Re: NTP vs SNTP

Hello Rob,

Am 19.11.2019 um 16:19 schrieb Rob Berendt <rob@xxxxxxxxx>:

Are you talking about the output of netstat *cnn on 5250?

No. See the above steps on how to check it using the webby Navigator for i.

Can't reproduce, don't have access to the webby Navigator for i. Therefore I asked if you're talking about the clicky equivalent of netstat *cnn, which gives you a list of open ports and connected TCP services. Sorry if I wasn't clear about that.

I am only talking about the SNTP client service, not serving to others. When you set up the SNTP client you can specify if the client is SNTP or NTP.

See above, can't do. Sorry.

I don't get what you want to tell but ntp and sntp is *always* UDP port 123.

Client or server or both?

The server offers it's NTP service via UDP port 123. The client connects with source port 123 to the server destination port 123. This is true regardless of NTP or SNTP client mode.

There's no such thing as an SNTP server

Are you saying there are only NTP servers and you access those using either a SNTP or a NTP client?

Exactly. Please read the Wikipedia link I posted.

What is "it"?

Changing the sntp client from sntp to ntp

The whole difference as I know it from other platforms is:

- SNTP: After a timer runs off, SNTP starts an UDP exchange with an NTP server and asks about time. Then it will set the local clock *hard* to that value and go back to inactive until the timer again reaches zero.

- NTP: A local job/task/whatever constantly polls multiple NTP servers and picks a best one and a second best one for backup purposes based on network connection quality and maybe also stratum value (the less stratum value is, the more "direct" is a server connected to a trustable time source). Depending on the differences between local clock and NTP derived values, the local clock speed will be slightly increased or decreased to compensate for deviations in a "soft" way.

Since a full NTP client is running as a permanent task/job/whatever anyhow, often there's a server component integrated which acts as an NTP server itself.

See also the comment from Kevin.

:wq! PoC

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