[ntp:questions] Garmin 18 LVC: whether to fudge

Danny Mayer mayer at ntp.org
Mon Feb 16 14:38:25 UTC 2009


Uwe Klein wrote:
> Danny Mayer wrote:
>> Be warned that ping uses ICMP and not UDP so the costs are different.
> 
> 
> Danny,
> 
> we are looking at the physical transport layer i.e.
> "physical link layer" which does not care about protocol.
> 
> Latencies on a DSL line are impacted by packet size,
> effective datarate, lookahead error correction
> and some ancilary stuff _per_ direction.
> 
> Aditionally depending on configuration up and down stream
> utilisation can have impact on the opposite path.
> 
> uwe

Yes, I know all that. Nevertheless routers and the like also treat ICMP
packets differently from UDP and TCP. There are lots of reasons to do so
but we are getting far afield from the original question at this point.

Danny



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