TWI731237B - Transparent bridging over mesh network - Google Patents

Abstract

A method of transparent bridging over mesh network is provided which comprises the following steps. A first mesh node (a6) is used to receive a first packet from outside the mesh network. The first mesh node (a6) is used to query the forwarding table of the first mesh node (a6); when the forwarding list of the first mesh node (a6) does not include the forwarding data of the external destination address (b1), the mesh source address (a6) of the first mesh node is encapsulated into the first packet, and the first The mesh node (a6) transmits the first packet to the second mesh node (a2) in multicast mode. The second mesh node (a2) is used to record the external source address (b3) and the mesh source address of the first mesh node (a6) into the forwarding table of the second mesh node (a2).

Description

Transparent bridging method applied to mesh network

The present invention relates to a transparent bridging method applied to a mesh network, and more particularly to a transparent bridging method applied to a mesh network that enables external nodes to communicate.

Mesh networks can use multicast or routing technology to deliver data to any node. However, when data transmission between external nodes of the mesh network is to be carried out, since the address domains of the internal and external nodes of the mesh network are independent and different from each other, routing technology cannot be used for transmission. In the conventional technology, a group broadcast method can be used for data transmission.

Figure 1 shows a schematic diagram of using multicast to transmit packets. In Figure 1, the inside of the mesh network Mesh contains most of the mesh nodes a1~a6, and the external nodes b1~b3 of the mesh network Mesh do not belong to the mesh network Mesh. The mesh nodes a1~a6 are randomly composed of the mesh network Mesh, and its routing table only records the address domain a of the internal mesh nodes a1~a6 of the mesh network Mesh; and the transmission path between the two nodes, such as mesh The routing table of node a6 records the next hop (Next Hop) of the destination mesh node a2 as mesh node a4.

When the external nodes b1~b3 transmit data through the mesh nodes a1~a6 inside the mesh, the external node b3 sends a packet T destined for the external node b1 to the mesh node a6 and the mesh node a6 After receiving it, looking up its own routing table does not find the information about the address field b of the external node. This is because the packet T cannot be forwarded because of the difference in the address field. To solve the aforementioned problems, you can use group broadcasting.

When the external node b3 wants to transmit the packet T to the external node b1 through the mesh network, the external node b3 first transmits the data point mesh node a6 (step S01), because the mesh node a6 does not know that the external node b1 is in the mesh node After a2, the mesh node a6 sends the packet T to all the mesh nodes a1~a6 in the Mesh through the multicast method, and these mesh nodes a1~a6 then send the packet T to the back (step S02) , The mesh nodes a1 and a5 send the packet T behind them, but there are no nodes behind the mesh nodes a1 and a5, so there is no device to receive them. After the mesh node a3 receives the packet T, it can directly transmit the packet T to the back of it without knowing that there is an external node b3. The external node b3 receives the packet T from the mesh node a3, and decodes it to know the value of the packet T. The destination is not the external node b3 and the packet T is ignored (step S03). After the mesh node a2 receives the packet T, it can directly transmit the packet T to the back of it without knowing that there is an external node b1. The external node b1 receives the packet T from the mesh node a2, and after decoding it, it knows that the packet T is The destination is the external node b1 and the packet T is correctly received (step S04).

This method of flooding multicasting can record the connection of different address domains without any correspondence table, but each packet is transmitted in this way, it will indeed cause a lot of invalid transmission, excessive traffic, and reduce the transmission efficiency of the ground network, and it is safe. Doubts. Another approach is to rely on the network administrator to manually set the internal and external address mapping table, but when the number of nodes increases or the nodes move, it will increase the management burden.

US Patent US8908670 discloses a method for locating a route between a source node and a destination node in a wireless network. The source node uses an extended route request (eRREQ) message to expand the wireless network. Flooding (flooding) broadcast to identify whether the connection source node is in the mesh network. When the connection source node is in the mesh network, the extended route request message contains (a) the mesh source node The source address of (mesh source node) and (b) the source address of the connection source node. In this way, the routing table in the node is updated.

However, the extended routing request (eRREQ) technology is only suitable for reactive routing, because it can issue a routing request (RREQ), change the routing request into an extended routing request, and extend the routing request and routing Respond (route reply, RREP) to carry the address of the external route. But it is not suitable for use in proactive routing technology. In addition, the aforementioned extended route request (eRREQ) technology must record the external node b3 in the mesh node a6 in advance, so that the mesh node a6 can replace the external node b3 Responsive Route Response (RREP), so additional operations are required before the operation A registration action (registration) to record the external node b3 in the mesh node a6.

