NAT Router In-Band Return Path Resolution
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Solution Overview
Problem
Existing network address translation (NAT) solutions face challenges in scalable networks due to overheads associated with routing and pose security risks, particularly when managing routing states for multiple devices connected to a NAT-enabled device.
Innovation Solution
A method for a NAT-enabled router to determine a return path for packets based on pre-recorded security association data or identifiers in a routing table, established during the forward packet transmission, allowing for efficient in-band return path resolution without the need for extensive routing state management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If state-based routing solutions are used to manage return paths for NAT devices, then routing accuracy is improved, but device complexity and overhead increase significantly
Solution Approach 1:
The patent extracts the routing state information from the NAT device itself and places it in the data packets (using TTL and TOS fields). This removes the burden of maintaining large routing state tables from the NAT device while preserving the ability to accurately route return packets. The routing information is carried in-band within the packets rather than being stored externally.
Solution Approach 2:
The data packets carry their own routing information (TTL and TOS values) that enable them to be routed back to the correct NAT device and internal device without requiring the NAT device to query external routing tables or maintain state. The packets essentially route themselves using the embedded timing and type-of-service information.
2Reliability
If extensive routing states are maintained for multiple devices, then return path accuracy is improved, but security risks increase
Solution Approach 1:
The patent removes sensitive routing state information from the NAT device's memory and embeds it in the packets themselves. This eliminates the security vulnerability of storing large amounts of routing state data that could be targeted by attacks, while maintaining the ability to accurately trace and route return packets to the correct internal devices.
3Reliability
If traditional routing protocols are used to manage NAT routing states, then routing completeness is improved, but productivity decreases due to management overhead
Solution Approach 1:
The patent performs preliminary encoding of routing information (TTL and TOS values) into the data packets during the forward transmission. This preliminary action eliminates the need for complex real-time routing state management and protocol exchanges during return packet transmission, significantly improving packet transmission efficiency while maintaining complete routing information.
Data Source
AI summary
Embodiments of a method of communicating a packet by a network address translation (NAT) enabled router, are described. In an embodiment, the method includes receiving a return packet to be communicated to a destination. The destination is associated with a first source address in the context of a forward packet. The method further includes determining a return path to transmit the return packet to the destination based on security association data. The security association data is pre-recorded in a routing table of the NAT enabled router when the forward packet is received, prior to receiving the return packet, over a forward path established between the NAT enabled router and an enterprise node. The security association data uniquely identifies the forward path as the return path.