CN100423503C - Communication adapter switching method and device - Google Patents

Abstract

Provided is a communication adapter switching method in a system having a plurality of communication adapters, the method comprising: setting the address of the plurality of communication adapters to be the same as the address of the first one of the plurality of communication adapters; The packet filtering modes of all communication adapters other than the adapter are set to a mode in which all packets are accepted; and when one communication adapter is disconnected during communication, switching from the communication adapter to another of the plurality of communication adapters. Therefore, since the TCP/IP session is maintained at the same IP address, seamless switching from wired LAN to wireless LAN is possible.

Description

Communication adapter switching method and device

This application claims the benefit of Korean Patent Application No. 10-2004-0073299 filed on September 14, 2004 and Korean Patent Application No. 10-2004-0102304 filed on December 7, 2004 at the Korean Intellectual Property Office, which are in full Published here for reference.

technical field

The present invention relates to the network field, and more specifically, relates to a communication adapter switching method and equipment.

Background technique

In Windows OS, multiple physical adapters can be installed for communication. Communication can be performed by assigning an Internet Protocol (IP) address to each physical adapter. Communication with another party may be attempted by setting up a session using a pair consisting of a network layer IP address and a transport layer port address. If one of the pairs is changed, the session is disconnected immediately.

If there are two physical adapters of the same kind (eg, 802.3), a different IP address is assigned to each physical adapter. When a communication application connects a communication session, one IP address is selected based on an optimal routing path, and communication with another party is performed via a physical adapter to which the IP address is allocated. For example, even if there are physical adapters of other schemes such as 802.3 and 802.11, communication is performed in the same manner as described above.

If the user performs communication while a wired local area network (LAN) and a wireless LAN are simultaneously activated in a personal computer (PC) on which the Windows OS is installed and has different kinds of physical adapters, and if two of these physical adapters are connected to the same domain, communication will generally be performed using a wired LAN with faster communication speeds. That is, the IP address used in this case will be the IP address assigned to the wired LAN. Here, if the wired LAN is disconnected, the Windows OS automatically disconnects the session of the application communicating using the Transmission Control Protocol/User Datagram Protocol (TCP/UDP) since the assigned IP address can no longer be used.

Figure 1 shows the core-level library provided by Microsoft for providing the networking function of Windows OS. These libraries are known as Network Driver Interface Specification (NDIS) drivers. The actual physical adapter needs a driver when it is connected to a Peripheral Interconnect (PCI) interface, which is a miniport driver provided by the developer to conform to the NDIS miniport specification. Therefore, the actual physical adapter is activated to receive packets from the other side (LAN) and send them to the upper layer, and to receive packets from the upper layer and send these packets to the LAN.

The ubiquitous TCP/IP and NETBIOS are actually called protocol drivers and run at the upper layer rather than at the NDIS layer. Typically, the kernel level is handled by protocol drivers, and applications are user level.

Referring to Fig. 1, the network driver system includes WIN32 package driver 110, upper level (LAN) protocol driver 120, NDIS 130, middle driver 140, miniport drivers 150 and 160, network interface cards (NIC) 170 and 180.

The device driver connects an operating system (OS) to an input/output device, analyzes general requests received from the OS, and converts the requests into commands that a specific peripheral controller can understand.

NICs 170 and 180 are physical devices that operate as gateways for sending and receiving data frames in the network.

The NDIS 130 provides an interface for communication between at least one NIC driver and at least one protocol driver in upper layers including the OS. That is, the NDIS 130 provides a library of functions (called wrappers) used by upper-level (TCP/IP) drivers and NIC drivers. The NIC driver relies on NDIS 130 for various external functions, including: communicating with protocol drivers, registering and intercepting NIC hardware interrupts, and communicating with NICs 170 and 180 at lower levels.

The NDIS driver includes a NIC driver, an intermediate driver 140 , and an upper-level protocol driver 120 .

The NIC driver manages the NIC. The NIC driver is directly connected to the hardware (NIC) at the lower level and provides an interface with the upper level driver.

