I use both Ipv4 and Ipv6 in SD-WAN. These are the NIST time servers. I configured 1 and 3 to use IPv6 and 2 to use only IPv4. The interval is every 60 seconds. NIST won’t allow quicker than 4 seconds. I am not that concerned that time will drift in a minute.
Firewall (ntp) # show full-configuration
config system ntp
set ntpsync enable
set type custom
set syncinterval 60
config ntpserver
edit 1
set server "time-e-g.nist.gov"
set ntpv3 disable
set authentication disable
set interface-select-method auto
next
edit 2
set server "time-b-g.nist.gov"
set ntpv3 disable
set authentication disable
set interface-select-method auto
next
edit 3
set server "time-d-g.nist.gov"
set ntpv3 disable
set authentication disable
set interface-select-method auto
next
end
set source-ip 0.0.0.0
set source-ip6 ::
set server-mode enable
set authentication disable
set interface "internal6"
end
diag sys ntp status
synchronized: yes, ntpsync: enabled, server-mode: enabled
ipv6 server(time-e-g.nist.gov) 2610:20:6f15:15::26 — reachable(0xff) S:1 T:569
server-version=3, stratum=1
reference time is e971d880.0 — UTC Sat Feb 10 11:12:00 2024
clock offset is 0.004695 sec, root delay is 0.000244 sec
root dispersion is 0.000488 sec, peer dispersion is 7 msec
ipv4 server(time-e-g.nist.gov) 129.6.15.26 — reachable(0xff) S:1 T:569 selected
server-version=3, stratum=1
reference time is e971d880.0 — UTC Sat Feb 10 11:12:00 2024
clock offset is 0.001536 sec, root delay is 0.000244 sec
root dispersion is 0.000488 sec, peer dispersion is 27 msec
ipv6 server(time-d-g.nist.gov) 2610:20:6f15:15::27 — reachable(0xff) S:1 T:569
server-version=3, stratum=1
reference time is e971d880.0 — UTC Sat Feb 10 11:12:00 2024
clock offset is 0.004526 sec, root delay is 0.000244 sec
root dispersion is 0.000488 sec, peer dispersion is 15 msec
ipv4 server(time-d-g.nist.gov) 129.6.15.27 — reachable(0xff) S:1 T:569
server-version=3, stratum=1
reference time is e971d880.0 — UTC Sat Feb 10 11:12:00 2024
clock offset is 0.002762 sec, root delay is 0.000244 sec
root dispersion is 0.000488 sec, peer dispersion is 5 msec
ipv6 server(time-b-g.nist.gov) unresolved — unreachable(0xff) S:0 T:9
no data
ipv4 server(time-b-g.nist.gov) 129.6.15.29 — reachable(0xff) S:1 T:569
server-version=3, stratum=1
reference time is e971d880.0 — UTC Sat Feb 10 11:12:00 2024
clock offset is 0.002496 sec, root delay is 0.000244 sec
root dispersion is 0.000488 sec, peer dispersion is 5 msec