CN100536425C - Network address translation system and method for supporting mobile IP operation in private network - Google Patents

Abstract

The invention is a network address translation system and method for supporting mobile IP to run in private network, wherein, a mobile node moves from its home network to a foreign private network, and gets a temporary address from the private network, the mobile node sends a registration packet to the home agent of its home network, and the registration packet has a switching address field; the NAT device of private network exchanges the source address and exchange address of the register packet, and then converts the source address into the public address of NAT device to transmit the register packet to the local proxy; after receiving the registration packet, the home agent replies a registration response packet, which has a switch address field whose content includes the temporary address; the NAT device exchanges the destination address and the switching address of the registration response packet to transmit the registration response packet to the mobile node.

Description

Network address translation system and method for supporting mobile IP running in private network

technical field

The present invention relates to the technical field of network address translation, in particular to a network address translation system and method for supporting mobile IP (Mobile IP) running on a private network.

Background technique

In the Internet (Internet), the Internet Protocol (IP) address is used to represent a machine, and the transmission of packets in the network also uses the IP address to represent the source and destination of its transmission. Currently widely used in the Internet is version four (IPv4) of IP technology, which is characterized by the use of addresses with a length of 32 bits. However, due to the rapid growth of the number of machines on the network and the limitation of address length, the available public IP (public IP) addresses tend to be gradually insufficient.

In order to solve the problem of insufficient addresses, there is the introduction of Network Address Translation (NAT) devices, which can slow down the rate of IP address consumption and allow areas that lack IP addresses to continue to operate. However, with the introduction of NAT devices, the problem of IP loss of transparency (Transparency) also follows. For example, NAT devices will cause the mobile IP (Mobile IP) protocol to fail to operate normally. Refer to Figure 1 to operate with the Mobile IP protocol In the schematic diagram of the private network 102 using the NAT device 14, when a mobile node (MN) 11 moves from its local network 101 to a foreign private network 102, the mobile node 11 will be the dynamic host of the private network 102 Configuration protocol (Dynamic Host Configuration Protocol, DHCP) server 13 obtains a temporary address (Care of Address, CoA) (192.168.0.1), according to the Mobile IP agreement, the mobile node 11 that moves to the field after obtaining the temporary address , will register with the home agent (HA) 12 of its local network 101, as shown in the figure, the header source (source) and destination (destination) of the registration packet 15 sent by it are respectively the temporary address (192.168 .0.1) and the address (120.105.1.1) of the home agent 12, and the content of the registration packet 15 includes the temporary address (192.163.0.1) where the mobile node 11 is currently located. The registration packet 15 is processed by the NAT device 14 to convert the source of the header from the temporary address (192.168.0.1) to the public IP address (140.113.1.1) of the NAT device 14, and then the registration packet 15 is delivered to The home agent 12 . Home agent 12, after receiving this registration packet 15, unravels its content and learns that this action node 11 is in this temporary address (192.168.0.1) at present, and replies the source (source) of a header and purpose ( destination) are respectively the address (120.105.1.1) of the home agent 12 and the registration response packet 16 of the public IP address (140.113.1.1) of the NAT device 14, and the destination is changed from the public IP address through the NAT device 14 (140.113.1.1) is converted to the temporary address (192.168.0.1), and the registration response packet 16 can be delivered to the mobile node 11 correctly, and the registration procedure is completed. Afterwards, the home agent 12 transmits the data packet 17 to the mobile node 11 according to the temporary address (192.168. 0.1) is a private address, and cannot be correctly delivered from the local network 101 to the private network 102, thus causing the Mobile IP protocol to fail to operate.

