[time-nuts] GPS, NTP, and Cisco routers...

Dave hartzell hartzell at gmail.com
Sun Oct 5 05:00:51 UTC 2008

Looks like Trimble and Cisco got together on a PPS implementation for
the 7200, starting with 12.0T trainwreck:


Since I don't have any 7200s any longer (thank goodness), I checked
and it seems that the 6500s support this as well on the console serial

6509-rtr(config-line)#ntp ?
  pps-discipline  Use PPS pulse to discipline system clock
  refclock        NTP Reference Clock


6509-rtr(config-line)#ntp refclock ?
  telecom-solutions  Telecom Solutions GPS
  trimble            Trimble Navigation TSIP Protocol

It looks interesting, and if the code is just looking for a PPS
transition on the CTS or RI, you might be in luck with any external

BUT be forewarned, IOS is a cooperative multitasking operating system
(at least prior to the new "modular" stuff), so your accuracy is going
to vary depending on loads, processes, etc.  I wouldn't count on this
being to spectacular...  probably no better than an external NTP

And of course, you can always call the TAC for more assistance!  ;-)


On Fri, Oct 3, 2008 at 2:39 PM, Robert Vassar <rvassar at rob-vassar.com> wrote:
> I've been fiddling around with an old Cisco router here at the house
> to brush up.  We have an IPv6 project going at work, and our WAN
> provider provides no native transit, so I'm looking at doing some
> tunneling.  Anyhow... I discovered IOS 12.1 and above have native NTP
> capability.  I don't have the exhaustive IOS command reference, and I
> suspect it's a limited NTP implementation. I'm wondering if it's
> possible to tie a GPS unit to a router serial port and gain a stratum
> 0 refclock.
> Any Cisco guru's on the list?  :-)
> Cheers,
> Rob
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

More information about the time-nuts mailing list