CN102572007B - Method for forwarding IPv6 (Internet Protocol Version 6) multicasting message across IPv4 (Internet Protocol Version 4) network, and edge equipment - Google Patents

Abstract

The invention discloses a method and an edge device for forwarding IPv6 multicast messages across an IPv4 network, belonging to the communication field. After receiving the IPv6 multicast access request sent by the user, the first edge device encapsulates the IPv6 multicast access request into an IPv4 multicast access request and sends it to the second edge device, and receives the IPv4 packet sent by the second edge device , decapsulating the IPv4 message to obtain an IPv6 multicast message, and sending the IPv6 multicast message to the user. Through the present invention, it is possible to realize the transmission of IPv6 multicast messages across the IPv4 network between two IPv6 isolated islands.

Description

Method and edge device for forwarding IPv6 multicast message across IPv4 network

technical field

The embodiment of the present invention relates to the technical field of communication, and in particular to a method and an edge device for forwarding IPv6 multicast messages across an IPv4 network.

Background technique

Since the Internet Protocol (IP) was proposed in the 1970s, it has established itself and the TCP/IP protocol family derived from it as the core of digital communication with its advantages of ease of use and strong portability. The status of the agreement has become the mainstream framework agreement of the global network. The current common IP protocol is IPv4, and some deficiencies in the design of IPv4 are gradually exposed, mainly as follows:

1. Address shortage. In April 2011, the global IPv4 address allocation was exhausted. Although VPN, NAT and other technologies can realize the reuse of addresses, due to the application of mobile network IP and Internet of Things, the global IP terminals are increasing rapidly, which will inevitably consume a lot of IPv4 addresses. Therefore, it is an indisputable fact that IPv4 addresses are in short supply.

2. The length of the IP header is not fixed, and the analysis overhead is relatively large. In order to increase its scalability, IPv4 allows the IP header itself to carry an option field of up to 40 bytes, which makes the IP header longer, brings certain difficulties to packet parsing, and increases the overhead of parsing packets.

3. Less security considerations. The IPv4 protocol itself has little security considerations. Although the encryption of IPv4 packets is realized through technologies such as GRE and IPSEC, the IPv4 protocol itself does not have a security authentication function after all.

In order to solve the above defects of the IPv4 protocol, especially the address shortage problem, the IPv6 protocol came into being. The IPv6 protocol extends the address space to 128b, providing almost inexhaustible addresses. The IPv6 protocol solves the problems of message parsing and security authentication by fixing the length of the IPv6 header and adding an extension header. Therefore, it is the general trend that the IPv6 protocol replaces the IPv4 protocol.

In the process of replacing IPv4 with IPv6, due to factors such as equipment cost and business stability, the process of upgrading the old IPv4 network to IPv6 network is a gradual process, and it is based on the process from edge equipment to core equipment, from new networks to The existing network is gradually promoted. Therefore, it can be predicted that for a long period of time in the future, the coexistence of IPv4 network and IPv6 network will be a normal state, and the compatibility and intercommunication between the two is a major problem that needs to be solved. In the early stage of the evolution process, because edge devices and new networks will first adopt the IPv6 protocol, there will be a problem of IPv6 islands crossing the IPv4 network for mutual access. Currently, there are various transition technologies for unicast tunnels between IPv6 islands, mainly divided into two categories: IP tunnel technology and MPLS technology; however, there is no mature transition technology for IPv6 multicast at present.

Contents of the invention

Embodiments of the present invention provide a method and an edge device for forwarding IPv6 multicast messages across an IPv4 network, which are used to solve the problem that multicast messages in an IPv6 isolated island traverse the IPv4 network.

Embodiments of the present invention provide a method for forwarding IPv6 multicast packets across an IPv4 network on the one hand, including:

The first edge device receives an IPv6 multicast join request sent by an IPv6 user, where the IPv6 multicast join request carries multicast information, and the multicast information includes a multicast source address and a multicast group address that the user requests to join; The multicast group address is an IPv6 automatic mapping multicast address, wherein the automatic mapping address flag is 1; the IPv6 user is located on the user island, the multicast source is located on the source island, and the user island passes through the first edge The device is connected to the IPv4 network, and the first edge device supports the IPv6 protocol and the IPv4 protocol;

