What do you need to know about NTP on IOS? - I've been working with
Cisco gear longer than I care to admit and have a bunch of CC*
certifications but that's not relevant here

Generally IOS devices actually speak SNTP - Not sure whether they can
use an external reference clock I don't think so BUT it might be
possible to replace the cheap TCXO universally used by cisco with a
buffer circuit and derive your clock from there and configure the
device as a ntp server.    Let me peek inside one of the routers
hanging around here and I'll see what can be done

• Scott

On Fri, Oct 3, 2008 at 5:39 PM, Robert Vassar rvassar@rob-vassar.com wrote:

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

http://www.cisco.com/en/US/docs/ios/12_1t/12_1t1/feature/guide/dtrimble.html

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
port:

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

and

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
PPS...

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
source.

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

73,
Dave
AF6KD

On Fri, Oct 3, 2008 at 2:39 PM, Robert Vassar rvassar@rob-vassar.com wrote:

It looks like the feature set varies significantly with the router
model, and by IOS feature set.  The router I have here is an eBay
special, an old 2514.  It's probably 10 years old, though I think
Cisco continued to make them until about 2003.  It's only configured
with 8mb flash, so it can only run the stripped down IP subset.
(which lacks the IPv6 stuff I need too...)  Every few years I dabble
with ploughing thru the CC** tests, but I'm a QA engineer, so it
never becomes a priority.

It's running c2500-i-l.121-27b.bin, and my ntp menu looks quite
different:

Router2#config t
Enter configuration commands, one per line.  End with CNTL/Z.
Router2(config)#ntp ?
access-group        Control NTP access
authenticate        Authenticate time sources
authentication-key  Authentication key for trusted time sources
broadcastdelay      Estimated round-trip delay
clock-period        Length of hardware clock tick
master              Act as NTP master clock
max-associations    Set maximum number of associations
peer                Configure NTP peer
server              Configure NTP server
source              Configure interface for source address
trusted-key        Key numbers for trusted time sources

Router2(config)#^Z

No "refclock" option.  If I had a 16mb flash card, I could run the
"Enterprise" image, which might have different features.  But a 16mb
flash card and FPM SIMM cost more than this router is worth.  It
appears to be NTP v3 as well, though all my Solaris boxes run v3 due
to some issues with NTP 4.x and the kernel clock code. (It's being
fixed...)

I'll have to look at one of the newer models I have in the lab at
work.  I've also been thinking of buying an 851w for my DSL line here
at the house.  I've outgrown my WRT54G, even running Tomato, perhaps
I'll be pleasantly surprised.  I hadn't even looked at Cisco stuff
since 2002 or so, certainly pre-12.1 anyway.  I was just kind of
surprised to come across an NTP server at all, and I was curious what
its "Time-Nuts hackability" rating was.  :-)

Thanks and 73,

Rob
KC6OOM/5

On Oct 5, 2008, at 12:00 AM, Dave hartzell wrote:

Actually you might get pretty good results if you have a 6509 as any
activity on the serial port triggers a CPU interrupt which is why on a
overloaded 6509 the first thing to try is "no logging console" to get
the cpu down from 100% - usually in the context of DDoS and the
control plane is slammed as the EOBC is only a 1 megabit channel even
on the 3BXL's.    This is one of the advantages of the annual trek out
to Bldg 14 in San Jose - one gets to meet the guys who developed the
code for the routers.

This has more than passing interest for me as one could take a NovaTel
GPSCard which has a 1PPS output and runs on a single 12-36V supply and
has a dedicated 1PPS output at serial levels and install one at each
router location.    Still have not disassembled the 2501 and 2611 to
see which cheapo TCXO Cisco has installed.

What do you have available at your shop - we are running SUP720-3BXL's
running 12.2 SXF

On Sun, Oct 5, 2008 at 1:00 AM, Dave hartzell hartzell@gmail.com wrote:

This runs on the aux port, and the sup720 doesn't have an aux port...
There are always obscure features that slip into the production releases
that aren't tested and they just forget to exclude them during builds.
TAC will probably have no clue about this...
You could try the cisco-nsp mailling list for support, but beware, it's
frequented by cisco developers that will just as soon open a bug-id to
drop 'feature' from the production release if it was never supposed to
be there in the first place.

I wonder if this was originally used as an alternative method to time
the MIX midplane in the VXR chassis and the NTP feature was side
benefit?  Most telecom gear that needs synchronization will take a
BITS input or some other frequency reference.  I've used that extensively
with SONET gear and the good old Datum OT-21.  I never used the
7200 MIX, so I'm not sure if it could take an external reference or
just recover clock from a DS1 port.

Seems like a good use for an AUX port if you don't need a modem or
reverse telnet!

Scott

Scott McGrath wrote:

I remember running this on "line aux 0" in the IOS version 11.x days (circa 1999).  Was supported on the 7000, 4000 and 2500 series routers.  It was originally designed for a Telecom Solutions (bought by Symmetricom) clock that would be co-located with the routers in a data centre .  I have a PDF copy of "Application Note 600" that shows how it was intended to be used (mail me if you need a copy).  I ditched the solution in favour of a FreeBSD+GPS based solution; Cisco was (and still is) only supporting version 3 of NTP specification.  I do not have any data left on how well it worked but I recall it was better with the PPS support than without.

Regards.

Mark.

--
Mark Allwright CCIE #1088

National Hosting Services - Senior Data Analyst
2100 111 - 5th Avenue SW
Calgary, AB T2P 3Y6

T: 403 410-0733 | F: 403 216-6050

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Scott Mace
Sent: Sunday, October 05, 2008 11:33 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] GPS, NTP, and Cisco routers...

This runs on the aux port, and the sup720 doesn't have an aux port...
There are always obscure features that slip into the production releases that aren't tested and they just forget to exclude them during builds.
TAC will probably have no clue about this...
You could try the cisco-nsp mailling list for support, but beware, it's frequented by cisco developers that will just as soon open a bug-id to drop 'feature' from the production release if it was never supposed to be there in the first place.

I wonder if this was originally used as an alternative method to time the MIX midplane in the VXR chassis and the NTP feature was side benefit?  Most telecom gear that needs synchronization will take a BITS input or some other frequency reference.  I've used that extensively with SONET gear and the good old Datum OT-21.  I never used the 7200 MIX, so I'm not sure if it could take an external reference or just recover clock from a DS1 port.

Seems like a good use for an AUX port if you don't need a modem or reverse telnet!

    Scott

Scott McGrath wrote:

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