CN104023317A - Low-power-consumption multicast routing network and multicast routing method thereof - Google Patents

Abstract

The present invention provides a low-power multicast routing network, including at least one multicast group, each multicast group includes several multicast nodes forming a tree structure, and the multicast nodes are used to receive and forward according to the IPv6 protocol Multicast data flow; in the multicast group, the multicast node is also used to periodically send a multicast greeting message to its child nodes, and the multicast greeting message carries the identifier of the multicast group to which the multicast node belongs; The multicast node is also used to listen to the multicast greeting message sent by its parent node, and according to the listening situation of the multicast greeting message, choose not to process or send a multicast message to its parent node to apply for joining the corresponding multicast group. The join message, the multicast hello message and the multicast join message are implemented by extending the IPv6-based ICMPv6 message. The invention also provides a corresponding multicast routing method. The corresponding multicast data flow can be accurately sent to all member nodes of a specific multicast group with low network overhead and node energy consumption.

Description

A low-power multicast routing network and its multicast routing method

technical field

The invention relates to the technical field of computer networks, in particular, the invention relates to a low-power consumption multicast routing network and a multicast routing method thereof.

Background technique

With the increasingly higher requirements of industrial automation and the increasingly powerful functions of various sensor terminals, a special low-power lossy network——Low-power and Lossy Networks (LLNs) is more and more used in daily life. more extensive. This low-power lossy network usually consists of sensors, actuators, routers, and control centers, which can be organized into a tree network. In one example, the control center acts as the root node, routers act as intermediate nodes, and sensors and actuators act as leaf nodes. node. This kind of network can be deployed in the municipal system, for example, all street lights can be connected with this network, so as to realize the control of all street lights in the whole city.

In some applications of low-power lossy networks, one-to-many data transmission is sometimes required. For example, the control center needs to individually control the street lights of a certain street. For another example, the information monitoring sensor sends the monitored data to the monitoring station in real time, and at the same time, these data may also need to be sent to some alarms in real time. Therefore, the problem of multicast transmission in lossy network with low power consumption has great practical and research significance.

At present, the existing IPv6 multicast protocol can theoretically support the above-mentioned low-power lossy network. However, the devices in the low-power lossy network usually have the characteristics of low power consumption and small storage. If the IPv6 protocol is directly transplanted into the low-power lossy network, there will be problems of large network overhead and high energy consumption of nodes. Therefore, there is an urgent need for a low-power IPv6 multicast routing solution suitable for low-power lossy networks.

Contents of the invention

The task of the present invention is to provide a low-power multicast routing solution that can overcome the above-mentioned technical problems and is suitable for low-power lossy networks.

The present invention provides a low-power multicast routing network, which includes at least one multicast group, each multicast group includes several multicast nodes forming a tree structure, and the multicast nodes are used to receive and send messages according to the IPv6 protocol. Forward the multicast data stream of the multicast group to which it belongs;

In the multicast group, the multicast node is also used to periodically send a multicast greeting message to its child nodes, the multicast greeting message is implemented by extending the ICMPv6 message in the IPv6 protocol, and the multicast greeting message includes Carry the identification of the multicast group to which the multicast node belongs; the multicast node is also used to listen to the multicast greeting message sent by its parent node, and choose not to process or send Its parent node sends a multicast join message for applying to join the corresponding multicast group, and the multicast join message is implemented by extending the ICMPv6 message in the IPv6 protocol.

Wherein, the types of the multicast nodes of the multicast group include root nodes, intermediate nodes and leaf nodes.

Wherein, each multicast node is also used to maintain a local multicast table, and each entry of the multicast table stores the multicast group identifier to which the node belongs, the corresponding multicast address, and the multicast group belonging to the multicast group. The address of the child node of , where a multicast node can belong to multiple multicast groups.

Wherein, the root node is used to listen to and receive the multicast join message carrying the multicast group identifier sent by its child nodes, and register the corresponding entry in the local multicast table according to the multicast group identifier carried by the multicast join message Add the address of the corresponding child node in; also be used for according to the address of the child node in the item stored in the local multicast table, automatically send multicast greeting message to each child node at the preset interval time, the multicast greeting message It carries the multicast group identifier stored in the local multicast table; it is also used to send the multicast data flow to the multicast address in the local multicast table.

