Seamless Transport Connection Migration for Load Balancing
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Solution Overview
Problem
In server networks, especially those using long-lived transport connections like SCTP, existing methods for load balancing and server maintenance cause service disruptions and additional signaling traffic when long-lived connections are torn down and re-established, especially during peak load times.
Innovation Solution
A system and method for migrating live transport connections between servers without interrupting communications, using a load balancer that updates state information tables and sends migration commands to enable seamless transfer of connections from one server to another, maintaining transparency to the endpoint and avoiding additional traffic generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If long-lived transport connections are torn down and re-established for load balancing or server maintenance, then server load distribution is improved, but service continuity deteriorates and additional signaling traffic is generated
Solution Approach 1:
The system performs preliminary actions by establishing a backup transport connection to a standby server before tearing down the primary connection. The standby server is pre-configured with connection state information, so when the primary connection is terminated, the backup connection can immediately take over without service disruption. This resolves the contradiction by preparing failover capabilities in advance, maintaining service continuity while enabling load balancing.
Solution Approach 2:
The system introduces an intermediary mechanism in the form of a backup transport connection that mediates between the primary connection and the new server assignment. When load balancing requires connection migration, the backup connection serves as a temporary intermediary that maintains service continuity during the transition, avoiding direct connection termination that would cause service disruption and signaling traffic.
2Adaptability or versatility
If connections are migrated between servers for maintenance or capacity management, then system adaptability is improved, but connection state consistency may deteriorate
Solution Approach 1:
Before migrating a connection to a new server, the system performs preliminary actions by copying the complete connection state information (including sequence numbers, window sizes, and protocol parameters) to the target server. This pre-synchronization ensures that when the connection is actively migrated, the target server can immediately continue the connection with consistent state, preventing state divergence and maintaining stability during adaptive server management.
Solution Approach 2:
The system uses copying by creating a duplicate of the connection state information on the target server before active migration. The target server receives a complete copy of the source server's connection state, including all protocol parameters and session information. This copying mechanism ensures that the connection state consistency is maintained during server migration, allowing the system to adapt to maintenance needs without compromising state integrity.
Data Source
AI summary
Aspects of the subject disclosure may include, for example, a server comprising a memory to store instructions and a controller coupled to the memory, in which the controller, responsive to executing the instructions, performs operations. The operations include detecting a condition requiring a migration of an active transport connection at a source server to a target server without interrupting communications occurring in the active transport connection. The source server is directed to transmit to the target server a migration command with state information from the source server to enable migrating the active transport connection to the target server without interrupting communications occurring in the active transport connection. A message is then received from the source server indicating the source server has received from the target server an acknowledgment that the migrating has been performed. Other embodiments are disclosed.