[ntp:questions] Re: Known asymmetry (DSL) compensation

Mark Martinec Mark.Martinec at ijs.si
Tue Feb 15 16:17:01 UTC 2005


>>I know it's not possible to know or compensate for all asymmetry in the
>>packets between two machines.  However where there is a fixed, known,
>>asymmetry - like on a DSL line shouldn't it be possible to calculate a
>>fudge factor?
>... 
> What you want to correct is the difference in latency in the upstream
> vs. downstream directions. The trouble is that this cannot be readily
> calculated from any known and constant values, such as the upstream
> and downstream bitrates.

I would very much like to see 'fudge time1' being applicable to
network reference servers. Like John, I see a very predictive and
stable offsets for network peers due to an asymmetric cable connection.

Inability to correct for the systematic network offset forces
one to either fudge local refclocks to wrong time, or declares
networked references falsetickers.

  Mark



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