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

Richard B. Gilbert rgilbert88 at comcast.net
Wed Feb 11 19:37:22 UTC 2009

Chris Adams wrote:
> Once upon a time, Richard B. Gilbert <rgilbert88 at comcast.net> said:
>> My bet would be that there is an asymmetry in your ADSL link!   If I'm 
>> not mistaken, the "A" in ADSL stands for asymmetric!
> The asymmetry in ADSL is in bandwidth, not path or latency.  More
> frequency space is used for downstream (ISP->end user) communication
> than for upstream, but both travel the same path.
> There may be asymmetric routing going on (very often the case when you
> talk to a host across the Internet, especially if either your ISP or the
> remote host's ISP are multihomed), but it is highly unlikely it is
> happening between the end user and his own ISP.

The difference in bandwidth would mean that a packet of N bytes would 
take more time in one direction than the other!  I don't know if that 
would be sufficient to account for the observed behavior but I can't 
think of another explanation.

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