The miniport drivers 150 and 160 , that is, a kind of NIC driver, send data to and receive data from the NICs 170 and 180 , and perform hardware-oriented operations required to manage the NICs 170 and 180 . Miniport drivers 150 and 160 cannot directly call the OS. Instead, miniport drivers 150 and 160 may call functions exported by NDIS 130. In addition, the miniport drivers 150 and 160 are connected to upper drivers such as the intermediate driver 140 and the transport protocol driver.

An intermediate driver 140 exists between existing protocol drivers and miniport drivers 150 and 160 . Intermediate driver 140 appears to the upper-level transport driver as a miniport driver and to miniport drivers 150 and 160 as a protocol driver. The intermediate driver 140 is mainly used to perform media conversion between an existing protocol driver and manage a miniport of a new media type not recognized by the existing protocol driver.

Since the intermediate driver 140 has an intermediate position among drivers, it communicates with the miniport drivers 150 and 160 at the lower level, and with the protocol driver 120 at the upper level. The intermediate driver 140 provides protocol entry points to lower levels and miniport entry points to upper levels. The intermediate driver 140 is used to transmit requests for the upper protocol driver 120 for the NDIS 130. Intermediate driver 140 appears to upper-level protocol driver 120 as a miniport driver.

In order to provide services to users, the upper-level protocol driver 120 provides a transport driver interface (TDI) or an application-oriented interface. The upper-level protocol driver 120 sends the packet to the lower-level driver by packing data, distributing the packet to the lower-level driver, and calling the NDIS 130. In addition, the upper-level protocol driver 120 provides a protocol interface with the lower-level to receive packets from the lower-level driver. The transport protocol driver sends the received data to the appropriate client application.

As shown in Figure 2, in the current Windows OS, if a communication line between heterogeneous or homogeneous physical adapters is disconnected, its associated sessions are automatically disconnected. In the case of TCP, the information of the medium is stored in the TCP Control Block (TCB), and if the information of interface disconnection is entered, since the IP address assigned to the interface can no longer be used, TCP automatically disconnects its associated session. In Windows OS, even if TCP does not disconnect the session, the same IP address cannot be assigned to another interface at the same time. If an attempt is made to assign the same IP address to another interface, all other existing sessions are disconnected due to the TCP/IP protocol driver itself being rejected (turn down)/found (turn up).

Because of these problems, in order to pretend that only one interface exists when viewed from the actual protocol driver's point of view, Windows OS uses a bridge function that can create a virtual adapter. A bridge provides the same IP address to several interfaces. However, it takes about 30 seconds to perform a handoff. That is, even if a bridge is used, if communication of one physical adapter is disconnected, a disconnection signal is automatically input to a virtual adapter generated by the bridge, and all sessions of the TCP/IP protocol driver are automatically disconnected. Also, switching from one medium to another takes too much time in a bridge scenario. Experimental results show that switching from one medium to another takes 30 seconds or more, which corresponds to the TCP timeout time. Therefore, even though disconnected messages are blocked, the session is still disconnected due to TCP timeout.

Contents of the invention

Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention.

The present invention provides a communication adapter switching method and apparatus for maintaining a communication session of an application in an upper layer and providing seamless communication when switching between heterogeneous communication adapters.

According to an aspect of the present invention, there is provided a communication adapter switching method in a system having a plurality of communication adapters, the method comprising: setting the address of the plurality of communication adapters to be the same as that of the first of the plurality of communication adapters address of the communication adapter; the packet filtering mode of the communication adapters other than the first communication adapter is set to a mode in which all packets are accepted; and when a communication adapter is disconnected during communication, from the plurality of communication adapters Communication adapter switched to another.

According to another aspect of the present invention, there is provided a communication adapter switching method in a system having a plurality of communication adapters, the method comprising: setting a Media Access Control (MAC) address of a wired LAN communication adapter and a MAC address of a wireless LAN communication adapter The addresses are the same, and the packet filtering mode of the wired LAN communication adapter is set to an indiscriminate mode in which all packets are accepted; and when the wired LAN is disconnected during communication using the wired LAN communication adapter, using Wireless LAN information is switched from the wired LAN communication adapter to the wireless LAN communication adapter.

