[cisco-voip] CCX and NTP

[Anthony Holloway]

And 5 for a falseticker fault protection:

*"Note that four upstream time servers will protect you against only one
falseticker. Using the 2n+1 algorithm, five upstreams will protect you
against two falsetickers, seven will protect you against three
falsetickers, etc....*
*Conventional wisdom is that using at least five upstream time servers
would probably be a good idea, and you may want more."*

Source: 5.3.4. Excessive Number of Upstream Time Servers
<http://support.ntp.org/bin/view/Support/SelectingOffsiteNTPServers#Section_5.3.3>

On Mon, May 8, 2017 at 9:49 AM Matthew Huff <mhuff at ox.com> wrote:

> If you are going to have local NTP servers,  you will need 3 for a quorum.
> 4 for redundancy.
>
>
>
> ----
>
> Matthew Huff             | 1 Manhattanville Rd
>
> Director of Operations   | Purchase, NY 10577
>
> OTA Management LLC       | Phone: 914-460-4039 <(914)%20460-4039>
>
> aim: matthewbhuff        | Fax:   914-694-5669 <(914)%20694-5669>
>
>
>
> *From:* cisco-voip [mailto:cisco-voip-bounces at puck.nether.net] *On Behalf
> Of *Ryan Huff
> *Sent:* Monday, May 8, 2017 10:42 AM
> *To:* Ben Amick <bamick at HumanArc.com>; cisco-voip at puck.nether.net
> *Subject:* Re: [cisco-voip] CCX and NTP
>
>
>
> Hey Ben,
>
>
>
> This has less to do with UCCX and more to do with the lack of time
> precision in Windows SNTP / NTP compared to the needs of UCOS. Yes, I know,
> die hard Redmond boys and girls will say that ever since Win2003 that isn't
> the case but sorry, it is. (read:
> https://technet.microsoft.com/en-us/library/cc773013%28v=ws.10%29.aspx).
> In fact, on page 84 (PDF page) of the latest SRND (
> http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab11/collab11.pdf)
> Windows NTP is a flat nono for Cisco UC period.
>
>
>
> IOS routers are great but here is how I like to roll (excuse the crudeness
> of the drawing, put it together this morning before coffee). I typically
> use Linux servers for NTP because they are so darn useful for other
> utilitarian things ..... can't count how many times just having a Linux box
> on the network somewhere helped me out.
>
>
>
> [image: image001.png]
>
>
>
> = Ryan =
>
>
>
>
> ------------------------------
>
> *From:* cisco-voip <cisco-voip-bounces at puck.nether.net> on behalf of Ben
> Amick <bamick at HumanArc.com>
> *Sent:* Monday, May 8, 2017 10:12 AM
> *To:* cisco-voip at puck.nether.net
> *Subject:* [cisco-voip] CCX and NTP
>
>
>
> What do you guys use for NTP on your CCX hosts? I’ve been informed by TAC
> that “CCX does not support Windows based NTP” so I was thinking about just
> pointing NTP towards my CCM hosts – is that a valid scenario? I figure that
> since CCM is pretty much authoritative on everything for CCX as it is it
> wouldn’t be a problem?
>
>
>
> *Ben Amick*
>
> Telecom Analyst
>
>
>
>
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