The first edge device determines to obtain the IPv4 address of the second edge device from the multicast group address according to the automatic mapping address flag of the IPv6 automatic mapping multicast address being 1; the IPv4 network passes the second The edge device is connected to the source island, and the second edge device supports IPv6 protocol and IPv4 protocol;

The first edge device sends an IPv4 multicast join request generated according to the IPv6 multicast join request to the second edge device, the IPv4 multicast join request carries the multicast information; the IPv4 multicast join request The source address of the request is the IPv4 address of the first edge device, and the destination address is the IPv4 address of the second edge device;

The first edge device receives the IPv4 message sent by the second edge device, the source address of the IPv4 message is the IPv4 address of the second edge device, and the destination address is the IPv4 address of the first edge device ; Decapsulating the IPv4 message to obtain an IPv6 multicast message, and sending the IPv6 multicast message to the user.

On the other hand, the embodiments of the present invention provide an edge device for forwarding IPv6 multicast packets across an IPv4 network, including:

The second edge device receives the IPv4 multicast join request sent by the first edge device, the source address of the IPv4 multicast join request is the IPv4 address of the first edge device, and the destination address is the IPv4 address of the second edge device The IPv4 multicast join request is generated by the first edge device according to the IPv6 multicast join request of the IPv6 user, and the IPv4 multicast join request carries multicast information, and the multicast information includes a multicast source address and the multicast group address; the multicast group address is an IPv6 automatic mapping multicast address, wherein the automatic mapping address flag is 1; the IPv6 user is located in the user island, the multicast source is located in the source island, and the user island Connect the IPv4 network through the first edge device, connect the IPv4 network to the source island through the second edge device, the first edge device and the second edge device support IPv6 protocol and IPv4 protocol;

The second edge device obtains the multicast information in the IPv4 multicast join request, joins the multicast group according to the multicast information, and establishes a multicast forwarding entry; the multicast forwarding entry includes the group Broadcast source address, multicast group address, IPv4 address and IPv6 address of the first edge device, and IPv4 address and IPv6 address of the second edge device;

The second edge device receives an IPv6 multicast packet from a multicast source;

The second edge device copies the IPv6 multicast message according to the multicast forwarding entry, and encapsulates the copied IPv6 multicast message into an IPv4 message, and the source address of the IPv4 message is the first An IPv4 address of the edge device, the destination address being the IPv4 address of the first edge device; sending the IPv4 packet to the first edge device.

Another aspect of the embodiments of the present invention provides an edge device that supports the IPv6 protocol and the IPv4 protocol, and connects the IPv4 network and the user island, and the edge device includes:

A receiver, configured to receive an IPv6 multicast join request sent by an IPv6 user, where the IPv6 multicast join request carries multicast information, and the multicast information includes a multicast source address and a multicast group address that the user requests to join ; The multicast group address is an IPv6 automatic mapping multicast address, wherein the automatic mapping address flag is 1; the IPv6 user is located in the user island, and the multicast source is located in the source island;

An acquisition unit, configured to determine to obtain the IPv4 address of the second edge device from the multicast group address according to the automatic mapping address flag of the IPv6 automatic mapping multicast address being 1; the IPv4 network passes through the second edge The device is connected to the source island, and the second edge device supports IPv6 protocol and IPv4 protocol;

A first processor, configured to generate an IPv4 multicast join request according to the IPv6 multicast join request, and send the IPv4 multicast join request to the second edge device, the IPv4 multicast join request carrying the group broadcast information; the automatic mapping address flag of the IPv6 automatic mapping multicast address is 1, and it is determined from the multicast group address

The second processor is configured to receive the IPv4 message sent by the second edge device, the source address of the IPv4 message is the IPv4 address of the second edge device, and the destination address is the IPv4 address of the first edge device address; decapsulating the IPv4 message to obtain an IPv6 multicast message, and sending the IPv6 multicast message to the user.

