CN1691664A - Conversion Method of ICMP Error Message in PAT Mode in NAT-PT Gateway - Google Patents

Abstract

The invention relates to ICMP error message conversion method on the PAT mode in NAT-PT gateway. On the PAT mode, when receiving ICMP error message from IPv4 network, NAT-PT gateway need to take address conversion treating according to interior message-head address and port information. Thereby, for address conversion conditions of intercommunication by PAT mode for IPv4 net and IPv6 net, this invention can ensure ICMP error message back from IPv4 net to go back accurately to source node of IPv6, then realizes control and treat to error during process of intercommunication for IPv4 net and IPv6 net, and improves network performance.

Description

Conversion method of ICMP error message in PAT mode in NAT-PT gateway

technical field

The invention relates to the technical field of network communication, in particular to a method for converting ICMP (Internet Control Message Protocol) error messages in PAT (Port Number-Based Address Translation) mode in NAT-PT (Internet Address Translation Protocol).

Background technique

The current data network is dominated by IPv4 (Internet Protocol Version 4) technology. With the expansion of network scale, IPv6 (Internet Protocol Version 6) technology will gradually replace the current IPv4 technology with its advantages such as huge address space. However, such a thorough replacement requires a long-term process. In this long-term evolution process from IPv4 technology to IPv6 technology, in order to share network resources, it is necessary to solve the problem of intercommunication between IPv4 network and IPv6 network, that is, to enable nodes in the IPv6 network and nodes in the IPv4 network to communicate with each other. vice versa. The NAT-PT technology provides a major solution, and the protocol specification is defined by RFC2766 (RFC, Request for Comments).

A NAT-PT gateway is a NAT-PT-based gateway device set between an IPv6 network and an IPv4 network. When the IPv6 network node and the IPv4 network node communicate with each other, the NAT-PT gateway converts the IPv6 message and the IPv4 message between them, so as to adapt to the IP (Internet Protocol) type of the opposite end. The conversion generally includes IP address conversion and protocol conversion, for example, protocol conversion between IPv4 message header and IPv6 message header.

The processing process of the conversion is shown in Figure 1. In the message conversion process, it is necessary to replace the IPv6 address with an identifiable IPv4 address. The method is to allocate a temporary IPv4 address from the IPv4 address pool to map the IPv6 address. For the problem of replacing IPv4 addresses with IPv6 addresses, the method is to assign a special IPv6 prefix, called NAT-PT prefix, and use the prefix + IPv4 address to form a new IPv6 address to map the original IPv4 address.

The following uses an example to describe the conversion process of NAT-PT:

The IPv6 message sent from the node in the IPv6 network to the node in the IPv4 network arrives at the NAT-PT gateway, first performs IP address conversion, and then performs protocol conversion, specifically including:

The IPv6 packet header is converted into an IPv4 packet header;

The transport layer header becomes the transport layer header of the IPv4 packet after checksum adjustment or port translation;

After the application layer protocol message in the message data body is processed by the application layer ALG (that is, if it contains an IP address, IP address translation may be required), it becomes the IPv4 message data body.

When an IPv4 message sent from an IPv4 node to an IPv6 node arrives at the NAT-PT gateway, it first converts the IPv4 address to the IPv6 address, and then performs protocol conversion, including:

The IPv4 header is converted to an IPv6 header;

The transport layer header in the IPv4 message becomes the transport layer header of the IPv6 message after checksum adjustment or port translation;

After the application layer protocol message in the message data body is processed by the application layer ALG (that is, if it contains an IP address, IP address translation may be required), it becomes the IPv6 message data body.

For specific details of packet protocol conversion, the NAT-PT protocol requires compliance with the SIIT (Header Transformation Protocol) protocol specification.

In the NAT-PT message protocol conversion process, there are the following situations. As shown in Figure 2, the source node in the IPv6 network sends the original message to the destination node in the IPv4 network, and it is converted into an IPv4 message when passing through the NAT-PT gateway. When the IPv4 message arrives at the intermediate node of the IPv4 network, an error occurs (such as the destination is unreachable, etc.), the intermediate node generates an ICMPv4 (IPv4-based ICMP) error message and sends it back to the IPv6 source node, and the ICMPv4 error report The text contains an error IPv4 message (that is, the IPv4 original message converted by the NAT-PT gateway). The IPv4 header of an ICMPv4 error packet is called the outer IP header, and the IPv4 header in the original IPv4 packet included later is called the inner IP header.

