[168960] in North American Network Operators' Group
RE: Need trusted NTP Sources
daemon@ATHENA.MIT.EDU (Matthew Huff)
Fri Feb 7 10:57:13 2014
From: Matthew Huff <mhuff@ox.com>
To: "nanog@nanog.org" <nanog@nanog.org>
Date: Fri, 7 Feb 2014 10:56:35 -0500
In-Reply-To: <52F4FA6A.60807@gmail.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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Working in the financial world, the best practices is to have 4 ntp servers=
(if not using PTP).
1) You need 3 to determine the correct time (and detect bad tickers)
2) If you lose 1 of the 3 above, then you no longer can determine the corre=
ct time
3) Therefore with 4, you have redundancy.
We have two Symmetricom Stratum 1 time servers synced via GPS with Rubidiu=
m oscillators, and two RHEL 6 servers running ntpd for our 4 servers.
----
Matthew Huff=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 | 1 Manhattanville Rd
Director of Operations=A0=A0 | Purchase, NY 10577
OTA Management LLC=A0=A0=A0 =A0=A0=A0| Phone: 914-460-4039
-----Original Message-----
From: Roy [mailto:r.engehausen@gmail.com]=20
Sent: Friday, February 7, 2014 10:23 AM
To: nanog@nanog.org
Subject: Re: Need trusted NTP Sources
On 2/7/2014 3:35 AM, Saku Ytti wrote:
> On (2014-02-06 21:14 -0500), Jay Ashworth wrote:
>
>> My usual practice is to set up two in house servers, each of which=20
>> talks to:
>>
>> And then point everyone in house to both of them, assuming they=20
>> accept multiple server names.
> Two is worst possible amount of NTP servers to have. Either one fails=20
> and your timing is wrong, because you cannot vote false ticker. And=20
> chance of either of two failing is higher than one specific of them.
>
"A man with a watch knows what time it is. A man with two watches is never =
sure."
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