LSN Flow Processor Hash Routing Session Persistence
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Solution Overview
Problem
Existing Large Scale NAT (LSN) systems face challenges in scaling out without complex session sharing, additional hardware requirements, and high computational overhead, especially when managing packet flow among multiple LSN appliances.
Innovation Solution
The enhanced LSN system equips each appliance with a flow processor that includes a hash function and a look-up table to manage session ownership and routing, allowing for seamless scaling out without additional equipment or significant computational overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple LSN appliances are deployed for scale-out, then system capacity and redundancy are improved, but packet flow management complexity and session persistence challenges worsen
Solution Approach 1:
The patent segments the LSN system into multiple independent appliances, each capable of handling packet flows autonomously. By dividing the system into modular units with standardized interfaces, scalability is achieved without proportionally increasing management complexity. Each appliance operates as an independent unit that can be added or removed without affecting others.
Solution Approach 2:
The patent introduces a flow processor as an intermediary component within each appliance that manages session state and packet routing decisions. This mediator handles the complexity of session persistence and packet flow management locally, preventing this complexity from propagating across the entire distributed system and making management more tractable.
2Productivity
If ECMP routing is used to forward communications to LSN appliances, then load distribution is improved, but arbitrary appliance selection and session persistence worsen
Solution Approach 1:
The patent implements preliminary hashing of packet flow identifiers to determine the destination appliance before packets are routed. This pre-computed routing decision ensures that all packets belonging to the same session are consistently directed to the same appliance, establishing session persistence before the packets traverse the network. This preliminary action prevents the session persistence problem that would otherwise occur with arbitrary ECMP routing.
Solution Approach 2:
The patent changes the routing parameter from arbitrary appliance selection (based on ECMP hash of destination IP only) to a deterministic selection based on a hash of the packet flow identifier. This parameter change transforms the routing behavior from random distribution to controlled distribution that maintains session affinity while still achieving load balancing across appliances.
3Reliability
If session sharing mechanisms are implemented among LSN appliances, then session persistence is improved, but computational overhead and system complexity worsen
Solution Approach 1:
The patent extracts the session state management functionality from a centralized or shared mechanism and embeds it directly within each individual LSN appliance. Each appliance maintains its own session table and flow processor, eliminating the need for inter-appliance session sharing mechanisms. This extraction reduces computational overhead by removing the complexity of session synchronization and sharing while maintaining session persistence through local state management.
Data Source
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AI summary
A system, method and program product for provisioning a large scale network address translation (LSN) system. A system is disclosed that processes packets between a router and a TCP/IP network. The system includes a plurality of LSN appliances and a flow processor embedded in each of the plurality of LSN appliances. Each flow processor includes: a hash function that determines an owner appliance from the plurality of LSN appliances for a request received from the router based on a private IP address of the request; a look-up table that that determines the owner appliance from the plurality of LSN appliances for a response received from the TCP/IP network based on a public IP address of the response; and a packet routing system that routes a received request or a received response to the owner appliance.