Re: ntp peer

Sounds nonsense to me...

Just try it out, wait a few minutes and see.

As for invalid, it is documented as "Peer time is believed to be
invalid." This would be because, e.g, time offset is greater than some
out of bounds value...

-Carlos

Imran Ali @ 30/10/2013 18:49 -0300 dixit:
> 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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-- 
Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
Blogs and organic groups at http://www.ccie.net