Wherein, the intermediate node is used to listen to and receive the multicast join message carrying the multicast group identifier sent by its child node, and register the corresponding entry in the local multicast table according to the multicast group identifier carried by the multicast join message Add the address of the corresponding child node in; also be used for according to the address of the child node in the entry stored in the local multicast table, automatically send the multicast greeting message to each child node at a preset interval time; also be used for detecting Listening to and receiving the multicast greeting message sent by the parent node, if the multicast greeting message sent by the parent node is not heard within the time corresponding to the preset interval time, according to the stored multicast greeting message in the local multicast entry The multicast group identifier is used to send the multicast join message to the parent node; it is also used to listen to and receive the multicast data flow sent by the parent node to the multicast address of the multicast group to which the intermediate node belongs, and to send the multicast data stream to the local multicast table The child node address in the corresponding entry forwards the multicast data flow.

Wherein, the leaf node is used to listen to and receive the multicast greeting message sent by its parent node, if the multicast greeting message sent by the parent node is not heard within the time corresponding to the preset interval time, then Send the multicast join message to the parent node according to the multicast group identifier stored in the local multicast entry; it is also used to listen to and receive the multicast message sent by the parent node to the multicast address of the multicast group to which the leaf node belongs broadcast data stream.

Wherein, the root node is also used as a multicast source to send a multicast data stream to the multicast address of the specified multicast group.

Wherein, the leaf node and the intermediate node are also used as a multicast source to send a multicast data stream to the multicast address of the specified multicast group;

The intermediate node is also used to listen to and receive the multicast data flow sent by its child nodes to the multicast address of the multicast group it belongs to, and send the multicast data flow to the parent node of the intermediate node and the child nodes except for the multicast data flow Other child nodes other than forwarding the multicast data flow;

The root node is also used to listen to and receive the multicast data flow sent by its child nodes to the multicast address of the multicast group, and forward the multicast data flow to other child nodes except the child node that sent the multicast data flow. Multicast streams.

The present invention also provides a multicast routing method based on the above-mentioned low-power multicast routing network, the types of the multicast nodes in the multicast group include root nodes, intermediate nodes and leaf nodes, and the multicast The group multicast routing method includes the following steps:

1) The root node sends a multicast data stream to the multicast address of the specified multicast group;

2) Each intermediate node listens to and receives the multicast data flow sent by the parent node to the multicast group it belongs to, and forwards the multicast data flow to the child node address in the corresponding entry of the local multicast table;

3) Each leaf node listens to and receives the multicast data flow sent by the parent node to the multicast group to which it belongs.

Wherein, said step 1) includes the following sub-steps:

11) A leaf node or an intermediate node acts as a source node as a source node, and the leaf node or an intermediate node acts as a source node to send a multicast data flow to the multicast address of the specified multicast group;

12) Each intermediate node listens to and receives the multicast data flow sent by the child node to the multicast address of the multicast group to which it belongs, and transmits data to the parent node of the intermediate node and other child nodes except the child node that sent the multicast data flow The child node forwards the multicast data flow;

13) The root node listens to and receives the multicast data flow sent by the child node to the multicast address of the multicast group to which it belongs, and forwards the multicast data flow to other child nodes except the child node sending the multicast data flow .

Wherein, the multicast routing method of the multicast group also includes the following steps:

4) For a node that is broadcasting or forwarding a multicast data stream to a certain multicast group G, automatically send the multicast greeting message to each child node belonging to the multicast group G at a preset interval;

5) Each intermediate node and leaf node belonging to the multicast group G listens to the multicast greeting message, if the multicast message sent by the parent node is not heard within the time corresponding to the preset interval time Hello message, then send the multicast join message to the parent node according to the multicast identification of the multicast group G stored in the local multicast entry; if the parent node is heard within the time corresponding to the preset interval time The multicast greeting message sent by the node is not processed, and continues to listen to and receive the data stream of the corresponding multicast address;

6) The root node and the intermediate node receive the multicast join message sent by the child node, and add the address of the child node to the entry of the multicast group G in the local multicast table.

Wherein, the multicast routing method of the multicast group also includes the following steps:

7) For a node A that needs to exit a certain multicast group G, the node A deletes the entry corresponding to the multicast group G from the local multicast table, and sends a multicast group exit message to the parent node, and the multicast group G exits. The broadcast group exit message is implemented by extending the ICMPv6 message in the IPv6 protocol, and the multicast group exit message carries the identifier of the multicast group G;

8) The parent node of the node A receives the multicast group exit message, and deletes the address of the node A from the child node address item of the entry of the multicast group G in the local multicast table.