According to an embodiment of the present invention, a transparent bridging method applied to a mesh network is provided to enable a plurality of external nodes to communicate through the mesh network. The mesh network includes a first forwarding table respectively stored therein. A mesh node (a6) and a second mesh node (a2). The method includes the following steps. The first mesh node (a6) is used to receive a first packet from outside the mesh network. The first packet includes an external destination address (b1) and an external source address (b3). Use the first mesh node (a6) to query the forwarding table of the first mesh node (a6). When the forwarding table of the first mesh node (a6) does not include the forwarding data of the external destination address (b1), the first The mesh source address (a6) of the mesh node is loaded into the first packet, and the first mesh node (a6) transmits the first packet to the second mesh node (a2) in a multicast manner. Using the second mesh node (a2), the external source address (b3) and the mesh source address of the first mesh node (a6) are recorded in the transfer table of the second mesh node (a2).

In one embodiment, the second mesh node (a2) uses the external source address (b3) as an external destination (b3); the mesh source address (a6) of the first mesh node is used as a tunnel (a6), and record the forwarding information including the external destination (b3) and the tunnel (a6) in the forwarding table of the second mesh node (a2).

In one embodiment, the method further includes the following steps. Use the first mesh node (a6) to receive a second packet from inside the mesh network. The second packet contains an external destination address (b3) and an external source address (b1); and the mesh destination address (a6) And the mesh source address (a2). Using the first mesh node (a6), the external source address (b1) and the mesh source address (a2) of the second mesh node are recorded in the forwarding table of the first mesh node (a6).

In one embodiment, the mesh network further includes a third mesh node (a1), and the transparent bridging method applied to a mesh network further includes: detecting a first external of the external nodes The node (b1) is coupled to the third mesh node (a1); and the third mesh node (a1) is used to send an address update message to the first mesh node (a6). In an embodiment, preferably, it further includes: the first mesh node (a6) updates the forwarding table of the first mesh node (a6) according to the address update message.

In one embodiment, the transparent bridging method applied to a mesh network further includes: counting with a timer, and updating the forwarding table of the second mesh node (a2) after a predetermined time has elapsed.

According to the transparent bridging method applied to the mesh network according to an embodiment of the present invention, the establishment of the tunnel is based on the learning of the packet address, which can save the trouble of manual setting. In one embodiment, there may be no need to send additional routing request (RREQ) procedures, and the format and behavior of the original mesh routing may not be changed. Therefore, it may be applicable to reactive routing (reactive) or pre-type routing. (proactive routing).

300‧‧‧Network Device

310‧‧‧Receiving circuit

320‧‧‧Packet processing circuit

330‧‧‧Judging circuit

340‧‧‧Memory Unit

350‧‧‧Transmission circuit

360‧‧‧Timer

a1~a6‧‧‧Mesh Node

b1~b3‧‧‧External node

Mesh‧‧‧Mesh Network

Fig. 1 shows a schematic diagram of conventional multicast transmission of packets.

2A shows a schematic diagram of transmitting packets according to a transparent bridging method applied to a mesh network according to an embodiment of the present invention.

2B shows a flowchart of a transparent bridging method applied to a mesh network according to an embodiment of the present invention.

FIG. 3A shows a flow chart of a transmission process for transparent bridging applied to a mesh network according to an embodiment of the present invention.

FIG. 3B shows a flow chart of a transmission process for transparent bridging applied to a mesh network according to an embodiment of the present invention.

FIG. 4 shows a functional block diagram of a network device according to an embodiment of the invention.

FIG. 5 shows a schematic diagram of transmitting packets according to a transparent bridging method applied to a mesh network according to an embodiment of the present invention.

The terms "device" and "node" in the following description are used in an equivalent manner. In addition, group broadcasting refers to a communication method in which a single device sends messages to multiple devices, and it can include broadcasting and the like. Mesh path (mesh path) refers to the path in the mesh network Mesh.

2A shows a schematic diagram of transmitting packets according to a transparent bridging method applied to a mesh network according to an embodiment of the present invention. 2B shows a flowchart of a transparent bridging method applied to a mesh network according to an embodiment of the present invention. As shown in FIGS. 2A and 2B, the mesh network Mesh includes a plurality of mesh nodes a1 to a6, and each of these nodes includes a forwarding table (Forwarding Table). The external nodes b1~b3 communicate through the Mesh network. In the following, it will be explained that the mesh nodes a2 and a6 establish the forwarding tables of the address domains a and b through learning. In this embodiment, the transparent bridging method applied to the mesh network includes the following steps. Step S20: The external node b3 sends a packet T to the mesh network Mesh, which includes the external destination address b1 and the external source address b3.

