You don¹t want to use both an ³ntp master² (my clock is the master) and an
ntp server (this is the ntp server I want to sync with) command together.
Cisco IOS will respond to ntp requests if a) it is the ntp master (ntp
master command) or b) it is synced to an ntp source (ntp server command).
So, for example, let¹s say that you want to sync R1 to a backbone ntp
server, and have R2 and R3 sync to R1. You would do:
R1:
ntp server <backbone ntp server¹s ip address> ! You¹re telling R1 to use
ntp to sync to the backbone server
ntp source <interface name> ! Optional - You¹re telling R1 to use a
specific interface for sourcing all of its NTP traffic
R2 & R3:
ntp server <R1¹s ip address use the address of the interface you set
in the ³ntp source² command on R1 if you set one>
In the above scenario, R1 will respond to ntp requests, R2 will respond to
ntp requests, and R3 will respond to ntp requests. No need for an ³ntp
master² command.
Scenario 2: You want R1 to provide ntp to R2 and R3, but are not using
another ntp server:
R1:
ntp master <stratum number> ! You¹re telling R1 to respond to NTP
requests and say he¹s a certain stratum clock.
ntp source <interface name> ! Optional - You¹re telling R1 to use a
specific interface for sourcing all of its NTP traffic
R2 & R3:
ntp server <R1¹s ip address use the address of the interface you set
in the ³ntp source² command on R1 if you set one>
HTH,
DQ
On 6/8/12 1:19 PM, "Mann Chaddha" <mann.chad...@gmail.com> wrote:
> Hi Experts
>
> I am due for my next Lab attempt in 5 days time. I so far have never been able
> to get marks for NTP section.
>
> So I ask this question to the forum that if someone has ever scored 100% in
> the Infra Section (without breaking the NDA of course) , can they lend some
> light on this innocuous looking command, ntp master.
>
> Here are some finding from my POD: [10.10.100.1 = PSTN RTR & 10.10.110.1=HQ
> RTR]
> 1. With NTP Master Command
>
> R1:
> ntp source Loopback0
> ntp master 10
> ntp server 10.10.100.1 source Loopback0
> !
> clock timezone PST -8
> clock summer-time PDT recurring
>
> R2:
> ntp server 10.10.110.1
>
> Show commands:
> R1:
> HQ-R1#sh ntp status
> Clock is unsynchronized, stratum 16, no reference clock
> nominal freq is 250.0000 Hz, actual freq is 250.0008 Hz, precision is 2**24
> reference time is D37C1C18.AAB00668 (23:37:12.666 PDT Thu Jun 7 2012)
> clock offset is 0.0000 msec, root delay is 0.00 msec
> root dispersion is 0.00 msec, peer dispersion is 0.00 msec
> loopfilter state is 'CTRL' (Normal Controlled Loop), drift is -0.000003145 s/s
> system poll interval is 64, last update was 384 sec ago.
> HQ-R1#
> HQ-R1#
> HQ-R1#sh ntp ass
> HQ-R1#sh ntp associations
>
> address ref clock st when poll reach delay offset disp
> x~127.127.1.1 .LOCL. 9 16 16 377 0.000 0.000 0.240
> x~10.10.100.1 .LOCL. 1 50 64 377 0.000 13194.1 3.293
> * sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured
>
>
> R2:
> BR1-R2#sh ntp status
> Clock is unsynchronized, stratum 16, no reference clock
> nominal freq is 250.0000 Hz, actual freq is 249.9990 Hz, precision is 2**24
> reference time is 00000000.00000000 (16:00:00.000 PST Wed Dec 31 1899)
> clock offset is 0.0000 msec, root delay is 0.00 msec
> root dispersion is 0.01 msec, peer dispersion is 0.00 msec
> loopfilter state is 'CTRL' (Normal Controlled Loop), drift is 0.000003885 s/s
> system poll interval is 64, never updated.
> BR1-R2#
> BR1-R2#sh ntp ass
>
> address ref clock st when poll reach delay offset disp
> ~10.10.110.1 73.78.73.84 16 55 64 300 0.000 1325166 944.35
> * sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured
>
> CUCM:
> admin:utils ntp status
> ntpd (pid 6322) is running...
>
> remote refid st t when poll reach delay offset jitter
> ==============================================================================
> *127.127.1.0 LOCAL(0) 10 l 63 64 377 0.000 0.000 0.001
> 10.10.110.1 .INIT. 16 u 64 128 370 1.897 -2.990 1087693
>
>
> synchronised to local net at stratum 11
> time correct to within 12 ms
> polling server every 512 s
>
> Current time in UTC is : Fri Jun 8 06:22:22 UTC 2012
> Current time in America/Los_Angeles is : Thu Jun 7 23:22:22 PDT 2012
>
>
>
> ------------------------------------------------------------------------------
>
> Scenario 2: Without NTP Master Command.
