Session Migration Controller for Seamless Multi-Homed Content Retrieval
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Solution Overview
Problem
Existing technologies fail to seamlessly migrate content retrieval sessions for multi-homed or mobile hosts between communication networks without disrupting the session, particularly due to limitations in transport protocols like TCP, SCTP, and MPTCP, and are not compliant with existing IP-layer and transport-layer protocols.
Innovation Solution
A controller function is implemented within the TCP/IP stack or session layer to monitor and manage state and status information, enabling seamless migration of content retrieval sessions from one server and interface to another by establishing new connections, transmitting content requests, and forwarding identified content portions, while maintaining compliance with existing transport protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCP is used as the underlying transport protocol, then reliable and in-order delivery of content is ensured, but the transport connection cannot be migrated to a different interface without disrupting the client-server session
Solution Approach 1:
The patent segments the content retrieval session into two independent parts: (1) the transport connection (TCP) which maintains reliability, and (2) the content delivery path which can be migrated. By separating these functions, the system allows interface migration without disrupting the TCP connection's reliable delivery guarantee.
Solution Approach 2:
The patent introduces a controller function as an intermediary between the client application and the transport layer. This controller manages the complexity of session migration by coordinating between the existing TCP connection and the new interface, allowing both reliability and adaptability to coexist.
2Adaptability or versatility
If SCTP is used, then the client can migrate the traffic flow from the old to the new interface, but it is not possible to change the server at the same time since the SCTP control block on the old server holds connection-specific information
Solution Approach 1:
The patent extracts the server change capability from the transport layer (SCTP) and handles it at the application layer through the controller function. This separation allows traffic flow migration via SCTP while independently managing server changes through application-level coordination, avoiding the complexity of modifying SCTP control blocks on servers.
3Adaptability or versatility
If application-layer solutions are implemented to support mobility and server changes, then seamless migration is achieved, but every client application must implement the solution separately which is very cumbersome
Solution Approach 1:
The patent implements a universal controller function that can operate with any client application and any transport protocol. This single controller design provides multi-functionality by handling interface migration, server changes, and protocol compatibility without requiring application-specific implementations, thereby reducing overall system complexity.
4Adaptability or versatility
If content retrieval sessions are disrupted to allow server changes, then the client can request remaining data from a new server, but the session continuity is broken
Solution Approach 1:
The patent performs preliminary actions by establishing a new transport connection to the target server before actually migrating the session. The controller pre-establishes the new connection and prepares the transfer, then executes the migration smoothly without disrupting session continuity, allowing the client to continue receiving data without interruption.
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AI summary
A controller function residing underneath a client application in a TCP/IP stack or session layer monitors state and status information associated with session-based application layer functions (e.g., content retrieval) and uses this information to migrate one or more sessions from a first client interface to a second client interface (e.g., 3G, 4G, LTE, 802.1 1x, WiMAX) and to a different application function serving entity (e.g., a different content server, cache server, service provider).