NTP Server

John Kristoff jtk at cymru.com
Mon Oct 25 07:07:17 UTC 2010


On Sun, 24 Oct 2010 20:15:56 -0400
Brandon Kim <brandon.kim at brandontek.com> wrote:

> I have heard that routers don't make good NTP servers since they
> weren't designed to keep track of time. This, I have read from a
> Cisco source. Can't remember where though. Or maybe they were just
> referring to older less powerful routers like 2500 series...

I've implemented a two separate sets of stratum-2 services in two
different academic networks using retired Cisco router gear.  As far as
I know they are still operating fine, providing time primarily to the
institution's other infrastructure and server devices.  They only
provide time services.  I had done some rudimentary stress testing and
benchmarking at the time.  They performed sufficiently.

The advantage of this setup was that they were simple to setup, easy to
manage and cheap to replace with the same retired gear we had an
abundance of.  Maybe the clock resolution isn't as precise as some other
hardware, but for the purposes I had used it for it seemed fine.  I
doubt the underlying code has changed all that much, but at one time
David Mills gave his stamp of approval:

  <http://groups.google.com/group/comp.protocols.time.ntp/msg/1afed797bf898dd0?dmode=source>

On another note, contrary to another's position, I'd advocate not
implementing public NTP service along with your DNS infrastrucure if at
all possible.  Co-mingling of critical network services such as naming,
routing and time not only with themselves, but also with other less
critical network infrastructure subsystems (e.g. web, mail) should
generally be avoided in all, but the most resource constrained
environments.

John




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