Wherein, said step 7) includes the following sub-steps:

71) The node A checks the corresponding entry of the multicast group G in the local multicast table, and judges whether the item of the child node address in the entry is empty, if yes, then execute step 72), otherwise, execute step 73 );

72) The node A directly deletes the entry corresponding to the multicast group G from the local multicast table, and sends the multicast group exit message to the parent node;

73) The node A sends a multicast pruning message to the child node recorded in the corresponding entry of the multicast group G in the local multicast table; the multicast pruning message is implemented by extending the ICMPv6 message in the IPv6 protocol, and The multicast pruning message carries the identifier of the multicast group G; and, the node A deletes the entry corresponding to the multicast group G from the local multicast table, and sends the multicast group G to the parent node exit message;

74) After receiving the multicast pruning message, any child node deletes the entry corresponding to the multicast group G from the local multicast table, and at the same time adds the corresponding entry to the multicast group G in the local multicast table The sub-nodes of forwarding the multicast pruning message.

Compared with the prior art, the present invention has the following technical effects:

1. Able to accurately send corresponding multicast data streams to all member nodes of a specific multicast group with low network overhead and node energy consumption.

2. Under the premise of low network overhead and node energy consumption, the joining and exiting of each multicast group node can be controlled in an orderly manner as required.

Description of drawings

Below, describe the present invention in detail with reference to accompanying drawing in conjunction with embodiment, wherein:

Fig. 1 shows the structure of the low power consumption IPv6 multicast routing network of an embodiment of the present invention;

Fig. 2 shows the example of the ROOT tree corresponding to a multicast group in one embodiment of the present invention;

Fig. 3 shows the forwarding example of the member multicast flow based on a ROOT tree in one embodiment of the present invention;

Fig. 4 shows the forwarding example of non-member multicast flow based on a ROOT tree in one embodiment of the present invention;

Fig. 5 shows the example that the member exits in a ROOT tree in one embodiment of the present invention;

FIG. 6 shows another example of member exit in a ROOT tree in an embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

According to one embodiment of the present invention, a low-power consumption IPv6 multicast routing network is provided, which adopts a directed tree topology (hereinafter referred to as a tree structure) suitable for low-power lossy networks, as shown in FIG. 1. The node at the root of the low-power IPv6 multicast routing network is a root node, the node without child nodes is a leaf node, and the remaining nodes are intermediate nodes. Each of the nodes is used to maintain a local multicast table, and each entry in the multicast table stores the multicast group identifier to which the node belongs, the corresponding multicast address, and the child nodes belonging to the multicast group address. Each multicast group is also constructed with a directed tree topology, and the tree structure corresponding to each multicast group is a subtree on the low-power IPv6 multicast routing network. This subtree corresponding to the multicast group is referred to as ROOT tree herein. The ROOT tree is a shared tree, and all source nodes of the same multicast group share the same tree. FIG. 2 shows an example of a ROOT tree corresponding to a multicast group, and the multicast group is composed of node R and nodes N1-N8. The ROOT tree corresponding to the multicast group can also be any other subtree in the tree structure of the low-power IPv6 multicast routing network shown in Figure 1. For example, the multicast group can also be composed of R nodes and N1-N4 nodes. R node, N1 node, N6 node, or N1-N5 nodes. In the low-power IPv6 multicast routing network, multicast control is implemented based on a series of MRPL (Multicast Routing Protocol) control messages. In one embodiment, all MRPL control messages are implemented by extending ICMPv6 messages. MRPL control messages consist of an ICMPv6 message header followed by a message body. MRPL control messages mainly include the following types: M_Join message, M_Hello message, M_Prune message and M_Clear message.

The following describes four aspects of a node joining a multicast group, maintaining connectivity between a node and the multicast group it joins, sending multicast traffic, and leaving a node from a multicast group.

1. The node joins the multicast group.

When a node joins a multicast group, between an intermediate node or a leaf node and its parent node, the node joining operation is completed through the M__Join message and the M_Hello message, which specifically includes the following steps:

Step 11: When an intermediate node or leaf node tries to join and listen to a multicast group G, it expresses this requirement to its parent node, that is, sends an M_Join message to its parent node in the form of unicast. The content of the M_Join message indicates the multicast group to be joined by the node and is sent up hop by hop. Eventually the message will be sent to the root node or an intermediate node that has joined the group G. The M_Join message format is shown in Table 1.