Step S22: When the mesh node a6 receives the packet T from the external node b3 for the first time, the mesh node a6 queries its forwarding table and knows that its forwarding table does not have the forwarding information of the external destination address b1, and the mesh node a6 will After the source address a6 and the multicast information are encapsulated in the packet T, the packet T enters the tunnel and multicasts it to each mesh node a1~a5 of the mesh network. The encapsulated data is as follows 1 shown.

According to an embodiment, in step S22, the mesh node a6 can also only encapsulate the mesh source address a6 in the packet T, so that the packet T enters the tunnel, and multicasts it to the mesh network. Each mesh node a1~a5. In this embodiment, the packet T does not contain the information of the mesh destination address.

Step S24: After the mesh nodes a1~a5 receive the packet T broadcasted by the mesh node a6, the packet T is transmitted to the rear, and the mesh nodes a1~a5 unpack the packet T, and then transfer the external source The associated information between the address b3 and the mesh source address a6 of the mesh network is recorded in its own forwarding table, for example, forwarding information: {external destination b3, tunnel a6}.

Step S26: If the external node b1 wants to respond to the external node b3, the external node b1 generates another packet P containing the source address b1 and the destination address b3, and sends it to the mesh node a2. After the mesh node a2 receives the packet P from the external node b1, the mesh node a2 knows that the destination of the packet P is b3, and the mesh node a2 will query its own forwarding table, because its own forwarding table already has {external destination B3, tunnel a6} forwarding information, so the mesh node a2 encapsulates the mesh source address a2 and mesh destination address a6 in the packet P, so that after entering the tunnel a6, it follows the mesh path of the routing table (mesh path ) Unicast to mesh node a6, and the encapsulated data is shown in Table 2 below.

Step S28: When the mesh node a6 receives the unicast packet P from the mesh node a2, decapsulates it, and associates the external source address b1 with the mesh source address a2 of the mesh network Mesh The information is recorded in its own forwarding table, such as forwarding information: {external destination b1, tunnel a2}, and the mesh node a6 transmits the packet P to the external node b1. In this way, both the mesh nodes a2 and a6 have established the forwarding information of the address domain b.

Step S30: When the mesh node a6 receives the packet T from the external node b3 for the second time or more, the mesh node a6 queries its forwarding table and learns that the transmission information contains {external destination b1, tunnel a2}. The state node a6 encapsulates the packet T and makes it enter the tunnel a2, and then transmits the packet T to the mesh node a2 in a unicast manner.

In one embodiment, the transparent bridging method applied to a mesh network further includes the following steps. Step 32: Detect that the external node b1 is coupled to the mesh node a1.

Step 34: Use the mesh node a1 to send an address update message to the mesh node a6.

Step 34: The mesh node a6 updates the forwarding table of the mesh node a6 according to the address update message.

In one embodiment, each of the mesh nodes a1 to a6 has a timer 360. The transparent bridging method applied to the mesh network further includes step 36: when a predetermined time has passed, the mesh nodes a1 to a6 update the forwarding tables of the mesh nodes a1 to a6. More specifically, the mesh nodes a1 to a6 delete the forwarded data in their forwarding tables that exceed the predetermined time, so as to avoid the problem of erroneously transmitting messages due to changes in the coupling position of the external nodes.

FIG. 3A shows a flow chart of a transmission process for transparent bridging applied to a mesh network according to an embodiment of the present invention. As shown in FIGS. 2A and 3A, in one embodiment, the transmission process of transparent bridging in the mesh network includes the following steps. The transmission process starts when the mesh node a6 receives a packet T from the outside of the mesh network Mesh (step S40), and the mesh node a6 first queries its forwarding table for information about external destinations (step S42). If not, encapsulate the multicast method in packet T (step S44), and then transfer the packet T into the mesh network Mesh, more specifically, after entering the multicast tunnel, send it to all the mesh networks of the mesh network. Shape nodes a1 to a5 (step S48). If so, encapsulate the tunnel address recorded in the forwarding table in the packet T (step S46), and then transfer the packet T into the mesh network Mesh, more specifically, send it to the tunnel address after entering the tunnel (Step S50).

