[70662] in North American Network Operators' Group
Re: ntp config tech note
daemon@ATHENA.MIT.EDU (Michael Sinatra)
Fri May 21 00:09:10 2004
Date: Thu, 20 May 2004 21:08:43 -0700
From: Michael Sinatra <michael@rancid.berkeley.edu>
To: nanog@nanog.org
In-Reply-To: <20040520213322.GA32355@puck.nether.net>
Errors-To: owner-nanog-outgoing@merit.edu
Jared Mauch wrote:
>
> I've found it useful on older machines (PCs with cheap clocks and
> oscilators) to cron ntpdate once an hour to prevent the clock from
> getting too far off by itself. I've found the daemon doesn't do good enough
> of a job to sync on it's own...
>
> I'm also wondering, how many people are using the ntp.mcast.net
> messages to sync their clocks? what about providing ntp
> to your customers via the "ntp broadcast" command on
> serial links, etc..?
I run two stratum-1 servers and a few stratum-2s and I provide time via
multicast (224.0.0.1), but I don't use it for my servers, except for
testing and verification. I am also providing anycast ntp, and, if the
belt and suspenders weren't enough, I am experimenting with manycast.
That's an NTPv4 feature where the *client* sends a multicast message to
an administratively-scoped group soliciting servers and then the servers
respond and set up associations. From a client-configuration
standpoint, it's about as convenient as multicast or anycast, but it's
more accurate than multicast (since the servers set up true associations
with the client) and it allows you to do NTP authentication (which I
think breaks with anycast). It seems to work pretty well--the client
builds up several associations as if they were all configured manually.
michael