> ------------------------------------------------------------------------------
> R1:
> ntp source Loopback0
> ntp server 10.10.100.1 source Loopback0
> !
> clock timezone PST -8
> clock summer-time PDT recurring
>
> R2:
> BR1-R2#r | s ntp
> ntp server 10.10.110.1
>
> Show Commands:
>
> HQ-R1#sh ntp status
> Clock is synchronized, stratum 2, reference is 10.10.100.1
> nominal freq is 250.0000 Hz, actual freq is 250.0008 Hz, precision is 2**24
> reference time is D37C21AB.D80D6753 (00:00:59.843 PDT Fri Jun 8 2012)
> clock offset is -0.0078 msec, root delay is 0.00 msec
> root dispersion is 0.01 msec, peer dispersion is 0.00 msec
> loopfilter state is 'CTRL' (Normal Controlled Loop), drift is -0.000003182 s/s
> system poll interval is 64, last update was 264 sec ago.
> HQ-R1#
>
> HQ-R1#sh ntp ass
>
> address ref clock st when poll reach delay offset disp
> *~10.10.100.1 .LOCL. 1 11 64 377 0.000 -7.866 2.813
> * sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured
>
> HQ-R1#sh ntp ass d
> 10.10.100.1 configured, our_master, sane, valid, stratum 1
> ref ID .LOCL., time D37C229E.73B36D17 (00:05:02.451 PDT Fri Jun 8 2012)
> our mode client, peer mode server, our poll intvl 64, peer poll intvl 64
> root delay 0.00 msec, root disp 0.47, reach 377, sync dist 0.00
> delay 0.00 msec, offset -7.8662 msec, dispersion 2.81
> precision 2**24, version 4
> org time D37C22AE.D47DF91B (00:05:18.830 PDT Fri Jun 8 2012)
> rec time D37C22AE.D7653258 (00:05:18.841 PDT Fri Jun 8 2012)
> xmt time D37C22AE.D6E2248F (00:05:18.839 PDT Fri Jun 8 2012)
> filtdelay = 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
> filtoffset = -0.01 -0.00 -0.00 -0.00 -0.00 -0.00 -0.00 -0.00
> filterror = 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
> minpoll = 6, maxpoll = 10
>
>
> BR1-R2#sh ntp s
> Clock is synchronized, stratum 3, reference is 10.10.110.1
> nominal freq is 250.0000 Hz, actual freq is 249.9990 Hz, precision is 2**24
> reference time is D37C2310.A8751D42 (00:06:56.658 PDT Fri Jun 8 2012)
> clock offset is 0.0034 msec, root delay is 0.00 msec
> root dispersion is 0.96 msec, peer dispersion is 0.93 msec
> loopfilter state is 'CTRL' (Normal Controlled Loop), drift is 0.000003898 s/s
> system poll interval is 64, last update was 7 sec ago.
> BR1-R2#
> BR1-R2#
> BR1-R2#
> BR1-R2#sh ntp ass
>
> address ref clock st when poll reach delay offset disp
> *~10.10.110.1 10.10.100.1 2 11 64 17 0.000 3.472 939.41
> * sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured
>
>
> admin:utils ntp status
> ntpd (pid 13103) is running...
>
> remote refid st t when poll reach delay offset jitter
> ==============================================================================
> 127.127.1.0 LOCAL(0) 10 l 60 64 377 0.000 0.000 0.001
> *10.10.110.1 10.10.100.1 2 u 57 64 377 1.718 1.677 5.437
>
>
> synchronised to NTP server (10.10.110.1) at stratum 3
> time correct to within 29 ms
> polling server every 64 s
>
> Current time in UTC is : Fri Jun 8 07:07:22 UTC 2012
> Current time in America/Los_Angeles is : Fri Jun 8 00:07:22 PDT 2012
> admin:
>
>
> As soon as I apply NTP master command, it breaks my NTP Sync.
>
> Am I missing something stupid in here. Please chime in.
>
> Thanks
> Mann
>
>
>
> _______________________________________________
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--
Dan Quinlan
Collaboration Engineering
PA Territory
Cisco Systems, Inc.
323 North Shore Drive
Suite 300
Pittsburgh, PA 15212
United States
Cisco.com <http://www.cisco.com>
Phone: 412.237.6268
d...@cisco.com
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