The fourth aspect of the embodiments of the present invention provides an edge device that supports the IPv6 protocol and the IPv4 protocol, and connects the IPv4 network and the source island, and the edge device includes:

The first receiver is configured to receive the IPv4 multicast join request sent by the first edge device, the source address of the IPv4 multicast join request is the IPv4 address of the first edge device, and the destination address is the second edge device IPv4 address; the IPv4 multicast join request is generated by the first edge device according to the IPv6 multicast join request of the IPv6 user, and the IPv4 multicast join request carries multicast information, and the multicast information includes group broadcast source address and multicast group address; the multicast group address is an IPv6 automatic mapping multicast address, wherein the automatic mapping address flag is 1; the IPv6 user is located on a user island, and the multicast source is located on the source island , the user island is connected to the IPv4 network through the first edge device, and the first edge device supports IPv6 protocol and IPv4 protocol;

A first processor, configured to acquire multicast information in the IPv4 message, join a multicast group according to the multicast information, and establish a multicast forwarding entry; the multicast forwarding entry includes the multicast source address, multicast group address, IPv4 address and IPv6 address of the first edge device, and IPv4 address and IPv6 address of the second edge device;

The second receiver is used to receive the IPv6 multicast message from the multicast source;

The second processor is configured to copy the IPv6 multicast message according to the multicast forwarding entry, and encapsulate the copied IPv6 multicast message into an IPv4 message, and the source address of the IPv4 message is the The IPv4 address of the second edge device, the destination address being the IPv4 address of the first edge device; sending the IPv4 packet to the first edge device.

In the embodiment of the present invention, after receiving the IPv6 multicast access request sent by the user, the first edge device encapsulates the IPv6 multicast access request into an IPv4 multicast access request and sends it to the second edge device, and receives the second Decapsulate the IPv4 message sent by the edge device to obtain an IPv6 multicast message, and send the IPv6 multicast message to the user. Through the present invention, it is possible to realize the transmission of IPv6 multicast messages across the IPv4 network between two IPv6 isolated islands.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

FIG. 1 is an application scene diagram of an embodiment of the present invention;

Fig. 2 is a schematic flow diagram of a method for forwarding IPv6 multicast packets across an IPv4 network in an embodiment of the present invention;

Fig. 3 is the structural representation of IPv6 automatic mapping multicast address in the embodiment of the present invention;

FIG. 4 is a schematic flow diagram of another method for forwarding IPv6 multicast packets across an IPv4 network in an embodiment of the present invention;

Fig. 5 is a schematic structural diagram of an edge device in an embodiment of the present invention

FIG. 6 is a schematic structural diagram of another edge device in an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

As shown in FIG. 1 , it is an application scenario diagram of the embodiment of the present invention. Among them, the user for multicast request to join the multicast group is located in an IPv6 island (called user island, user island 1 and user island 2 are shown in the figure), and the multicast source is located in another IPv6 island (called source island ), user islands and source islands are connected to the IPv4 backbone network through their respective edge devices (Provider Edge, PE). Wherein, each edge equipment PE1-PE3 supports IPv6 protocol and IPv4 protocol, and the IPv6 isolated island communicates with another IPv6 isolated island through its edge equipment. When user 1 needs to join a multicast group, user 1 sends an IPv6 multicast join request to PE1 of user island 1 where it is located, and PE1 encapsulates the IPv6 multicast join request into an IPv4 multicast join request and sends it to PE2. After the IPv4 multicast access request establishes a multicast forwarding entry, it establishes a connection with the multicast source, obtains IPv6 multicast packets from the multicast source, encapsulates the obtained IPv6 multicast packets into IPv4 packets, and sends them to PE1. , PE1 converts the IPv4 packet into an IPv6 multicast packet and sends it to User 1. Through the above method, it is possible to realize the forwarding of IPv6 multicast packets across the IPv4 backbone network and between IPv6 isolated islands.

As shown in Figure 2, the method for forwarding the IPv6 multicast message across the IPv4 network in the embodiment of the present invention specifically includes:

202. The first edge device receives an IPv6 multicast join request sent by an IPv6 user, where the IPv6 multicast join request carries multicast information.

Specifically, the first edge device is an edge device of a user island, and the multicast information includes multicast source information and multicast group information. The first edge device receives the multicast join request sent by the IPv6 users in the local island. Optionally, the destination address of the multicast join request (that is, the address of the multicast group that the user requests to join) is an IPv6 automatic mapping multicast address, and the IPv6 automatic mapping multicast address includes the IPv4 address of the edge device of the source island .

