the bblog

ntpblogging II

(previously)

So now bbot.org is a Stratum 2 NTP Pool server. (Its wiki page.)

Joining the pool is pretty easy: You create an account, give them your server's IP address, wait for the monitoring server to decide you're stable enough (~8 hours) and boom, you're in.

(The interface is a bit awkward: you paste the address in there, you don't click the "Add a server" link, which apparently doesn't do anything.)

I found four upstream servers by pinging 0.us.pool.ntp.org repeatedly, and choosing the one that were closest to me. Since bbot.org is in a datacenter right on the internet backbone, close can be very close:

# ntpq -np
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
-72.26.198.240   209.51.161.238   2 u  273 1024  377    2.320    3.100   1.201
+69.164.217.193  128.59.59.177    3 u  825 1024  377    3.713    0.239   0.371
-108.61.73.243   209.51.161.238   2 u  237 1024  377    3.174   -1.069   0.398
+128.113.28.67   18.26.4.105      2 u  383 1024  377    6.828    0.382   0.141
*128.118.25.5    .WWV.            1 u  426 1024  377   11.537    0.225   0.310

I had hoped that <10ms ping times would result in magically low offset numbers, measured in the tens of microseconds, but apparently jitter becomes a bigger problem when you get that low.

My reference stratum 1 server is wwv.tns.its.psu.edu, an open-access tier 1 server that John Balogh runs. Thanks John!