When the ICMPv4 error message is returned to the NAT-PT gateway, it needs to be converted into an ICMPv6 error message of the IPv6 protocol type. It is required that the external IPv4 packet header, ICMPv4 header, and the internal IPv4 packet header and transport layer need to be converted to the corresponding IPv6 protocol type.

For the conversion of the external IPv4 message header and the internal IPv4 message header, it is necessary to convert the source address and the destination address according to the mapping relationship between IPv4 and IPv6 addresses. However, for the PAT address translation method of NAT-PT to save IPv4 addresses, because it needs to be translated according to the address+port number of the transport layer, the address pair cannot be converted to the ICMP error message. When the original IPv6 message passes through the NAT-PT gateway, PAT address translation is performed to convert the IPv6 source address+IPv6 source port into IPv4 source address+IPv4 source port (assumed to be ADDR4+PORT4). When the ICMPv4 error message generated by the intermediate node returns through the NAT-PT gateway, the IPv4 header needs to determine the IPv6 destination address to be converted according to the IPv4 destination address+IPv4 destination port (ADDR4+PORT4 at this time). But for the external IPv4 header, because the transport layer is not the transport layer of the original message, but the ICMPv4 header, there is no required destination port information, and the IPv6 destination address that should be converted cannot be determined. Therefore, the ICMP Error messages cannot be returned to the source node in the IPv6 network. In this way, it is impossible to guarantee the control and processing of errors during the intercommunication process between the IPv4 network and the IPv6 network.

Contents of the invention

The purpose of the present invention is to provide a conversion method of ICMP error messages in PAT mode in a NAT-PT gateway, thereby realizing the control and processing of the errors that occur during the intercommunication process between the IPv4 network and the IPv6 network.

The purpose of the present invention is achieved through the following technical solutions:

The invention provides a method for converting ICMP error message under PAT mode in a NAT-PT gateway. When receiving an ICMP (Internetwork Control Protocol) error message from the IPv4 network, perform address translation processing of the ICMP error message according to the address and port information of the inner header of the message.

The conversion method of ICMP error message under the PAT mode in the described NAT-PT gateway further comprises:

A, NAT-PT gateway obtains the IPv4 address information and the corresponding port information of the internal header of the ICMP error message that IPv4 network sends;

B, search and determine corresponding IPv6 address information and corresponding port information according to the IPv4 address information and corresponding port information;

C. Using the determined IPv6 address information and corresponding port information to convert the ICMP error message.

In the present invention, before performing the step A, it also includes:

The source node in the IPv6 network sends a message to the destination node in the IPv4 network;

When the message passes through the NAT-PT gateway, the corresponding relationship between the IPv6 source address and IPv6 source port and the IPv4 source address and IPv4 source port is stored in the NAT-PT gateway.

Described step A comprises:

At the NAT-PT gateway, it is determined as the ICMP error message according to the information carried by the received IPv4 network return message, and the IPv4 address information and corresponding port information of the inner header of the ICMP error message are obtained.

Described step C comprises:

Use the determined IPv6 address information as the destination address of the external header of the ICMP error message sent to the source node in the IPv6 network, and use the determined IPv6 address information and corresponding port information as the ICMP error message sent to the source node in the IPv6 network The source address and source port information of the internal header of the document.

The ICMP error message is an ICMP error message generated by an intermediate node in the IPv4 network, and the intermediate node is a node whose destination address is a node in the IPv4 network before reaching the destination node in the IPv4 network.

The conversion method of the ICMP error message under the PAT mode in the described NAT-PT gateway also includes:

D. When the NAT-PT gateway receives the ICMP error message from the IPv6 network, it performs address conversion processing of the ICMP error message according to the address information of the outer header or the inner header of the message.

Described step D comprises:

D1. The NAT-PT gateway receives the ICMP error message from the IPv6 network;

D2. Obtain the address information of the external header from the ICMP error message, and determine the address information required for address translation processing according to the obtained address information of the external header;

D3. Perform the conversion processing of the ICMP error message according to the determined address information required for the address conversion processing.

