[time-nuts] GPS, NTP, and Cisco routers...
Tom Arnold
xyzzy at sysabend.org
Sat Oct 4 00:02:15 UTC 2008
On Fri, Oct 03, 2008 at 06:46:17PM -0400, time-nuts-request at febo.com wrote:
> From: Robert Vassar <rvassar at rob-vassar.com>
> Subject: [time-nuts] GPS, NTP, and Cisco routers...
>
> 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? :-)
Cisco routers have a fairly basic NTP capability. No chance right now of
using the serial port to speak to a GPS or synced clock on 90% of the gear.
I can't say for certain on some of the really high-end stuff but I kinda
doubt it.
Its really only intended for redistribution, heck, you can even *set* what
Stratum you claim to be ( by default I think Cisco uses 8 ). The only
"extra" features they support is they will do ntp/multicast which is nice
from a client config point of view for us at least.
I'm using a pair of Endrun CDMA based ntp servers because they will work
inside a colo without external antennas, they sync our Cisco cores which
multicast out to the clients. We're within a few milliseconds which is
close enough. For redistribution to customers we sync a bunch of unix ntp
servers directly off the CDMA servers so our customers get Stratum 2. I
hope to be adding a third Endrun box to the mix shortly where I can put up
an external GPS antenna...
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