NTp sources that work in a datacenter (was Re: Is latency equivalent to RTT?)

Joel Jaeggli joelja at darkwing.uoregon.edu
Wed May 14 15:13:12 UTC 2003

On Wed, 14 May 2003, Steve Francis wrote:

> Michael.Dillon at radianz.com wrote:
> > I assume that it's fairly common for people to have Solaris or Linux 
> > boxes
> >
> >in every PoP to do measurements. In that case, the difficulty isn't in 
> >measuring one-way latency, it's in synchronizing the time on all the 
> >servers. And with fairly cheap GPS and CDMA clocks that is a lot 
> >easier/cheaper than it once was.
> >
> But what GPS clock can you install in a datacenter? AFAIK, they all 
> require roof (or at least window) access in order to install the 
> antenna. (At least, all the GPS based ntp servers I've looked at do).
> Is that not true of CDMA servers?

cdma recievers require a visible cdma signal so if your cdma phone works 
in the datacenter the cdma reciver will as well...
> How have others solved this issue? (Short of owning their datacenters.)

Ask/pay/rent for roof access for the antenna, it's not large but it does 
work better with an unobstructed video of the sky. There's also the 
question of how many stratum=1 time sources a given datacenter needs. if 
there's someone else with one it should be fairly unintrusive to share.

Also if you just need  a high level of syncronization between the time on 
all your hosts you can just deploy one standalone ntp server, sync it 
against public time sources and get everything synced against that. its 
probably a 95% solution to most people's timeing needs.

Joel Jaeggli	      Academic User Services   joelja at darkwing.uoregon.edu    
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