clock time reference

[suthomas1]

Hi,

Is it reliable to use network switch or router as time source for other systems/applications in the network?

if not, what is the other possible options.

Thanks in advance.

[Joseph W. Doherty]

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Posting

Define "reliable".

I've used Cisco devices as both NTP clients and NTP sources.

You could use a server or servers for NTP.

Do you also need SNTP or Windows time services?

[Leo Laohoo]

Is it reliable to use network switch or router as time source for other systems/applications in the network?

This is the most "loaded" question I've ever encountered. 

The answer to that question will depend entirely on how you plan to deploy NTP/SNTP.

In our network, all of your access switches synchronize witha distro for NTP.  Distro synch with the core and core goes to a dedicated NTP source/server.  Typical tree-and-branch.  We want to keep "local" traffic local so all the clients (computers, laptops, printers, site's clock controller) synch to the default gateway of their respective IP addresses.  The default gateway are the site's distribution switch.

We don't/never use Microsoft's "version" of NTP.

The traffic for SNTP/NTP is "cheap".  Even if implemented like a dog's-breakfast, it is still relatively "cheap", i.  e.  wouldn't overwhelm a low-speed WAN link.  

So to make a long story short, if your LAN switches synch to a trustworthy NTP/SNTP source, it's "reliable". 

[suthomas1]

Thanks.

If we use the Distribution to sync with Core for time, where will the core sync its time correction with.

Can the core switch itself be used as the master for time source to other servers, edge switches in the network?

Is it necessary for the Core to sync itself to dedicated source like an internet based clock?

[Leo Laohoo]

where will the core sync its time correction with.

You have two options:

1.  You can get an appliance, i.  e.  a switch, router or firewall, to synchronize to a known NTP source over the internet; or

2.  Get a dedicated NTP server.

NOTE:  When I mean DEDICATED NTP server, I don't mean a box that needs to go to the internet to synchronize NTP.  When I mean dedicated NTP server I mean an independent NTP server which has a GPS antenna and synchronizes NTP with the GPS satellite.

[usasigcis]

Use a reliable source regardless it's type

Maybe multiple sources with anycast

-Sinan

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