Service Header NAT Indicator for Symmetric Traffic Flow
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Solution Overview
Problem
Network Address Translation (NAT) poses challenges in service chains by altering the original destination, making it difficult to ensure symmetric traffic flow in conventional networks, requiring operator intervention for consistent return traffic classification and traversal.
Innovation Solution
The solution involves using the control plane to inform the service chaining infrastructure about NAT occurrences and employing in-band NAT detection in the data plane, ensuring symmetric service chaining without operator intervention, by inserting a NAT indicator into a service header that remains unchanged through NAT, allowing the policy layer to bind pre-NAT and post-NAT flows for consistent routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If NAT is deployed in service chains, then network address translation functionality is provided, but symmetric service chaining becomes difficult to maintain
Solution Approach 1:
A service header is introduced as an intermediary element that carries flow identification information through the service chain. This service header enables the classifier to identify and bind pre-NAT and post-NAT flows, ensuring symmetric service chaining is maintained even when NAT alters the original destination addresses.
Solution Approach 2:
The classifier performs preliminary flow binding before NAT occurs by examining packets with service headers and creating associations between pre-NAT and post-NAT flows. This preliminary action ensures that when return traffic arrives, the classifier can immediately route it through the correct service chain without requiring operator intervention.
2Ease of manufacture
If conventional NAT deployment is used, then address translation is achieved, but operator intervention is required for consistent return traffic classification
Solution Approach 1:
The system implements self-service automation where the classifier automatically detects NAT occurrences, binds flows using service header information, and routes return traffic without operator intervention. The classifier examines packets, identifies NAT translations, and maintains flow bindings autonomously, eliminating the need for manual configuration.
Solution Approach 2:
The system uses feedback mechanisms where the classifier continuously monitors service chain traffic, detects when NAT has occurred by comparing pre-NAT and post-NAT flow characteristics, and automatically adjusts return traffic routing based on this feedback. This closed-loop approach ensures consistent service chaining without manual intervention.
3Productivity
If dynamic NAT deployment is implemented, then scalability is improved, but automatic detection and handling mechanisms are required
Solution Approach 1:
The service header is populated with flow identification information in advance, before NAT occurs. This preliminary action enables the classifier to quickly match pre-NAT and post-NAT flows without complex real-time analysis, maintaining high processing speed while enabling automatic detection and handling of NAT in dynamic service chains.
Data Source
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AI summary
In one embodiment, a method includes receiving a packet associated with a flow at a network device, classifying the packet at the network device based on information received from a policy layer, inserting a Network Address Translation (NAT) indicator for the flow into the packet, and transmitting the packet in a service chain comprising network address translation. The NAT indicator is associated with the flows before and after network address translation to provide symmetry between the service chain and a return traffic service chain. An apparatus and logic are also disclosed herein.