Table 1

Version number: The version number of the MRPL protocol, which is currently version 1.

Type: The MRPL control message is an ICMPv6 information message with a type value of 156, that is, all MRPL control messages have a type value of 156.

Definition field: The definition field defines the type of this MRPL control message. In this embodiment, the types of MRPL control messages whose fields are the following values are defined.

1) 0x00 M_Join message

2) 0x01 M_Hello message

3) 0x02 M_Prune message

4) 0x03 M_Clear message

If a node receives an MRPL control message with unknown defined fields, the node MUST discard the message without any further processing.

Checksum: The checksum field is obtained according to the international common standard calculation method.

Generally, the multicast group address can be provided by the upper layer application. For example, if an application specifies a multicast group address as the communication address of the application function, all nodes that want to realize this function will automatically apply to join the multicast group.

Step 12: When the root node or an intermediate node that has joined the group G receives an M_Join message, it returns an M_Hello message to the node that sent the M_Join message. This M_Hello message is equivalent to the "M_Join_ACK" message in the traditional IPv6 protocol. The M_Hello message format is shown in Table 2.

Table 2

Step 13: The sender of the M_Join message receives the M_Hello message, indicating that the child node has successfully joined the multicast group and can begin to receive the multicast traffic of the multicast group.

2. Maintain connectivity between nodes and the multicast groups they join

After the node successfully joins the multicast group, it is necessary to maintain the connection between the node and the multicast group, so as to monitor and confirm and ensure the connection. In one embodiment, a "parent node is responsible" mechanism is implemented by using the M_Hello message, so as to maintain the connection between the node and the multicast group with less channel overhead and energy consumption. Specific steps are as follows:

Step 21: The root node and each intermediate node periodically send M_Hello messages to the child nodes recorded in their local multicast table. The M_Hello message will list all multicast groups whose parent node forwards multicast packets on this link. At this time, the function of the M_Hello message is to maintain the connection status between the node and its parent node.

Step 22: If the leaf node or intermediate node maintains a normal connection with the multicast group it belongs to, the node will periodically receive the M_Hello message sent by the parent node, and can confirm that it remains connected with the multicast group it has joined. If the leaf node or intermediate node has not received the M_Hello message from its parent node during the preset timing period (for example, 30 seconds), or during the timing period, there is no M_Hello message received by the child node that it listens to. multicast group address entries, it means that the node has been disconnected from the multicast group, go to step 23.

Step 23: After confirming that the node has been disconnected from the multicast group, the node re-sends the M_Join message to its parent node, so as to continue to listen to the group's multicast data (that is, re-initiate the process of joining the corresponding multicast group , including steps 11 to 13 above.

3. Multicast traffic sending

In a multicast group, data streams need to be sent from a multicast source to each node of the multicast group, which is called multicast traffic sending in this paper. In an embodiment, the sending of multicast traffic is mainly divided into two types, one is sending traffic from member sources, and the other is sending traffic from non-member sources.

Among them, for the member source traffic, that is, the sender of the multicast traffic is a member of the ROOT tree corresponding to the multicast group, since the member source is directly connected to the ROOT tree, the member source traffic can be directly sent to the group The various members of , see Figure 3 for details. When the source node is a leaf node or an intermediate node, member source traffic sending includes the following steps:

Step 311: When a node initiates a multicast packet of the multicast group, it first sends the multicast packet upward to its parent node. For example, when node N3 initiates a multicast packet of the multicast group, it first sends the multicast packet to its parent node N2.

Step 312: Each intermediate node listens to and receives the multicast data flow sent by its child node to the multicast address of the multicast group it belongs to, and transmits the multicast data flow to the parent node of the intermediate node and other than the child nodes sending the multicast data flow The other child nodes of forwarding the multicast data flow. For example, when the node N2 listens to and receives the multicast data stream of its child node N3, it forwards the multicast data stream to the parent node N1. When the intermediate node N1 listens to and receives the multicast data flow of its child node N2, it forwards the multicast data flow to the parent node R and the child node N4 other than the node N2.

Step 313: the root node listens to and receives the multicast data flow sent by the child node to the multicast address of the multicast group to which it belongs, and forwards the multicast data to other child nodes except the child node sending the multicast data flow flow. For example, when the root node R listens to and receives the multicast data flow of its child node N1, it forwards the multicast data flow to the child node N6 other than the node N1.

