[ntp:questions] NTS multicast response on IPv6

Danny Mayer mayer at ntp.isc.org
Thu Jan 19 04:04:05 UTC 2006

Mauricio Schramm wrote:
> Thanks Danny,
> I think I was not totally clear in my question, what I need is to make
> my NTP client to discover by multicast a NTP server on my IPv6 network.
> I can do it using IPv4 broadcast, but I'm unable to do the same with
> IPv6 multicast. Do you have any suggestion to solve this problem?

Post your ntp.conf file. I suspect that you are not using authentication
and therefore either need to set it up or disable it on the client. Your
server needs to have something like:

broadcast ff05::101 autokey

if you have autokey set up on that server.

On the client you need to specify

multicastclient ff05::101

If you are running without authentication you need to also specify
disable auth

so that it does not try and authenticate.
> In the environment I'm working the NTP clients request the time
> periodically to the server, the server is not multicasting/broadcasting
> anything to the clients, do you think the authentication issue you
> talked about may be the cause of the problem? I will double check that,
> but I don't think I am facing any authentication problem since direct
> queries (IPv6 or IPv4) to the server are working just fine.

Without seeing your configuration files, how would anyone know? Have you
used tcpdump to see if the server is sending the multicast packets?


> Thanks again,
> Mauricio

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