Network Device Probe Detection for Forwarding State Verification
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Solution Overview
Problem
Current network switch testing methods are inadequate for effectively verifying forwarding states, leading to potential packet loss due to undetected incorrect forwarding states, and they primarily focus on testing links rather than device forwarding behaviors.
Innovation Solution
A deterministic model is introduced that uses probes transmitted between neighbor network devices to test forwarding states by employing a lightweight agent on the source device, which manages probe allocation based on layer 3 routing tables and ECMP links, and utilizes probe detection logic within the network devices to verify correct forwarding behavior by reflecting probes back to the source device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional test probes are sent from source host device through network switches to destination host device, then link paths can be tested, but forwarding states of network devices cannot be effectively tested
Solution Approach 1:
The patent introduces an intermediary probe detection mechanism within network devices themselves. Instead of relying on external host devices to test forwarding states, the system embeds probe detection capabilities directly in the network switches. This intermediary approach allows the switches to self-test their forwarding states by detecting probes internally, thereby achieving precise measurement of forwarding states without adding external testing complexity.
2Reliability
If manual troubleshooting is used to verify forwarding states, then packet loss can be identified, but testing efficiency is low and packet loss may occur due to undetected incorrect forwarding states
Solution Approach 1:
The patent implements a self-service mechanism where network devices automatically test their own forwarding states using embedded probe detection logic. Each network device can autonomously generate, send, and detect probes to verify its forwarding states without requiring manual intervention. This self-testing capability continuously monitors forwarding accuracy, immediately detecting incorrect states before they cause packet loss, while maintaining high testing efficiency through automated operation.
3Extent of automation
If probes are reflected back to source device using probe detection logic, then forwarding states can be automatically tested, but device complexity increases due to additional detection logic
Solution Approach 1:
The patent achieves automation by making the probe detection logic a universal, integrated function within the network device's existing infrastructure. Rather than adding separate dedicated testing hardware, the detection logic is embedded within the device's standard packet processing and forwarding architecture. This multi-functional approach allows the same hardware resources to handle both normal data forwarding and probe detection, thereby achieving high automation without proportionally increasing device complexity.
Data Source
AI summary
A deterministic model is described that is used for testing networks by exercising forwarding rules (e.g., layer 2 and layer 3) on network devices. Probe detection on a peer network device B can be implemented using a global register available to all input pipelines. The global register can be used to check a source and destination port in a User Datagram Protocol (UDP) header. If there is a match, the packet is considered a probe, and a probe detection signal is transmitted to an output pipeline to redirect the probe back to the input port. Network device A can then capture the reflected probe using layer 2 hardware and redirect it to the CPU in order to verify the actual forwarding behavior applied on the probe packet. In an alternative embodiment, probe detection logic can be incorporated in an ACL at a beginning of a pipeline for switching packets.