From: Hunt Lee (huntl@webcentral.com.au)
Date: Tue Jan 07 2003 - 01:47:11 GMT-3
Hey group,
Got 2 questions regarding NTP.
I have the following setup in my lab:-
NTP Server (win XP) RTA (NTP Master) RTB (NTP
Broadcast Client)
| |
|
----------------------------------------------------------------------------
-------------------------------------- Ethernet
Win XP - 25.100.61.10 /24
RTA - 25.100.61.1 /24
RTB - 25.100.61.2 /24
Ok. The NTP server is setup to broadcast NTP (out 255.255.255.255) on the
Ethernet. I have 2 things that I am confused about.
- Firstly, on RTA, I have set it up as NTP Master 7, yet RTB failed to pick
it up.
At RTA:-
ntp master 7
& I have setup RTA's clock with the "clock set" command...
RTA#sh ntp associations
address ref clock st when poll reach delay offset
disp
*~127.127.7.1 127.127.7.1 6 23 64 377 0.0 0.00
0.0
* master (synced), # master (unsynced), + selected, - candidate, ~
configured
RTA#
RTA#sh ntp status
Clock is synchronized, stratum 7, reference is 127.127.7.1
nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**16
reference time is C1C56122.1DB66112 (14:22:26.116 UTC Tue Jan 7 2003)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 0.02 msec, peer dispersion is 0.02 msec
RTA#
But at RTB, even though it is running in NTP client broadcast, it only
manages to receive the NTP broadcast from the NTP Server (Win XP), but not
from RTA...
RTB#sh ntp associations
address ref clock st when poll reach delay offset
disp
* 25.100.61.10 204.123.2.5 12 2056 8192 3 30.1 3.19
1.0
* master (synced), # master (unsynced), + selected, - candidate, ~
configured
RTB#
RTB#sh ntp status
Clock is synchronized, stratum 13, reference is 25.100.61.10
nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**18
reference time is C1C4CCFD.919D5ADB (03:50:21.568 UTC Tue Jan 7 2003)
clock offset is 3.1927 msec, root delay is 30.14 msec
root dispersion is 4.15 msec, peer dispersion is 0.96 msec
RTB#
So my first question is, if a router is running "ntp broadcast client", can
it only receive one NTP source's broadcast???
Or is there any other commands that I will need to add on top of the "ntp
master <7>" command?
My second question is that, how often does the NTP gets synchronized?? Does
it gets any forms of "hello packets" / keepalive packets to see if it's NTP
server is up??? The reason I asked is because even if I took off the "ntp
broadcast client" command (given that I don't have any static NTP servers by
"ntp server" command or anything else at all, how come RTB is still saying
it sync to the Win XP??
n.b:- I even tried to disconnect the Ethernet cable from the Win XP, yet
RTB still claims that it is sync to it...
Any help would be greatly appreciated.
Best Regards,
Hunt Lee
.
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