Test Packet Injection for Network Forwarding Prediction
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Solution Overview
Problem
Tracking specific network traffic flows through large production networks is challenging due to the high volume of traffic, and existing techniques are computationally expensive and resource-intensive, often relying on software implementations.
Innovation Solution
A network device uses its forwarding hardware to predict egress destinations by injecting a test packet into the hardware processing pipeline, simulating ingress at a specified interface, and capturing metadata to determine the egress interface, thereby reducing resource usage and improving visibility in complex network configurations like LAGs and ECMPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If software-based flow tracking techniques are used, then network traffic flow visibility is improved, but computational resources and processing time are excessively consumed
Solution Approach 1:
The patent replaces software-based flow tracking with hardware-based forwarding plane techniques. The control plane device sends test packets that are processed by the forwarding hardware (ASICs, FPGAs, or network processors) which naturally forward packets according to configured routing tables and policies. This substitution of software computation with hardware forwarding operations dramatically reduces computational resource consumption while maintaining flow tracking capability.
Solution Approach 2:
The patent uses test packets as simplified copies of actual traffic flows to probe network behavior. Instead of analyzing every real packet or using complex software sampling, the system injects representative test packets through the forwarding plane to determine egress interfaces. This copying approach provides sufficient visibility information without the computational overhead of processing actual high-volume traffic.
2Loss of information
If comprehensive flow tracking is implemented, then network diagnostic capability is improved, but device complexity and implementation difficulty increase
Solution Approach 1:
The patent leverages the existing self-service capability of network device forwarding planes. The forwarding hardware already contains routing tables, policy configurations, and packet forwarding logic that automatically determine egress interfaces. By injecting test packets and observing the natural forwarding behavior, the system extracts flow path information without requiring additional complex tracking infrastructure or manual configuration.
Solution Approach 2:
The patent makes the forwarding plane serve dual purposes: its primary function of actual packet forwarding and a secondary function of flow tracking through test packet injection. The same forwarding tables, routing logic, and hardware pipelines that handle production traffic are reused to process test packets, eliminating the need for separate dedicated tracking hardware or complex software agents.
3Use of energy by moving object
If test packet injection is used for forwarding prediction, then resource consumption is reduced, but the accuracy of egress interface determination may be affected by load balancing algorithms
Solution Approach 1:
The patent performs preliminary probing with test packets under controlled conditions to establish baseline forwarding behavior before actual high-volume traffic arrives. The test packets are sent at low rates and with known characteristics, allowing the system to determine egress interfaces under stable conditions. This preliminary action captures the intended forwarding behavior configured in routing tables before dynamic load balancing algorithms interfere with production traffic.
Solution Approach 2:
The patent systematically varies test packet parameters (source/destination IP addresses, ports, protocols, ingress interfaces) to probe different forwarding paths and load balancing scenarios. By changing these parameters, the system can map out the complete forwarding behavior including how load balancing algorithms distribute traffic across multiple equal-cost paths, thereby improving prediction accuracy for diverse actual traffic flows.
Data Source
AI summary
Some embodiments provide a method, executable by a network device, that receives a set of commands specifying an ingress interface of the network device and a set of packet attributes. The method further generates a test packet based on the set of packet attributes. The method also injects the test packet into a hardware packet processing pipeline of the network device so that the test packet appears, from the perspective of the hardware packet processing pipeline, to be received at the ingress interface of the network device. The method further processes the test packet through the hardware packet processing pipeline of the network device. The method also captures the test packet before the test packet exits an egress interface of a plurality of egress interfaces of the network device.