The communication adapter switching method may further include switching from the wireless LAN communication adapter to the wired LAN communication using wired LAN information when an event notifying or indicating that a wired LAN is connected occurs during communication using the wireless LAN communication adapter. adapter.

The communication adapter switching method may further include: setting the packet filtering mode of the wireless LAN communication adapter to direct, multicast, or broadcast mode.

The communication adapter switching method may further include mapping wireless LAN information to a virtual adapter if the wired LAN communication adapter is disconnected.

According to another aspect of the present invention, there is provided a communication adapter switching device in a system having a plurality of communication adapters, the device comprising: a virtual adapter, which sets the addresses of the plurality of communication adapters to those of the plurality of communication adapters the same address of the first one, and set the packet filtering mode of the communication adapters other than the first communication adapter to a mode in which all packets are accepted; and a virtual protocol driver which, during communication, when a communication adapter is On disconnect, switch from one of the multiple communications adapters to another.

According to another aspect of the present invention, there is provided a communication adapter switching device in a system having a plurality of communication adapters, the device comprising: a virtual adapter that sets a MAC address of a wired LAN communication adapter and a MAC address of a wireless LAN communication adapter the same, and the packet filtering mode of the wired LAN communication adapter is set to an indiscriminate mode in which all packets are accepted; and a virtual protocol driver which, during communication using the wired LAN communication adapter, when the wired LAN is When disconnected, switching from the wired LAN communication adapter to the wireless LAN communication adapter is performed using wireless LAN information.

The virtual protocol driver may include: a link status detector for providing a connection or disconnection status whenever a connection or disconnection event occurs.

The virtual protocol driver may also include a best adapter selector that determines a best adapter for communication based on information provided by the link state detector.

Packets received from a physical adapter may be sent unconditionally to the virtual adapter, and packets to be sent to a physical adapter may be sent to the determined best adapter.

Description of drawings

These and/or other aspects and advantages of the present invention will become clearer and easier to understand through the following description of embodiments in conjunction with the accompanying drawings, wherein:

Figure 1 is a block diagram of a conventional network driver system;

Figure 2 is a block diagram of a traditional network driver;

3 is a block diagram of a network driver system according to an embodiment of the invention;

Figure 4 is a block diagram of the intermediate driver shown in Figure 3;

5A and FIG. 5B are flowcharts showing a virtual driver loading process according to an embodiment of the present invention;

FIG. 6 is a flow chart illustrating a connection operation according to an embodiment of the present invention; and

FIG. 7 is a flowchart illustrating a disconnection operation according to an embodiment of the present invention.

Detailed ways

Embodiments of the invention will now be described in detail, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like parts throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

Hereinafter, the invention will be described more fully with reference to the accompanying drawings, in which embodiments of the invention are shown.

FIG. 3 is a block diagram of a network driver system according to an embodiment of the present invention.

According to this embodiment, the actual miniport driver is only bound to the virtual protocol driver included in the Internet driver. A virtual miniport driver is generated, and a virtual protocol driver is bound to the virtual miniport driver. The actual protocol drivers such as TCP/IP are then only bound to this virtual miniport driver. Therefore, the actual protocol driver only uses information from the virtual driver to get information about the state of the connection and sends and receives all packets through the virtual driver.

Referring to FIG. 3, the network driver system includes an intermediate driver 400, NICs 350 and 360, 802.3 miniport driver 330, 802.11 miniport driver 340, protocol driver 310, and NDIS 320 according to the present embodiment.

The intermediate driver 400 includes a virtual protocol driver 420 at a lower level and a virtual miniport driver 410 at an upper level. That is, in the interrelationship between the virtual protocol driver 420 at the lower level of the intermediate driver 400 and the miniport drivers 330 and 340, the intermediate driver 400 has the function of a protocol driver, and In the relationship between the virtual miniport driver 410 at the upper level and the protocol driver 310, the intermediate driver 400 has the function of a miniport driver. Virtual miniport driver 410 appears to be an adapter for protocol driver 310 . A virtual adapter is created to prevent the session of the TCP/IP protocol driver from being disconnected due to the disconnection information of the actual physical adapter. That is, the transmission of disconnection information from the actual physical adapter to the protocol driver 310 can be prevented by filtering in the intermediate driver 400 . Therefore, the TCP session is continuously maintained.

