Mobile Entity Handover Using Proxy Address Resolution
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Solution Overview
Problem
In mobile IP networks, handovers between access routers are challenging when the global address of one or both participating network access entities is unknown to the mobile entity or another network access entity, particularly in scenarios like GPRS networks where the Gateway GPRS Support Node's globally routable IP address is unknown, preventing proper routing during handover procedures.
Innovation Solution
The solution involves the mobile entity sending a message with identifying information to the second network access entity, enabling it to direct traffic to the first network access entity, even if its global address is unknown, by using link local addresses and additional parameters like old network identity and access point names to determine the globally routable IP address, and optionally employing a proxy function to facilitate IP address discovery and signaling without revealing confidential addressing information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mobile entity uses traditional IP handover procedures requiring globally routable IP addresses, then proper routing and traffic redirection can be achieved, but handover fails when global addresses are unknown (e.g., in GPRS networks)
Solution Approach 1:
The patent introduces a proxy entity that acts as an intermediary between the mobile entity and the target access router. The proxy receives binding update messages from the mobile entity, determines the global IP address of the target access router using parameters like old network identity and access point names, and forwards the messages appropriately. This mediator enables handover in networks where global addresses are not directly known to the mobile entity.
Solution Approach 2:
The patent performs preliminary address determination by the proxy entity before the mobile entity completes its handover. The proxy proactively determines the global IP address of the target access router using available parameters (old network identity, access point names, link local addresses) before the mobile entity needs to communicate with it, enabling seamless handover without requiring the mobile entity to know global addresses in advance.
2Reliability
If the globally routable IP address of the Gateway GPRS Support Node is made known to the mobile entity, then proper routing during handover can be achieved, but confidentiality of addressing information is compromised
Solution Approach 1:
The proxy entity serves as a confidential intermediary that knows the global IP addresses of access routers but does not reveal them to the mobile entity. The proxy uses its knowledge of network parameters (old network identity, access point names) to determine addresses internally, while communicating only with link local addresses or other non-confidential identifiers to the mobile entity, thus preserving addressing confidentiality.
Solution Approach 2:
The patent extracts the confidential address determination function from the mobile entity and places it in the proxy entity. The mobile entity sends only non-confidential parameters (old network identity, access point names, link local addresses), and the proxy extracts the global IP address information from these parameters without the mobile entity ever seeing or handling the confidential global addresses.
3Adaptability or versatility
If the mobile entity sends binding update messages with identifying information to the target access router, then traffic redirection can be achieved without global addresses, but additional signaling overhead is introduced
Solution Approach 1:
The patent enhances existing binding update messages with multiple pieces of identifying information (old network identity, access point names, link local addresses) that serve multiple functions: identifying the mobile entity, identifying the previous network, and enabling the proxy to determine the target address. This multi-functionality reduces the need for separate signaling messages.
Solution Approach 2:
The mobile entity copies relevant identifying parameters (old network identity, access point names, link local addresses) from its existing context and includes them in the binding update message. This copying approach reuses existing information rather than requiring new signaling protocols or additional message exchanges.
Data Source
AI summary
A method for performing a change of a connection of a mobile entity from a first network access entity to a second network access entity, wherein a global address of the first network access entity is not known to the mobile entity is provided. According to one embodiment, the method includes the step of sending a message including information for identifying the first network access entity from the mobile entity to the second network access entity which enables the second network entity to direct traffic to the first network entity. According to another embodiment, the invention also provides a method for the reverse direction. Namely, the invention provides a method for sending IP signaling from the mobile entity or from the first network access entity towards the second network access entity, whose global IP address is not known by the mobile entity or first network access entity.