A method and apparatus for isolating wireless data transmissions between cascaded APs

Abstract

The application discloses a method and device for wireless data transmission between cascaded APs, comprising a first AP, a second AP and a first backbone SSID; the first AP provides wireless access service by configuring the first backbone SSID as a superior AP; the second AP accesses the first backbone SSID of the first AP by running a STA mode to establish a first backbone wireless connection with the first AP, and a static two-layer VPN tunnel is established between the second AP and the first AP. The method and the wireless access point can realize the transmission of VLAN messages in the cascaded mode of the wireless access point, and can realize the data flow isolation of various services in the air interface message in the cascaded mode of the AP, and solve the problem of the VLAN data isolation transmission in the cascaded mode of the AP in some application scenarios.

Description

Technical Field

[0001] This invention relates to the field of wireless local area network communication technology, and in particular to a method and apparatus for isolating and transmitting wireless data between cascaded access points (APs). Background Technology

[0002] Wireless local area network (WLAN) is a widely used wireless communication technology applied in various scenarios such as homes, factories, and offices. A wireless WLAN network consists of several wireless access points (APs) and several wireless terminals (STAs).

[0003] In a WLAN networking environment, a single access point (AP) can provide signal coverage within a limited space. When a larger coverage area is required, multiple APs need to be deployed in suitable locations. In this case, the AP's data backhaul, i.e., wireless data to the wired network, typically uses a wired Ethernet network (Ethernet cable or fiber optic cable). However, in some application scenarios, laying Ethernet cables or fiber optic cables is inconvenient, necessitating AP cascading to transmit network traffic from terminals via the wireless network. The widely used MESH wireless network in homes employs this method. In some industrial applications, wireless cascading is also required to achieve STA data backhaul. For example, in some substation scenarios, due to limitations imposed by construction wiring, two or three hop APs may be cascaded to extend the wireless network, requiring cascading between multiple APs to achieve data backhaul.

[0004] A typical example is the substation wireless network. Since it is inconvenient to run wired connections as AP backhaul in some older substations, the AP cascading method is used for wireless data backhaul. In this scenario, the AP is inside the substation, the AC is located in the municipal power equipment room, and the AP and AC are connected by a comprehensive power data network.

[0005] There are two modes for forwarding wireless data packets:

[0006] (1) Centralized forwarding: A data channel is established between the AP and the wireless controller. The wireless packets obtained by the AP from the wireless STA (including wireless devices in STA mode) are forwarded to the AC through the data channel, or the data packets obtained by the AC from the wired network are forwarded to the AP through the data channel. The AP then forwards the traffic to the STA through the air interface.

[0007] (2) Local forwarding: Locally forwarded traffic is not sent to the AC for centralized forwarding processing, but is directly forwarded by the AP.

[0008] In office or industrial applications, it is often necessary to isolate various business data traffic on the network. When using a wired network, Ethernet VLANs are usually used for data isolation. In this case, the traffic of different wireless SSIDs (Service Set Identifiers) is bound to the VLANs of the wired network.

[0009] For wireless traffic forwarding, in centralized forwarding mode at the access point (AP), the lower-level APs in a cascaded network can send received data packets to the AC (Access Controller) via the data channel. The AC then binds the packets to VLANs, achieving data isolation. However, centralized forwarding mode is not used in substation wireless network applications. Some service servers are deployed in the substation's computer room. If centralized forwarding mode were used, wireless data would be sent from the substation to the municipal power computer room and then back to the substation. This centralized forwarding mode increases network latency and the traffic pressure on the power integrated data network. Therefore, various services in substations use local forwarding.

[0010] In local forwarding mode, VLAN isolation cannot be implemented between APs in AP cascading mode because the 801.11 wireless data frame does not define a VLAN identifier field, and the AP chip is limited by the lack of the possibility to extend the frame field definition to support VLANs.