Described step D3 comprises:

Further determine the address information of the external IPv6 message header, the ICMPv6 (IPv6-based ICMP) message header and the address information of the internal IPv6 message header and the port information of the internal transport layer according to the address information needed for the determined address translation process;

According to the further determined address information and port information, the conversion processing of the ICMP error message that needs to be sent to the IPv4 network is performed.

It can be seen from the above-mentioned technical solution provided by the present invention that the present invention provides a method for converting and processing received ICMP error messages on the NAT-PT gateway, which facilitates the control and processing of errors occurring in the network. And, when adopting PAT mode to carry out the situation of address translation processing when IPv4 network and IPv6 network intercommunicate, the present invention is by extracting the address information and the transport layer of the internal header of the ICMP error message that the IPv4 network on the NAT-PT gateway returns The port information is used to convert the error message, which ensures that the ICMP error message returned from the IPv4 network to the NAT-PT gateway can be correctly returned to the source node in the IPv6 network, thereby realizing the process of intercommunication between the IPv4 network and the IPv6 network It can control and process the errors that occur in the network, which improves the performance of the network.

Description of drawings

Fig. 1 is a schematic diagram of the networking structure of IPv4 network and IPv6 network intercommunication;

Fig. 2 is a schematic diagram of the conversion process of the message when the IPv4 network and the IPv6 network are intercommunicated;

Fig. 3 is the schematic diagram of the conversion process of the error message generated when the IPv6 network and the IPv4 network intercommunicate;

Fig. 4 is a flowchart of the method of the present invention.

Detailed ways

During the intercommunication between the IPv4 network and the IPv6 network, the two networks need to pass through the NAT-PT gateway for packet conversion, so as to ensure the intercommunication between the two networks. At the same time, in the IP network, when an error occurs in the transmission process of the message, an ICMP error message will be generated at the node where the error occurs, and the message carries the information of the original message and the header information of the generated ICMP error message , the ICMP error message needs to be returned to the source node that sent the original message. Therefore, in the process of message interaction between the two networks, the following two situations may occur:

First, after the message sent from the IPv4 network to the IPv6 network passes through the NAT-PT gateway and enters the IPv6 network, an error occurs at the intermediate node. At this time, the intermediate node will return a corresponding ICMP error message to the NAT-PT, and the message returns After arriving at the NAT-PT gateway, it will be sent to the source node that sent the original message in the IPv4 network through corresponding conversion processing;

Second, after the message sent from the IPv6 network to the IPv4 network passes through the NAT-PT gateway and enters the IPv4 network, an error occurs at the intermediate node. At this time, the intermediate node will return a corresponding ICMP error message to the NAT-PT gateway. After returning to the NAT-PT gateway, it will be sent to the source node that sent the original message in the IPv6 network through corresponding conversion processing.

For the first case in the above two cases: after the NAT-PT gateway receives the ICMP error message, it obtains the destination IPv6 address information of the message, and replaces it according to the mapping relationship of the IPv6 address The corresponding IPv4 address is enough. For the internal header of the error message, it is also converted according to the address mapping relationship saved by the NAT-PT gateway, that is, the address information and port information of the internal header are obtained, and the corresponding address is searched according to the saved address mapping relationship. Corresponding IPv4 address and port information, and perform corresponding conversion processing. The transport layer may be TCP (Transmission Control Protocol) or UDP (Datagram Protocol).

And for above-mentioned second kind of situation: under the PAT-based mode, the external destination address (IPv4 address) of described error message, because same IPv4 address can form mapping relationship with a plurality of IPv6 addresses, so if still according to first kind The method that situation adopts can't find definite IPv6 address to replace this IPv4 address; Simultaneously, because the external transport layer port information of described error message is not the transport layer port information of original message, so can't according to the external transport layer port information of error message. The corresponding conversion process is performed on the header; for this reason, the present invention adopts a solution for address conversion based on the address of the internal header of the error message and the port information of the transport layer.

When an error occurs at an intermediate node in the IPv4 network for the message sent to the IPv4 network by the IPv6 network, the address conversion method provided by the present invention according to the address of the internal header of the error message and the transport layer port information will be further described Illustrate, among the present invention, adopt PAT mode for the conversion of the original message by IPv6 network to IPv4 network, therefore, the concrete implementation mode of the present invention is referring to Fig. 3 and Fig. 4, comprises the following steps:

Step 41: The source node in the IPv6 network sends a message 6packet to the destination node in the IPv4 network. The source address and source port of the message 6packet are 6SourceAddr and 6SourcePort, respectively, which are the source address and source port of IPv6.