Step 314: Each intermediate node listens to and receives the multicast data flow sent by the parent node to the multicast group it belongs to, and forwards the multicast data flow to the address of the child node in the corresponding entry of the local multicast table. For example, when the intermediate node N4 listens to and receives the multicast data flow of its parent node N1, it forwards the multicast data flow to its child node N5. When the intermediate node N6 listens to and receives the multicast data flow of its parent node R, it forwards the multicast data flow to its child node N7. When the intermediate node N7 listens to and receives the multicast data stream of its parent node N6, it forwards the multicast data stream to its child node N8.

Step 315: Each leaf node listens to and receives the multicast data flow sent by the parent node to the multicast group to which it belongs. For example, the leaf node N5 listens to and directly receives the multicast data stream sent by its parent node N4 to the multicast group to which it belongs. The leaf node N8 listens to and directly receives the multicast data stream sent by its parent node N7 to the multicast group it belongs to.

In addition, if there are still listeners of the multicast group outside the ROOT tree (the information of such listeners is recorded in the root node), then the multicast packet will be sent out through the root node and delivered to the multicast group listener. This completes the sending of member source traffic.

In one embodiment, a method for sending non-member source traffic is also provided. This is because it cannot be guaranteed that all multicast sources are members of the ROOT tree. At this time, the non-member source traffic transmission line can be seen in Figure 4. The non-member source traffic transmission process specifically includes the following steps

Step 321: When the multicast source is not on the ROOT tree of the specified multicast group, the node as the multicast source sends the multicast data stream to the root node of the specified ROOT tree through the tunnel. For example, when non-member node N9 is used as a multicast source, the multicast data packet

Step 322: The root node of the ROOT tree sends the multicast traffic to its child nodes in the downlink direction. For example, the root node forwards the multicast data stream to its child nodes N1 and N6.

Step 323: Each intermediate node listens to and receives the multicast data flow sent by the parent node to the multicast group it belongs to, and forwards the multicast data flow to the address of the child node in the corresponding entry of the local multicast table. For example: when the intermediate node N1 listens to and receives the multicast data flow of its parent node R, it forwards the multicast data flow to its child nodes N2 and N4. When the intermediate node N2 listens to and receives the multicast data stream of its parent node N1, it forwards the multicast data stream to its child node N3. When the intermediate node N4 listens to and receives the multicast data flow of its parent node N1, it forwards the multicast data flow to its child node N5. When the intermediate node N6 listens to and receives the multicast data flow of its parent node R, it forwards the multicast data flow to its child node N7. When the intermediate node N7 listens to and receives the multicast data stream of its parent node N6, it forwards the multicast data stream to its child node N8.

Step 324: Each leaf node listens to and receives the multicast data flow sent by the parent node to the multicast group to which it belongs. For example, the leaf node N3 listens to and directly receives the multicast data stream sent by its parent node N2 to the multicast group to which it belongs. The leaf node N5 listens to and directly receives the multicast data stream sent by its parent node N4 to the multicast group it belongs to. The leaf node N8 listens to and directly receives the multicast data stream sent by its parent node N7 to the multicast group it belongs to.

The above steps 323, 324 are actually consistent with steps 314, 315.

In addition, when the root node of the ROOT tree is used as the source node, the above steps 322 to 324 can be directly performed, and details will not be repeated here.

4. The node leaves the multicast group

In one embodiment, there are two situations for a node to leave the multicast group, one is that the node actively leaves the ROOT tree, and the other is that the parent node prunes the child node. These two methods are realized through M_Prune message and M_Clear message respectively. Table 3 shows the format of the M_Prune message. Table 4 shows the format of the M_Clear message.

table 3

Table 4

The process for a node to voluntarily leave the ROOT tree is as follows: when the node itself no longer needs to receive data from a multicast group G, or for an intermediate node on the ROOT tree, there are no listeners of group G among its child nodes , the node will actively leave the ROOT tree through the M_Prune message. Specifically include the following steps:

Step 411: When the node itself needs to leave the ROOT tree, it will first send an M_Prune message to the parent node. The M_Prune message lists the group addresses of all multicast groups that the node no longer listens to.

Step 412: After the node sends the M_Prune message, the node assumes that the operation is successful, and the parent node does not need to send a confirmation signal to the child node. However, in particular, if the node still receives the M_Hello message containing the multicast group G afterwards, it means that some kind of error may have occurred in the M_Prune message it sent before, causing it to fail to perform the pruning operation successfully. At this time, the node needs to send the M_Prune message to its parent node again.