[0011] Patent CN200610104432.2, "Method for Implementing Virtual Local Area Network Based on WAPI System in Wireless Local Area Network", is based on the WAPI technology system. The WAPI certificate includes the user group attribute UGID. By binding / mapping UGID with VLAN-ID, group isolation based on UGID is achieved. This method has two problems: (1) It is limited to wireless networks based on the WAPI technology system and does not have the universality of WLAN networks; (2) The network maintenance workload is large, and it is necessary to specify UGID for each user. Summary of the Invention

[0012] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method and device for isolating and transmitting wireless data between cascaded access points.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] A method and apparatus for isolated transmission of wireless data between cascaded APs, including a first AP, a second AP, and a first backbone SSID;

[0015] The first AP, acting as the superior AP, is configured with the first backbone SSID to provide wireless access services;

[0016] The second AP connects to the first backbone SSID of the first AP by running STA mode, thereby establishing a first backbone wireless connection with the first AP. A static Layer 2 VPN tunnel is established between the second AP and the first AP.

[0017] As a further aspect of the present invention, the second AP, acting as a subordinate AP, is configured with multiple access SSIDs to provide wireless access services for wireless network terminal devices (STAs). When the second AP receives a wireless data packet from the STA and converts it into an Ethernet packet (i.e., the original payload packet), or when the first AP receives an Ethernet packet (i.e., the original payload packet) from the wired network, these original payload packets are encapsulated into static Layer 2 VPN tunnel packets. The static Layer 2 VPN tunnel packets are then sent to the peer via wireless packets. After receiving the wireless packets, the packet receiver converts the wireless packets into Ethernet packets to obtain tunnel encapsulation packets, obtains the original payload packets from the static Layer 2 VPN tunnel packets, and then forwards the original payload packets according to the general packet processing procedure.

[0018] As a further aspect of the present invention, the first AP achieves traffic isolation and forwarding of packets from the first AP to the second AP by encapsulating the VLAN-ID in the packets from the wired network into the tunnel header.

[0019] As a further aspect of the present invention, the second AP determines the VLAN-ID encapsulated in the tunnel header by using the VLAN-ID bound to the SSID associated with the wireless terminal STA, thereby achieving traffic isolation and forwarding of packets from the second AP to the first AP.

[0020] As a further aspect of the present invention, in order to achieve automatic configuration and establishment of the static Layer 2 VPN tunnel, the first AP includes the correspondence between SSID and VLAN-ID in the associated response frame sent to the second AP through the Vendor IE (Vendor Information Element). The second AP obtains the correspondence between SSID and VLAN from the associated response frame and automatically configures the Layer 2 VPN.

[0021] As a further aspect of the present invention, in order to enable the establishment of a static Layer 2 VPN tunnel between the first AP and the second AP based on TCP / IP, the first AP includes a first IP address and a second IP address through the Vendor IE. The first IP address is an IP address of the first AP, and the second IP address is an IP address in the same network segment assigned by the first AP to the second AP. The second AP uses the first IP address as the IP address of the wireless interface corresponding to the wireless connection between the second AP and the backbone SSID of the first AP.

[0022] As a further aspect of the present invention, the second IP address assigned to the second AP is reclaimed after the second AP disconnects the wireless connection of the backbone SSID from the first AP.

[0023] As a further aspect of the present invention, a wireless access point (AP) device is included, which enables data isolation transmission between cascaded APs. The AP device includes an AP mode wireless service software module and a STA mode wireless connection software module, and can operate in both AP mode and STA mode simultaneously.

[0024] As a further embodiment of the present invention, the AP device also includes a manufacturer information element processing software module and a Layer 2 VPN tunnel module;

[0025] Through the manufacturer information element processing software module, the AP can send the Vendor IE in the association response message after the backbone SSID is associated. The Vendor IE includes the correspondence between SSID and VLAN-ID, the first IP address, and the second IP address. After receiving the association response, the AP can also parse the correspondence between SSID and VLAN-ID, the first IP address, and the second IP address from the Vendor IE.

[0026] Through the Layer 2 VPN tunnel module, the second AP can automatically configure the IP address of the virtual wireless interface corresponding to the wireless connection of the second AP to the backbone SSID of the first AP using the second IP address. Both the first AP and the second AP can automatically configure a static Layer 2 VPN tunnel after association is completed, and can perform VPN tunnel encapsulation, packet forwarding and decapsulation of data packets based on this tunnel. The VPN tunnel encapsulation includes a VLAN-ID.