As shown in Figure 3, the IPv6 automatic mapping multicast address is a special multicast address, the total length of the address is 128bit, and the first 8bit is fixed as 11111111, which is used to identify the address as a multicast address, and the 9th to 12bit are In the flag field, currently only the 12th bit is clearly defined, that is, when this bit is set to 1, it indicates a non-reserved multicast group. In the embodiment of the present invention, any one of the 9th bit to the 11th bit can be used, such as the 11th bit to identify the automatic mapping address, and when the flag field is 0011, it indicates that the IPv6 address is an automatic mapping address of a non-reserved multicast group. The scope is a reserved field in the IPv6 address, 4 bits in total, the next 80 bits are used to identify the multicast group, and the last 32 bits are an IPv4 address, which in the embodiment of the present invention refers to the IPv4 address of the edge device of the source island.

With reference to Fig. 1, in the present embodiment, assume that the multicast source IPv6 address is: 2001::100, the multicast source supports two multicast groups G1 and G2, G1 is FF30:0001::10.0.0.2, and G2 is FF30: 0002::10.0.0.2. The IPv4 address of PE1 in the user island is 20.0.0.2, and the IPv6 address is 2002.20.0.0.2::1/64. The IPv4 address of PE2 on the source island is 10.0.0.2, and the IPv6 address is 2002:10.0.0.2::1/64. The source address of the IPv6 multicast join request sent by the user is the user's IPv6 address, the destination address is the multicast group G1:FF30:0001::10.0.0.2, and the specified multicast source address is 2001::100.

204. The first edge device acquires the IPv4 address of the second edge device according to the IPv6 multicast join request.

Specifically, the second edge device is an edge device of the source island. After receiving the IPv6 multicast join request sent by the user, the edge device of the user island obtains the destination address of the IPv6 multicast join request, that is, the IPv6 automatic mapping multicast address, and obtains the edge of the source island from the IPv6 automatic mapping multicast address The IPv4 address of the device, the IPv4 address of the edge device of the source island is the last 32 bits of the IPv6 auto-mapped multicast address.

Further, the edge device of the user island decides whether to obtain the IPv4 address of the edge device of the source island from the IPv6 auto-mapping multicast address according to the auto-mapping address flag of the IPv6 auto-mapping multicast address.

When the destination address of the IPv6 multicast join request sent by user 1 is FF30:0001::10.0.0.2, the auto-mapping address flag of this address is 1, so it is determined that the IPv4 address of the edge device PE2 of the source island needs to be obtained, and It may be further determined that the IPv4 address of PE2 is 10.0.0.2.

206. The first edge device sends an IPv4 multicast join request generated according to the IPv6 multicast join request to the second edge device, where the IPv4 multicast join request carries the multicast information.

After the first edge device obtains the IPv4 address of the second edge device from the IPv6 multicast join request, it generates an IPv4 multicast join request according to the IPv6 multicast join request, and sends the IPv4 address to the second edge device. A multicast join request, the IPv4 multicast join request may be a multicast listener discovery report (Multicast Listener Discovery, MLD, report), and the MLD report carries multicast information.

Specifically, the source address of the MLD report is 20.0.0.2, and the destination address is 10.0.0.2, wherein the multicast information includes the multicast source 2001::100, the multicast group FF30:0001::10.0.0.2, the The MLDreport further includes the IPv6 address 2002.20.0.0.2::1/64 of PE1 and the IPv6 address 2002.10.0.0.2::1/64 of PE2.

Wherein, generating an IPv4 multicast join request according to the IPv6 multicast join request may be to encapsulate an IPv4 packet header for the IPv6 multicast join request.

After receiving the MLD report, PE2 joins the multicast group FF30:0001::10.0.0.2 according to the MLD report, and creates a multicast forwarding entry corresponding to the MLD report. The PE includes a multicast forwarding table for storing multicast forwarding table items. The multicast forwarding table includes the multicast source, the multicast group, the IPv4 address of the first edge device, the IPv6 address and the IPv4 address and the IPv6 address of the second edge device, specifically in this embodiment, the multicast forwarding table can be as follows Table 1 shows.

Table 1

After generating the multicast forwarding entry, the second edge device establishes a connection with the multicast source, receives the IPv6 multicast packet from the multicast source, copies the IPv6 multicast packet according to the multicast forwarding entry, and copies the obtained IPv6 The multicast packet is encapsulated into an IPv4 packet, and then the encapsulated IPv4 packet is sent to the first edge device.

208. The first edge device receives the IPv4 packet sent by the second edge device, decapsulates the IPv4 packet to obtain an IPv6 multicast packet, and sends the IPv6 multicast packet to the user.

