Distributed SNAT via IPv6 Encapsulation
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Solution Overview
Problem
Distributed source network address translation (SNAT) architectures face bottlenecks and misdirection issues due to stateful load balancing and SNAT operations, leading to inefficiencies in middlebox services like SNAT and load balancing.
Innovation Solution
Implementing a distributed middlebox service that uses off-the-shelf gateway devices for IPv6 encapsulation of IPv4 packets and assigns locally unique IPv6 addresses to each host computer, allowing for stateful operations and reducing packet misdirection by configuring gateway devices to forward packets based on identified IPv6 addresses and using BGP for route advertisement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centralized SNAT is used, then stateful service is provided, but network bottleneck occurs at the centralized SNAT provider
Solution Approach 1:
The patent segments the centralized SNAT function into distributed SNAT instances deployed across multiple host computers. Each host computer runs one or more SNAT instances that independently perform stateful address translation, eliminating the single-point bottleneck while maintaining stateful service capabilities through local state tracking.
2Productivity
If distributed SNAT is used, then network bottleneck is avoided, but packet misdirection occurs to wrong SNAT instances
Solution Approach 1:
The patent introduces an intermediary component (load balancer or gateway) that sits between external networks and distributed SNAT instances. This intermediary maintains a mapping between SNAT instance identifiers and their current state information, intercepting packets and redirecting them to the correct SNAT instance based on the mapped relationships, thereby preventing packet misdirection.
Solution Approach 2:
The patent performs preliminary establishment of state mappings before packet arrival. The load balancer pre-establishes mappings between SNAT instances and their state information, and between external addresses and SNAT instance identifiers. This preliminary action ensures that when packets arrive, the correct SNAT instance can be identified and selected without misdirection.
3Reliability
If distributed middlebox service is implemented, then service availability is improved, but device complexity increases
Solution Approach 1:
The patent makes gateway devices and host computers universal by enabling them to perform multiple functions: standard routing, IPv6 encapsulation for IPv4 packets, and participation in distributed SNAT operations. This multi-functionality reduces the need for specialized dedicated hardware, simplifying the overall system architecture while maintaining service availability through distribution.
Data Source
AI summary
Some embodiments of the invention provide novel methods for facilitating a distributed SNAT (dSNAT) middlebox service operation for a first network at a host computer in the first network on which the dSNAT middlebox service operation is performed and a gateway device between the first network and a second network. The novel methods enable dSNAT that provides stateful SNAT at multiple host computers, thus avoiding the bottleneck problem associated with providing stateful SNAT at gateways and also significantly reduces the need to redirect packets received at the wrong host by using a capacity of off-the-shelf gateway devices to perform IPv6 encapsulation for IPv4 packets and assigning locally unique IPv6 addresses to each host executing a dSNAT middlebox service instance that are used by the gateway device.