DHCP request message is sent to a DHCP server of the domain.

(2) After receiving the request, the DHCP server in LD1 sends an extended DHCP reply message to host 1, which adds the address of BR1 and the ID of domain LD1 in the addition option field.

(3) The DHCP client in the host 1 analyzes the received DHCP reply message, and acquires the address of BR1 and the ID of the domain LD1 in addition to acquiring its IPv4 address.

(4) Host 1 starts an ISATAP tunnel to form an ISATAP local link address, and host 1 establishes an ISATAP tunnel with BR1 by using the address.

(5) The host 1 compares the analyzed ID of the domain LD1 with the locally stored ID, and the ID is started for the first time, the ID is not locally stored, and the comparison result is that the two are different, which indicates that an ISATAP address prefix is to be applied to the BR 1; after the comparison, host 1 stores the domain ID of the LD1 domain locally.

(6) After interacting with the BR1 through a Router Solicitation (RS) message and a Router Advertisement (RA) message, the host 1 obtains prefix information of the ISATAP address of the local domain.

(7) The host 1 automatically forms a globally routable ISATAP address, i.e. the Locator of the host 1, locally by using an ISATAP tunneling technique.

Under the network architecture with ID/Locator separation, the host 1 and the host 2, besides having the Locator (IP address), also have an ID (hit) used in the transport layer and the application layer to identify the host identity, and then start to establish initial communication, which is described in detail as follows:

(1) the host 1 and the host 2 acquire their respective IDs in an off-line manner, that is, the user gets the ID and the related information of the ID to a designated ID management organization.

(2) The two hosts register the mapping information of the ID/Locator to the ID/Locator mapping server respectively.

(3) Host 1 only knows the ID of host 2, so communication is initiated to host 2 at a higher layer by the ID. The host 1 firstly sends a query message to the ID/Locator mapping server, and queries the Locator of the host 2 through the ID of the host 2. When sent, host 1 wants to establish ISATAP tunnel communication with BR1, and then the query message is sent to the ID/Locator mapping server in LD2 via standard routing mechanisms.

(4) And after receiving the query message of the host 1, the ID/Locator mapping server sends a query reply message to the host 1 to inform the host 2 of the Locator. After the query reply message is sent to BR1 via standard routing mechanisms, BR1 also establishes an ISATAP tunnel with host 1.

(5) After the host 1 obtains the Locator of the host 2, the two parties can establish communication in the network layer. During the communication, the host 1 and the BR1 always communicate with each other using an ISATAP tunnel.

Referring to fig. 14, after the initial communication is established, the host 1 moves to the IPv 4-only domain LD3, and the working process after the movement supported by the method of the present invention is described as follows:

(6) the host 1 first performs mobility detection through a link state detection procedure.

(7) Host 1, upon detecting the movement, sends a DHCP request message to the DHCP server in LD 3.

(8) After receiving the request, the DHCP server in LD3 sends an extended DHCP reply message to host 1, which adds the address of BR3 and the ID of domain LD3 in the addition option field.

(9) The DHCP client in the host 1 analyzes the received DHCP reply message, and acquires the address of BR3 and the ID of the domain LD3 in addition to acquiring the new IPv4 address of itself.

(10) Host 1 initiates an ISATAP tunnel, forms an ISATAP local link address in LD3 domain, and host 1 uses this address to establish an ISATAP tunnel with BR 3.

(11) Host 1 compares the resolved ID of LD3 in domain with the locally stored ID of LD1 in domain, and if the two are different, it indicates that inter-domain movement has occurred; after the comparison, host 1 stores the domain ID of LD3 domain locally, replacing the domain ID of LD1 domain stored locally.

(12) After interacting with the BR3 with a Router Solicitation (RS) message and a Router Advertisement (RA) message, the host 1 obtains prefix information of the ISATAP address of the domain LD 3.

(13) The host 1 automatically forms a new globally routable ISATAP address, i.e. a new Locator of the moved host 1, locally by using an ISATAP tunneling technique.

(14) After the Locator of the host 1 is changed, the mapping information of the ID/Locator of the host needs to be updated to the ID/Locator mapping server, and after the ID/Locator mapping server receives and completes the operation, the updating success message is returned to the host 1. In this process, the communication between host 1 and BR3 is always using an ISATAP tunnel.

(15) In addition to updating the ID/Locator mapping information of the host to the ID/Locator mapping server, the host 1 also sends an update message to the host 2 to notify the host 2 that the own Locator has changed, and the host 2 sends an update confirmation message to the host 1 after receiving the update message. In this process, host 1 and BR3 always use ISATAP tunnel communication.

