[ntp:questions] NTP orphan mode with manycast configuration

sylcournoyer at gmail.com sylcournoyer at gmail.com
Tue Aug 14 17:37:44 UTC 2007

On Aug 14, 11:25 am, Steve Kostecke <koste... at ntp.org> wrote:
> On 2007-08-14, sylcourno... at gmail.com <sylcourno... at gmail.com> wrote:
> > Has anybody been able to make the orphan mode work with manycast
> > clients/servers?
> Yes, I have with IPv4.
> It is easiest to set-up if you use symmetric keys instead of Autokey.
> Each node in the "orphan mesh" can use the following files:
> -------------------------------------8X------------------------------------­-
> # /etc/ntp.conf, configuration for ntpd
> # IPv4 Multicast + Symmetric Keys + Orphan mode
> # Adjust for your OS
> driftfile /var/lib/ntp/ntp.drift
> # Symmetric keys
> keys    /etc/ntp.keys
> trustedkey 1
> # Orphan Mode
> tos orphan 5
> # Multicast "mesh node" - the order of these directives is critical
> multicastclient
> broadcast key 1
> # Add some server lines here for those systems that will be synchronized
> # to remote time servers or local ref-clocks. Append iburst to the
> # server lines for remote time servers.
> -------------------------------------8X------------------------------------­-
> # /etc/ntp.keys
> 1 M your_shared_password
> -------------------------------------8X------------------------------------­-
> Please note that you must configure routing for the multicast address on
> all of the systems in the "orphan mesh".
> FWIW I'm currently running Manycast (w/ Symmetric Keys) / Orphan mode
> (over IPv6) on my LAN. ...
> --
> Steve Kostecke <koste... at ntp.org>
> NTP Public Services Project -http://support.ntp.org/

Thanks for the quick reply.

With regard to your reply, just to be sure I am understanding the
right thing and based on my readings, the ntp configuration that I
want to test/use eventually would use the config parameters
"manycastclient" and "manycastserver" instead of "multicastclient" and
"broadcast" :

disable auth # I am already on a secure network and I want the
smallest IP packets possible
server iburst prefer minpoll 4 maxpoll 10 # Each computer
connected to a local NEMA GPS
tos orphan 7
manycastclient #instead of "multicastclient"
manycastserver #instead of "broadcast"
driftfile /etc/ntp.drift

If all the GPS devices loose their lines of sight with satellites,
then NTP will automatically enter the orphan mode on each computer,
which means that one of the computer will be automatically "elected"
as the "time master" and that all the other computers will be
synchronized on it (of course then the time in the system will drift
with respect to the UCT time)

Will that work?

Thanks and regards.

Sylvain Cournoyer

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