In order to solve the problem that the above-mentioned use of the NAT device 14 causes the Mobile IP protocol to fail to operate normally, a direct way is to further determine the mobile node contained in the content after the home agent 12 receives and unpacks the registration packet 15 11 Whether the address (temporary address) is the same as the source address of the registration packet, if it is different, it means that the registration packet 15 has been converted through NAT. Therefore, after the registration is completed in response to the registration, the local agent 12 will use the original registration packet The source address of 15 is used as the destination address to send the packet to the mobile node 11, rather than the temporary address of the mobile node 11 known from the content of the registration packet, so that the data packet 17 can be correctly delivered to the NAT device 14, to be further sent to the mobile node 11 after address conversion. However, the premise of the foregoing solution is that the NAT device 14 needs to convert the temporary addresses of different mobile devices 11 into different public addresses, so that the NAT device 14 can distinguish the mobile device 11 to which the data packet is to be delivered, which will As a result of failing to save any public addresses.

Contents of the invention

The main purpose of the present invention is to provide a network address translation system and method for supporting mobile IP running on a private network, which can make mobile IP running on a private network without using any tables and interface numbers, And it can be compatible with the existing network address translation technology.

According to a feature of the present invention, a method for supporting mobile IP running on a private network is proposed, wherein a mobile node moves from its local network to a private network in a foreign country, and the mobile node is transferred from the private network The private network has a NAT device. In this method, the mobile node sends a registration packet to the local agent of its local network. The source address field of the header of the registration packet and The destination address field is respectively the address of the temporary address and the home agent, and the registration packet has an exchange address selection field; the NAT device combines the contents of the source address field of the registration packet with the The content of the exchange address field is handed over, and then according to the rules of NAT conversion, the content of the source address field is converted into the public address of the NAT device, so as to transmit the registration packet to the local agent; the local agent After receiving the registration packet, the contents of the source address field and the destination address field of a header are respectively the address of the local agent and the public address of the NAT device in the registration response packet, the registration response The packet has an exchange address selection field, and its content includes the temporary address; the NAT device exchanges the content of the destination address field of the registration response packet with the content of the exchange address field, so that the registration response packet Teleport to action node.

According to another characteristic of the present invention, a system for supporting mobile IP running on a private network is proposed, which includes: a local agent, at least one mobile node, and a NAT device. The local agent is set in a local network. The mobile node can move from the local network to a foreign private network, and obtain a temporary address from the private network. The mobile node sends a registration packet to the local agent, and the header source bit of the registration packet is The address field and the destination address field are respectively the temporary address and the address of the home agent, and the registration packet has an exchange address selection field. The NAT device is installed on the private network, and it exchanges the content of the source address field of the registration packet with the content of the exchange address field, and then converts the content of the source address field according to the rules of NAT conversion For the public address of the NAT device, to send the registration packet to the home agent; or to exchange the content of the destination address field of a registration response packet with the content of the exchange address field, so that the registration response The packet is sent to the mobile node; after receiving the registration packet, the home agent replies to the registration response packet, and the contents of the header source address field and destination address field of the registration response packet are the home agent The address of the device and the public address of the NAT device, the registration response packet has an exchange address selection field, and its content includes the temporary address.

Description of drawings

FIG. 1 is a schematic diagram of a known Mobile IP protocol operating on a private network using a NAT device.

Figure 2 shows the contents of a standard packet header.

FIG. 3 is a structural diagram of the NAT system used to support mobile IP running on a private network according to the present invention, which illustrates the registration process.

FIG. 4 is a structural diagram of a NAT system for supporting mobile IP running on a private network according to the present invention, which illustrates the process of transmitting data packets.

Detailed ways

In order to better understand the technical content of the present invention, preferred specific embodiments are given as follows.

The NAT system and method thereof for supporting mobile IP running on a private network of the present invention are to newly define an optional field of an existing IP header (Header)-exchange address optional field (Swap addtess) option field), and provide an address exchange function, so as to realize the purpose of supporting MobileIP to run on the private network.