Furthermore, if there are two actual physical adapters, since two IP addresses must be assigned to the two adapters respectively, continuity of communication cannot be guaranteed. Thus, intermediate driver 400 is used as a virtual adapter linked to the two physical adapters. Therefore, since the application layer (not shown) located above the protocol driver 310 communicates with a virtual adapter, the application layer is not concerned with the type and state of the physical adapter located below the virtual driver.

Therefore, in the intermediate driver 400, the packet routing path can be changed. That is, in the intermediate driver 400, a communication medium is selected on a case-by-case basis, and packets are sent and received via a physical adapter. Thus, wired and wireless communications can be switched in almost real-time without affecting the protocol driver 310 .

FIG. 4 is a block diagram of the intermediate driver 400 shown in FIG. 3 .

Referring to FIG. 4 , the intermediate driver 400 includes a virtual miniport driver 410 and a virtual protocol driver 420 .

The virtual miniport driver 410 includes a virtual adapter controller 411 . The virtual adapter controller 411 generates a virtual adapter and controls the virtual adapter so that the protocol driver 310 binds to the virtual adapter and uses the virtual adapter.

Additionally, when the virtual protocol driver 420 is bound to a physical adapter, attributes for each physical adapter are set. Here, the virtual adapter controller 411 sets the same address to each bound physical adapter. When setting is performed, in the case of wired LAN, the packet filter value is set to indiscriminate mode in which all packets are accepted, and in wireless LAN, the packet filter value is set to direct/multicast/ Broadcast mode, as is usually used. The MAC address of the virtual adapter is set to the MAC address of the wireless LAN. That is, in the case of a wired LAN, the indiscriminate mode is set and the MAC address of the wired LAN does not seem to be set, and in the case of a wireless LAN, since the general mode is used, the MAC address of the virtual adapter depends on the wireless The MAC address of the LAN. Thus, in both cases, only the MAC address of the wireless LAN appears to be set on the part of the protocol driver 310 .

Using the same MAC address prevents retransmission of ARP packets in order to update the hub's Address Resolution Protocol (ARP) table. In addition, when dynamic address assignment is performed using the Dynamic Host Configuration Protocol (DHCP), the MAC address is used to differentiate the PCs by being an option used by the DHCP. In this case, since the DHCP server recognizes the connected PCs as the same PC because they use the same MAC address, the virtual adapter can be used without problems in a DHCP environment. Furthermore, when an Internet Protocol version 6 (IPv6) address is assigned according to automatic configuration using a MAC address, in the next-generation Internet IPv6, since the MAC addresses are all the same, address assignment can be performed without problems.

When the virtual adapter controller 411 requests information from the protocol driver in the upper layer, the virtual adapter controller 411 reports the optimal adapter information selected by the optimal adapter selector 421 to the protocol driver in the upper layer. That is, the virtual adapter controller 411 selects the lower layer link state information and reports the selected information to the protocol driver in the upper layer. Furthermore, when virtual adapter controller 411 sends packets to physical adapters, virtual adapter controller 411 uses the binding handle of the best adapter selected by best adapter selector 421 to send these packets.

The virtual protocol driver 420 includes a best adapter selector 421 , a link state detector 422 , and an adapter binding unit 423 .

The optimal adapter selector 421 determines a physical adapter for communication based on the connection information of wired or wireless LAN input from the link state detector 422 .

The link state detector 422 detects link state information of wired or wireless LAN and outputs the detected link state information to the optimal adapter selector 421 .

The adapter binding unit 423 binds all activated adapters and generates a binding list 424 . The adapter binding unit 423 includes binding handles for controlling bound physical adapters. In this embodiment, the adapter binding unit 423 includes an 802.3 binding handle 425 for wired LAN and an 802.11 binding handle 426 for wireless LAN. Each binding handle is like a key used by the virtual adapter to communicate with the miniport driver in the lower level. Furthermore, when the adapter binding unit 423 receives packets, it unconditionally sends these packets to the virtual adapter.

