[ntp:questions] NTP 4.2.6p3 multicast server not visible in orphan peer to peer mode?

Steve Kostecke kostecke at ntp.org
Thu Apr 7 01:10:41 UTC 2011

On 2011-04-06, Wu, Bailey <Bailey.Wu at thalesgroup.com.au> wrote:

> Steve, I like your second configuration. I applied it yesterday with
> the following modifications:
> # /etc/ntp.conf for server 1
> driftfile /var/ntp/ntp.drift
> broadcastserver
> server
> fudge stratum 4
> # /etc/ntp.conf for server 2
> driftfile /var/ntp/ntp.drift
> broadcastserver
> server
> fudge stratum 6
> server server1 true maxpoll 6 prefer

You've re-implemented your original broken configuration and thrown away
everything I gave you.

If you want to use manycast associations you need to use
'manycastclient' on the manycast clients and 'manycastserver' on the
manycast servers.

BTW What is 'true' on your 'server server1' line ? Why do you think you
need 'maxpoll 6'? Why prefer?

> It seems to do what I want. But fail over to server2 is very slow,
> takes about 10min for server2 to sync with it's own clock

This is normal. A time source must become unreachable before ntpd will
deselect it. This can take 8 * maxpoll.

> and all clients to then sync to server2. I had to use for
> server2 otherwise it will refuse to sync with server1 because it fails
> the peer loop test.

The configuration I gave you set up the following:

1. Server 1 is the LAN master (using the Undisciplined Local Clock at
stratum 10)

2. Server 1 is a manycastserver for both the clients _and_ server 2.

3. Server 2 can degrade to orphan mode at stratum 12 if server 1 becomes
unreachable (i.e. goes down)

4. Server 2 is a manycastclient (this could be changed to a regular
unicast client) and is also a manycast server for 

> I'm curious about the "tos orphan 12" line you have for server2,
> what's the effect of this?

It is to allow server2 to become the LAN time server (at stratum 12) in
the event that server 1 goes down.

The reason for operating server 1 at stratum 10 and server 2 at stratum
12 is to prevent problems if your network does gain an external
connection and real time sources become reachable.

> would this make server2 realise server1 is down and then switch to its
> local clock faster?


> Does this mean all clients that are connected need to have this orphan
> mode line as well?

No. Only the machines which will be orphan mode servers need the tos
orphan line.

Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/

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