[0027] The beneficial effects of this invention are as follows:

[0028] The method and wireless access point described in this patent enable the transmission of VLAN packets in wireless access point cascading mode, thereby achieving data stream isolation for multiple services in air interface packets in AP cascading mode, and solving the problem of VLAN data isolation transmission in AP cascading mode in certain application scenarios. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the AP cascading network topology, illustrating the method and device for isolating and transmitting wireless data between cascaded APs proposed in this invention.

[0030] Figure 2 This is a schematic diagram illustrating the method and device for isolating and transmitting wireless data between cascaded APs using a Layer 2 VPN tunnel, as proposed in this invention.

[0031] Figure 3 This is a schematic diagram illustrating the VendorIE method and device for isolating and transmitting wireless data between cascaded APs, as proposed in this invention, and the transmission of VLAN and IP addresses.

[0032] Figure 4 This is a schematic diagram of the Layer 2 VPN tunnel packet encapsulation structure of a method and device for isolating and transmitting wireless data between cascaded APs proposed in this invention.

[0033] In the diagram: 110, switch; 210, first AP; 220, second AP; 310, STA1; 320, STA2. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] Example

[0037] Reference Figure 1-4 A method and apparatus for isolating and transmitting wireless data between cascaded APs, including a first AP, a second AP, and a first backbone SSID;

[0038] The first AP, acting as the superior AP, is configured with the first backbone SSID to provide wireless access services;

[0039] The second AP connects to the first backbone SSID of the first AP by running STA mode, thereby establishing a first backbone wireless connection with the first AP. A static Layer 2 VPN tunnel is established between the second AP and the first AP.

[0040] In this embodiment, the second AP, as a lower-level AP, configures multiple access SSIDs to provide wireless access services for wireless network terminal devices (STAs). When the second AP receives a wireless data packet from the STA and converts it into an Ethernet packet (i.e., the original payload packet), or when the first AP receives an Ethernet packet (i.e., the original payload packet) from the wired network, these original payload packets will be encapsulated in a static Layer 2 VPN tunnel packet. The static Layer 2 VPN tunnel packet is then sent to the peer via a wireless packet. After receiving the wireless packet, the packet receiver converts the wireless packet into an Ethernet packet to obtain a tunnel encapsulation packet, obtains the original payload packet from the static Layer 2 VPN tunnel packet, and then forwards the original payload packet according to the general packet processing procedure.

[0041] In this embodiment, the first AP achieves traffic isolation and forwarding of packets from the first AP to the second AP by encapsulating the VLAN-ID in the packets from the wired network into the tunnel header.

[0042] In this embodiment, the second AP determines the VLAN-ID encapsulated in the tunnel header by the VLAN-ID bound to the SSID associated with the wireless terminal STA, thereby achieving traffic isolation and forwarding of packets from the second AP to the first AP.

[0043] In this embodiment, in order to achieve automatic configuration and establishment of the static Layer 2 VPN tunnel, the first AP includes the correspondence between SSID and VLAN-ID in the associated response frame sent to the second AP through the Vendor IE (Vendor Information Element). The second AP obtains the correspondence between SSID and VLAN from the associated response frame and automatically configures the Layer 2 VPN.

[0044] In this embodiment, in order to enable the first AP and the second AP to establish a static Layer 2 VPN tunnel based on TCP / IP, the first AP includes a first IP address and a second IP address through the Vendor IE. The first IP address is an IP address of the first AP, and the second IP address is an IP address in the same network segment assigned by the first AP to the second AP. The second AP uses the first IP address as the IP address of the wireless interface corresponding to the wireless connection of the second AP to the backbone SSID of the first AP.

[0045] In this embodiment, the second IP address assigned to the second AP is reclaimed after the second AP disconnects the wireless connection of the backbone SSID from the first AP.

[0046] In this embodiment, a wireless access point (AP) device is included, which can realize data isolation transmission between cascaded APs. The AP device includes an AP mode wireless service software module and a STA mode wireless connection software module, which can run in both AP mode and STA mode simultaneously. In AP mode, a certain SSID can be specified as the backbone SSID, and the correspondence between SSID and VLAN can be specified.

