Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

NTP best practice and capabilitys

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

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

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

Everyone's tags (2)

NTP best practice and capabilitys


for the switch to receive NTP broadcasts:

- interface fx/x

   ntp broadcast client

for the router to send broadcasts:

-interface fx/x

  ntp broadcast



Don't forget to rate helpful posts.
Hall of Fame Super Gold

NTP best practice and capabilitys

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".

Hall of Fame Super Silver

Re: NTP best practice and capabilitys

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.



Sent from Cisco Technical Support iPhone App

CreatePlease to create content