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

Robert Vassar rvassar at rob-vassar.com
Sun Oct 5 13:22:02 UTC 2008



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:

> 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 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.
>>
>
> _______________________________________________
> 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