Re: ntp peer

Tony as per your understanding both peers can be configured as "
symmetric active

but quote from cisco 360 suggests it will break association

*understanding the difference between these modes is important
 becasue it is a very common cause for NTP peer associations
to go to into an " invalid " or incorrect state

if you configure an NTP peer statement on R3 pointing to R4
and on R4 pointing to R3 . then after few minutes , you will
see that R4 has marked its peer association with R3 as invalid

this is because both routers are operating in NTP symmetric
active mode*

On Thu, Oct 31, 2013 at 12:11 AM, Tony Singh <mothafungla_at_gmail.com> wrote:

>
> *peer*
>
> Allows time requests and NTP control queries and allows the system to
> synchronize to the remote system.
>
> Basically you can have two ntp peers that synchronise their time somewhere
> in the medium with this command but this isn't a authoritative clock source
> such as when we declare "ntp server x.x.x.x" which is the correct way to
> configure an ntp peer to the server then "ntp master 1" on the server, also
> worth noting in order to update the software clock from the hardware clock
> then use "clock callander-valid" note this overrides a software update
> source hence you would also serve your peers with the hardware clock not
> best practice I read.
>
> For the biggest caveat with ntp I'd refer to the md5 one-way and two-way
> authentication and INE's blog:
>
> http://blog.ine.com/2007/12/28/how-does-ntp-authentication-work/
>
> --
> BR
>
> Tony
>
> Sent from my iPad
>
> On 30 Oct 2013, at 18:25, Imran Ali <immrccie_at_gmail.com> wrote:
>
> BUMPING ..
>
> in many labs i have seen both routers have ntp peers commands
> pointed out at each other , (like bgp )
>
> however which case is true ?
>
> show we need to point at only one router to make one active and
> other passive
> or issue command :ntp peer x.x.x.x on both routers
>
>
> guys with access to real gear can lab this up quickly to know that
> " show ntp associations"
> is not showing one peer as " invalid "
>
>
>
>
> On Wed, Oct 30, 2013 at 6:28 PM, Imran Ali <immrccie_at_gmail.com> wrote:
>
> Experts
>
>
> it is mentioned (in 360) that if we configure NTP peers commands on
>
> should not be given on both routers.
>
>
> issuing ntp peer command makes the router in ntp symmetric acitve mode
>
> and if both routers becomes active , one of them will make the
>
> association as invalid
>
>
> any thoughts on this
>
>
> if in lab it says to configure R1 and R2 as ntp peers for each other
>
> , then i guess we need to only configure router as ntp peer.
>
>
>
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Received on Thu Oct 31 2013 - 00:49:46 ART