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New Member

NTP problem


i have a problem regarding ntp syncronisation. I have a router which connects eight branches over isdn to the main branch. There is a time range configured on the main router because the lines should only be open from 7:00 to 18:00.

Because there are a lot of power failures in the main branch i want to configure router to get the time from a time server via NTP. In the Networtk is Proxy Server which is connected to the internet. After configuring the ntp server on the router i get a stratum of 16?! As i know startum 16 means that the server is not connected to the atomic clock. I have tried the same configuration on another router which is directliy connected to the internet. There i get a strum of 2 and the ntp works. On the proxy server there is a firewall,too, but ntp is not blocked by the firewall. What can i do anaginst this?! Does anybody have an idea?!




Re: NTP problem

Most likely the adress your router uses to connect to NTP is unreachable to the outside. Just like with ping & telnet, by default the router uses it's outgoing interface's IP adress. In your case this might be a serial line in an IP range that is not allowed to pass the proxy. Try configuring a different adress (loopback or ethernet) using the global command: ntp source xxx



New Member

Re: NTP problem

Dear Christian,

Since you are trying to access a NTP server on the internet it will not be possible. There is nothing on a router which facilitates the use of a proxy to access internet services. The best solution to achieve this is to use a NTP server software on any of your LAN machine to synchronize with the internet NTP server through the proxy. You can then configure your router with the ntp server address of this machine on your LAN.

Hope this helps



New Member

Re: NTP problem

Try to debug ntp or you can see the "sh ntp ass":

*~ 3 755 1024 377 2.9 -0.29 0.3

If your reach. is 0 you do not have any reply from your server.


New Member

Re: NTP problem

You can try this:

1.Implement a show ntp association command to see if there are any UDP packets being propagated to your router via IP.

2.If not, then try to ping the NTP server from the router you want to recieve NTP advertisements.

3.Configure both routers as NTP peers and configure the server connected to the internet as the NTP server.

4.Run some NTP debug commands and document the results.

What you want is for the NTP UDP packets to be propagated via IP do not configure the router as the NTP source configure the command in the router as the server as the NTP source.