Fig. 2 shows the content of a standard packet header, wherein, after the source address (Source address) field 21 and the destination address (Destinatioil address) field 22, there may be an optional (Option) field 23, in RFC 791 defines the purposes of several optional fields 23. For example, when the type (Type) field 232 is 0×07, the optional field 23 is used to record the router through which the packet passes. When the type field 232 is 0×44, The optional field 23 is used to record time, and when the type field 232 is 0×83 or 0×89, the optional field 23 is used to specify the router through which the packet passes. The present invention defines an optional field 23 as an exchange address Select the field, when the type field 232 in the field 23 is set to the exchange address field of the present invention (such as Type=0 * 2a), then the exchange address field 231 in the field 23 is recorded The exchange address used by the NAT system of the present invention. The initial address of the exchange address field 231 is 0.0.0.0 for use by the system and method of the present invention.

FIG. 3 is a system architecture diagram illustrating the NAT system and method thereof for supporting mobile IP operation in a private network of the present invention. When a mobile node (MN) 11 moves from its local network 101 to a private network in a foreign country At 102, the mobile node 11 will obtain a temporary address (CoA) (192.168.0.1) from the dynamic host configuration agreement server 13 of the private network 20. According to the Mobile IP agreement, the mobile node 11 that moves to the field will obtain After the temporary address, it will register with the home agent (HA) 12 of its local network 10. As shown in the figure, the header source (source) and destination (destination) of the registration packet 15 sent by it are respectively the temporary Address (192.168.0.1) and this home agent 12 field (120.105.1.1), and the content of registering packet 15 promptly comprises the temporary address (192.168.0.1) where this action node 11 is at present, and registering packet 15 Contains the Exchange Address field with the Exchange Address value set to 0.0.0.0.0. The registration packet 15 is processed by the NAT device 14, wherein the NAT device 14 detects that the registration packet 15 has an exchange address field, and then sends the content of the source address field (temporary address (192.163.0.1)) Swap with the content of the exchange address field (address 0.0.0.0), so that the content of the exchange address field is the temporary address (192.168.0.1), and the content of the source address field is address 0.0.0.0. The NAT device 14 then converts the source address (address 0.0.0.0) into the public IP address (140.113.1.1) of the NAT device 14 according to the NAT conversion rules. The registration packet 15 is sent to the home agent 12 of the local network 101 .

After receiving the registration packet 15, the home agent 12 unpacks its data content and learns that the mobile node 11 is currently at the temporary address (192.168.0.1). The home agent 12 replies with a registration response whose header source (source) and destination (destination) are respectively the address (120.105.1.1) of the home agent 12 and the public IP address (140.113.1.1) of the NAT device 14 Packet 16, the registration response packet 16 also includes an exchange address field, and fills the temporary address (192.168.0.1) into the registration response packet according to the temporary address (192.163.0.1) of the mobile node 11 known by the registration 16 exchange address field, this registration response packet 16 is processed by the NAT device 14, wherein, the NAT device 14 detects that this registration response packet 16 has an exchange address field, and the content of the destination address field (the public address 140.113.1.1 of the NAT device 14) is exchanged with the content of the exchange address column (temporary address 192.168.0.1), so that the content of the destination address column is the temporary address (192.168.0.1), and the exchange The content of the address field is the public address of NAT (140.113.1.1). Therefore, the registration response packet 16 can be sent to the mobile node 11 to complete the registration.

After the registration is completed, if the mobile node 11 of the private network 102 moving to the other place intends to send a data packet to the home agent 12, as shown in Figure 4, the source address field of the data packet 17 is a temporary address (192.168. 0.1), the destination address field is the address (120.105.1.1) of the local agent 12, the data packet 17 does not include the exchange address field, and the NAT device 14 converts the source of the data packet 17 according to the general NAT conversion The address (temporary address (192.163.0.1)) is converted to the public IP address (140.113.1.1) of the NAT device 14, and the data packet 17 is delivered to the home agent 12.

