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NTP Server on 3600 and 1600
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| Hi
I have a problem for you.
I have a network of Cisco 1600 routers connecting back to a hub, 3600 Cisco router, running Frame Relay point to point PVCs and RIP.
I want to run Network Time Protocol between the routers, using the 3600 as a timing source and the 1600s slaving to the 3600. Additionally, I want the 3600 to get its clock source from the Telco 2Meg
Frame-Stream leased line.
I have looked on the Cisco web site, but I can find nothing specific for 3600 and 1600.
Can anyone point me in the right direction; the config should be fairly straightforward, just a few line maybe.
Cheers
Hippo
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|  Cheers Yeti
Looks like the first link may be more appropriate, since the 1600s can only run SNTP. I am going to try this on a live network; luckily, all the sites are closed for the day, so I have until 07:00 tomorrow morning to get it right, or remove it.
Hippo
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| Yeti-GBR1 2002-04-03, 6:23 pm |
| Hmmm any luck? | |
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|  Yeti
Yeah, sort of. The 3620 has NTP enabled by default. It gets its clock source from an SNMP server (someone else configured that).
The 1600s run SNTP, I am now configuring them to look at the 3620 WAN interface for an NTP clock. Then I will run debug on both to see what results.
More later.
Cheers Yeti
Hippo | |
| Hippo 2002-04-03, 11:09 pm |
| ,, now it's down to my senior colleagues on the day shift to verify it for me.
Cheers Yeti & thanks for the help
Hippo  | |
| haseeb_eng 2002-04-03, 11:26 pm |
| Hippo can you just give me your show conf if possible ? so i can have a look what commands are their whats the process ?
haseeb | |
| Hippo 2002-04-03, 11:29 pm |
| I am just going off shift right and I have shut down my seesions with the routers.
I will post the configs when I come back tonight, after 19:00 BST (UTC).
Cheers
Hippo
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| haseeb_eng 2002-04-03, 11:46 pm |
| ok thanks | |
| Yeti-GBR1 2002-04-04, 12:22 pm |
| Ok Hippo its 19:20 hours whats the verdict? | |
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| My main man liked it. He can also see NTP packet exchange using debug. The real test would be for the 1600 router to be powered off, and then see if it synchronised with NTP packets from the 3620 router clock. But we cannot do that without permission from the client whose network we manage. This is really a nicety for us; to get real-time alarm and statuses for all the routers in the network, instead of having to look at each router's clock and calculating real-time based on the timestamp in the system logs. Eventually, the four hub routers in this network will have NTP associations for failover purposes, but for now, the config has been kept fairly simple, as detailed below. The IP address aaa.b.ccc.d is our SNMP server and therefore the address has been changed for security reasons.
1600(config)#clock summer-time BST recurring last Sun Mar 2:00 last Sun Oct 2:00
1600(config)#service timestamps debug uptime
1600(config)#service timestamps log datetime msec localtime
1600(config)#sntp server 10.20.0.2
1600#sh sntp
1600#SNTP server Stratum Version Last Receive
10.20.0.2 11 1 00:00:36 Synced
3620(config)#clock summer-time BST recurring last Sun Mar 2:00 last Sun Oct 2:00
3620(config)#service timestamps debug uptime
3620(config)#service timestamps log datetime msec localtime
3620(config)#ntp server aaa.b.ccc.d prefer
3620#sh ntp
3620#Clock is synchronized, stratum 11, reference is aaa.b.ccc.d
nominal freq is 250.0000 Hz, actual freq is 249.9968 Hz, precision is 2**24
reference time is C05720D9.534097E1 (19:58:33.325 BST Thu Apr 4 2002)
clock offset is 4.3382 msec, root delay is 56.11 msec
root dispersion is 15.95 msec, peer dispersion is 1.17 msec
Cheers
Hippo | |
| ccnpman 2002-04-04, 1:37 pm |
| is it possible to get clock from Leased or FR link instead of Time Server? | |
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| The definitive source for our NTP clock is our SNMP sever. That's a UNIX based box - and now I am completely lost - so I am not sure where it gets its clock source. I will ask the UNIX guru here at work when I am next on days.
However, I believe it is possible to get a clock from the leased line cos Telcos like BT use several atomic clock sources throughout their networks.
Hippo
(Don't know UNIX ) | |
| MadChef 2002-04-04, 8:17 pm |
| quote:
Originally posted by Hippo
The definitive source for our NTP clock is our SNMP sever. That's a UNIX based box - and now I am completely lost - so I am not sure where it gets its clock source.
It doesn't have to get its time from anywhere. The important thing is that all devices are synchronized, even if they're not synced to the millisecond or even a few seconds (beyond a couple of minutes could be a problem though). Your 3600 is now at stratum 11, so that means the unix box is at stratum 10. That a long, long way from an atomic clock (at stratum 1) so I'm guessing that someone just set the time on the unix box and set it to be stratum 10. And if everyone ultimately pulls from that source (like your routers are) then that's a perfectly fine way to do things.
And you're not going to get time from any link. The only place you're going to get time is from another NTP server, which may or may not live at your provider. There are many publicly available stratum 2 servers out there on the internet if you look.
MadChef | |
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| Thanks for the clarification Mad Chef.
I was wondering what the stratum levels meant, now I know. My senior engineer wanted to find a definitive clock source, hence the query about using the clock from a Telco leased line. I can see that doesn't matter now; just so long as all the routers are synched to the one stratum 10 UNIX NTP server.
Cheers
Hippo | |
| MadChef 2002-04-05, 10:22 am |
| See http://www.eecis.udel.edu/~mills/ntp/clock2.htm
There are quite a number of open access stratum 2 servers in the UK. A quick perusal didn't show any in BT, but you certainly have a selection if you want a more authoritive source.
MadChef |
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