To put some numbers on this, I gathered some data on 58.216.105.122
for roughly 5 1/2 days from Texas and had someone with a server in
Shanghai gather data as well.
(Me) USA to China: 391 NTP requests sent, 70 lost (17% packetloss)
Offset Graph: https://dan.drown.org/ntp/us-to-china.png
So aside from the packet loss and the various spikes in latency in
either direction, this is a pretty good source of time.
Shanghai to this NTP server in China: 455 NTP requests sent, 0 lost
(0% packetloss)
Offset Graphs: https://dan.drown.org/ntp/sha.html
The Shanghai local clock isn't as good because of jitter reaching its
other upstreams. But this NTP server in China is a much better source
of time than the other choices.
I think this should illustrate why local time service in China is
important, and has special needs compared to other regions. Please
let me know if I forgot to include any details.
Quoting 彭勇 <[email protected]>:
i start a new thread to discuss ntp pool service China.
China is a country with over 1 billion population and only about 10
ntp pool servers available. The ntp pool service is not stable in
China, the ntp pool servers load are high and with high packet lost.
so we join some of our servers with GPS( Stratum 1) to pool, but the
score drop frequently and leave the pool. there are two main reason:
1. high packet loss from monitor node to China ntp server
2. the load server is high, it get about 20k requests per second with
3Mbps setting. the server can't keep up with request and have high
packet loss.
maybe some ntp server administrator in China tried to join pool and
failed for same reason.
--
Peng Yong
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