NTP question

Mel Beckman mel at beckman.org
Thu May 2 01:29:57 UTC 2019


LOL. That’s not a real problem with today’s microprocessors. The TM1000A, for example:

“...is capable of serving 135+ synchronizations per second. 
That provides support for over 120,000+ devices updating 
every 15 minutes on the network.”

As for ARP traffic deluges, if that’s happening on your LAN, you have bigger problems :)


> On May 1, 2019, at 6:21 PM, Stephen Satchell <list at satchell.net> wrote:
> One word of caution when using a low-priced NTP appliance: your network
> activity could overwhelm the TCP/IP stack of the poor thing, especially
> if you want to sync your entire shop to it.  In the case of the networks
> I set up, I set up a VLAN specific to the NTP appliance and to the two
> servers that sync up with it.  Everything else in the network is
> configured to talk to the two servers, but NOT on the three-device "NTP
> Appliance VLAN".
> NOTE: Don't depend on the appliance to provide VLAN capability; use a
> configuration in a connected switch.  How you wire from the appliance to
> a port on your network leaves you with a lot of options to reach a
> window with good satellite visibility, as CAT 5 at 10 megabits/s can
> extend a long way successfully.  Watch your cable dress, particularly
> splices and runs against metal. (Or through rooms with MRI machines --
> I'm not joking.)
> The two servers in question also sync up with NTP servers in the cloud
> using whatever baseband or VLANs (other than the "NTP VLAN") you
> configure.  Ditto clients using the two servers as time sources.
> The goal here is to minimize the amount of traffic in the "NTP Appliance
> VLAN".  What killed one installation I did was the huge amount of ARP
> traffic that the appliance had to discard; it wasn't up to the deluge.
> Learn from my mistakes.

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