NTP question

[rmv72]

i have several Cisco's swithes in LAN and want synchronize all switches from one switch.I set time at main switch(172.20.5.14), at others i made next:

Switch2(config)#ntp peer 172.20.5.14 source fa0/1 prefer

But time is still old-

Switch2#sh clock

*20:15:34.611 UTC Sat Mar 13 1993

#sh ntp s

Clock is unsynchronized, stratum 16, no reference clock

nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**18

reference time is 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900)

clock offset is 0.0000 msec, root delay is 0.00 msec

root dispersion is 0.00 msec, peer dispersion is 0.00 msec

----

#sh ntp a

address ref clock st when poll reach delay offset disp

~172.20.5.14 0.0.0.0 16 - 64 0 0.0 0.00 16000.

* master (synced), # master (unsynced), + selected, - candidate, ~ configured

--------------

Where i was wrong? How to resolve it?

[rwiesmann]

hi

Is the ntp server reachable from your source interface you have given along with the command?

I guess you tested that...so in this case undo the whole ntp config and

configure it new....if still does not work start a debugging and post the output again.

Hope that helps

Roger

[rjackson]

I think peering only works if the server being peered to is successfully getting time from a source. You need to use the NTP SERVER x.x.x.x command in the clients and NTP MASTER in the server. Or you can use the broadcast (in the server) and broadcast client in the clients.

[rmv72]

yes, i started debug ntp at Switch2. Here output-

1w6d: NTP: xmit packet to 172.20.5.14:

1w6d: leap 3, mode 1, version 3, stratum 0, ppoll 64

1w6d: rtdel 0000 (0.000), rtdsp 10001 (1000.015), refid 00000000 (0.0.0.0)

1w6d: ref 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900)

1w6d: org 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900)

1w6d: rec 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900)

1w6d: xmt AF4DB8BD.82E5E0DB (13:59:25.511 UTC Sun Mar 14 1993)

1w6d: NTP: rcv packet from 172.20.5.14 to 172.20.5.11 on Vlan1:

1w6d: leap 3, mode 2, version 3, stratum 0, ppoll 64

1w6d: rtdel 0000 (0.000), rtdsp 10001 (1000.015), refid 00000000 (0.0.0.0)

1w6d: ref 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900)

1w6d: org AF4DB8BD.82E5E0DB (13:59:25.511 UTC Sun Mar 14 1993)

1w6d: rec C250DD14.2221C11B (09:36:20.133 UTC Wed Apr 23 2003)

1w6d: xmt C250DD14.224253F7 (09:36:20.133 UTC Wed Apr 23 2003)

1w6d: inp AF4DB8BD.84CD7E72 (13:59:25.518 UTC Sun Mar 14 1993)

[xge]

You may try tune stratum level to make the clock source have lower stratum, say Stratum 3 and make the clients have stratum say 5.

[rmv72]

i really sorry for that question-but i can't find it on my client switch(2950).Can you show it exactly?

[rwiesmann]

Hi

Thanks for the output.....loks o.k for me.

I usually have the vlan 1 used as the management vlan....as it looks

is that the same with the setup you got.

So what i configure it's like the following:

ntp source VLAN1

ntp server x.x.x.x

I did not experience problem with this setup. You could try to move your source as in my sample to VLAN1.

Hope that helps

Roger

[rmv72]

Thank you Roger!

it's from #sh run from Switch2(client)-

.......

!

ntp source Vlan1

ntp server 172.20.5.14 version 2

end

...........

But from debug i see same as before-

1w6d: NTP: xmit packet to 172.20.5.14:

1w6d: leap 3, mode 3, version 2, stratum 0, ppoll 64

1w6d: rtdel 0000 (0.000), rtdsp 10001 (1000.015), refid 00000000 (0.0.0.0)

1w6d: ref 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900)

1w6d: org C250E9BB.2F2F5EE7 (10:30:19.184 UTC Wed Apr 23 2003)

1w6d: rec AF4DC564.853CFC20 (14:53:24.520 UTC Sun Mar 14 1993)

1w6d: xmt AF4DC5A4.82D7129E (14:54:28.511 UTC Sun Mar 14 1993)

1w6d: NTP: rcv packet from 172.20.5.14 to 172.20.5.11 on Vlan1:

1w6d: leap 3, mode 4, version 2, stratum 0, ppoll 64

1w6d: rtdel 0000 (0.000), rtdsp 10001 (1000.015), refid 00000000 (0.0.0.0)

1w6d: ref 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900)

1w6d: org AF4DC5A4.82D7129E (14:54:28.511 UTC Sun Mar 14 1993)

1w6d: rec C250E9FB.2E64C220 (10:31:23.181 UTC Wed Apr 23 2003)

1w6d: xmt C250E9FB.2FBD775E (10:31:23.186 UTC Wed Apr 23 2003)

1w6d: inp AF4DC5A4.85922E18 (14:54:28.521 UTC Sun Mar 14 1993)

Where is the problem?

[rmv72]

Can you explain me debug output

1w6d: NTP: xmit packet to 172.20.5.14:

1w6d: leap 3, mode 3, version 2, stratum 0, ppoll 64

1w6d: rtdel 0000 (0.000), rtdsp 10001 (1000.015), refid 00000000 (0.0.0.0)

1w6d: ref 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900)

1w6d: org C250E9BB.2F2F5EE7 (10:30:19.184 UTC Wed Apr 23 2003)

1w6d: rec AF4DC564.853CFC20 (14:53:24.520 UTC Sun Mar 14 1993)

1w6d: xmt AF4DC5A4.82D7129E (14:54:28.511 UTC Sun Mar 14 1993)

I see here that my client switch send right time to main switch

1w6d: org C250E9BB.2F2F5EE7 (10:30:19.184 UTC Wed Apr 23 2003)

What is't?