[ntp:questions] NTS multicast response on IPv6

Mauricio Schramm mauricio.schramm at gmail.com
Wed Jan 18 19:27:44 UTC 2006

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?

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.

Thanks again,

On 1/18/06, Danny Mayer <mayer at ntp.isc.org> wrote:
> Mauricio Schramm wrote:
> > Hi,
> >
> >     I'm trying to set up an NTP server that answers multicast requests
> from
> > IPv6 clients without any success.
> Please understand that is not how multicast works. The clients are
> passive and only receive multicast packets from the server (modulo the
> authentication keydance).
> > I just don't know if the problem is with
> > the client or with the server and I don't have a reliable test tool to
> make
> > sure if any of them is correctly set. Does someone already tried this
> with
> > success? I tried it with up to date Red Hat Linux and Free BSD and Open
> > servers and it never worked. Does someone know if I can use tools like
> ntpq
> > to do my tests?
> >
> IPv4 and IPv6 multicast work in the latest ntp-dev release. Please note
> however that you must set up authentication on both the client and the
> server unless you explicitly disable authentication on the client.
> > Do you know if something like that is supposed to work:
> >     ntpq -n -c rv ff05::101
> > or
> >     ntpq -n -c rv ff01::101
> >
> This is wrong. ntpq can only request information about a specific host.
> Danny
> > Thanks,
> > Mauricio

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