SDN TCP State Replication with Minimal Sync Messages
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Solution Overview
Problem
Existing SDN networks face inefficiencies in synchronizing connection states between primary and backup devices, leading to high overhead and reduced throughput due to the need to send multiple packets for each TCP connection setup and teardown, which consumes significant computing resources and network bandwidth.
Innovation Solution
A method is introduced to efficiently communicate connection state by sending a minimal message containing a connection tuple and state information, reducing the number of packets required for synchronization, and allowing the backup device to create or update connection records without performing extensive calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional TCP packet synchronization (SYN/SYN-ACK, ACK, FIN/FIN-ACK) is used to replicate connection state from primary to backup device, then connection state accuracy is maintained, but network bandwidth consumption increases and throughput decreases
Solution Approach 1:
The patent extracts only the essential connection state information (connection tuple and state) from the complete TCP packet exchange sequence. Instead of transmitting all TCP packets (SYN, SYN-ACK, ACK, FIN, FIN-ACK), the system extracts and transmits only the critical state data needed for backup synchronization, significantly reducing bandwidth consumption while maintaining connection state accuracy.
Solution Approach 2:
The patent changes the parameter representation of connection state from complete packet sequences to condensed state tuples. By representing connections as structured tuples containing essential parameters (source/destination IP, source/destination port, protocol, state) rather than transmitting actual TCP packets, the system achieves the same synchronization goal with minimal data transmission.
2Reliability
If multiple TCP packets are sent for each connection setup and teardown synchronization, then complete connection state is replicated, but processing overhead increases and resource efficiency decreases
Solution Approach 1:
The patent creates simplified copies of connection state information in the form of structured tuples rather than replicating actual TCP packets. The backup device receives condensed connection state representations that can be directly installed in its connection tracking table, eliminating the need to process multiple packet sequences while maintaining complete connection state information.
3Reliability
If connection state synchronization is performed for tens of millions of connections per second, then high availability is achieved, but network bandwidth and computing resources are excessively consumed
Solution Approach 1:
The patent extracts only the minimal necessary information (connection tuple and state) from the full TCP packet exchange, enabling efficient synchronization of tens of millions of connections without proportionally increasing bandwidth consumption. This extraction approach allows high availability through rapid failover while consuming minimal network resources.
Data Source
AI summary
Transmission Control Protocol (TCP) states of an active device are replicated at a backup device configured to track connections in a software defined network (SDN). The backup device receives, from the active device, a TCP packet with a TCP flag including one or more of SYN, SYN-ACK, ACK, FIN, FIN-ACK, ACK, or RESET. When the TCP packet has a SYN flag, the backup device adds a connection record to a connection table. Otherwise, the backup device derives an updated connection state for the connection record using a TCP state machine. The connection state is updated as future packets are received by the backup device.