• Using VRRP virtual IP address as NTP server's IP address

    From nazeerhussain.f@gmail.com@1:0/0 to All on Tue May 13 05:23:33 2014
    Can we use VRRP's virtual IP address as the NTP server's IP address on NTP client.
    What are the problem that we might encounter if we use the virtual ip as ntp server's ip.

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  • From Rick Jones@110:110/2002 to All on Tue May 13 17:11:25 2014
    nazeerhussain.f@gmail.com wrote:
    Can we use VRRP's virtual IP address as the NTP server's IP address
    on NTP client. What are the problem that we might encounter if we
    use the virtual ip as ntp server's ip.

    A VRRP virtual IP is somewhat like an "anycast" IP right? At some
    point it may flip from one system to another. The timelords in comp.protocols.time.ntp are not terribly fond of the idea of using
    anycast for an NTP server's IP because as it flips from one to another
    there will be added jitter and possibly even loss of synchronization.

    I have seen the effect upon jitter that use of an anycast IP as the
    NTP server IP can cause. So I tend to agree with the opinion of the
    timelords.

    I assume you have more than one actual router device on which NTP is
    running, yes? That being the case I would simply suggest configuring
    the client(s) to point at the specific IP of each router and let the
    ntp client do what it has been able to do for decades - automatically
    select the "best" source of time from a list of several time sources.

    Put another way, NTP has "HA" built-in. There is no need/call for
    wizzy things like anycast, VRRP or server failover.

    Based on my eavesdropping on the timelords, ideally, one should
    configure four (or more) independent sources of time. This allows for
    one of those sources to "fail" and there still be enough sources of
    time for the bad clock detection heuristics/algorithms to work.

    rick jones
    --
    "You can't do a damn thing in this house without having to do three
    other things first!" - my father (It seems universally applicable :)
    these opinions are mine, all mine; HP might not want them anyway... :)
    feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

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