Re: SNTP implementation recommendations (was "Re: [ntpwg] SNTP clients")

Probably the most important thing to include is that KOD packets need
to be obeyed. In IETF terms this is a MUST. There are far to many
NTP/SNTP clients that do not know or care about KOD packets and
continue to make requests are they are told to go away.

In addition there are clients that will continuously send requests
as frequently as 1 second apart and will ignore that fact that the
servers are dropping their packets or telling it to go away, see above.
The CSIRO incident a year or so ago points out that when CSIRO changed
their NTP server address, not only did the traffic not go away, the
traffic actually increased as clients became even more insistent in
getting their time from a non-existent server.

SNTP clients, in short, need to be good net citizens and understand
both responses and lack of responses. This goes for ntp servers too.

Danny
----- Original Message Follows -----
> Hi Jason,
> 
> On Thu, Apr 28, 2005 at 09:37:24AM -0400, Jason Terry wrote:
> > 
> > I am trying to improve an SNTP client implementation.  I was
> > wondering if anyone could point me to a resource that has
> > information on the real-world issues developers face when
> implementing an SNTP client.
> 
> I made some comments/recommendations in this BCP RFC (numbers yet to
> be assigned):
> 
>   
> http://www.ietf.org/internet-drafts/draft-ietf-grow-embed-addr-05.txt
> 
> Also, I believe one of the vendor consortiums (perhaps DOCSIS?)
> codified some of our recommendations in their specs, but I've lots the
> reference.  If someone knows where I can find it, please let me know.
> 
> In addtion to RFC2030:
> 
>    ftp://ftp.rfc-editor.org/in-notes/rfc2030.txt
> 
> we worked on this updated draft which is probably closest to what you
> want:
> 
>   
>
http://www.eecis.udel.edu/~mills/database/rfc/draft-mills-sntp-v4-00.txt
> 
> Dave
> 
> P.S. You might also find this backgroun info pertient - in my
> technical report here:
> 
>    http://www.cs.wisc.edu/~plonka/netgear-sntp/
> 
> and in the related presentations, for instance at LISA and NANOG:
> 
>    http://net.doit.wisc.edu/~plonka/lisa/lisa2003/
>    http://www.nanog.org/mtg-0310/plonka.html
> 
> -- 
> plonka@doit.wisc.edu  http://net.doit.wisc.edu/~plonka  ARS:N9HZF 
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