Re: NTP

Have you tried appending the bb statements with the 'prefer' keyword?

2009/7/6 Anantha Subramanian Natarajan <anantha.natarajan_at_gravitant.com>

> Hi All,
>
> I was working on one of the lab requirements based on NTP and have few
> questions on the same.The lab requirement ask R3 to take clock from BB3 and
> R6 to take clock from BB1.Also ask to R3 and R6 peer each other to get
> clock
> if there respective BB clock goesaway.I used the below configuration on R3
> and R6
>
> R3
>
> ntp server <bb3 ip address>
> ntp peer <r6 ip address>
>
> R6
>
> ntp server <bb1 ip address>
> ntp peer <r3 ip address>
>
> BBs are giving Stratum 5 clock and so I as assuming both R3 and R6 should
> see BBs as the preferred server.Is this understanding right ? The actual
> result which I obtained was on R3,it sees the R6 as preferred clock server
> and even it doesn't keep the BB3 server as selected backup.So I removed the
> ntp peer statement on R3 to R6 and found the R3 takes the BB3 clock as
> server and gets synchronised.So I added back again the ntp peer statement
> on
> R3 and found again R3 choosing the R6 and ignoring BB3.I ran debug based on
> NTP and found the below messages
>
> Mar 1 04:18:37.119: NTP: nlist 3, allow 0, found 3, low -7.964615, high
> 7.962570
> Mar 1 04:18:37.119: *NTP: 204.12.1.254 discarded, outlier*
> Mar 1 04:18:37.119: NTP: candidate 183.1.46.6 cdist 87.963593 error
> 7.893570
> Mar 1 04:18:37.119: NTP: candidate 150.1.6.6 cdist 95.960403 error
> 15.891159
> Mar 1 04:18:37.119: NTP: survivor 183.1.46.6 offset -0.001007, cdist
> 87.96359
> Mar 1 04:18:37.119: NTP: survivor 150.1.6.6 offset -0.001109, cdist
> 95.96040
> Mar 1 04:18:37.123: NTP: synced to new peer 183.1.46.6
>
> It gave message as outlier and tried to understand what is that mean ,my
> understanding was that if the clock offset is too high when compared to
> other peers,it may ignore the one which have high offset.I am not sure
> whether I understood right .Kindly correct me if I am wrong in
> that.Assuming
> my understanding on that is right,is not always the high stratum clock wins
> ?.Does this means it compars the offset before comparing the startum
> clock.I
> am sure missing some basic on NTP.
>
> How to make in this scenario,R3 prefering BB clock and not the R6 even
> though the offset for BB clock is comparitvely higher.
>
> Thanks for the assistance.
>
> Regards
> Anantha Subramanian Natarajan
>
>
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Received on Mon Jul 06 2009 - 19:03:38 ART