From: Scott Morris (smorris@internetworkexpert.com)
Date: Mon Aug 25 2008 - 14:37:31 ART
If they are NTP peers, this helps. The max shift in ntp peer is 2 minutes
at a time. Client/server can jump from whenever.
But you are right, the sync time is god-awful slow! It's one of those tasks
that you put the config in, go do something else, then come back and
verify/fix things.
HTH,
Scott Morris, CCIE4 #4713, JNCIE-M #153, JNCIS-ER, CISSP, et al.
CCSI/JNCI-M/JNCI-ER
Senior CCIE Instructor
smorris@internetworkexpert.com
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-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Huan
Pham
Sent: Monday, August 25, 2008 3:11 AM
To: ccielab@groupstudy.com
Subject: Tips to speed up NTP synchronization
Hi GS,
My NTP session takes normally 3 minutes to sync. On Dynamips sometimes it
takes 10 minutes or even forever to get synched.
Even 3 minutes is still too painfull to wait in a lab. I cannot stand
waiting in sane for the router that looks like doing nothing!
Any tips to get NTP synched faster? Or any verification (show/debug) to make
sure that the router is on the right track to getting clock synchronized?
One of the tips I get from Brian Dennis in his CoD is to set clock manually
to so that routers clocks are not too apart. This does not seems to help
much. I still have it painfully 3 minutes long!
NTP on actuall routers takes 3 minutes to sync
----------------------------------------------
R1#sh run | in ntp
ntp master 1
R1#clock set 12:00:00 AUG 25 2008
R2#sh run | in ntp
ntp source Loopback0
ntp server 1.1.1.1
R2#debug ntp sync
NTP clock synchronization debugging is on R2#debug ntp events NTP events
debugging is on
R2#clock set 12:00:00 AUG 25 2008
R2#
Aug 25 12:00:00.000: NTP: peer stratum change Aug 25 12:00:00.000: NTP: sync
lost .Aug 25 12:00:00.000: %SYS-6-CLOCKUPDATE: System clock has been updated
from 12:06:56 UTC Mon Aug 25 2008 to 12:00:00 UTC Mon Aug 25 2008,
configured from console by console.
R2#
.Aug 25 12:02:48.845: NTP: synced to new peer 1.1.1.1 Aug 25 12:02:48.845:
NTP: 1.1.1.1 synced to new peer Aug 25 12:02:48.845: NTP: sync change Aug 25
12:02:48.845: NTP: peer stratum change Aug 25 12:02:48.849: NTP: 1.1.1.1
reachable R2# R2#sh ntp associations detail | in san
1.1.1.1 configured, our_master, sane, valid, stratum 1
NTP on Dynamips takes 10 minutes to sync
----------------------------------------
R1#sh run | in ntp|access-list
access-list 2 permit 2.2.2.2
ntp access-group serve 2
ntp master 1
R2#clock set 14:00:00 Aug 25 2008
R2#
Aug 25 14:00:00.000: NTP: peer stratum change Aug 25 14:00:00.000: NTP: sync
lost
R2#
.Aug 25 14:01:01.054: NTP: synced to new peer 1.1.1.1 .Aug 25 14:10:42.931:
NTP: peer stratum change .Aug 25 14:10:42.935: NTP: clock reset R2# .Aug 25
14:11:46.955: NTP: synced to new peer 1.1.1.1 Aug 25 14:11:46.955: NTP:
1.1.1.1 synced to new peer Aug 25 14:11:46.959: NTP: sync change Aug 25
14:11:46.959: NTP: peer stratum change Aug 25 14:11:46.959: NTP: 1.1.1.1
reachable
NTP on Dynamips does not sync
-----------------------------
R1#sh run | in ntp|access-list
access-list 2 permit 2.2.2.2
ntp access-group serve 2
ntp master 1
R2#sh run | in ntp
ntp source Loopback0
ntp server 1.1.1.1
R2#clock set 14:00:00 Aug 25 2008
R2#
Aug 25 14:00:00.000: NTP: peer stratum change Aug 25 14:00:00.000: NTP: sync
lost
R2#sh clock
.14:29:53.256 UTC Mon Aug 25 2008
R2#sh ntp association detail
1.1.1.1 configured, insane, invalid, stratum 1 ref ID .LOCL., time
CC5D3A8B.28F8AE75 (14:04:59.160 UTC Mon Aug 25 2008) our mode client, peer
mode server, our poll intvl 64, peer poll intvl 64 root delay 0.00 msec,
root disp 0.03, reach 0, sync dist 7932.266 delay 92.19 msec, offset 9.4140
msec, dispersion 16000.00 precision 2**24, version 3 org time
CC5D4031.831262C4 (14:29:05.511 UTC Mon Aug 25 2008) rcv time
CC5D402E.1ED77782 (14:29:02.120 UTC Mon Aug 25 2008) xmt time
CC5D402E.0A515629 (14:29:02.040 UTC Mon Aug 25 2008)
filtdelay = 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00
filtoffset = 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00
filterror = 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0
R2#sh ntp status
Clock is unsynchronized, stratum 16, no reference clock nominal freq is
250.0000 Hz, actual freq is 250.0000 Hz, precision is
2**24
reference time is CC5D3C62.F5F303BE (14:12:50.960 UTC Mon Aug 25 2008) clock
offset is 9.4140 msec, root delay is 92.19 msec root dispersion is 7889.71
msec, peer dispersion is 7880.28 msec
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