In the embodiment of the present invention, when the first edge device receives the IPv6 multicast join request sent by the user, it will record the corresponding relationship between the user and the multicast group that the user requests to join, and when receiving the IPv4 message sent by the second edge device Afterwards, the message is decapsulated to obtain an IPv6 multicast message, and the IPv6 multicast message is sent to the user according to the corresponding relationship.

As shown in Figure 4, another kind of method for forwarding IPv6 multicast message across IPv4 network in the embodiment of the present invention specifically includes:

402. The second edge device receives an IPv4 multicast join request sent by the first edge device, the IPv4 multicast join request is generated by the first edge device according to the IPv6 multicast join request, and the IPv4 multicast join request includes Carry multicast information.

Wherein, the second edge device is an edge device of a source island, the first edge device is an edge device of a user island, and the multicast information includes multicast source information and multicast group information.

404. The second edge device obtains the multicast information in the IPv4 multicast join request, joins a multicast group according to the multicast information, and creates a multicast forwarding entry.

The multicast forwarding entry includes a multicast source, a multicast group, an IPv4 address, an IPv6 address of the first edge device, and an IPv4 address and an IPv6 address of the second edge device.

406. The second edge device receives an IPv6 multicast packet from a multicast source.

408. The second edge device copies the IPv6 multicast packet according to the multicast forwarding entry, encapsulates the copied IPv6 multicast packet into an IPv4 packet, and sends the IPv4 packet to the first edge device.

The embodiment shown in FIG. 4 of the present invention is a further explanation of the embodiment shown in FIG. 2 from the perspective of the second edge device. Therefore, the parts not described in detail in the embodiment shown in FIG. 4 can be implemented by referring to FIG. 2 Example description.

In the above embodiment of the present invention, the edge device of the user island and the edge device of the source island convert the IPv6 message sent by the user and the multicast source into an IPv4 message for interaction, and realize the forwarding of the IPv6 multicast message across the IPv4 network.

As shown in FIG. 5, an embodiment of the present invention provides an edge device for implementing the method shown in FIG. 2, and the edge device includes:

The receiver 502 is configured to receive an IPv6 multicast join request sent by an IPv6 user, where the IPv6 multicast join request carries multicast information.

Wherein, the edge device is an edge device of an isolated user island, and the multicast information includes multicast source information and multicast group information. The destination address of the multicast join request is an IPv6 automatic mapping multicast address, and the IPv6 automatic mapping multicast address includes the IPv4 address of the edge device of the source isolated island.

The obtaining unit 504 is configured to obtain the IPv4 address of the second edge device according to the IPv6 multicast join request.

Wherein, the second edge device is an edge device of the source island. The obtaining unit 504 is specifically used to obtain the destination address of the IPv6 multicast join request, that is, the IPv6 automatic mapping multicast address, and obtain the IPv4 address of the edge device of the source island from the IPv6 automatic mapping multicast address, that is, the destination The last 32 bits of the address are used as the IPv4 address of the second edge device.

The first processor 506 is configured to generate an IPv4 multicast join request according to the IPv6 multicast join request, and send the IPv4 multicast join request to the second edge device, the IPv4 multicast join request carrying the Multicast information.

The second processor 508 is configured to receive the IPv4 packet sent by the second edge device, decapsulate the IPv4 packet to obtain an IPv6 multicast packet, and send the IPv6 multicast packet to the user.

In addition, the edge device may further include a recording unit 510, configured to record the correspondence between the user and the multicast group that the user requests to join after the receiver 502 receives the IPv6 multicast join request. The second processor 508 is specifically configured to send the IPv6 multicast packet to the user according to the correspondence between the user and the multicast group recorded by the recording unit.

As shown in FIG. 6, an embodiment of the present invention additionally provides an edge device for implementing the method shown in FIG. 4, and the edge device includes:

The first receiver 602 is configured to receive the IPv4 multicast join request sent by the first edge device, the IPv4 multicast join request is generated by the first edge device according to the IPv6 multicast join request, and the IPv4 multicast join request The request carries multicast information.

The first processor 604 is configured to acquire multicast information in the IPv4 message, join a multicast group according to the multicast information, and establish a multicast forwarding entry.

The second receiver 606 is configured to receive an IPv6 multicast packet from a multicast source.

