time server for router help

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Oct 5th, 2008
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Hi,


I was wondering how I can sync my router with a time server? Is there one on the Internet or can I simply use a my Windows Domain Controllers clock? It doesn't have any special clock program just its default clock.


If external do you have an IP source?


Thanks

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Gerald Vogt Sun, 10/05/2008 - 02:40
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The router uses NTP. Unless you install an NTP server on the DC it won't be a time source. A good source to pick is your ISP if they run a time server. It has the least number of hops to your router. Otherwise you could check the NTP pool project http://www.pool.ntp.org/ It explains how you can choose multiple servers for time synchronization.

whiteford Sun, 10/05/2008 - 03:06
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Thanks, what is SNTP used for as I can see that in the list of commands.


Also what is the best wat to test? just change the clock and wait?

eweralan Sun, 10/05/2008 - 04:21
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Hi

SNTP is (i think) Simple NTP..

Command is from memory:

conf t

sntp server < ip address>


end


then do a sh ntp assoc to show effectiveness of sync...usually takes a few minutes to get a <+/~/*> in the front of the command.. for SNTP the show command may be " show sntp assoc"


regds

Al

whiteford Mon, 10/06/2008 - 02:00
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What is the difference between ntp and sntp? One of my routers seems to have both configured.

Gerald Vogt Mon, 10/06/2008 - 03:17
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NTP is the "full" network time protocol. SNTP is the simple variant which is not so complex but also not so accurate. NTP is used for highly precise time synchronization. If you configure two or more computers as peers they synchronize to each other increasing stability through each other's feedback.


SNTP on the other hand is simplified version of NTP mainly used to synchronize the clocks on clients to a server. It is just a simple poll which is enough at places where you don't need a very precise clock.


See also http://en.wikipedia.org/wiki/Network_Time_Protocol


Regarding the configuration you have to distinguish between whether a device is configured as client, server or even as peer.

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