[0047] In this embodiment, the AP device further includes a manufacturer information element processing software module and a Layer 2 VPN tunnel module;

[0048] Through the manufacturer information element processing software module, the AP can send the Vendor IE in the association response message after the backbone SSID is associated. The Vendor IE includes the correspondence between SSID and VLAN-ID, the first IP address, and the second IP address. After receiving the association response, the AP can also parse the correspondence between SSID and VLAN-ID, the first IP address, and the second IP address from the Vendor IE.

[0049] Through the Layer 2 VPN tunnel module, the second AP can automatically configure the IP address of the virtual wireless interface corresponding to the wireless connection of the second AP to the backbone SSID of the first AP using the second IP address. Both the first AP and the second AP can automatically configure a static Layer 2 VPN tunnel after association is completed, and can perform VPN tunnel encapsulation, packet forwarding and decapsulation of data packets based on this tunnel. The VPN tunnel encapsulation includes a VLAN-ID.

[0050] Reference Figure 1 The first AP 210 is connected to the switch 110 on the wired side and configured with backbone SSID 500 on the wireless side. The second AP 220 is connected to the first AP's SSID 500 to establish a backbone wireless connection 501. At the same time, the second AP 220 is configured with two access SSIDs, namely SSID 610 and SSID 620. STA1 310 is connected to the second AP's SSID 610, and STA2 320 is connected to the second AP's SSID 620.

[0051] In this AP cascaded topology, two virtual networks, VLAN 10 and VLAN 20, are created within the wired network, including switch 110 and the first AP 210. The wireless network SSID 610 of the second AP 220 is bound to VLAN 10, and its SSID 620 is bound to VLAN 20. Within the wired network, switch 110 and the wired connection between switch 110 and the first AP 210 enable VLAN-based traffic isolation. The second AP 220 enables SSID-based traffic isolation. The problem to be solved is achieving STA1 and ST2 traffic isolation between the wireless traffic of AP 210 and AP 220.

[0052] To solve this problem, after the second AP 220 establishes a wireless connection with the first AP 210, both the first AP and the second AP automatically establish a Layer 2 VPN tunnel and forward traffic based on the Layer 2 VPN tunnel.

[0053] Reference Figure 2 The relevant processes include:

[0054] S1: The second AP 220 is associated with the backbone SSID 500 of the first AP 210.

[0055] S2: The first AP 210 is automatically configured to establish a static Layer 2 VPN tunnel with the second AP 220. The source IP address of the Layer 2 VPN tunnel, i.e., the first IP, is the IP address of an interface of the first AP 210. It can typically be the address of the bridge interface corresponding to a certain VLAN, or the IP address of the wireless interface corresponding to the backbone SSID. The target IP address of the Layer 2 VPN tunnel, i.e., the second IP address, is dynamically assigned by the first AP 210 to the second AP 220. The second IP address and the first IP address are in the same network segment. At the same time, the first AP 210 automatically configures SESSION 10 to be bound to VLAN 10 and SESSION 20 to be bound to VLAN 20 for the tunnel.

[0056] S3: The first AP 210 replies to the second AP 220 with a radio association response message, which includes a specific Vendor Information Element (IE) (an information entry in the radio management frame), as shown in the example below. Figure 3 The diagram shows the correspondence between SSID and VLAN-ID (SSID 610, VLAN-ID 10) and (SSID 620, VLAN-ID 20), the first IP address, and the second IP address. The second AP 220 receives the wireless association response message, identifies the Vendor IE, and in addition to establishing a wireless connection, parses the binding / mapping relationship between SSID and VLAN-ID, the first IP address, and the second IP address from it.

[0057] S4: The second AP 220 automatically configures the IP address of the wireless interface of the backbone SSID 500 of the first AP 210 to be the second IP address, and automatically configures a static Layer 2 VPN tunnel, wherein the target IP address of the tunnel is the first IP address, the source address of the tunnel is the second IP address, and configures the tunnel SESSION 10 to bind VLAN 10 and SESSION 20 to bind VLAN 20.

[0058] S5: Data traffic is forwarded between the first AP 210 and the second AP 220 based on a Layer 2 VPN tunnel, wherein the Layer 2 VPN tunnel header includes VLAN-ID information.

