<story><title>Splitting the Ping</title><url>https://blog.benjojo.co.uk/post/ping-with-loss-latency-split</url></story><parent_chain></parent_chain><comment><author>great_wubwub</author><text>Everybody is talking about clock accuracy and totally missing that devices in the middle of the network path &lt;i&gt;do not care about responding quickly to pings&lt;/i&gt;. Middle devices are generally routers or firewalls, and their job is to route and firewall, not to respond to a packet as quickly as it comes in. Transit traffic is far more important than processing control plane packets. Devices can add several msec or more in latency by sticking ICMP echo requests and the like in a low-priority queue and getting around to responding eventually.  This will dwarf any gains produced by &amp;quot;the best NTP server&amp;quot;.&lt;p&gt;And no, setting QoS bits on the packet will not help.</text></comment>
<story><title>Splitting the Ping</title><url>https://blog.benjojo.co.uk/post/ping-with-loss-latency-split</url></story><parent_chain></parent_chain><comment><author>pxx</author><text>Not entirely related, but a fun and interesting tangent: There&amp;#x27;s actually no way that we know of to measure the &amp;quot;one-way&amp;quot; speed of light, as the specific synchronization that you use (and this post uses to do its calculation) assumes that the speed of light is the same in both directions. For all we know, light travels infinitely quickly in one direction and at c&amp;#x2F;2 in the return direction.&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;One-way_speed_of_light&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;One-way_speed_of_light&lt;/a&gt;&lt;p&gt;recent-ish video about this: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.youtube.com&amp;#x2F;watch?v=pTn6Ewhb27k&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.youtube.com&amp;#x2F;watch?v=pTn6Ewhb27k&lt;/a&gt;</text></comment>