Step 42: when the message sent to the IPv4 network by the IPv6 network passes through the NAT-PT gateway, generate and record the conversion relationship from the IPv6 source address+IPv6 source port to the IPv4 source address+IPv4 source port;

Described message 6packet needs to be converted into IPv4 message 4packet when passing through NAT-PT gateway, if address translation adopts PAT mode to realize, then the IPv4 source address and source port after assuming conversion are respectively 4SourceAddr and 4SourcePort, at this moment, in The reserved address mapping relationship in the NAT-PT gateway is: 6SourceAddr+6SourcePort<----->4SourceAddr+4SourcePort, in order to save IPv4 address resources, usually an IPv4 address can be associated with multiple different IPv6 addresses by cooperating with different port numbers establish a corresponding relationship;

That is to say, in this step, when the message sent to the IPv4 network by the IPv6 network passes through the NAT-PT gateway, it is necessary to allocate a free IPv4 address and a free IPv4 port for the source IPv6 address and port number of the message number, and record the mapping relationship between the source IPv6 address and port number and the assigned idle IPv4 address and idle IPv4 port number, thereby ensuring that the message sent by the source node is correspondingly addressed, and for the returned The message can be correctly returned to the source node in the IPv6 network.

Step 43: the IPv4 message 4packet through conversion is sent to IPv4 destination node by NAT-PT gateway, produces error when passing through the intermediate node of IPv4 network, generates ICMPv4 (ICMP based on IPv4) error message 4IcmpErrorPacket, message 4IcmpErrorPacket contains the IP header and the transport layer information of the error message 4packet (i.e. the original message), because the said message 4IcmpErrorPacket needs to be sent back to the source node of the wrong original message, so the purpose of the message 4IcmpErrorPacket The address is set to 4SourceAddr so that said message will first be returned to the NAT-PT gateway.

Step 44: After the NAT-PT gateway receives the ICMP error message returned by the IPv4 network, in order to perform corresponding address translation, it needs to extract the IPv4 source address+IPv4 from the internal IPv4 header of the error message and the transport layer source port information;

That is, according to the destination address 4SourceAddr, the message 4IcmpErrorPacket is sent to the NAT-PT gateway, and the NAT-PT gateway needs to convert the message 4IcmpErrorPacket into the corresponding IPv6ICMP error message 6IcmpErrorPacket, so as to send it to the IPv6 source node, in order to send the received message 4IcmpErrorPacket is converted into IPv6ICMP error message 6IcmpErrorPacket, the IPv6 destination address of 6IcmpErrorPacket must be determined, which should actually be the address of the IPv6 source node, namely 6SourceAddr;

Since the message 4IcmpErrorPacket contains the IP header and transport layer information of the error message 4packet, the IPv4 source address 4SourceAddr and source port 4SourcePort converted by the NAT-PT gateway can be obtained therefrom.

Step 45: through the extracted IPv4 source address and IPv4 source port information, search for the conversion relationship of the saved record, so as to determine the IPv6 source address+IPv6 source port that needs to be converted;

Specifically: use the 4SourceAddr+4SourcePort keyword, through the address mapping relationship reserved by the NAT-PT gateway: 6SourceAddr+6SourcePort<----->4SourceAddr+4SourcePort, reverse lookup to the corresponding IPv6 address 6SourceAddr and IPv6 port 6SourcePort.

Step 46: use the IPv6 source address determined by searching, as the IPv6 destination address to be converted by the IPv4 destination address in the outer IPv4 header, about 6SourceAddr is used as the IPv6 destination address of the converted IPv6ICMP error message 6IcmpErrorPacket;

At the same time, the IPv6 source address + IPv6 source port determined by the search is used to convert the internal IPv4 message, that is, the IPv4 source address and IPv4 source port information 4SourceAddr+4SourcePort of the internal IPv4 message header is converted into the IPv6 source address + IPv6 source port determined by the search. Port 6SourceAddr+6SourcePort.

Step 47: send the converted IPv6 ICMP error message 6IcmpErrorPacket to the source node in the IPv6 network.