FIG. 4 shows a functional block diagram of a network device according to an embodiment of the invention. As shown in FIG. 4, the network device 300 includes a receiving circuit 310, a packet processing circuit 320, a determining circuit 330, a memory unit 340, and a transmitting circuit 350. The receiving circuit 310 receives the packet T from outside the mesh network Mesh. The packet processing circuit 320 decapsulates the packet T to obtain information about an external destination in the packet T. The memory unit 340 stores a data table, which includes the routing table of most nodes inside the mesh network; and the transfer table of most nodes outside the mesh network Mesh. The judging circuit 330 first queries whether the transfer table in the memory unit 340 has external destination information. If not, the packet processing circuit 320 encapsulates the mesh source address in the packet T. The transmission circuit 350 causes the packet T to enter the multicast tunnel and transmit it to all nodes of the mesh network. If so, the packet processing circuit 320 encapsulates the tunnel address recorded in the forwarding table in the packet T. The transmission circuit 350 transmits the packet T to the tunnel address in a unicast manner after the packet T enters the tunnel.

FIG. 3B shows a flow chart of a transmission process for transparent bridging applied to a mesh network according to an embodiment of the present invention. As shown in FIGS. 2A and 3B, in this embodiment, the transmission process of the transparent bridging in the mesh network includes the following steps. The transmission process starts when the mesh node a2 receives the packet T from the mesh network Mesh (step S60), if it is the packet T encapsulated by the tunnel, it is decapsulated, and it is judged whether the source address of the inner header is recorded In the transfer table (step S62). If not, add a transfer data of {the source address of the inner header, the source address of the outer tunnel header}, and then record it in the transfer table (step S64). In one embodiment, a timer 360 is started to start timing (step S66). In one embodiment, if yes, reset the timing function of the timer 360 (step S68). Finally, the packet T is decapsulated (step S70), and the decapsulated packet T is sent to the outside of the mesh network (step S72).

The receiving circuit 310 receives the packet T from the inside of the mesh network Mesh. The packet processing circuit 320 decapsulates the packet T. If the packet T is a tunnel encapsulated packet, the judgment circuit 330 judges whether the source address of the inner header is recorded in the transmission table of the memory unit 340. If not, the judgment circuit 330 adds a piece of forwarding data of {the source address of the inner header, the source address of the outer tunnel header}, and records it in the transmission table of the memory unit 340. Finally, the transmission circuit 350 sends the decapsulated packet T to the outside of the mesh network.

In one embodiment, considering the possibility that the external nodes of the mesh network may move or disappear, optionally or preferably, the network device 300 may include a timer 360, and the timer 360 may elapse after a predetermined time has elapsed. Indicates that the information in the forwarding table has expired, and this expired record is deleted. During the receiving process, if there is a record of the destination in the forwarding table, the timing function of the timer 360 is reset.

Although the timer 360 can update the forwarding table when the external node of the mesh network moves, it cannot be updated in time because it needs to wait for the timer to expire. If the node moves frequently or needs to be updated in time to meet the needs of the application layer, the nodes of the mesh network must have the ability to detect back-end devices, and are not limited to actively learning the source of the external data of the mesh network during the transmission process. Address, or through an additional passive communication mechanism to detect that the back-end device is connected to a node inside the mesh network. When this event occurs, as shown in Figure 5, the internal node of the mesh network Mesh can send an address update message to notify all tunnel device nodes in its forwarding table to update the forwarding table. For example, when the external node b1 moves to the back of the mesh node a1, the mesh node a1 detects this event and informs it of the mesh node a6 in the forwarding table, and the mesh node a6 updates b1 information accordingly.

According to an embodiment of the present invention, it can be applied to a smart meter. More specifically, in the smart meter system, the concentrator transmits DLT645 packets to the meter through the mesh network, in order to resolve the inconsistency between the external address of the mesh network (meter ID) and the internal address of the mesh network (Mesh Address) The problem is to use a one-to-one correspondence method to use the Meter ID as the EUI64 of the mesh network node.

The transparent bridging method applied to a mesh network according to an embodiment of the present invention has at least one of the following advantages.

1. The tunnel technology is used in the Mesh network, so it can be compatible with any user network.

2. When transferring data that does not exist in the forwarding table by group broadcasting, the nodes in the mesh network can be divided into different group broadcasting groups to establish a more flexible network configuration.

