将NTP机器与高根时间服务器同步

Question

我有一个小网络的机器使用systemd-timesyncd.service，需要他们的时钟是同步的。他们不需要是正确的，只是同步。我已经指定其中一台机器为NTP服务器，其余的机器都指向这一台，但是它们需要几个小时来同步，当它们同步时，这是非常不一致的：

Jun 22 18:09:16 host systemd-timesyncd[10515]: Initial synchronization to time server 10.10.1.30:123 (10.10.1.30).
Jun 22 18:25:50 host systemd-timesyncd[10515]: Server has too large root distance. Disconnecting.
Jun 22 18:34:22 host systemd-timesyncd[10515]: Server has too large root distance. Disconnecting.
Jun 22 18:51:26 host systemd-timesyncd[10515]: Server has too large root distance. Disconnecting.
Jun 22 19:25:34 host systemd-timesyncd[10515]: Server has too large root distance. Disconnecting.
Jun 22 19:59:43 host systemd-timesyncd[10515]: Server has too large root distance. Disconnecting.
Jun 22 20:33:51 host systemd-timesyncd[10515]: Initial synchronization to time server 10.10.1.30:123 (10.10.1.30).
Jun 22 21:07:59 host systemd-timesyncd[10515]: Server has too large root distance. Disconnecting.
Jun 22 21:42:07 host systemd-timesyncd[10515]: Server has too large root distance. Disconnecting.
Jun 22 22:16:16 host systemd-timesyncd[10515]: Initial synchronization to time server 10.10.1.30:123 (10.10.1.30).

我该怎么解决这个问题？

Answer 1

罪魁祸首似乎是“根距离”。这是整个路由从每个客户端通过本地NTP服务器(尽管是任何其他NTP服务器)引入到具有GNSS接收方或原子钟的“local 1”服务器的延迟。

              +---------------------+              +---------------------+
+---------+   |   Stratum 1 server  |  20ms delay  |   Stratum 2 server  |
|GNSS rcvr|---|  Root distance: 0ms +--------------+ Root distance: 20ms |
+---------+   |       nasa.gov      |              |   0.pool.ntp.org    |
              +---------------------+              +----------+----------+
                                                              |
                                                              | 5040ms delay
                                                              |
                                              ==LAN=FIREWALL==+================
                                                              |
           +-----------------------+              +-----------+-----------+
           |      Clients          |   1ms delay  |    Stratum 3 server   |
           | Root distance: 5061ms +--------------+ Root distance: 5060ms |
           |    10.10.1.0/24       |              |      10.10.1.30       |
           +-----------------------+              +-----------------------+

由于与分层1服务器的对齐不太重要，所以您可以将每个客户端上的RootDistanceMaxSec=增加到一个更舒适的值。30秒就可以了。缺省值是5s，所以您可能非常接近这个数字。编辑/etc/systemd/timesyncd.conf：

# See timesyncd.conf(5) for details.
[Time]
NTP=10.10.1.30
#FallbackNTP=
RootDistanceMaxSec=30
#PollIntervalMinSec=32
#PollIntervalMaxSec=2048

这将导致客户端接受10.10.1.30作为NTP服务器，即使它可能远离等级1服务器。