5A and 5B are flowcharts illustrating a process of initializing the intermediate driver 400 using the DriverEntry function according to an embodiment of the present invention. The DriverEntry function allocates a packet pool and a buffer pool for ARP, registers a driver handle for miniport drivers 330 and 340 and a protocol handle for protocol driver 310, and notifies NDIS 320 of the driver handle and the protocol handle Associated. FIG. 5A shows the process of initializing the intermediate driver 400 .

Referring to FIG. 5A , in operation 510 , initialization of the intermediate driver 400 starts with calling a DriverEntry function that operates through the OS as an entry point of the intermediate driver 400 .

In operation 520, the virtual adapter controller 411 binds the 802.3 adapter. Whenever the virtual adapter controller 411 binds a physical adapter, a virtual adapter data structure is created to store information of the physical adapter. Thus, the same number of data structures are generated as there are physical adapters. This virtual adapter data structure is bound to the actual protocol driver in the upper layer. Obtains the binding handle for the physical adapter by binding the data structure to the physical adapter.

The binding handle data structure in the virtual adapter data structure stores a list of multiple data structures in the subordinate.

During the 802.3 adapter binding process, the packet filtering attribute of the 802.3 wired LAN adapter is set to an indiscriminate mode in operation 521 . An adapter in indiscriminate mode accepts all packets it receives.

In operation 522, the address of the wired LAN adapter is set to the MAC address of the 802.11 layer 2 wireless LAN adapter.

Therefore, the 802.3 wired LAN adapter has the MAC address of the 802.11 wireless LAN adapter, and can receive all packets input through the wired LAN.

In operation 530, the virtual adapter controller 411 binds the 802.11 adapter.

In operation 531, the packet filtering property of the 802.11 wireless LAN adapter is set to direct, multicast, or broadcast mode, as is commonly used.

In direct mode, frames sent to a specific machine have the physical address (Ethernet address) of the destination machine assigned as the destination address. The machine with that physical address accepts the frame, other machines do not.

In multicast mode, frames sent to a batch of specific machines (multicast frames) have a multicast address assigned as the destination address. This particular batch of machines forms a multicast group. Therefore, every machine included in the multicast group can accept the frame. Even if the NIC does not belong to the multicast group, it can still be programmed to enter a multicast mode where all multicast frames are accepted.

In broadcast mode, frames sent to all machines in the network are broadcast to the network with destination address "0xffffff". The destination address "0xffffff" is regarded as a frame broadcast address. A NIC in broadcast mode accepts all frames with destination address "0xffffff". Normally, all NICs are configured so that broadcast frames can be accepted.

After binding is performed for all physical adapters, the virtual adapter controller 411 generates a virtual adapter in operation 540 and initializes the virtual adapter in operation 550 . The initialization of the virtual adapter includes: storing binding handle information by allocating a binding handle data structure; generating a binding handle list; and storing binding handle information and point information of the bound adapter in the binding handle list.

Referring to FIG. 5B, in operation 560, the connection status is queried using the virtual protocol driver 420. Referring to FIG.

The link state detector 422 included in the virtual protocol driver 420 having received the query detects the 802.3 connection state information and the 802.11 connection state information in operation 570, and sends the detected connection state information to the optimal adapter selector 421 .

In operation 580, the best adapter selector 421 selects the best adapter. When both the wired LAN and the wireless LAN are connected, the wired LAN is selected as the optimal adapter because the wired LAN is faster, and when no wired LAN is connected, the wireless LAN is selected as the optimal adapter. The optimum adapter selector 421 sends the information of the selected optimum adapter to the virtual adapter controller 411 .

In operation 590, the virtual adapter controller 411 maps the received information of the selected best adapter. The intermediate driver 400 is then ready for communication.

FIG. 6 is a flowchart showing a connection operation according to an embodiment of the present invention.

Referring to FIG. 6, when both the 802.3 wired LAN and the 802.11 wireless LAN are disconnected in operation 601, if a connection event is generated in operation 602, then in operation 603, the virtual miniport driver 410 reports the connection status to the upper layer protocol driver 310 . The upper protocol driver 310 determines whether the connected adapter is an 802.3 adapter in operation 604 , and if the connected adapter is an 802.3 adapter, the upper protocol driver 310 communicates with the 802.3 wired LAN in operation 607 . When communicating with the 802.3 wired LAN, if an 802.11 connection event is generated in operation 605 , the 802.11 connection status information is updated in operation 606 .