(16) After the update is completed, the host 1 continues the communication with the host 2 before the host 1 moves, and because the IDs of the host 1 and the host 2 are not changed in the moving process, the ID/Locator separation network architecture ensures that the high-level connection in the moving process is continuous, and only the host 1 in the network layer communicates with the host 2 by using a new Locator.

In conclusion, the experiments of the embodiments of the present invention were successful and achieved the objects of the invention.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A network system supporting host mobility in IPv4 and IPv6 hybrid network environment is provided with a dynamic host configuration protocol DHCP server, a host and a boundary router; the method is characterized in that: in order to support mobility of a mixed scene of IPv4 and IPv6, the system expands functional modules for both a DHCP server and a host, and is additionally provided with a mapping server; wherein,

2. The system of claim 1, wherein: the newly added option field of the DHCP response message is a field added by the DHCP server in the returned DHCP response message when the mobile host applies for a new IPv4 address to the DHCP server of the domain where the mobile host is located after the mobile host moves, and is used for informing the host of the ID of the domain and the address of the boundary router of the domain, so that the host can automatically acquire a new ISATAP tunnel address prefix after moving into a pure IPv4 domain.

3. The system of claim 1, wherein: the format of the new option field of the DHCP reply message includes 4 parts: type, Length, Domain identification Domain ID, and border Router address Edge Router Addresses, wherein,

the Type is the mark of the newly added option field, is formed by specific numbers, characters or the mixture of the numbers and the characters, and is used for explaining that the stored content of the field is the domain mark and the address of the boundary router, so that the host can quickly and definitely find the field after receiving the DHCP response message;

length is the Length of the option field;

4. The system of claim 1, wherein: in order to complete the extended function of the DHCP server, in addition to the existing DHCP request message receiving/processing module, IPv4 address information setting module and DHCP response message sending module, a module is added: and the domain ID and boundary router information storage and setting module is responsible for storing the ID of the domain where the DHCP server is located and the boundary router address in the DHCP server and setting the ID and the boundary router address in a newly-added option field in the DHCP response message.

5. The system of claim 1, wherein: the host adds the following five modules in order to detect whether the host moves so as to acquire the ID of a domain and the address of a boundary router, form an ISATAP tunnel address capable of being globally routed, and respectively send mapping update messages to a mapping server and a communication opposite terminal: the system comprises a link state detection module, a newly added field analysis module, a domain ID comparison and storage module, a global ISATAP tunnel address forming module and an update mapping information sending/receiving module; wherein

The link state detection module is responsible for monitoring the connection condition of a host link so as to judge whether the host moves; if the mobile terminal moves, triggering the host to send a DHCP request message;

the newly added field analysis module is responsible for analyzing a newly added option field in the DHCP response message and acquiring the ID of the domain where the host is located and the address of the boundary router;

the domain ID comparison and storage module is responsible for comparing a new domain ID obtained by analyzing the DHCP response message with a domain ID stored in the local host computer and judging whether the host computer moves in the domain or between the domains; if the two are the same, the host is moved in the domain, and the domain ID stored in the local host does not need to be changed; if the two are different, the host is inter-domain movement, and the domain ID stored in the local host needs to be changed into a new domain ID obtained by analysis;

the global ISATAP tunnel address forming module is used for forming a global ISATAP tunnel address according to the comparison result of the domain ID comparison and storage module; if the mobile terminal moves in the domain, directly forming a global ISATAP tunnel address locally; if the inter-domain movement is carried out, a new ISATAP tunnel address prefix is applied to the boundary router, and after the prefix is obtained, a global ISATAP tunnel address is formed locally;

6. The system of claim 1, wherein: the mapping server has the functions of the three modules:

the mapping information receiving/sending module is responsible for receiving the updating mapping information of the host and constructing and sending an updating response message to the host;

the mapping information storage management module is responsible for storing and maintaining one or more pieces of received mapping information of each host in a local database, and the mapping information is the mapping between two addresses with the length of 128 bits;

and the mapping information query module is responsible for querying the mapping information from a local database for storing the mapping information and returning the query result to the mapping information receiving/sending module for processing.

7. A method of operating a network system supporting host mobility in a hybrid network environment of IPv4 and IPv6, the host mobility including two types: the host moves in the domain of site migration in the same border router administrative range, and the host moves from one border router administrative range to another border router administrative range; the method is characterized in that: the method comprises the following operation steps:

8. The method of claim 7, wherein: the step (1) further comprises the following operations:

9. The method of claim 7, wherein: the step (2) further comprises the following operations:

10. The method of claim 7, wherein: the step (3) further comprises the following operations: