TWC (AS11351) blocking all NTP?

Joe Greco jgreco at ns.sol.net
Mon Feb 3 17:29:21 UTC 2014


> >> I was thinking that the ntp.org servers on any particular network are a small set of exceptions to a general rule to rate limit outgoing NTP traffic.
> >
> > www.pool.ntp.org allows any NTP operator to opt-in to receive NTP traffic should their clock be available and accurate.
> 
> I believe you, but I don't believe that the set of ntp.org servers changes 
> so rapidly that it is beyond the ability of network operators to handle 
> the ones on their own networks as a special case.

There's a bootstrap issue here.  I'm guessing that you may be picturing
a scenario where a network operator simply queries to obtain the list of
ntp.org servers and special-cases their own.  However, I believe that
the system won't add NTP servers that appear to be nonresponsive to the
list (bootstrap paradox), and in any case the list of returned servers 
is quite large and a response basically picks a few random servers, so 
it is quite difficult to know what servers are on your network in an 
automated fashion.

... JG
-- 
Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
"We call it the 'one bite at the apple' rule. Give me one chance [and] then I
won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN)
With 24 million small businesses in the US alone, that's way too many apples.



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