[ntp:questions] NTP over redundant peer links, undetected loops

Danny Mayer mayer at ntp.org
Mon Feb 16 04:25:26 UTC 2009

Joseph Gwinn wrote:
> In article 
> <5d7f07420902151105m48a5e210s72e8e168e67d17a2 at mail.gmail.com>,
>  malayter at gmail.com (Ryan Malayter) wrote:
>> On Sun, Feb 15, 2009 at 12:23 PM, Danny Mayer <mayer at ntp.org> wrote:
>>> Because I want to get away from the notion that these are meant to be IP
>>> addresses. In addition in an IPv6-only environment that wouldn't work
>>> either. Why create work when it's unnecessary just to find a valid IP
>>> address? In addition with anycast addresses are not globally unique. The
>>> chances that you will create a non-unique random number within a network
>>> is extremely low.
>> It depends on the size of the network. The chances of a duplicate
>> 32-bit number on a network including 65000 hosts is about 40%. The NTP
>> Pool network, which comprises at least 10^6 hosts, for example, would
>> have collision probability very close to 1.
> How did you compute that?  Given that 2^32= ~4*10^9, it's hard to see 
> how 10^6 hosts spread at random in a 10^9 codespace could achieve 100% 
> collision probability.
> Joe Gwinn

Lying with statistics is very easy especially given that you are going
to use no more than about 10 servers for your own server and they all
need to be at the same stratum.


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