NTP Cisco client and NTP Microsoft Server

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Sep 19th, 2008
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Hello, I am trying to configure NTP client in this equipements:


- Cisco IOS Software, Catalyst 4000 L3 Switch Software (cat4000-I9K91S-M), Version 12.2(25)EWA6, RELEASE SOFTWARE (fc1)

- Cisco IOS Software, C3750 Software (C3750-IPBASE-M), Version 12.2(35)SE5, RELEASE SOFTWARE (fc1)

- Cisco IOS Software, C3750 Software (C3750-IPBASEK9-M), Version 12.2(25)SEE2, RELEASE SOFTWARE (fc1)

- Cisco IOS Software, C3560 Software (C3560-IPBASEK9-M), Version 12.2(44)SE, RELEASE SOFTWARE (fc1)

And I am trying to configure NTP Server in Microsoft Windows Server 2003 R2 Enterprise x64 Edition SP2, I have tried with this document but It did not work: http://support.microsoft.com/kb/816042


The Cisco equipements, can not synchonize with Microsoft Domain Controller, I have test the Microsoft NTP Server with a NTP Soft Client and it is working good, but NTP on Cisco equipments do not work against Microsoft.


I want to know if Cisco NTP is compatible with Microsoft NTP.


Thanks a lot

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Richard Burts Fri, 09/19/2008 - 13:58
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Gabriel


The article that you reference is about how to use W32Time, the Time Service tool for Windows. W32Time is a simplified version of NTP but is not a full implementation of NTP. The Cisco NTP client wants to synchronize with a full implementation of NTP on the server and will not synch to W32Time.


So the basic answer to your question is that no Cisco NTP is not compatible with Microsoft NTP.


There are some software packeges that you can run on Windows servers which do a full implementation of NTP and Cisco can synch with them on Windows servers. But not with W32Time.


HTH


Rick

andrew.butterworth Sat, 09/20/2008 - 03:10
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I agree with Rick. I attempted to configure what you are trying a while ago and after much debugging and searching I gave up. The Microsoft NTP implementation is SNTP and the NTP client in IOS doesn't like it. SOHO routers and AP's that only have SNTP are happy to sync with it though.


As the Windows W32Time service is happy to sync with NTP what I ended up doing was flipping it around the other way - i.e. sync your Internet facing router (or last-hop router before your firewall) with a real NTP server on the internet, or better still get a GPS or Radio clock. Then sync your PDC emulator with this. I have had this setup now for about 2-years and it works perfectly.

I also have a hierarchal NTP setup internally for my network infrastructure devices where the top of the tree are the internet facing routers.


HTH


Andy

g.careaga Mon, 09/22/2008 - 04:21
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Ok my friend, first thanks a lot for your time, and second I have understood that NTP over Cisco IOS (as client) does not work with Microsoft NTP (as server), do you know if there is a legal document published by Cisco that I could send to my client ?


And here I have the lines that I will configure in the Switches, could you tell me if I am rigth ?



***Server -


Cisco IOS Software, Catalyst 4000 L3 Switch Software (cat4000-I9K91S-M), Version 12.2(25)EWA6, RELEASE SOFTWARE (fc1):


Line: ntp master


***Clients -


Cisco IOS Software, C3750 Software (C3750-IPBASE-M), Version 12.2(35)SE5, RELEASE SOFTWARE (fc1)

Cisco IOS Software, C3750 Software (C3750-IPBASEK9-M), Version 12.2(25)SEE2, RELEASE SOFTWARE (fc1)

Cisco IOS Software, C3560 Software (C3560-IPBASEK9-M), Version 12.2(44)SE, RELEASE SOFTWARE (fc1)


Line 1: clock timezone GMT-3 -3

Line 2: ntp server [Catalist 4000 IP Address]


Thanks a lot again.

Richard Burts Mon, 09/22/2008 - 07:43
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Gabriel


I am not clear what kind of legal document you might need. But perhaps this document from Microsoft would help:

NTP is a more accurate time protocol than the Simple Network Time Protocol (SNTP) that is used in some versions of Windows; however W32Time continues to support SNTP to enable backward compatibility with computers running SNTP-based time services, such as Windows 2000.


Here is the link that has that information:

http://technet.microsoft.com/en-us/library/cc772694.aspx


Also I want to clarify that we are not saying that you can not run NTP on Windows. What we are saying is that the Windows Time Service (W32Time), which was the focus of the link that you reference, does not operate as an NTP server. You can run other software on Windows which can serve very well as NTP server. The Meinberg mentioned by Danilo is one good alternative for this.


The syntax of the commands that you ask about looks ok. I would ask whether the Catalyst 4000 which will become your NTP server will be learning time from anywhere? Or will it just use its own clock as the time source?


HTH


Rick

g.careaga Mon, 09/29/2008 - 12:53
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Hello people, I want to thank to all. It worked good. The C4507 as master worked good an the rest as clients too.


Thanks to all.

Danilo Dy Sat, 09/20/2008 - 04:00
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I agree with Rick and Andrew. If you still want to use your Windows Server as NTP Server, you can install Meinberg http://www.meinberg.de/english/sw/ntp.htm I use it in small data centres and works like a charm. However, in major data centres, I use Linux (DNS/NTP since DNS not taking much resources :) ).

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