If the connected adapter in operation 604 is an 802.11 adapter instead of an 802.3 adapter, then in operation 608 the 802.11 adapter information is mapped to the virtual adapter. In operation 609, the upper layer protocol driver 310 communicates using the 802.11 wireless LAN.

When communicating with an 802.11 adapter, if an 802.3 connection event is generated in operation 610, the 802.3 adapter information is mapped to the virtual adapter in operation 611. In operation 612, the upper layer protocol driver 310 communicates using the 802.3 wired LAN.

FIG. 7 is a flowchart illustrating a disconnection operation according to an embodiment of the present invention.

Referring to FIG. 7, when the upper layer protocol driver 310 communicates with the 802.3 wired LAN in operation 701, if a disconnect event occurs in operation 702, the virtual adapter controller 411 determines whether the disconnected adapter is an 802.3 adapter in operation 703. adapter, and if the disconnected adapter is an 802.3 adapter, then in operation 704 the 802.11 adapter information is remapped to the virtual adapter. Then, in operation 705, the upper layer protocol driver 310 communicates using the 802.11 wireless LAN.

If the disconnected adapter is not an 802.3 adapter, the connection status of the 802.3 wired LAN is checked in operation 706 .

If the 802.3 wired LAN is found to be connected, the upper layer protocol driver 310 communicates with the 802.3 wired LAN in operation 707 .

If the 802.3 wired LAN is found to be disconnected, the virtual miniport driver 410 reports the disconnection status to the upper layer protocol driver 310 in operation 708 and the 802.3 adapter information is remapped to the virtual adapter in operation 709 . Then, both the 802.3 wired LAN and the 802.11 wireless LAN are disconnected.

As described above, according to the embodiment of the present invention, a unique virtual adapter for a heterogeneous communication medium is generated, and an IP address is assigned to the generated virtual adapter. When both the wired LAN and the wireless LAN are connected, the high-speed wired LAN is used, and if the wired LAN is disconnected, the disconnection is automatically detected and packets are rerouted to the wireless LAN. Therefore, protocol drivers such as TCP/IP only recognize virtual adapters. Therefore, since the IP address does not change even if the port address changes, a continuous session can be maintained.

That is, since the TCP/IP session is maintained at the same IP address, seamless handover from wired LAN to wireless LAN is possible. Furthermore, since the same MAC address is used, communication continuity is ensured with the IP address assigned by DHCP. Furthermore, in the next-generation Internet IPv6, seamless communication is possible in a stateless autoconfiguration environment in which an IPv6 address is generated from a MAC address.

The present invention can be implemented in a general-purpose computer by executing a program from a computer-readable medium including, but not limited to, a storage medium such as a magnetic storage medium (ROM, RAM, floppy disk, magnetic tape, etc.), an optically Read media (CD-ROM, DVD, etc.), and carrier waves (transmission via the Internet). The present invention can be implemented as a computer-readable medium having computer-readable program code elements embodied therein to enable distributed processing over many computer systems connected via a network. Functional programs for realizing the present invention. Codes and code segments can be easily derived by programmers in the technical field to which the present invention pertains.

While the invention has been shown and described with reference to its preferred embodiments, it will be understood by those skilled in the art that changes may be made in form and detail thereof without departing from the spirit and scope of the invention as defined by the appended claims. various changes. These preferred embodiments should be considered in a descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.

While a few embodiments of the present invention have been shown and described, it should be understood by those skilled in the art that changes may be made without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents. These examples vary.

