NTP Issue

Unanswered Question
Jan 17th, 2012


I am needing a NTP Server in "Windows Server" in such a way to use the NTP in my infrastructure with cisco routers with authentication supports.

I'm testing with "NTP 4.X". The application works without authentication but I can not run with authentication required.

Someone has already gone through this need?

Help me please.

Edgar Servín

I have this problem too.
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Edgar Servin Thu, 01/19/2012 - 15:19

Hi Tkatsiaounis,

Meinberg NTP 4.X is the software I am using.

Its documentation is not very understandable to me.

I can't make it work correctly with authentication.

I set up in my "Cisco router" with the command "ntp authenticate". The "NTP server" continues to operate but by entering the command: "show ntp asso detail" don't shows me the message "authenticated".

Do you have a sample configuration? Could you guide me in my setup, please?

Leo Laohoo Thu, 01/19/2012 - 20:24

Ok then.  It's either you let the routers go out to the net for an authoritative NTP source or you can purchase a "true" NTP server.

When I mean a "true" NTP server, it's not the kind which has to go out to the internet and to get an authoritative source.  I mean the ones with built-in GPS receivers. 

Edgar Servin Fri, 01/20/2012 - 13:13

I think it's very difficult to add a GPS for NTP on our infrastructure.

Although I think would be good.

I need an example of configuration of meinberg NTP.


Leo Laohoo Fri, 01/20/2012 - 22:47

You don't need to install the NTP server inside the DC.  Find a cabinet that's closest to the ceiling and it'll do fine.  The servers normally come with a magnetic antenna.

Edgar Servin Mon, 01/23/2012 - 03:45

Hi Leo,

We didn't planning an acquisition of a GPS for NTP.

Just for that I'm looking for the solution through the Meinberg NTP.

It is not necessary for our infrastructure a NTP server so specialized.

Only one that allows us to maintain uniform time in the network of PCs and routers, that provides NTP authentication.


Gerardo Marciales Sun, 04/08/2012 - 10:12

Hello, I was looking for a solution between many devices on my networks, finally I find a option, use a border router like a NTP Proxy.

I try many setting between MS Windows like a NTP Server over other devices no PCs, in my case don't work, but I try with a Router like NTP Server, perfect work.

Other good practice is send params over DHCP sending to the clients option 42.

Let the commands and screens:

NTP Server ~ Client on the Router:

ntp logging

ntp clock-period 17179973

ntp master

ntp update-calendar

ntp server source FastEthernet1

ntp server source FastEthernet0

Config NTP on DHCP Server:

ip dhcp pool LAN


   update dns both

   domain-name example.ext



   netbios-node-type b-node

   option 42 ip

   lease 0 0 5

   update arp

Analyzing DHCP behavior with Wireshark:

Set on MS Windows:

Depend of MS Windows behaviour, Windows Domain (atomically) Vs Workgroup (set in MS Clients IP or Router FQDN Master NTP)



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Posted January 17, 2012 at 9:25 AM
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Tags: ntp

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