Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
2000-03-06
2003-12-02
Chin, Wellington (Department: 2664)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C455S436000
Reexamination Certificate
active
06657981
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention provides a wireless network communication system and method for integrating the communication mechanism of mobile IP and IAPP and allowing mobile host to roam among various access points and across different subnets, especially to a wireless network communication system and method using packet filters for reducing unnecessary traffic on the wireless network.
B. Description of the Prior Art
The current IEEE 802.11 standard only defines the protocols below the MAC layer for wireless LAN (hereinafter WLAN). The protocols on network layer have not been defined for WLAN yet. The communication among the Access Points (AP) in the WLANs is following the communication mechanisms defined by the Inter Access Point Protocol (IAPP). Accordingly, the IAPP is implemented on top of UDP/IP following the IEEE 802.11 standard. According to IAPP, the access points can obtain the information about other access points by exchanging broadcast packets. When an access point is initially activated, it broadcasts announce request packets to the WLAN. Other access points in the same WLAN will respond with announce response packets upon receiving the announce request packets. In an announce response packet, it contains the information about the access point, such as the MAC address of the access point. When a mobile host roams to another WLAN served by another access point, the mobile host will send a reassociation request to the new access point. The new access point will have to find the IP address of the access point originally served for the mobile host so as to complete a handover procedure, which will allow the new access point to replace the role of the original access point and provide services for the mobile host.
However, if the mobile host moves to another WLAN in a different IP subnet, the conventional IAPP communication mechanism will be blocked by the router. Consequently, the new access point will not be able to obtain the IP address of the original access point via broadcasting packets. The reason is because most routers are configured to block the traffic of broadcast packets so as to prevent the occurrence of broadcast storm. For this reason, access points in different IP subnets will not be able to obtain the IP address of another access point in different IP subnet via broadcasting packets. In other words, when a new access point receives a reassociation request from a mobile host, it has no way to get the IP address of the original access point if they are in different IP subnets. Consequently, a handover procedure will not be completed. As a result, the mobile host can only roam among various access points in the same subnet. Moreover, if the access points continuously broadcast the individual access point information to the access points in various subnets, it will inevitably increase the network traffic and reduce the bandwidth.
On the other hand, Mobile IP is a protocol defined for the, WLAN communication. Mobile IP defines the communication protocol on the network layer for allowing mobile hosts to roam among different subnets. Mobile IP depends on the Agents in each WLAN to record the current IP address of the mobile host. Whenever a mobile host moves from one WLAN to another WLAN, the new Agent will encapsulate the packets destined for the mobile host, and then forward the encapsulated packets to the mobile host according to its new IP address. Thus, the mobile host can roam among various subnets and still be able to receive/transmit data as usual.
Currently, since the mobile IP and IAPP are defined based on different network layers, so there is no solution for integrating the mobile IP and IAPP yet. Thus, it would be desirable to provide a method and system for integrating the mobile IP and IAPP communication mechanism.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide a wirelss network card driver and IAPP manager program with packet filters for communicating the wired LAN and wireless LAN, thereby to allow the mobile hosts to roam among various Basic Service Stations (RSS) in the same subnet.
It is another object of the present invention to provide a system and method for integrating the communication mechanism of mobile IP and IAPP on an access point, thereby allowing the mobile hosts to roam across different subnets.
It is still another object of the present invention to provide a communication system and method for filtering out unnecessary packet transmission, thereby to reduce the traffic on the wireless LAN.
Accordingly, the present invention implements an access point following the IAPP protocol to solve the handover problem occurred when the mobile hosts roam among different Basic Service Sets in the same subnet. Moreover, the present invention integrates the IAPP and Mobile IP technology on the access points to allow the mobile hosts to roam across different subnets. The present invention also provides the packet filters in the wireless LAN card driver and the bridge program for reducing the unnecessary traffic of packet transmission, and increasing the bandwidth efficiency of the wireless networks.
The communication system of the present invention mainly includes: an IAPP manager program in the user level of the access point for performing IAPP communication procedure and maintaining a mapping table for storing the physical address and the associated IP address of an access point. It also includes a wireless LAN card driver in the kernel level of the access point for performing IAPP communication procedure in response to the system calls of the IAPP manager program. The wireless LAN card driver includes a packet filter for determining if an incoming packet will be forwarded to the WLAN. The wired LAN card driver is connected to the wired LAN and acts as an interface for the wired LAN. A bridge program acts as an interface for communicating the wired LAN card driver and the wireless LAN card driver. The bridge program also includes a packet filter for controlling the traffic flow towards the WLAN.
REFERENCES:
patent: 6195705 (2001-02-01), Leung
patent: 6393482 (2002-05-01), Rai et al.
patent: 6473413 (2002-10-01), Chiou et al.
patent: 6510151 (2003-01-01), Cioli et al.
Chang Ruei-chuan
Chiang Mei-ling
Huang Liang-yi
Lee Hong-Yuh
Accton Technology Corporation
Birch & Stewart Kolasch & Birch, LLP
Chin Wellington
Fox Jamal A.
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