Hybrid NAT Session Synchronization for Gateway Failover
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Solution Overview
Problem
Datacenters face inefficiencies in synchronizing Network Address Translation (NAT) sessions due to the vulnerability of NAT devices, which can lead to disruptions when active gateways fail without standby backups, and existing methods of full record synchronization consume valuable bandwidth.
Innovation Solution
Implementing methods to encode NAT records, synchronize them selectively based on flow type, and adapt synchronization intervals to reduce data transmission, including encoding external and internal IP addresses, and prioritizing long-term flows over short-term flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full NAT records are synchronized to standby gateway, then reliability is improved, but bandwidth consumption increases
Solution Approach 1:
The patent extracts and transmits only the essential synchronization data (external IP address, external port, internal IP address, internal port, protocol, and action) from the full NAT record, omitting redundant information such as internal IP prefix and detailed flow characteristics. This extraction principle reduces the synchronization data size while maintaining the ability to restore NAT sessions reliably.
Solution Approach 2:
The NAT record is segmented into critical synchronization fields (external IP, external port, internal IP, internal port, protocol, action) and non-critical fields (internal IP prefix, flow duration, byte counts). Only the essential segments are transmitted to the standby gateway, reducing bandwidth consumption while preserving session restoration capability.
2Reliability
If NAT records are synchronized frequently, then reliability is improved, but bandwidth consumption increases
Solution Approach 1:
The patent implements periodic synchronization of NAT records from active gateway to standby gateway at predetermined intervals. This periodic action ensures the standby gateway has up-to-date NAT session information for failover while avoiding continuous synchronization that would consume excessive bandwidth. The system balances reliability with resource conservation through this time-based approach.
3Reliability
If all NAT records are synchronized, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies different treatment to different NAT records based on their characteristics. Long-term flows (elephant flows) are synchronized with higher priority and more frequent updates, while short-term flows (mouse flows) are synchronized less frequently or not at all. This local quality differentiation reduces overall synchronization complexity while maintaining reliability for critical sessions.
Solution Approach 2:
The patent implements partial synchronization by selecting only certain NAT records for synchronization based on flow duration and importance. Not all NAT records are synchronized with the same frequency and detail level. This partial action approach reduces processing complexity and bandwidth consumption while ensuring critical sessions are protected.
Data Source
AI summary
The method of synchronizes network address translation (NAT) records between an active gateway and a standby gateway. The method of some embodiments synchronizes NAT records of long-term data flows more frequently than those of short-term flows. Multiple data flows pass between a device at an internal source address and a device at an external destination address through the active NAT gateway. For each flow, the method generates a NAT record. The method then determines whether the data flow is a short-term flow or a long-term flow and synchronizes the NAT records of the long-term flows, but not the NAT records of the short-term flows, with the standby gateway. The method of some embodiments synchronizing NAT records more frequently when NAT records are being generated quickly relative to prior generation rates and less frequently when NAT records are being generated slowly relative to the prior generation rates.