Claims (18)

1. A communication adapter switching method in a system with a plurality of communication adapters, the method comprising: setting the address of the plurality of communication adapters to the same address as the first of the plurality of communication adapters; setting the packet filtering mode of all communications adapters except the first communications adapter to a mode in which all packets are accepted; and Switching from one of the plurality of communications adapters to another communications adapter when the communications adapter is disconnected during communications. 2. A communication adapter switching method in a system with a plurality of communication adapters, the method comprising: Setting the media access control address of the wired local area network communication adapter to the same media access control address as the media access control address of the wireless local area network communication adapter; setting the packet filtering mode of the wired LAN communications adapter to an indiscriminate mode in which all packets are accepted; and When the wired LAN is disconnected during communication using the wired LAN communication adapter, wireless LAN information is used to switch from the wired LAN communication adapter to the wireless LAN communication adapter. 3. The method of claim 2, further comprising: When an event indicating that the wired LAN is connected is generated during communication using the wireless LAN communication adapter, the wired LAN information is used to switch from the wireless LAN communication adapter to the wired LAN communication adapter. 4. The method of claim 2, further comprising: Set the packet filter mode of the wireless LAN communication adapter to direct, multicast, or broadcast mode. 5. The method of claim 2, further comprising: If the wired LAN communications adapter is disconnected, mapping the wireless LAN information to a virtual adapter for setting the wired LAN communications adapter's media access control address to the same medium as the wireless LAN communications adapter's media access control address access control address, and set the packet filter mode of the wired LAN communication adapter to indiscriminate mode in which all packets are accepted. 6. A communications adapter switching device in a system having a plurality of communications adapters, the device comprising: A virtual adapter that sets the address of a plurality of communication adapters to be the same as the address of a first of the plurality of communication adapters, and sets the packet filtering mode of all communication adapters except the first communication adapter to all packets in acceptable patterns; and A virtual protocol driver that switches from one of the plurality of communication adapters to another when the communication adapter is disconnected during communication. 7. A communications adapter switching device in a system having a plurality of communications adapters, the device comprising: a virtual adapter that sets the media access control address of the wired LAN communication adapter to be the same as the media access control address of the wireless local area network communication adapter, and sets the packet filtering mode of the wired local area network communication adapter to an indiscriminate mode in which all packets are accepted; and A virtual protocol driver that switches from the wired LAN communication adapter to the wireless LAN communication adapter using wireless LAN information when the wired LAN is disconnected during communication using the wired LAN communication adapter. 8. The apparatus of claim 7, wherein the virtual protocol driver includes a link state detector that provides connection or disconnection state information whenever a connection or disconnection event occurs. 9. The device of claim 8 , wherein the virtual protocol driver further includes a best adapter selector that determines an adapter for communication based on information provided by the link state detector. Best Adapter. 10. The apparatus of claim 9, wherein packets received from a physical adapter are sent to the virtual adapter unconditionally, and packets sent to a physical adapter are sent to the determined best adapter. 11. A method of communication adapter switching in a system with a plurality of communication adapters, the method comprising: setting the media access control address of the wired LAN communication adapter to the same media access control address as the media access control address of the wireless local area network communication adapter; Set the packet filter mode of the wired LAN communication adapter to an indiscriminate mode where all packets are accepted; Check whether the wired LAN is connected; If the wired local area network is connected, a wireless local area network connection event is generated; update WLAN connection information; and Communicate using a wired LAN. 12. The method of claim 11, further comprising: If the wired LAN is not connected, map the wireless LAN information to the virtual adapter; Communicate with wireless local area network; Generate wired LAN connection events; Map wired LAN information to virtual adapters; and Use this wired LAN for communication. 13. The method of claim 11 , wherein the wired local area network is an 802.3 wired local area network. 14. The method of claim 11 , wherein the wireless local area network is an 802.11 wireless local area network. 15. A method of selecting the best adapter comprising: setting the media access control address of the wired LAN communication adapter to the same media access control address as the media access control address of the wireless local area network communication adapter; Set the packet filter mode of the wired LAN communication adapter to an indiscriminate mode where all packets are accepted; Query connection status; Detect connection status information; selecting the best adapter based on the connection state information; and Information about the best adapter chosen by the map. 16. The method of claim 15, wherein if both wired LAN and wireless LAN are connected, the best adapter is the wired LAN, otherwise the best adapter is the one connected to it. 17. The method of claim 16, wherein the wired local area network is an 802.3 wired local area network. 18. The method of claim 16, wherein the wireless local area network is an 802.11 wireless local area network.

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