[0059] As one example, such as Figure 4This diagram illustrates a Layer 2 VPN tunnel packet encapsulation structure. This structure uses UDP to encapsulate Layer 2 packets. The VPN control word mainly includes a VPN identifier, which is a specific number of 2 or 4 bytes. The header also includes a VLAN-ID. As an example, the VLAN-ID can be directly placed in the VPN tunnel header, or the VLAN-ID can be mapped to an integer, with the integer ID corresponding to the VLAN-ID placed in the VPN tunnel header.

[0060] Based on a Layer 2 VPN tunnel, the packet forwarding process between the first AP 210 and the second AP 220 includes:

[0061] (1) Wireless terminal STA towards wired network:

[0062] When the second AP 220 receives the 802.11 wireless packet from STA1 310, it converts the wireless packet into an 802.3 Ethernet packet 'a'. Packet 'a' represents traffic from the SSID 610 wireless network and should be bound to the VLAN 10 virtual wireless network. Therefore, the AP's Layer 2 VPN tunnel module adds a tunnel header to packet 'a', where the destination IP address is the first IP address, the source IP address is the second IP address, and the VLAN-ID is 0x0a (i.e., VLAN-ID 10). The second AP 220 then wirelessly transmits this IP packet to the first AP 210. After receiving the wireless packet, the first AP 210 converts it into an Ethernet packet, thus obtaining the tunnel packet. It extracts the original payload packet, i.e., packet 'a', from the tunnel packet and obtains its VLAN-ID of 0x0a from the header. The first AP 210 then forwards packet 'a' to the VLAN 10 virtual network.

[0063] The second AP 220 processes the 802.11 wireless message received from STA 320 in the same way as described above, where the VLAN-ID is 0x14 (i.e., VLAN-ID 20); after receiving the tunnel message, the first AP 210 forwards the payload message to the VLAN 20 virtual network.

[0064] (2) Wired network to wireless terminal STA:

[0065] When the first AP 210 receives Ethernet packet b destined for STA1 310 from VLAN 10, its Layer 2 VPN tunnel module adds a tunnel header to packet b. The destination IP address is the second IP address, the source IP address is the first IP address, and the VLAN-ID is 0x0a (i.e., VLAN-ID 10). The first AP 210 then wirelessly transmits this tunnel packet to the second AP 220. Upon receiving the wireless packet, the second AP 220 converts it to an Ethernet packet, thus obtaining the tunnel packet. It extracts the original payload packet (packet b) from the tunnel packet and obtains its VLAN-ID (0x0a) from the header. The second AP 220 then forwards the packet to STA1 310 via the air interface.

[0066] The first AP 210 processes the Ethernet packets destined for STA2 320 received from the virtual network VLAN 210 in the same way as described above, where the VLAN-ID is 0x14 (i.e., VLAN-ID 20); after receiving the tunnel packet, the second AP 220 forwards the payload packet to STA2 320 through the air interface.

[0067] The aforementioned packet forwarding process also includes a MAC address learning process. For example, when the first AP 210 receives an encapsulated packet from the tunnel, after parsing the Layer 2 packet 'a' from the tunnel encapsulation, it performs MAC address learning. The learning result is (STA1-MAC, tunnel to the second AP 220), meaning the tunnel exit to STA1-MAC is the tunnel from the first AP 210 to the second AP 220. When the first AP 210 receives an Ethernet packet with a destination address of STA1-MAC from VLAN 10, it obtains the forwarding table entry (STA1-MAC, tunnel exit to the second AP 220) by looking up the MAC table, thus obtaining the tunnel information. Based on the tunnel configuration, it then encapsulates the packet to form a tunnel packet. This process also includes packet flooding when the packet exit is unknown, similar to the general Ethernet packet forwarding process.

[0068] Meanwhile, wireless packets between the first AP 210 and the second AP 220 can be protected based on the encryption method of the wireless packets, eliminating the need for a Layer 2 VPN tunnel module to encrypt the tunnel payload.

[0069] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: Through the method and wireless access point described in this patent, it is possible to realize the transmission of VLAN packets in the wireless access point cascading mode, thereby realizing the isolation of data streams of multiple services in the air interface packets in the AP cascading mode, solving the problem of VLAN data isolation transmission in the AP cascading mode in certain application scenarios. The specific connection methods and working principles of the multiple electrical components are well known in the art and will not be described in detail here.

