SDN Appliance State Replication for Seamless Failover
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Solution Overview
Problem
Existing SDN appliance deployments face delays and scalability issues due to the need for connection state recreation during failover, which is exacerbated by the use of central coordinators that introduce latency and become single points of failure.
Innovation Solution
A distributed system that replicates and manages SDN policy state across multiple appliances in real-time, allowing seamless failover without resetting connections by sharing unified flow states between SDN appliances, enabling them to transition from primary to backup without disrupting packet flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SDN appliances are replicated to provide high availability and disaster recovery, then reliability is improved, but connection loss during failover increases downtime
Solution Approach 1:
The patent applies preliminary action by pre-establishing synchronization connections between active and backup SDN appliances before failover events occur. The backup appliance proactively receives and stores connection state information (flow tables, packet metadata, sequence numbers) from the active appliance through synchronize packets, enabling immediate takeover without connection recreation delays when failover is needed.
2Device complexity
If central coordinators are used to manage SDN state, then device complexity is reduced, but latency increases and single point of failure risk increases
Solution Approach 1:
The patent extracts the central coordinator component from the SDN management architecture and replaces it with a distributed peer-to-peer synchronization mechanism. Each SDN appliance directly exchanges state information with its backup counterpart through synchronize and acknowledgement packets, eliminating the intermediary central coordinator and its associated latency and single point of failure vulnerabilities.
3Reliability
If connection state is recreated during failover, then reliability is maintained, but productivity decreases due to delayed packet communications
Solution Approach 1:
The patent applies copying by creating and maintaining duplicate copies of connection state information (flow tables, packet metadata, sequence numbers) at both active and backup SDN appliances simultaneously. When failover occurs, the backup appliance already possesses an up-to-date copy of the connection state, allowing it to immediately resume packet communications without recreation delays.
4Adaptability or versatility
If SDN appliances handle millions of connections, then scalability is improved, but state synchronization latency increases
Solution Approach 1:
The patent applies segmentation by dividing the monolithic state synchronization process into discrete, incremental updates organized in synchronized batches. Connection state information is segmented into manageable units (flow table entries, packet metadata records) that are transmitted and acknowledged in coordinated sequences, enabling efficient synchronization even when handling millions of connections across multiple appliances.
Data Source
AI summary
A computer implemented method includes receiving partially created software defined network (SDN) policy state information at a backup software defined network (SDN) appliance in response to the sending of a synchronize packet to establish a connection. The state information corresponds to a state of the connection between two endpoints that include a first active SDN appliance and a second active SDN appliance. A replica of the SDN policy state information is saved at the backup SDN appliance. An update to the SDN policy state information is received in response to the sending of an acknowledgement packet. The replica of the SDN policy state information updated at the backup SDN appliance to enable the backup SDN to transition to active.