FIG. 5 shows a schematic diagram of node N3 actively leaving the ROOT tree.

The parent node prunes the child nodes as follows: when an intermediate node on the ROOT tree and its parent node can no longer send and receive multicast data for the multicast group G, the parent node will delete the child node cut off. Specifically include the following steps:

Step 421: In the pruning operation, firstly, the parent node sends an M_Clear message to the child node, and the message contains "invalid" multicast group information.

Step 422: After receiving the M_Clear message from the parent node, the child node will clear the "invalid" multicast group information from its local multicast table according to the multicast groups listed in the M_Clear message. At the same time, the node also sends the M_Clear message which plays the same role to its child nodes.

FIG. 6 shows a schematic diagram of node N1 pruning its child node N2.

The above-mentioned node exit mechanism can ensure orderly control of the joining and exiting of each multicast group node on demand under the premise of low network overhead and node energy consumption.

Finally, it should be noted that the above embodiments are only used to describe the technical solutions of the present invention rather than limit the technical methods of the present invention. The present invention can be extended to other modifications, changes, applications and embodiments in application, and therefore it is considered that all such Modifications, changes, applications, and embodiments are all within the spirit and teaching scope of the present invention.

Claims (13)

1. A low-power multicast routing network, comprising at least one multicast group, each multicast group comprising several multicast nodes forming a tree structure, the multicast nodes are used to receive and forward multicast according to the IPv6 protocol broadcast data stream; The multicast node is also configured to regularly send a multicast greeting message to the child nodes of the multicast node in the multicast group to which it belongs, and the multicast greeting message carries the identifier of the multicast group to which the multicast node belongs; the The multicast node is also used to listen to the multicast greeting message sent by the parent node of the multicast node in the multicast group to which it belongs. According to the listening situation of the multicast greeting message, choose not to process it or send an application to its parent node Joining the multicast join message of the corresponding multicast group, the multicast hello message and the multicast join message are implemented by extending the ICMPv6 message based on the IPv6 protocol. 2. The low-power multicast routing network according to claim 1, characterized in that, for one multicast group, the types of its multicast nodes include root nodes, intermediate nodes and leaf nodes. 3. The low-power multicast routing network according to claim 2, wherein each multicast node is also used to maintain a local multicast table, and each entry of the multicast table stores the current node The identifier of the multicast group to which it belongs, the corresponding multicast address, and the addresses of the child nodes belonging to the multicast group, wherein a multicast node may belong to multiple multicast groups. 4. The low-power multicast routing network according to claim 3, wherein the root node is configured to listen to and receive a multicast join message carrying a multicast group identifier sent by its child nodes, and The multicast group identifier carried in the broadcast join message adds the address of the corresponding child node in the corresponding entry of the local multicast table; it is also used to store the address of the child node in the entry in the local multicast table according to the preset Automatically send a multicast greeting message to each child node at an interval time, and the multicast greeting message carries the multicast group identifier stored in the local multicast table; it is also used to send a multicast data stream to the multicast address in the local multicast table . 5. The low-power multicast routing network according to claim 4, wherein the intermediate node is configured to listen to and receive a multicast join message carrying a multicast group identifier sent by its child nodes, and according to the multicast The multicast group identifier carried in the broadcast join message adds the address of the corresponding child node in the corresponding entry of the local multicast table; it is also used to store the address of the child node in the entry in the local multicast table according to the preset The interval time automatically sends the multicast greeting message to each child node; it is also used to listen to and receive the multicast greeting message sent by the parent node, if the parent node is not heard within the time corresponding to the preset interval time The multicast hello message sent by the node sends the multicast join message to the parent node according to the multicast group identifier stored in the local multicast entry; it is also used to listen to and receive the parent node to send to the intermediate node. the multicast data flow of the multicast address of the multicast group, and forward the multicast data flow to the sub-node address in the corresponding entry of the local multicast table. 6. The low-power multicast routing network according to claim 5, wherein the leaf node is used to listen to and receive the multicast hello message sent by its parent node, if within the preset interval If the multicast hello message sent by the parent node is not heard within the time corresponding to the time, then the multicast join message is sent to the parent node according to the multicast group identifier stored in the local multicast entry; it is also used for listening And receive the multicast data flow sent by the parent node to the multicast address of the multicast group to which the leaf node belongs. 