Configuring 2621 To Use Proper Time 2

[Niall22]

Can anyone help me set up my 2621 Router to keep exact time?
Everytime the router gets rebooted I have to reset the time and date. Is there anyway I can configure it to get the time and date from an NTP server on the Internet everytime it's rebooted and stay in sync with it?

Any help is appreciated,

Niall

 

[jroysdon]

Find some local (ie, hop close and low latency) NTP servers and add the follow global line(s):
ntp server ntp_server_ip

3 "local" California NTP servers I prefer are:
ntp server 165.227.1.1
ntp server 63.192.96.2
ntp server 132.239.254.5

You can also make your router an NTP server as well (I do that on our external router, and point other inside routers and hosts at it):
ntp master

NTP Server listings (Use Secondaries):

http://www.eecis.udel.edu/~mills/ntp/clock2.htm

Once set, you can do ntp commands such as:
#show ntp associations

address ref clock st when poll reach delay offset disp
+~165.227.1.1 140.142.16.34 2 39 1024 377 35.1 -1.22 14.8
*~63.192.96.2 204.152.184.72 2 39 1024 377 51.5 2.14 6.0
+~132.239.254.5 164.67.62.194 2 842 1024 367 51.6 -8.64 3.4
* master (synced), # master (unsynced), + selected, - candidate, ~ configured

#show ntp status
Clock is synchronized, stratum 3, reference is 63.192.96.2
nominal freq is 252.0161 Hz, actual freq is 252.0211 Hz, precision is 2**7
reference time is BD5D98CD.9218F7CD (20:43:09.570 PDT Sun Sep 3 2000)
clock offset is -3.6675 msec, root delay is 65.66 msec
root dispersion is 18.48 msec, peer dispersion is 7.86 msec

 

[Niall22]

I have set that up like you explained but it won't syncronize with the NTP server.
I'm using a Stratum 2 NTP Version 3 server and I am allowing UDP packets to it through my firewall. Do I need to allow TCP packets through as well? This is what the sh ntp associations command shows me:

address ref clock st when poll reach delay offset disp
~209.87.233.53 0.0.0.0 16 - 64 0 0.0 0.00 16000.
* master (synced), # master (unsynced), + selected, - candidate, ~ configured

Here's what the sh ntp status command displays:

Clock is unsynchronized, stratum 16, no reference clock
nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**16
reference time is 00000000.00000000 (20:00:00.000 EST Thu Dec 31 1899)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 0.00 msec, peer dispersion is 0.00 msec

Is there an intial command to sync the clock?

Thanks,
Niall

 

[Kerzon]

Actually, NTP sites on the InterNet use tcp, not udp. And most likely it will be sntp (port 580, regular ntp uses port 123). Hope that helps

Andy [sig][/sig]

 

[jroysdon]

I can't speak in absolutes for all Cisco platforms, but my 1605R & 804 both use ntp's standard udp/123 port. I run a very tight config (IOS Firewall and an ACL that blocks everything except what I allow or the IOS Firewall opens up on the way out), and I know the NTP wouldn't work until I added this to my ACL:
access-list 101 permit udp host 165.227.1.1 host external_interface_ip eq ntp
access-list 101 permit udp host 63.192.96.2 host external_interface_ip eq ntp
access-list 101 permit udp host 132.239.254.5 host external_interface_ip eq ntp

ntp=123 of course (IOS just converts it to service name even if you specify port 123)

[sig][/sig]

 

[cpace]

How do I get NTP to work on a 1720 router ?