NTP best practice and capabilitys

[paulanthonywilliams]

I have a lab environment with 1 router and 3 switches connected via ADSL and I have setup NTP server on the Router

ntp update-calendar

ntp server 194.35.252.7

and i want to broadcast or multicast (preferred) and enable the switches to configure there clocks via this broadcast.

I can set the switches to ntp server to the Routers IP and this works ok but i dont want to specify any address in the switches config. Is it possible to update the switches via a NTP broadcast/Multicast and if so how is this archived.

Router IOS: c1841-advsecurityk9-mz.124-10a.bin

Switch IOS: c2950-i6q4l2-mz.121-22.EA6.bin

I have read thought

http://oreilly.com/catalog/hardcisco/chapter/ch10.html

But cant see how to configure or even if its possible to configure NTP on the switches to accept broadcast updates.

[cadet alain]

Hi,

for the switch to receive NTP broadcasts:

- interface fx/x

   ntp broadcast client

for the router to send broadcasts:

-interface fx/x

  ntp broadcast

Regards.

Alain

[Leo Laohoo]

Hmmm ... I don't know with you but if your router is getting correct NTP sync from the internet, then it's as easy as setting up your switch(es) to point to your router as the NTP source.  This is what we do in our networks.  We refrain from using the command "ntp master".

[Richard Burts]

The solution suggested by Leo sounds good to me. The original poster says that they do not want to configure addresses on the router and this does not require addresses on the router. It is possible to have the router send broadcasts with NTP but it seems to me that it makes the router work harder and it generates broadcast traffic that will go to every downstream device. I suggest that configure the switches to query the router is a preferable solution.

HTH

Rick

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