Path-Aware NAPT Session Management for SD-WAN
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Solution Overview
Problem
In Software-Defined Wide Area Networking (SD-WAN), Network Address and Port Translation (NAPT) sessions face network reachability issues and inconsistencies when the active path to the external network changes, leading to stale IP addresses being used, which requires manual intervention to resolve.
Innovation Solution
A path-aware NAPT session management scheme that dynamically updates IP addresses and ports based on changes in the active path, using a pool of IP addresses and comparing external interfaces to detect path changes, allowing seamless convergence without user intervention and maintaining efficiency by not requiring additional memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NAPT sessions use a fixed IP address assignment based on initial path, then session management is simple, but network reachability fails when active path changes
Solution Approach 1:
The patent implements dynamic session management where NAPT sessions can transition between different IP address pools based on the current active path. When path changes are detected, the session manager dynamically updates the IP address assignment for affected sessions, ensuring network reachability is maintained while adapting to changing network conditions.
Solution Approach 2:
The system employs feedback mechanisms by continuously monitoring path status and triggering session management updates when path changes are detected. The session manager receives feedback about active path changes from the routing system and automatically responds by reassigning IP addresses to affected sessions, creating a closed-loop control system that maintains reliability.
2Reliability
If NAPT sessions are updated manually when path changes, then IP address consistency is maintained, but operational efficiency decreases
Solution Approach 1:
The patent implements self-service automation where the session manager automatically detects path changes and updates NAPT session IP addresses without requiring manual intervention. The system monitors path status, identifies affected sessions, and performs IP address reassignment autonomously, maintaining IP address consistency while significantly improving operational efficiency through automation.
3Measurement precision
If additional memory is allocated for path-aware session management, then session convergence accuracy improves, but resource consumption increases
Solution Approach 1:
The patent merges the session management functionality with the existing path management infrastructure in the SD-WAN router. By integrating session state tracking with the routing decision-making process and utilizing existing path status data structures, the system achieves accurate session convergence without requiring separate dedicated memory resources, thus avoiding increased resource consumption.
Data Source
AI summary
Systems and methods include, responsive to routing a packet to a destination via an external interface of a plurality of external interfaces, receiving the packet; checking if the packet belongs to an existing session for network address and port translation based on a session key; if the packet does not belong to the existing session, assigning the packet an Internet Protocol (IP) address and port based on the routing; if the packet belongs to the existing session, checking if an active path has changed, and, if not, performing the network address and port translation based on the session; and, if the active path has changed, assigning the packet an Internet Protocol (IP) address and port based on another external interface associated with the changed active path.