If this home agent 12 intends to send a data packet to the mobile node 11 of the private network 102 that moves to the outside, as shown in Figure 4, the source address field of the data packet 17 is the address of the home agent 12 (120.105 .1.1), the destination address field is the public IP address (140.113.1.1) of the NAT device 14, the data packet will add the exchange address field, and according to the previously registered information, the temporary address of the mobile node 11 is known address (192.163.0.1), and fill this temporary address (192.168.0.1) into the exchange address field of the data packet 17.

This data packet is delivered to the NAT device 14 first, and the NAT device 14 detects that this data packet 17 has an exchange address field, and the content of the destination address field (the public address 140.113.1.1 of NAT) and the exchange bit The content of the address field (temporary address 192.168.0.1) is exchanged, so that the content of the destination address field is the temporary address (192.168.0.1), and the content of the exchanged IP address field is the public address of the NAT device 14 140.113.1.1. And the data packet 17 can be sent to the mobile node 11 correctly.

As can be seen from the above description, the present invention is designated as an exchange address selection field by utilizing an optional field of the existing packet header, and an address exchange function can be provided to preserve the mobile node's address of the private network that moves to the field. Temporary address, which is compatible with the existing NAT conversion, and does not need to use any tables and interface numbers, it can realize the purpose of supporting mobile IP to run on the private network.

The above-mentioned embodiments are only examples for convenience of description, and the scope of rights claimed by the present invention should be based on the scope of the patent application, rather than limited to the above-mentioned embodiments.

Claims (20)

1. one kind in order to support action IP to run on the method at privately owned networking, wherein, an action node moves to the privately owned networking in an other places by its local networking, and this action node is obtained a temporary transient address by this privately owned networking, this privately owned networking has a NAT device, and this method comprises:

One registration package transfer step, this action node sends a registration package to the Local proxy server at its local networking, the address that the header source address field of this registration package and purpose address field are respectively this temporary transient address and this Local proxy server, and this registration package has an exchange address field;

One the one NAT switch process, this NAT device will be registered the content of source address field of package and the content exchange of this exchange address field, again according to the rule of NAT conversion, the content of source address field is converted to the publicly-owned address of this NAT device, was sent to this Local proxy server should register package;

One registration response packet transfer step, this Local proxy server is after receiving this registration package, reply header source address field and purpose address field content and be respectively the registration response packet of the publicly-owned address of the address of this Local proxy server and this NAT device, this registration response packet has an exchange address field, and its content comprises this temporary transient address; And

One the 2nd NAT switch process, this NAT device will be registered the content and the content exchange that exchanges the address field of the purpose address field of response packet, so that this registration response packet is sent to action node.

2. the method for claim 1, it is characterized in that, in this registration package transfer step, the content of registration package comprises the temporary transient address at the present place of this action node, in this registration response packet transfer step, this Local proxy server is untied the content of this registration package and is learnt that this action node is in this temporary transient address at present.

3. the method for claim 1 is characterized in that, in this registration package transfer step, the content of this exchange address field is made as 0.0.0.0.

4. the method for claim 1, it is characterized in that, in this registration package transfer step, the exchange address field of this registration package is defined in selecting for use in the field of its header, in this registration response packet transfer step, the exchange address field of this registration response packet is defined in selecting for use in the field of its header.

5. method as claimed in claim 4 is characterized in that, the exchange address field of this registration package and registration response packet is set by setting the selecting the type field in the field for use of its header.

6. the method for claim 1 is characterized in that, also comprises after above-mentioned steps:

One first Datagram transfer step transmits one first Datagram by this action node and gives this Local proxy server, and the content of the source address field of this first Datagram is the address of the content of this temporary transient address, purpose address field for this Local proxy server; And

One the 3rd NAT switch process, this NAT device is converted to the publicly-owned address of this NAT device with the content of the source address field of this first Datagram, and this first Datagram is delivered to this Local proxy server.

