[ntp:questions] how to have offset < 1ms

Rick Jones rick.jones2 at hp.com
Wed Apr 14 23:38:54 UTC 2010

lhommedumatch <ludocluba at yahoo.com> wrote:

> The ACEB box is near my equipment.
> My PC and the ACEB box are both connected to a CISCO Catalyst 4510R.

The 4510R is a big-honking switch:



What else is connected to this switch?  Are the PC and the ACEB box
connected to the same line-card in the switch or different line-cards?
What other data is flowing through this switch?

> We have encountered problem with the ntp card of the clock several
> years ago.
> When too many clients are connected the clock used to have problems.

Details like that can be rather important... how many other clients
are asking for time from the ACEB?  Is the ACEB connecting to the
switch at a full 100 Mbit/s or only 10 Mbit/s?  Is the link running
full-duplex or only half-duplex?  I doubt there is a way to get
link-level stats from the ACEB, but how about from the port on the
4510W - if the link is half-duplex, how about collision counts or
excess retries?

rick jones

> May be this problem of latency and asymmetry comes from the ntp
> card.

The glass is neither half-empty nor half-full. The glass has a leak.
The real question is "Can it be patched?"
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

More information about the questions mailing list