Access Point Proxy Registration for Mobile IP Session Continuity
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Solution Overview
Problem
Clients running the Microsoft Windows operating system with the DHCP protocol face disruptions in maintaining Mobile IP sessions when roaming between wireless Access Points, as the media sense feature triggers Dynamic Host Configuration Protocol (DHCP) activation, leading to new IP address allocation and loss of existing Mobile IP connectivity.
Innovation Solution
The solution involves transmitting detection messages, such as ARP requests and ICMP PING messages, to determine if the client remains on its home network, and responding accordingly to prevent new IP address assignment, thereby maintaining existing Mobile IP sessions by indicating the client is still on its home network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the media sense feature triggers DHCP activation when a client roams between wireless Access Points, then the client obtains a new IP address, but the existing Mobile IP session is lost
Solution Approach 1:
The patent applies preliminary action by having the access point send a detection message to the client before DHCP address reassignment occurs. This detection message (such as an ARP request or ICMP ping) allows the client to verify its current IP address is still valid before the media sense feature triggers DHCP activation. By performing this verification in advance, the system prevents unnecessary IP address reassignment and maintains Mobile IP session continuity while still allowing client mobility.
2Reliability
If the client sends detection messages to verify IP address validity, then Mobile IP session continuity is maintained, but additional network traffic is generated
Solution Approach 1:
The patent applies local quality by making the detection message targeting specific - it is sent only to the client's current IP address (the one that should remain valid), rather than performing a comprehensive network scan. The detection message uses the client's known valid IP address as the destination, ensuring that traffic is localized and minimal. This targeted approach reduces unnecessary network bandwidth consumption while maintaining session continuity.
3Reliability
If the access point always sends detection messages to prevent IP reassignment, then Mobile IP sessions are maintained, but client response time increases
Solution Approach 1:
The patent applies partial action by implementing detection messages only under specific conditions - when the access point determines that the client's current IP address should remain valid based on the roaming scenario. Rather than continuously sending detection messages regardless of client state, the system activates this mechanism only when needed to prevent unnecessary IP reassignment, thereby reducing overall response time while maintaining reliability where required.
Data Source
AI summary
Methods and apparatus for preventing an IP address from being assigned to a client implementing a protocol such as DHCP are disclosed. This is particularly useful in an environment such as a Mobile IP environment in which a network device (e.g., Access Point) performs proxy registration on behalf of the client. When the client transmits a detection packet to detect whether its IP address is still valid (e.g., whether it is on the same sub-network on which the IP address was allocated), a response is transmitted to the client that indicates that the client is still on its home network. This response is transmitted regardless of whether the client is still on its home network. Since the client believes it is still on its home network, a new IP address will not be assigned to the client. As a result, an existing Mobile IP session will not be interrupted.