Re: [dhcwg] Re: [ntpwg] Network Time Protocol (NTP) Options for DHCPv6

["David W. Hankins" <[e-mail]>]

On Fri, Nov 23, 2007 at 10:46:12PM -0500, Danny Mayer wrote:
> That's currently the situation with the reference implementation of
> ntpd. It gets its configuration information and doesn't go back. You can

You can classify this as an ntpd problem, or a system integration
problem.

In the former, you might want to accept a HUP sometimes.  In the
latter, all the tools to restart the daemon are already available.

Whichever one you choose, you'll still get the job done.  If ntpd
accepts HUPs, maybe you can optimize 'keeping your clock synched'
across reconfiguration events.

> now. So for the DHCP client to have an influence on what it uses for
> servers it either needs to use ntpdc, send private mode 7 NTP packets,
> restart ntpd, or have some sort of interface for ntpd to get updated
> values from the DHCP client.

The client itself has no need to do this.  The operating system's
configuration management system which accepts DHCP input needs to
solve this problem.

For ISC, we call this "dhclient-script", and although we package
several examples with our software I know of no actual operating
systems that use them...they all cook their own scripts that
integrate with their configuration management.

Still, it is trivial;

	if [ x$new_ntp_servers != x$old_ntp_servers ] ; then
		rewrite_ntp_conf()
		rcntp force-reload
	fi

> Well, if ntpd can poke the DHCP client for new values, presumably it can
> request new values from the DHCP server to pass back to ntpd. That's not
> even defined.

Presently, all the poking is in the opposite direction.  What I was
referring to here is that there are Server->Client messages that can
suggest the client needs to update its config, rather than wait for
the usual lease renewal timer to expire.

-- 
Ash bugud-gul durbatuluk agh burzum-ishi krimpatul.
-- 
David W. Hankins	"If you don't do it right the first time,
Software Engineer		     you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins

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