7. The low-power multicast routing network according to claim 4, wherein the root node is also used as a multicast source to send a multicast data stream to the multicast address of the specified multicast group. 8. The low-power multicast routing network according to claim 6, wherein the leaf nodes and intermediate nodes are also used as multicast sources to send multicast data to the multicast address of the specified multicast group flow; The intermediate node is also used to listen to and receive the multicast data flow sent by its child nodes to the multicast address of the multicast group it belongs to, and send the multicast data flow to the parent node of the intermediate node and the child nodes except for the multicast data flow Other child nodes other than forwarding the multicast data flow; The root node is also used to listen to and receive the multicast data flow sent by its child nodes to the multicast address of the multicast group, and forward the multicast data flow to other child nodes except the child node that sent the multicast data flow. Multicast streams. 9. A multicast routing method based on the low power consumption multicast routing network according to claim 2, wherein, for one said multicast group, said method comprises the following steps: 1) The root node sends a multicast data stream to the multicast address of the specified multicast group; 2) Each intermediate node listens to and receives the multicast data flow sent by the parent node to the multicast group it belongs to, and forwards the multicast data flow to the child node address in the corresponding entry of the local multicast table; 3) Each leaf node listens to and receives the multicast data flow sent by the parent node to the multicast group to which it belongs. 10. The multicast routing method according to claim 9, characterized in that, said step 1) comprises the following sub-steps: 11) A leaf node or an intermediate node acts as a source node as a source node, and the leaf node or an intermediate node acts as a source node to send a multicast data flow to the multicast address of the specified multicast group; 12) Each intermediate node listens to and receives the multicast data flow sent by the child node to the multicast address of the multicast group to which it belongs, and transmits data to the parent node of the intermediate node and other child nodes except the child node that sent the multicast data flow The child node forwards the multicast data flow; 13) The root node listens to and receives the multicast data flow sent by the child node to the multicast address of the multicast group to which it belongs, and forwards the multicast data flow to other child nodes except the child node sending the multicast data flow . 11. The multicast routing method according to claim 10, characterized in that the method further comprises the following steps: 4) For the root node and the intermediate node that are broadcasting or forwarding the multicast data stream to the multicast group, automatically send the multicast greeting to each child node in the multicast group at a preset interval information; 5) Each intermediate node and leaf node belonging to the multicast group listens to the multicast greeting message, if the multicast greeting message sent by the parent node is not heard within the time corresponding to the preset interval time message, then send the multicast join message to the parent node according to the multicast identifier of the multicast group stored in the local multicast entry; if the parent node is heard within the time corresponding to the preset interval time The multicast greeting message sent by the node is not processed, and continues to listen to and receive the data stream of the corresponding multicast address; 6) The root node and intermediate nodes belonging to the multicast group receive the multicast join message sent by the child node, and add the address of the child node to the entry of the multicast group in the local multicast table. 12. multicast routing method according to claim 9, is characterized in that, described IPv6 multicast routing method also comprises the following steps: 7) For the node A that needs to exit the multicast group, the node A deletes the entry corresponding to the multicast group from the local multicast table, and sends a multicast group exit message to the parent node, and the multicast group The multicast group exit message carries the identifier of the multicast group, and the multicast group exit message is implemented by extending the ICMPv6 message based on the IPv6 protocol; 8) The parent node of the node A receives the multicast group exit message, and deletes the address of the node A from the child node address item of the entry of the multicast group G in the local multicast table. 13. The multicast routing method according to claim 12, characterized in that, said step 7) comprises the following sub-steps: 71) The node A checks the corresponding entry of the multicast group in the local multicast table, and judges whether the item of the child node address in the entry is empty, if yes, execute step 72), otherwise, execute step 73); 72) The node A directly deletes the entry corresponding to the multicast group from the local multicast table, and sends the multicast group exit message to the parent node; 73) The node A sends a multicast pruning message to the child node recorded in the corresponding entry of the multicast group in the local multicast table; the multicast pruning message carries the identifier of the multicast group; and , the node A deletes the entry corresponding to the multicast group from the local multicast table, and sends the multicast group exit message to the parent node; the multicast pruning message extends the IPv6-based ICMPv6 message implementation; 74) After receiving the multicast pruning message, any child node deletes the entry corresponding to the multicast group from the local multicast table, and at the same time sends the corresponding entry to the multicast group in the local multicast table. The child nodes in the item forward the multicast pruning message.