Path Tracing Timestamp Split for ASIC Edit-Depth Limits
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Solution Overview
Problem
Path tracing solutions face challenges due to headers being too deep in packets for certain ASICs, leading to edit-depth limitations and incomplete timestamp access, causing performance bottlenecks and high computational costs in network controllers.
Innovation Solution
Implement optimized behavior on source nodes with edit-depth limitations and incomplete timestamp access by using CPUs and NPUs to record partial timestamps in different headers, and redefine network controller behavior to combine these for full timestamps, while processing probe packets in hardware at sink nodes to reduce computational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If path tracing headers are placed deeper in packets to carry 64-bit timestamps, then timestamp accuracy is improved, but ASIC edit-depth capability is exceeded causing processing failure
Solution Approach 1:
The 64-bit timestamp is divided into two segments: a first portion (e.g., seconds) recorded in a first header at a shallower depth, and a second portion (e.g., nanoseconds) recorded in a second header at a deeper depth. This segmentation allows each header to be placed within the ASIC's edit-depth capability while collectively providing the full 64-bit timestamp accuracy.
Solution Approach 2:
The network controller acts as an intermediary that receives the first and second timestamp portions from different headers, combines them to form the complete 64-bit timestamp, and makes this combined timestamp available to path tracing analytics. This mediator approach resolves the conflict between header depth and timestamp completeness.
2Measurement precision
If network controller processes all probe packets to provide comprehensive path tracing analytics, then measurement precision is improved, but computational cost and processing time increase
Solution Approach 1:
The patent extracts and pre-processes timestamp information at the network controller before packets reach the analytics system. By combining timestamp portions and preparing path tracing data in advance, the system reduces the computational burden on analytics processors while maintaining measurement precision.
Solution Approach 2:
The network controller performs preliminary actions by combining timestamp portions and preparing path tracing analytics data before the packets are fully processed by the analytics system. This preliminary processing reduces real-time computational requirements and improves overall throughput.
Data Source
AI summary
Techniques for providing an optimized behavior to source node(s) of a path tracing sequence allowing for implementation of path tracing source node behavior on an ASIC with edit-depth limitations and/or on an ASIC that does not have access to the full 64-bit timestamp. A source node having optimized behavior may be configured to record a first full 64-bit timestamp in an SRH PT-TLV header of a probe packet using the CPU of the source node. A source node having the optimized behavior may also be configured to compute a midpoint compressed data (MCD) entry and record the entry into an MCD stack of a probe packet using the NPU of the source node. A sink node and/or network controller may be configured to determine a final timestamp for the probe packet through the network by leveraging the SRH PT-TLV header and the MCD entry.