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I am trying to configure a cisco switch as a ntp client, however I cannot get past the show ntp status of Clock is unsynchronized, stratum 16, no reference clock. I've tried setting the clock close to the UTC time, but i still don't show time synced. First I thought it was due to a bug I was reading about regarding Win32Timeservice, or something like that, however I confirmed that this is a NTPD server (10.0.0.8) running on Unix.

Here is running-config

ntp server 10.0.0.8

Here is show ntp status

Clock is unsynchronized, stratum 16, no reference clock
nominal freq is 119.2092 Hz, actual freq is 119.2092 Hz, precision is 2**17
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

Here is show ntp associations:

      address         ref clock     st  when  poll reach  delay  offset    disp
 ~10.0.0.8     73.0.0.84      16    11   128  377     1.8  24018.     4.7
 * master (synced), # master (unsynced), + selected, - candidate, ~ configured

Here is show ntp associatsions detail:

10.0.0.8 configured, insane, invalid, stratum 16
ref ID 73.78.73.84, time D4452E2F.F4727CEA (18:59:59.954 UTC Wed Nov 7 2012)
our mode active, peer mode active, our poll intvl 512, peer poll intvl 256
root delay 0.00 msec, root disp 8.65, reach 377, sync dist 13.535
delay 1.45 msec, offset 24014.6042 msec, dispersion 4.17
precision 2**20, version 3
org time D4452E2F.F472894E (18:59:59.954 UTC Wed Nov 7 2012)
rcv time D4452E17.F0E5117A (18:59:35.940 UTC Wed Nov 7 2012)
xmt time D4452E17.F083A829 (18:59:35.939 UTC Wed Nov 7 2012)
filtdelay =     1.45    2.44    1.80    1.71    1.91    1.72    1.31    2.37
filtoffset = 24014.6 24016.5 24018.8 24021.3 24023.6 24026.1 24028.7 24030.7
filterror =     0.02    0.99    1.79    2.76    3.74    4.71    5.69    6.67

Here is my debug ntp

1d03h: NTP: xmit packet to 10.0.0.8:
1d03h:  leap 3, mode 1, version 3, stratum 0, ppoll 64
1d03h:  rtdel 0000 (0.000), rtdsp 10001 (1000.015), refid 00000000 (0.0.0.0)
1d03h:  ref 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900)
1d03h:  org D4452CBB.F7C546BE (18:53:47.967 UTC Wed Nov 7 2012)
1d03h:  rec D4452CA3.F093A140 (18:53:23.939 UTC Wed Nov 7 2012)
1d03h:  xmt D4452CE3.F082CDCD (18:54:27.939 UTC Wed Nov 7 2012)
1d03h: NTP: rcv packet from 10.0.0.8 to 10.0.0.30 on Vlan20:
1d03h:  leap 0, mode 1, version 3, stratum 0, ppoll 64
1d03h:  rtdel 0000 (0.000), rtdsp 0108 (4.028), refid 494E4954 (73.78.73.84)
1d03h:  ref D4452CFB.F76D2086 (18:54:51.966 UTC Wed Nov 7 2012)
1d03h:  org D4452CE3.F082CDCD (18:54:27.939 UTC Wed Nov 7 2012)
1d03h:  rec D4452CFB.F76B8A2C (18:54:51.966 UTC Wed Nov 7 2012)
1d03h:  xmt D4452CFB.F76D2DB1 (18:54:51.966 UTC Wed Nov 7 2012)
1d03h:  inp D4452CE3.F0F5FBCA (18:54:27.941 UTC Wed Nov 7 2012)

I'm not really sure whwere to go to from here. I know under show ntp associations detail if insane or invalid or stratum 16 is in there the cisco switch won't sync time.

Here is the ntp.conf

server 0.north-america.pool.ntp.org
server 1.north-america.pool.ntp.org
server 2.north-america.pool.ntp.org
server 3.north-america.pool.ntp.org


server  127.127.1.0     # local clock
fudge   127.127.1.0 stratum 10


restrict 127.0.0.1
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1 Answer

up vote 1 down vote accepted

This debug line makes me curious about the validity of your NTP master:

1d03h: NTP: rcv packet from 10.0.0.8 to 10.0.0.30 on Vlan20:
1d03h:  leap 0, mode 1, version 3, stratum 0, ppoll 64

So your NTP server is declaring it is stratum 0 - that's not going to work.

I labbed this out with two routers to make sure how the format should look like from the NTP master.

.Mar  1 00:55:51.533: NTP: rcv packet from 10.0.0.8 to 10.0.0.30 on Serial0/0:
.Mar  1 00:55:51.537:  leap 0, mode 4, version 3, stratum 5, ppoll 64

Note the reasonable stratum from my NTP master (simple config on the master router was "ntp master 5")

NTP is a finicky protocol to be sure, but I'd take a closer look at your NTP master. One other thing that tends to help with NTP is to set network devices clock 'close' to the clock the NTP master will ultimately provide.

Masters whose updates are off by a very far distance from what the switch thinks the time should be can also be declared insane, or at the best case take a long time to converge.

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This is the ntp.conf server 0.north-america.pool.ntp.org server 1.north-america.pool.ntp.org server 2.north-america.pool.ntp.org server 3.north-america.pool.ntp.org server 127.127.1.0 # local clock fudge 127.127.1.0 stratum 10 restrict 127.0.0.1 –  Jim Nov 8 '12 at 15:18
    
Also, ntp master on the cisco switch. I don't have that command available. The switch is a C3750 v12.2 –  Jim Nov 8 '12 at 15:24
    
Thanks again, I finaly got it to sync. I ended up making sure my NTPD server had a master selected, then I did a reload on the Cisco Switch. –  Jim Nov 8 '12 at 16:12
    
Good to hear! Rarely do you want an internal switch to actually be a NTP master - its more useful for testing than anything. Generally you want your master to be an atomic clock or something useful :) –  Jason Seemann Nov 8 '12 at 19:53
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