cancelar
Mostrando los resultados de 
Buscar en lugar de 
Quiere decir: 
cancel
7846
Visitas
0
ÚTIL
2
Respuestas

Cisco Catalyst 3850 as ntp master

desmond.liew
Level 1
Level 1

Hi All,

I have 2 x Cisco Catalyst 3850 stacked together. What are your recommendations if I use the C3850 as a ntp master for all edge switches connected in my network? All edge switches must be authenticated if it needs NTP sychronization. But other than that, what are the downsides?

For example,

1. I heard that switches do not have an internal clock so is a poor device to be a centralized NTP master.

2. I have also read that switches also have slow CPU processors that may lack the processing required.

3. Its NTP sychronization will use external NTP servers which are resolved into IP addresses (e.g. pool.ntp.org). IP address can change. What other more reliable NTP sources are there?

4. Any other thoughts and comments are most welcome.

1 SOLUCIÓN ACEPTADA

Soluciones aceptadas

Leo Laohoo
Hall of Fame
Hall of Fame

Firstly, DO NOT use the command "ntp master".  Cisco do not recommend using this commands because this will confuse the NTP propagation inside the network.  

 

Next, all Cisco devices do not have a dedicated clock.  All appliances need to get SNTP/NTP time synch from somewhere.  This "somewhere" could either be a dedicated GPS-based NTP server and/or a time synch somewhere out in the internet.  

 

You can also use the command "ntp update-calendar".  This new command allows appliances to take regular "snapshot" of the time and save it into the NVRAM.  In case there was a reboot or a power failure, the appliance's time is not too far away instead of waiting 5 to 10 minutes for SNTP/NTP to synch.

Ver la solución en mensaje original publicado

2 RESPUESTAS 2

Leo Laohoo
Hall of Fame
Hall of Fame

Firstly, DO NOT use the command "ntp master".  Cisco do not recommend using this commands because this will confuse the NTP propagation inside the network.  

 

Next, all Cisco devices do not have a dedicated clock.  All appliances need to get SNTP/NTP time synch from somewhere.  This "somewhere" could either be a dedicated GPS-based NTP server and/or a time synch somewhere out in the internet.  

 

You can also use the command "ntp update-calendar".  This new command allows appliances to take regular "snapshot" of the time and save it into the NVRAM.  In case there was a reboot or a power failure, the appliance's time is not too far away instead of waiting 5 to 10 minutes for SNTP/NTP to synch.

Hi Leo,

This pretty much confirms what I have read so far. The 'ntp update-calender' is something new to me and good to know. As for the 'ntp master' command, what is the recommended command that should be used? I have been looking for a sample command and so far I still see 'ntp master' as the way to configure a NTP server on the switch. Or should I indicate a high stratum number, e.g. ntp master 10.

Review Cisco Networking for a $25 gift card