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New Member

NTP : Network time Protocol

i have cisco routers 3640 , 2610 and switches 2924 , 1924 ,1912 in my network set up . these devices have not system calendar clock built in their IOS. but i want to synchronize these devices with my windows2000 time server.

when i configured router 3640 for 2000server peer by giving command


ntp peer


the router started to receive NTP packets from server ,, but it is not synchronizing with server clock.

when i give this command .....

show ntp associations details

i get ..... configured, insane, invalid, stratum 2

ref ID, time C115D117.EADDDF43 (13:21:11.917 ast Tue Aug 27 200

our mode client, peer mode server, our poll intvl 1024, peer poll intvl 1024

root delay 0.00 msec, root disp 1000.02, reach 377, sync dist 1043.488

delay 1.62 msec, offset 202789.6536 msec, dispersion 42.66

precision 2**7, version 3

org time C115D2A7.DA1CAC07 (13:27:51.851 ast Tue Aug 27 2002)

rcv time C115D1DD.102B30D9 (13:24:29.063 ast Tue Aug 27 2002)

xmt time C115D1DD.0FC0ABC9 (13:24:29.061 ast Tue Aug 27 2002)

filtdelay = 1.62 19.30 2.88 1.59 1.71 1.62 1.62 1.63

filtoffset = 202789. 202818. 202833. 202852. 202866. 202868. 202873. 202871.

filterror = 0.02 15.64 31.27 46.89 54.70 58.61 60.56 61.54

please can u get me a solution for this


New Member

Re: NTP : Network time Protocol

There are three key fields here:

1. The router is clearly hearing from your NTP server. Aside from the fact it's measuring delay and offsets, the "reach" is listed as 377 which means the router heard the last eight (I think) packets from the time server.

2. But despite that, the router is marking the time packet is "invalid" and that the broadcast fails sanity checks (it's "insane.")

It's interesting that it's marked as stratum 2. How does your server get it's timestamp? Directly from NIST (or whomever)? If not, you should really mark your server as stratum 3.

Are you synching over a WAN? Over a noisy LAN? Are the NTP packets being corrupted? Do you have some other NTP commands (like clock-period which you should NOT use)...?

Barring that, I'd suggest opening a case with the TAC. It's not clear what IOS/CatOS you're using or what the entire configs are so it's harder to troubleshoot.

New Member

Re: NTP : Network time Protocol


thanks for interest

I have one 3640 , 2610 , 2924 devices in my LAN .

these devices are not having system clock calender.

I configured my PC (windows 2000 professional) as providng Time service

in LAN. I am not syncing over WAN ,,it is inside my LAN.

I have used just one command in 3640 router after configuring my PC as Time server ,,,

command is as follows .....


Ntp server prefer

! is my PC ip address and is 3640 router's ethernet ip address.

these are connected through Switch 2924

THough i am synchronizing my PC time through internet time servers , but i have enabled w32time service of windows 2000 Pro. and configred it as local time server for my LAN by editing registry keys.

i have not used any other command except ntp server prefer.

Also my router time is in skew of server.

my cisco ios version details ----

Cisco Internetwork Operating System Software

IOS (tm) 3600 Software (C3640-IS40-M), Version 12.0(4)T, RELEASE SOFTWARE (fc1)

Copyright (c) 1986-1999 by cisco Systems, Inc.

Compiled Thu 29-Apr-99 16:01 by kpma

Image text-base: 0x600088F0, data-base: 0x60B56000

ROM: System Bootstrap, Version 11.1(20)AA1, EARLY DEPLOYMENT RELEASE SOFTWARE (f


Head_Office uptime is 2 days, 3 hours, 29 minutes

System restarted by power-on at 10:29:38 ast Mon Aug 26 2002

System image file is "flash:c3640-is40-mz_120-4_T.bin"

cisco 3640 (R4700) processor (revision 0x00) with 28672K/4096K bytes of memory.

Processor board ID 14393449

R4700 CPU at 100Mhz, Implementation 33, Rev 1.0

Bridging software.

X.25 software, Version 3.0.0.

1 Ethernet/IEEE 802.3 interface(s)

5 Serial network interface(s)

DRAM configuration is 64 bits wide with parity disabled.

125K bytes of non-volatile configuration memory.

8192K bytes of processor board System flash (Read/Write)

Configuration register is 0x2102

suggest me what to do ?


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