On Tue, 7 Oct 2008, John Pettitt wrote:
> Date: Tue, 07 Oct 2008 09:52:14 -0700
> From: John Pettitt <[EMAIL PROTECTED]>
> To: Ryan Malayter <[EMAIL PROTECTED]>
> Cc: [email protected]
> Subject: Re: [time] getting foreign server from US host
> Sender: [EMAIL PROTECTED]
> I suspect that geographical location is less important than network
> location - as somebody pointed out if the delay is symmetrical the
> distance doesn't matter that much. It would be interesting to build a
> system that just looked looked at routing, specifically AS number to
> determine how many different networks a packet has to cross and picked
> the lowest (on the theory that it's crossing from one net to another
> that introduces asymmetric latencies).
Some time I ago I proposed to make ntpd 'pool aware' and make
ntpd look for 'good' pool servers. Ntpd already has a notion
of 'good' and 'bad' servers ; so, ntpd only has to
-- keep a list of pool servers (say 5) it is using
-- periodically (say once a day) remove one 'bad' server
(the 'worst' server) and pick a new one from the pool
some remarks:
-- one advantage is that 'zone' (geo aware) pools are unnecessary
-- distro's could have a simple ntp-config, that works everywhere
-- clients are happy because they evolve to using 'close' servers
-- servers are happy because they have happy clients,
who don't poll very often
-- simulation shows that a 'best 3 out of 5' set stabilizes nicely
-- a problem is how to avoid overloading pool servers that
become 'too popular' ;
good rate control facilities for servers are a must-have
-- it is a bit scary to implement, because it is hard to
predict how such a 'self organising' system would behave.
It would be very interesting to observe, I think.
> John
Henk Penning
---------------------------------------------------------------- _
Henk P. Penning, Computer Systems Group R Uithof CGN-A232 _/ \_
Dept of Computer Science, Utrecht University T +31 30 253 4106 / \_/ \
Padualaan 14, 3584CH Utrecht, the Netherlands F +31 30 253 2804 \_/ \_/
http://people.cs.uu.nl/henkp/ M [EMAIL PROTECTED] \_/
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