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asymmetric latency

A collection of 5 posts

ntp

DOCSIS 3.1 and NTP

Spectrum upgraded my area to DOCSIS 3.1 to offer 1G/40M service. I believe they have it configured for 1.7Gbit shared downstream (using DOCSIS 3.1) and ~100Mbit shared upstream (sharing

  • Dan Drown
2 min read
gps

Stratum 2 NTP over a Cable Modem

Goals I have a Stratum 1 NTP server at home, and ideally I'd like to join the ntp pool as a server. The problem is, my home connection isn't up to this task.

  • Dan Drown
3 min read
navspark

Measuring Asymmetric latency via NTP, part 3

Part 1, Part 2 Varying round trip times Asymmetric latency changes NTP's calculated clock offsets. What do the offsets look like when two clocks are in sync (or always within ~200us) and the

  • Dan Drown
2 min read
navspark

Measuring Asymmetric latency via NTP, part 2

See the first part for the math Let's use a third party (stratum 2) observer to compare the stratum 1 NTP clocks. Round trip times First, a graph of the $rtt times from

  • Dan Drown
2 min read
navspark

Measuring Asymmetric latency via NTP

Goal Learn more about the latency characteristics of my cable connection. Starting point I have a stratum 1 NTP server at home. Below is a graph of its performance. The offset between the

  • Dan Drown
4 min read
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