[0070] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0071] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0072] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for isolating and transmitting wireless data between cascaded access points (APs), characterized in that, Including the first AP, the second AP, and the first backbone SSID; The first AP, acting as the superior AP, is configured with the first backbone SSID to provide wireless access services; The second AP establishes a first backbone wireless connection with the first AP by accessing the first backbone SSID of the first AP through running STA mode, and a Layer 2 VPN tunnel is established between the second AP and the first AP. The first AP achieves traffic isolation and forwarding of packets from the first AP to the second AP by encapsulating the VLAN ID in the packets from the wired network into the tunnel header; The second AP determines the VLAN ID encapsulated in the tunnel header by using the VLAN ID bound to the SSID associated with the wireless terminal STA, thereby achieving traffic isolation and forwarding of packets from the second AP to the first AP.

2. The method for isolating and transmitting wireless data between cascaded APs according to claim 1, characterized in that, The second AP, acting as a subordinate AP, is configured with multiple access SSIDs to provide wireless access services to wireless network terminal devices (STAs). When the second AP receives a wireless data packet from the STA and converts it into an Ethernet packet (i.e., the original payload packet), or when the first AP receives an Ethernet packet (i.e., the original payload packet) from the wired network, these original payload packets will be encapsulated into a Layer 2 VPN tunnel packet. The Layer 2 VPN tunnel packet is then sent to the other end via a wireless packet. After receiving the wireless message, the message receiver converts the wireless message into an Ethernet message to obtain the tunnel encapsulation message. It then obtains the original payload message from the Layer 2 VPN tunnel message and forwards the original payload message according to the general message processing procedure.

3. The method for isolating and transmitting wireless data between cascaded APs according to claim 1, characterized in that, To enable the automatic configuration and establishment of the Layer 2 VPN tunnel, the first AP includes the correspondence between SSID and VLANID in the Vendor IE (Vendor Information Element) in the association response frame sent to the second AP. The second AP obtains the correspondence between SSID and VLAN from the association response frame and automatically configures the Layer 2 VPN.

4. The method for isolating and transmitting wireless data between cascaded APs according to claim 3, characterized in that, In order to enable the first AP and the second AP to establish a Layer 2 VPN tunnel based on TCP / IP, the first AP contains a first IP address and a second IP address through the Vendor IE. The first IP address is an IP address of the first AP, and the second IP address is an IP address in the same network segment assigned by the first AP to the second AP. The second AP uses the second IP address as the IP address of the wireless interface corresponding to the wireless connection of the second AP to the backbone SSID of the first AP.

5. The method for isolating and transmitting wireless data between cascaded APs according to claim 4, characterized in that, After the second AP disconnects the wireless connection of the backbone SSID from the first AP, the second IP address assigned to the second AP is reclaimed.

6. A device for isolating and transmitting wireless data between cascaded APs, comprising performing the method as described in any one of claims 1-5, characterized in that, This includes a wireless access point (AP) device capable of achieving data isolation transmission between cascaded APs. The AP device includes an AP mode wireless service software module and a STA mode wireless connection software module, and can run in both AP mode and STA mode simultaneously.

7. The device for isolating and transmitting wireless data between cascaded APs according to claim 6, characterized in that, The AP device also includes a manufacturer information element processing software module and a Layer 2 VPN tunnel module. Through the manufacturer information element processing software module, the AP can send a Vendor IE in the association response message after the backbone SSID is associated. The Vendor IE includes the correspondence between SSID and VLAN ID, a first IP address, and a second IP address. After receiving the association response, the manufacturer information element processing software module can also parse the correspondence between SSID and VLAN ID, the first IP address, and the second IP address from the Vendor IE. Through the Layer 2 VPN tunnel module, the second AP can automatically configure the IP address of the virtual wireless interface corresponding to the wireless connection between the second AP and the backbone SSID of the first AP using the second IP address. Both the first and second APs can automatically configure a Layer 2 VPN tunnel after association is completed, and can perform VPN tunnel encapsulation, packet forwarding, and decapsulation of data packets based on this tunnel. The VPN tunnel encapsulation includes the VLAN ID.

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