SDN Controller Datapath Analysis for Network Troubleshooting
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Solution Overview
Problem
Traditional network troubleshooting methods are limited in diagnosing packet-forwarding errors in MPLS-based networks, especially in L3VPN environments, due to the tight coupling of control-plane and forwarding-plane processes, which restricts the ability to inject test packets in the correct format and modify forwarding paths, leading to incomplete datapath troubleshooting.
Innovation Solution
Implementing a recursive routing mechanism using a software-defined network (SDN) controller that separates control-plane and forwarding-plane processing, allowing for the injection of test packets in appropriate formats and formats along the datapath, enabling effective troubleshooting by querying network elements and extracting test packets at any point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If control-plane and forwarding-plane processes are tightly coupled, then network element operation is simplified, but the ability to inject test packets and modify forwarding paths is restricted
Solution Approach 1:
The patent segments the network element into two distinct planes: control-plane and forwarding-plane. The control-plane handles routing decisions, packet classification, and test packet injection, while the forwarding-plane handles actual packet forwarding. This segmentation allows independent optimization of each plane, enabling test packet injection and forwarding path modification without compromising operational simplicity.
2Reliability
If traditional troubleshooting methods are used in MPLS-based networks, then existing network operations are maintained, but complete datapath troubleshooting is unable to be achieved
Solution Approach 1:
The patent introduces test packets as intermediary objects to detect and diagnose datapath issues. These test packets are injected by the control-plane and traverse the forwarding-plane, allowing operators to observe packet behavior, identify forwarding errors, and measure datapath characteristics without disrupting actual network traffic. The test packets serve as mediators between the troubleshooting objective and the network infrastructure.
3Productivity
If test packets are injected in incorrect formats, then troubleshooting can be performed, but accurate detection of packet-forwarding errors is prevented
Solution Approach 1:
The patent implements dynamic parameter adjustment for test packets based on the specific troubleshooting scenario. The control-plane modifies test packet parameters such as MPLS labels, IP headers, and encapsulation formats to match the expected format at each injection point. This ensures test packets are processed correctly by network elements, enabling accurate detection of forwarding errors and precise measurement of datapath behavior.
Data Source
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AI summary
In various embodiments, the techniques and supporting systems implement a recursive routing mechanism in hierarchical topological addressed environments to analyze and determine the presence of packet-forwarding errors within an IP network comprising a plurality of network-connected devices. This includes receiving, at a software defined network device, an indication of a potential packet-forwarding error between a first and second device of the plurality of network-connected devices and injecting, by the software defined network device, a test packet at an ingress to the first device. The test packet includes an initial ingress interface location identifying the first device, an alternate ingress interface location identifying the software defined network device and an egress interface location identifying the second device. A determination may then be made as to whether the test packet is received at the second device, thus indicating the existence or lack of routing errors.