Measuring the absolute accuracy of 10GbE packet timestamping

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Measuring the absolute accuracy of 10GbE packet timestamping

Posted on January 23, 2018 by Matthew Knight 23 January 2018

Being able to timestamp traffic precisely is used widely in such applications as compliance, troubleshooting, capacity planning, out-of-band networked application performance analysis, intrusion detection and prevention and others. Precise Ethernet timestamps are key to knowing exactly when a networked event occurred. These timestamps are delivered with the packet with which they are associated.

Though timestamps may appear to have nanosecond resolution, when it comes to knowing what their actual resolution and absolute accuracy is, things are less clear. Most vendors quote an advertised timestamp resolution and have a pretty good idea of the accuracy of the timestamps they place on packets relative to each other.

When it comes to their absolute accuracy however, the level of complexity increases; especially when taking into account the contribution of disciplining the oscillator generating the timestamp from an external time reference.

As an internal project, Metamako set out to design and implement a methodology to measure the absolute accuracy of GbE timestamps on its industry-leading MetaWatch product. In 2017, Metamako adapted this methodology to measure the absolutely accuracy of MetaWatch’s 10GbE timestamps and teamed up with the Securities Technology and Analysis Center (STAC) to implement it as part of an independently verified, new industry standard for measuring time synchronisation accuracy; the STAC-TS suite of benchmarks.

These benchmarks were enhanced and formalized by the STAC Benchmark Council and represent a large set of benchmark standards and software tools for time synchronization, timestamping, and event capture. The methodology described in this white paper was adopted by STAC for the absolute timestamp accuracy benchmark in the STAC-TS suite.

The technical whitepaper covers:

• The concept of absolute timestamp accuracy

• The concepts around clock accuracy and synchronisation

• The logic behind the choice of methodology

• The conceptual details of the implementation of the methodology

• The timestamp absolute accuracy results obtained


The full Technical Whitepaper "Measuring the absolute accuracy of 10GbE packet timestamping" can be downloaded here >>

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