[ntp:questions] Compensating for asymmetric delay on a per-peer/server basis?

Martin Burnicki martin.burnicki at meinberg.de
Fri Sep 12 08:07:59 UTC 2014

Rob wrote:
> Martin Burnicki <martin.burnicki at meinberg.de> wrote:
>> - NAT doesn't hurt at all, unless you are trying to use NTP's authentication
> NAT in itself does not hurt, but when you want to be a timeserver for
> a large number of clients, it can be a problem.
> Many home routers have no "static NAT" but only "portforwarding" which
> creates dynamic NAT entries on demand.  As UDP has no session concept,
> such NAT entries have a lifetime of usually a couple of minutes.
> When you serve thousands of clients, this tends to overflow the NAT
> table or stress the lookup code so much that it overloads the CPU.

Haven't had such case, yet since my home NTP server doesn't serv 1000s 
of clients, but sounds reasonable and should be kept in mind.

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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