The second processor 608 is configured to copy the IPv6 multicast message according to the multicast forwarding entry, encapsulate the copied IPv6 multicast message into an IPv4 message, and send the IPv4 message to the First edge device.

The edge device may further include a memory 610 configured to store the multicast forwarding entry established by the first processor 604 . The second processor 608 is specifically configured to obtain the multicast forwarding entry from the memory, and copy the IPv6 multicast packet according to the multicast forwarding entry.

The above-mentioned embodiments of the present invention belong to the same inventive concept, but each has its own emphases. Therefore, for features not described in a certain embodiment, reference can be made to other embodiments.

Those of ordinary skill in the art can understand that all or part of the steps for realizing the above-mentioned method embodiments can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the It includes the steps of the above method embodiments; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other various media that can store program codes.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (7)

1. cross over a method for IPv4 forwarded IPv6 multicast message, it is characterized in that, comprising:

First edge device receives the IPv6 multicast that IPv6 user sends and joins request, and carry multicast information during described IPv6 multicast joins request, described multicast information comprises the multicast group address that multicast source address and described user ask to add; Described multicast group address is IPv6 automatic mapping multicast address, and wherein automatic mapping address mark position is 1;

Described first edge device is 1 according to the automatic mapping address mark of described IPv6 automatic mapping multicast address, determines the IPv4 address obtaining the second edge device from described multicast group address; Wherein, described IPv6 user is positioned at user's isolated island, described multicast source is positioned at source isolated island, described user's isolated island connects IPv4 network by described first edge device, described source isolated island is by IPv4 network described in described second edge equipment connection, and described first edge device and described second edge device all support IPv6 agreement and IPv4 agreement;

Described first edge device joins request to described IPv6 multicast and encapsulates IPv4 heading, generate IPv4 multicast to join request, the source address that described IPv4 multicast joins request is the IPv4 address of described first edge device, and destination address is the IPv4 address of described second edge device; Described first edge device sends described IPv4 multicast to described second edge device and joins request, and sets up to make described second edge device the multicast forwarding list item joining request corresponding with described IPv6 multicast;

Described first edge device receives the IPv4 message that described second edge device sends according to described multicast forwarding list item, and the source address of described IPv4 message is the IPv4 address of described second edge device, and destination address is the IPv4 address of described first edge device; Decapsulation is carried out to described IPv4 message, obtains IPv6 multicast message, described IPv6 multicast message is sent to described user;

The IPv4 address obtaining the second edge device from described multicast group address comprises:

Obtain the IPv4 address of last 32bit as described second edge device of described multicast group address.

2. method according to claim 1, is characterized in that, after the IPv6 multicast that described reception IPv6 user sends joins request, described method also comprises the corresponding relation set up between multicast group that described user and described user ask to add,

Describedly described user is sent to specifically to comprise described IPv6 multicast message:

According to described corresponding relation, described IPv6 multicast message is sent to described user.

3. cross over a method for IPv4 forwarded IPv6 multicast message, it is characterized in that, comprising:

The IPv4 multicast that second edge device receives the first edge device transmission joins request, and the source address that described IPv4 multicast joins request is the IPv4 address of described first edge device, and destination address is the IPv4 address of described second edge device; Described IPv4 multicast joins request, and to be described first edge device to join request generation according to the IPv6 multicast of IPv6 user, and carry multicast information during described IPv4 multicast joins request, described multicast information comprises multicast source address and multicast group address; Described multicast group address is IPv6 automatic mapping multicast address, and wherein automatic mapping address mark position is 1; Described IPv6 user is positioned at user's isolated island, described multicast source is positioned at source isolated island, described user's isolated island connects IPv4 network by described first edge device, described source isolated island is by IPv4 network described in described second edge equipment connection, and described first edge device and described second edge device support IPv6 agreement and IPv4 agreement;

Described second edge device obtain described IPv4 multicast join request in multicast information, add multicast group according to described multicast information, and set up multicast forwarding list item; Described multicast forwarding list item comprises described multicast source address, multicast group address, the IPv4 address of described first edge device and IPv6 address, and the IPv4 address of described second edge device and IPv6 address;

Described second edge device receives IPv6 multicast message from multicast source;

Described second edge device copies described IPv6 multicast message according to described multicast forwarding list item, IPv4 message is packaged into by copying the IPv6 multicast message obtained, the source address of described IPv4 message is the IPv4 address of described second edge device, and destination address is the IPv4 address of described first edge device; Described IPv4 message is sent to described first edge device, after IPv6 multicast message being obtained to the decapsulation of described IPv4 message to make described first edge device, is transmitted to IPv6 user.

