SIP Proxy Server Intra-Domain Mobility Packet Reconstruction
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Solution Overview
Problem
Current mobile IP networks face inefficiencies in handling user mobility within roaming network domains, particularly due to the need for end-to-end signaling exchanges and packet tunneling, which increases overhead and is unsuitable for intra-domain handoffs, especially when Quality of Service (QoS) requirements are involved.
Innovation Solution
Assigning both local and global IP addresses to mobile hosts, with the domain server maintaining a mapping between these addresses, allowing for packet reconstruction that eliminates the need for intra-domain tunneling, thereby reducing packet size and improving communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If packet tunneling is used for mobile host communication in roaming network domains, then host mobility is supported, but packet overhead increases due to additional wrapper headers
Solution Approach 1:
The patent segments the network domain into a home network domain and roaming network domains, with the home agent acting as an intermediary. Mobile hosts use local IP addresses within roaming domains while the home agent maintains mapping to global IP addresses, eliminating the need for end-to-end tunneling wrappers and reducing packet overhead while maintaining mobility support.
Solution Approach 2:
The home agent serves as an intermediary between the mobile host and correspondent host. It maintains binding between local and global IP addresses and performs packet reconstruction, allowing mobile hosts to communicate without tunneling overhead while preserving mobility functionality.
2Adaptability or versatility
If end-to-end SIP session re-establishment is performed after handoff, then user mobility is handled, but communication continuity is disrupted and QoS requirements cannot be met
Solution Approach 1:
The home agent pre-establishes binding between local and global IP addresses before handoff occurs. When a mobile host moves to a new subnet, the home agent already has the mapping information ready, allowing immediate packet reconstruction and forwarding without session re-establishment delays, thus maintaining QoS requirements.
Solution Approach 2:
The home agent acts as a mediator that maintains session state and performs packet reconstruction. It intercepts packets destined for the mobile host's global IP address, reconstructs them with the current local IP address, and forwards them, ensuring seamless handoff without disrupting communication continuity or QoS.
3Adaptability or versatility
If tunneling is used for intra-domain handoffs, then mobility is supported, but communication efficiency decreases due to increased packet processing overhead
Solution Approach 1:
The patent extracts the tunneling function from the end-to-end communication path and relocates it to the home agent within the home network domain. Mobile hosts in roaming domains communicate using standard IP addressing without tunneling wrappers, eliminating processing overhead while maintaining handoff support through home agent-mediated packet reconstruction.
Data Source
AI summary
A method is described of using a mapping between a session initiation protocol (SIP)-Uniform Resource Identifier (URI), local IP address and a global IP address to identify a mobile host attached to a first subnet of a plurality of subnets included in a network domain, receiving a new local IP address of the mobile host upon the mobile host attaching to a second subnet of the plurality of subnets, replacing the local IP address with the new local IP address in the mapping, reformatting routing information of a SIP packet by replacing the global IP address in the routing information with the new local IP address, and communicating the reformatted packet to the mobile host. A proxy server and apparatus for use in this method are also disclosed.