7. method as claimed in claim 6 is characterized in that, also comprises after registration is finished:

One second Datagram transfer step, transmit second Datagram by this Local proxy server and give this action node, the content of the source address field of this second Datagram is the address of this Local proxy server, the content of purpose address field is the publicly-owned address of this NAT device, this second Datagram has an exchange address field, and its content comprises this temporary transient address; And

One the 4th NAT switch process, this NAT device is with the content of the purpose address field of this second Datagram and the content exchange of this exchange address field, so that this second Datagram is sent to this action node.

8. method as claimed in claim 7 is characterized in that, in this second Datagram transfer step, learns the temporary transient address of this action node according to previous registration, will this temporary transient address to insert the exchange address field of this second Datagram.

9. method as claimed in claim 7 is characterized in that, in this second Datagram transfer step, the exchange address field of this second Datagram is defined in selecting for use in the field of its header.

10. method as claimed in claim 9 is characterized in that, the exchange address field of this second Datagram is set by setting the selecting the type field in the field for use of its header.

11. a system that runs on privately owned networking in order to support action IP comprises:

One Local proxy server is arranged at a local networking;

At least one action node, it can be moved to the privately owned networking in an other places by this networking, this locality, and obtain a temporary transient address by this privately owned networking, this action node sends a registration package to this Local proxy server, the source address field of the header of this registration package and purpose address field are respectively the address of this temporary transient address and this Local proxy server, and this registration package has an exchange address field; And

One NAT device, be arranged at this privately owned networking, it will register the content of source address field of package and the content exchange of this exchange address field, again according to the rule of NAT conversion, the content of source address field is converted to the publicly-owned address of this NAT device, was sent to this Local proxy server should register package; Or, be sent to this action node should register response packet with the content of the purpose address field of a registration response packet and the content exchange of exchange address field;

Wherein, this Local proxy server is after receiving this registration package, reply this registration response packet, the source address field of the header of this registration response packet and the content of purpose address field are respectively the address of this Local proxy server and the publicly-owned address of this NAT device, this registration response packet has exchange address field, and its content comprises this temporary transient address.

12. system as claimed in claim 11, it is characterized in that, the content of the registration package that this action node is sent comprises the temporary transient address at the present place of this action node, and this Local proxy server is annotated this and conferred titles of nobility on the content of bag and learn that this action node is in this temporary transient address at present by untiing this.

13. system as claimed in claim 11 is characterized in that, the content of this exchange address field of the registration package that this action node is sent is made as 0.0.0.0.

14. system as claimed in claim 11 is characterized in that, the exchange address field of this registration package and registration response packet is defined in selecting for use in the field of its header.

15. system as claimed in claim 13 is characterized in that, the exchange address field of this registration package and registration response packet is defined by setting the selecting the type field in the field for use of its header.

16. system as claimed in claim 11, it is characterized in that, after registration was finished, this action node transmitted one first Datagram and gives this Local proxy server, and the source address field content of this first Datagram is that this temporary transient address, purpose address field content are the address of this Local proxy server; This NAT device is converted to the publicly-owned address of this NAT device with the source address field content of this first Datagram, and this first Datagram is delivered to this Local proxy server.

17. system as claimed in claim 11, it is characterized in that, after registration is finished, this Local proxy server transmits one second Datagram and gives this action node, the source address field content of this second Datagram is the address of this Local proxy server, purpose address field content is the publicly-owned address of this NAT device, and this second Datagram has an exchange address field, and its content comprises this temporary transient address; This NAT device is with purpose address field content and this exchange address field content exchange of this second Datagram, so that this second Datagram is sent to this action node.

18. system as claimed in claim 17 is characterized in that, this Local proxy server is learnt the temporary transient address of this action node according to previous registration, will this temporary transient address to insert the exchange address field of this second Datagram.

19. system as claimed in claim 17 is characterized in that, the exchange address field of this second Datagram is to be defined in its header to select for use in the field.

20. system as claimed in claim 19 is characterized in that, the exchange address field of this second Datagram is selected the type field in the field for use by its header of setting and is defined.

Images