In the present invention, for the ICMP error message returned to the NAT-PT gateway by the IPv6 network, the conversion process can be carried out according to the address information of the external header of the message, or according to the address information of the internal header of the message Information is converted.

As can be seen from the above description of the present invention, the present invention can effectively control and process the errors that occur when the IPv4 network and the IPv6 network communicate with each other under the PAT mode, no matter it is based on the message generated by the IPv4 network to the IPv6 network. The error message, or the error message generated based on the message sent from the IPv6 network to the IPv4 network, can use the information in the internal header and the corresponding address mapping relationship stored in the NAT-PT gateway to perform corresponding conversion processing, and The error message is returned to the corresponding source node, so as to control and process the error that occurs.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (9)

1, the conversion method of ICMP error message under the PAT pattern in a kind of NAT-PT gateway, it is characterized in that, under PAT (based on the address transition of port) pattern, when NAT-PT (IP(Internet Protocol) translation-protocol) gateway is received ICMP (control protocol between the net) error message that the IPv4 network sends, handle according to the address of the inner header of described message and the address transition that port information carries out the ICMP error message.

2, the conversion method of ICMP error message under the PAT pattern in the NAT-PT gateway according to claim 1 is characterized in that this method further comprises:

A, NAT-PT gateway obtain the IPv4 address information and the corresponding ports information of the inner header of the ICMP error message that the IPv4 network sends;

B, determine IPv6 address information and the corresponding ports information corresponding with it according to described IPv4 address information and corresponding ports information searching;

IPv6 address information and corresponding ports information that C, utilization are determined are carried out the conversion of ICMP error message.

3, the conversion method of ICMP error message under the PAT pattern in the NAT-PT gateway according to claim 2 also comprises before it is characterized in that carrying out described steps A:

The destination node of source node in the IPv6 network in the IPv4 network sends message;

When described message passes through the NAT-PT gateway, preserve the corresponding relation of IPv6 source address and IPv6 source port and IPv4 source address and IPv4 source port at the NAT-PT gateway.

4, according to the conversion method of ICMP error message under the PAT pattern in claim 2 or the 3 described NAT-PT gateways, it is characterized in that described steps A comprises:

At the NAT-PT gateway, according to receiving that IPv4 network returned packet loaded information is defined as described ICMP error message, obtains the IPv4 address information and the corresponding ports information of the inner header of ICMP error message.

5, according to the conversion method of ICMP error message under the PAT pattern in claim 2 or the 3 described NAT-PT gateways, it is characterized in that described step C comprises:

With the IPv6 address information determined destination address, with definite IPv6 address information and corresponding ports information source address and source port information as the inner header of the ICMP error message that sends to the source node in the IPv6 network as the ICMP error message external header that sends to the source node in the IPv6 network.

6, the conversion method of ICMP error message under the PAT pattern in the NAT-PT gateway according to claim 1 and 2, it is characterized in that described ICMP error message is the ICMP error message that the intermediate node in the IPv4 network produces, described intermediate node is that destination address is the message of the node in the IPv4 network arrives process before the destination node in the IPv4 network a node.

7, the conversion method of ICMP error message under the PAT pattern in the NAT-PT gateway according to claim 1 and 2 is characterized in that this method also comprises:

When D, NAT-PT gateway are received the ICMP error message that the IPv6 network sends, carry out the address transition of ICMP error message according to the address information of the external header of described message or inner header and handle.

8, the conversion method of ICMP error message under the PAT pattern in the NAT-PT gateway according to claim 7 is characterized in that described step D comprises:

D1, NAT-PT gateway are received the ICMP error message that the IPv6 network is sent;

D2, from described ICMP error message, obtain the address information of external header, and determine the address information of address conversion process needs according to the address information of the external header of obtaining;

The address information of the address transition processing needs that D3, basis are determined is carried out the conversion process of described ICMP error message.

9, the conversion method of ICMP error message under the PAT pattern in the NAT-PT gateway according to claim 8 is characterized in that described step D3 comprises:

Handle the address information of needs according to the address transition of determining and further determine the address information of external IP v6 heading, ICMPv6 (based on the ICMP of IPv6) heading and inner IPv6 heading and the port information of internal transmission layer;

Carry out the conversion process that needs send to the ICMP error message of IPv4 network according to described address information and the port information of further determining.

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