4. an edge device, is characterized in that, support IPv6 agreement and IPv4 agreement, and connect IPv4 network and user's isolated island, described edge device comprises:

Receiver, the IPv6 multicast sent for receiving IPv6 user joins request, and carries multicast information during described IPv6 multicast joins request, and described multicast information comprises the multicast group address that multicast source address and described user ask to add; Described multicast group address is IPv6 automatic mapping multicast address, and wherein automatic mapping address mark position is 1; Described IPv6 user is positioned at described user's isolated island, and described multicast source is positioned at source isolated island;

Acquiring unit, for being 1 according to the automatic mapping address mark of described IPv6 automatic mapping multicast address, determines the IPv4 address obtaining the second edge device from described multicast group address; Described IPv4 network is by source isolated island described in described second edge equipment connection, and described second edge device supports IPv6 agreement and IPv4 agreement;

First processor, join request for giving described IPv6 multicast and encapsulate IPv4 heading, generate IPv4 multicast to join request, and send described IPv4 multicast to described second edge device and join request, set up to make described second edge device the multicast forwarding list item joining request corresponding with described IPv6 multicast; The source address that described IPv4 multicast joins request is the IPv4 address of described first edge device, and destination address is the IPv4 address of described second edge device;

Second processor, for receiving the IPv4 message that described second edge device sends according to described multicast forwarding list item, the source address of described IPv4 message is the IPv4 address of described second edge device, and destination address is the IPv4 address of described first edge device; Decapsulation is carried out to described IPv4 message, obtains IPv6 multicast message, described IPv6 multicast message is sent to described user;

Described acquiring unit is specifically for obtaining the IPv4 address of last 32bit as described second edge device of described multicast group address.

5. edge device according to claim 4, it is characterized in that, described edge device also comprises record cell, and user receives after described IPv6 multicast joins request at described receiver, records the corresponding relation that described user and described user ask the multicast group added;

Described second processor, specifically for the corresponding relation of asking the multicast group added according to the described user of described recording unit records and described user, sends to described user by described IPv6 multicast message.

6. an edge device, is characterized in that, support IPv6 agreement and IPv4 agreement, and connect IPv4 network and source isolated island, described edge device comprises:

First receiver, the IPv4 multicast sent for receiving the first edge device joins request, and the source address that described IPv4 multicast joins request is the IPv4 address of described first edge device, and destination address is the IPv4 address of described second edge device; Described IPv4 multicast joins request, and to be described first edge device to join request generation according to the IPv6 multicast of IPv6 user, and carry multicast information during described IPv4 multicast joins request, described multicast information comprises multicast source address and multicast group address; Described multicast group address is IPv6 automatic mapping multicast address, and wherein automatic mapping address mark position is 1; Described IPv6 user is positioned at user's isolated island, and described multicast source is positioned at described source isolated island, and described user's isolated island connects described IPv4 network by described first edge device, and described first edge device supports IPv6 agreement and IPv4 agreement;

First processor, for obtaining the multicast information in described IPv4 message, adding multicast group according to described multicast information, setting up multicast forwarding list item; Described multicast forwarding list item comprises described multicast source address, multicast group address, the IPv4 address of described first edge device and IPv6 address, and the IPv4 address of described second edge device and IPv6 address;

Second receiver, for receiving IPv6 multicast message from multicast source;

Second processor, for copying described IPv6 multicast message according to described multicast forwarding list item, IPv4 message is packaged into by copying the IPv6 multicast message obtained, the source address of described IPv4 message is the IPv4 address of described second edge device, and destination address is the IPv4 address of described first edge device; Described IPv4 message is sent to described first edge device, after IPv6 multicast message being obtained to the decapsulation of described IPv4 message to make described first edge device, is transmitted to IPv6 user.

7. edge device according to claim 6, it is characterized in that, described edge device comprises memory further, for storing the multicast forwarding list item that described first processor is set up, described second processor specifically for obtaining this multicast forwarding list item from this memory, and copies described IPv6 multicast message according to this multicast forwarding list item.