Impact of ARP lookup on local NTP traffic

[Gary E. Miller]

Yo Hal!

On Mon, 30 May 2016 23:46:52 -0700
Hal Murray <hmurray at megapathdsl.net> wrote:

> gem at rellim.com said:
> >> > Changing minpoll fixes all OS, and keeps the change local to
> >> > avoid unintended consequences.  
> >> Only if they have a timeout in the right range.  
> > Oh, it is in the right range.  Linux by default has a gc_timeout of
> > 60 seconds.  Anytime after that Linux may delete the ARP entry.   
> 
> I meant only if the other OSes have the right timeout.

There are other OS's than Linux?  I refuse to acknowledge that.

> If they have a 30 second timeout, your maxpoll of 5 won't work.

RFC 826 defines ARP.  It makes no mention of how long the timeout
should be.

Cisco uses 4 hours.

I can not find the info on OS X.

Gack, I see Windows Vista can expire in 30 to 45 seconds.

Wow, that explains some bad Windows performance...

> gem at rellim.com said:
> > Maybe ntpd is reseting the kernel PLL to center on restart, instead
> > of leaving it at its current setting?   
> 
> I think it's worse than that.  I think it's using the time from the
> first response.

A target rich environment.  Reminding me why I prefer chronyd (for now).

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588
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