3. The establishment of the tunnel is based on the learning of the packet address, eliminating the trouble of manual setting. Preferably, address learning can be compatible with various protocols, such as protocols such as IPv4, IPv6, Ethernet, Modbus, or DLT645.

4. According to an embodiment of the present invention, a transparent bridging method applied to a mesh network can determine the transmission path according to the destination address (for example, MAC) in the packet. Moreover, the use of address learning and automatic stateless tunneling technology to transfer external data. No additional configuration is required, and the forwarding table in the node can be deployed automatically and simply to replace the existing network.

5. The format and behavior of the original mesh routing are not changed, so it can be applied to reactive routing (reactive) or proactive routing (proactive routing).

6. Transparent bridging (Transparent Bridging) is based on the destination address (MAC) in the packet to determine the route of transmission. In one embodiment, transparent bridging does not need to determine the transmission path through a route in the system.

a1~a6‧‧‧Mesh Node

b1~b3‧‧‧External node

Mesh‧‧‧Mesh Network

Claims (6)

A transparent bridging method applied to a mesh network to enable a plurality of external nodes to communicate using the mesh network. The mesh network includes a first mesh node (a6 ) And a second mesh node (a2), the method includes: using the first mesh node (a6) to receive a first packet from a first external node (b3) outside the mesh network, the first A letter containing a first external destination address (b1) and a first external source address (b3); using the first mesh node (a6) to query the forwarding table of the first mesh node (a6), when the When the forwarding table of the first mesh node (a6) does not contain the forwarding data of the first external destination address (b1), encapsulate the mesh source address (a6) of the first mesh node into the first packet , And make the first mesh node (a6) transmit the first packet in multicast mode; use the second mesh node (a2) to receive the first mesh node (a6) transmitted in multicast mode After a packet, send the first packet to the outside of the mesh network, and record the external source address (b3) and the mesh source address (a6) of the first mesh node on the second network State node (a2) in the forwarding table; and when a second external node (b1) receives the first packet and wants to respond to the first external node (b3), the second external node (b1) generates a The second packet, which contains a second external destination address (b3) and a second external source address (b1), and is sent to the second mesh node (a2); using the second mesh node ( a2) After receiving the second packet, encapsulate a mesh destination address (a6) and a mesh source address (a2) in the second packet; use the first mesh node (a6) to receive the The second packet inside the mesh network, the second packet includes the second external destination address (b3) and the second external source address (b1); and the mesh destination address (a6) and the mesh source Address (a2); and Using the first mesh node (a6), the second external source address (b1) and the mesh source address (a2) of the second mesh node are recorded in the first mesh node (a6) In the forwarding table, the first mesh node (a6) uses the second external source address (b1) as an external destination (b1); the mesh source address of the second mesh node ( a2) As a tunnel (a2), and record the forwarding information including the external destination (b1) and the tunnel (a2) in the forwarding table of the first mesh node (a6), where the use of The step of querying the forwarding table of the first mesh node (a6) by the first mesh node (a6) includes: when the forwarding table of the first mesh node (a6) contains the first external destination address (b1) And tunnel (a2) when transferring data, encapsulate the mesh source address (a6) of the first mesh node and the tunnel (a2) into the first packet, and make the first mesh node (a6) Transmit the first packet to the second mesh node in a unicast manner (a2). The transparent bridging method applied to a mesh network according to claim 1, wherein the second mesh node (a2) uses the first external source address (b3) as an external destination (b3) ; Use the mesh source address (a6) of the first mesh node as a tunnel (a6), and record the forwarding information including the external destination (b3) and the tunnel (a6) in the second mesh Node (a2) in the forwarding table. The transparent bridging method applied to a mesh network according to claim 1, wherein the mesh network further includes a third mesh node (a1), and the method further includes: the third mesh node (a1) Detect a first external node (b1) of the external nodes, coupled to the third mesh node (a1); and use the third mesh node (a1) to send an address update message to The first mesh node (a6). The transparent bridging method applied to a mesh network according to claim 3 further includes: The first mesh node (a6) updates the forwarding table of the first mesh node (a6) according to the address update message. The transparent bridging method applied to a mesh network according to any one of claims 1 to 4, further comprising: counting with a timer, and updating the second mesh node ( a2) the transfer table. The transparent bridging method applied to a mesh network according to any one of claims 1 to 4, wherein the second mesh node (a2) is used to transmit the first packet to the outside of the mesh network The step is to directly transmit the first packet to the outside of the mesh network when the second mesh node (a2) does not know that there is the second external node (b1).

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