[ntpwg] [dhcwg] NTP option: IP address and/or FQDN

[anthony.flavin at bt.com]

The main problem with the DHCP doing the DNS lookup on behalf of it's NTP clients, is that architecturally, that's a complete mess. The pools demonstrate why. Many NTP servers are set up with the same Pool address for say three servers. They get three different NTP servers to point at from the DNS queries they generate.

So are we going to move some of the NTP features into DHCP, or accept where the boundaries are and let each system do what it's good at?

Tony Flavin



-----Original Message-----
From: ntpwg-bounces+anthony.flavin=bt.com at lists.ntp.org [mailto:ntpwg-bounces+anthony.flavin=bt.com at lists.ntp.org] On Behalf Of MORAND Lionel RD-CORE-ISS
Sent: 09 December 2007 13:53
To: Danny Mayer
Cc: DHC WG; NTP Working Group; Ralph Droms
Subject: Re: [ntpwg] [dhcwg] NTP option: IP address and/or FQDN


Hi Danny,

In any case it was a statement on what the NTP wg should have had to do. I was just expressing my own understanding of the outcome of the dhc session. As I said, I met exactly the same troubles while defining a new dhcp option for locating pana agent in the network.

I think clear guidelines on this topic could be very useful. For instance, instead of providing FQDN, it is often said that the dhcp server could be just another user of the DNS, performing DNS lookup before providing IP address(es) to the dhcp client. The foreseen flexibility of the use of FQDN could be therefore provided while using IP address(es) in dhcp options.

I have no strong opinion on this topic, being not a dhcp expert myself. But as a "client" of the dhc wg, I'm interested by a clear statement.

BR,

Lionel


> -----Message d'origine-----
> De : Danny Mayer [mailto:mayer at ntp.org]
> Envoyé : dimanche 9 décembre 2007 05:19
> À : MORAND Lionel RD-CORE-ISS
> Cc : Ralph Droms; DHC WG; NTP Working Group
> Objet : Re: [dhcwg] NTP option: IP address and/or FQDN
> 
> MORAND Lionel RD-CORE-ISS wrote:
> > Hi all,
> > 
> > During the meeting, we discussed again the use of FQDN for
> advertizing
> > NTP servers.
> > 
> > During the work on the PANA option, we had exactly the same
> discussion
> > (in the meeting and on the mailing list) and the conclusions was the
> > same: we SHOULD use IP address list instead of FQDN. The SHOULD is
> > there to say that it might be some cases where the use of 
> FQDN would
> > be valuable/really required.
> 
> Don't you think that you should have also discussed this with
> the NTP folks as well? Most of the DHCP discussion only 
> happened because we were asked to review the draft.
> 
> > As it seems that, after at least two long discussions in the same
> > topic, there is a "common" understanding on how should be advertize 
> > servers, it could be useful to capture these conclusions as 
> guidelines
> > in the dhc-option-guidelines draft. This would help a lot other
> > working groups when they will have to design new options 
> for the same usage.
> 
> I'm not yet convinced that this conclusion is really
> warranted since this will force NTP to use only a single IP 
> address for each server instead of being able to use the pool 
> option which provides a lot of flexibility. It's not in the 
> NTPv4 draft but that shouldn't matter since  this is about 
> provisioning NTP and not about a specific implementation.
> Don't forget that NTP will have to live with the decisions 
> you make about what you tell it to use. It's either that or 
> the options will get ignored and neither result is desired. 
> I'd like to discuss how this will be operationally 
> implemented before we can make a decision on whether or not 
> IP addresses are the way to go.
> 
> I am copying the NTP WG on this so we can get other people's input.
> 
> Danny
> 
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