Reverse NAT Failover for Seamless Interface Switching
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Solution Overview
Problem
Modern networking configurations face interruptions when an interface fails, as existing failover methods require switching to a different NAT router, which breaks connections if interfaces have different IP addresses.
Innovation Solution
The system implements reverse network address translation failover by modifying the NAT table in a router to replace the address of a failed interface with a backup interface's address while keeping the port number unchanged, allowing seamless traffic routing without interrupting connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing failover methods are used, then interface failure can be detected, but connections are broken when switching to a different NAT router
Solution Approach 1:
Instead of switching to a different NAT router when interface fails, the patent inverts the approach by having the failed interface's backup information update the NAT table entry in-place. The router modifies the existing NAT mapping to point to the backup interface address, eliminating the need for router switching and maintaining connection continuity.
Solution Approach 2:
The system performs preliminary action by pre-configuring backup interface information in the NAT table before failure occurs. When interface failure is detected, the pre-stored backup information is immediately applied to update the NAT mapping, enabling seamless failover without interruption to active connections.
2Productivity
If interface failover is implemented, then traffic routing is maintained, but connections are broken if interfaces have different IP addresses
Solution Approach 1:
The patent applies parameter changes by modifying the IP address parameter in the NAT table entry when failover occurs. The router updates the destination IP address in the NAT mapping from the failed interface's address to the backup interface's address, while preserving the port number and other connection parameters, thus maintaining connection stability despite IP address changes.
3Reliability
If NAT table modification is used, then seamless failover is achieved, but router processing complexity increases
Solution Approach 1:
The system implements feedback by having the router continuously monitor interface status and automatically trigger NAT table updates when failure is detected. The router requests failover information from interfaces and uses this feedback to dynamically modify NAT mappings, creating a closed-loop failover mechanism that maintains reliability while managing processing complexity through automated responses.
Data Source
AI summary
In an example system, a first interface has a first address and a first port number. A second interface has a second address and a second port number. A router is in communication with the first and second interfaces over a network. The router is configured to request, a first set of failover information from the first interface. The router is further configured to receive the first set of failover information from the first interface. The first set of failover information includes the second address and the first port number. The router is configured to detect a failure on the first interface. The router is further configured to modify a network access translation (NAT) table stored within the router by replacing the first address of the first interface with the second address of the second interface while retaining the first port number, such that the first port number remains unchanged.