> I've been noticing some rather serious jitter between our
> client stations and our NOC or AP. When I ping from the
> client radio out towards the NOC or AP, I see anything
> between 15mS-300mS.
That's what I would expect from a polled system. Note that the polling
frequency has no correlation to your ping interval; the activity of other
systems influence how frequently this (idle) client is being permitted to
transmit. So some echo requests wait longer than others until they allowed
on the air.
> The ping time jitter has no correlation
> to system load, but responds well if I load the client that
> I'm testing from. (Start a download from the NOC towards
> the client, and the ping times drop down to 20-30mS )
That is because the PINGs can now "ride on the ACK packets" of your
download.
> Pinging back from the NOC to the client, I see stable 10mS or
> less ping times.
That is maybe because the base anticipates that if a packet goes out to a
satellite, there is likely a paket to come back - so it will poll this
satellite in its next round.
> Is it even a problem?
300 ms (your worst figure) seems to be too much unless the base has many
satellites and there is traffic to others. If the cell is idle and there are
not too many satellites being polled, it may be a sign of interference and
retransmission.
The question really is whether this was less significant in earlier versions
and if yes, if it is a side-effect from other optimizations in the recent
releases. I seem to remember there was something on the KN website along
with the release that talked about increased responsiveness in paket
forwarding vs. RTT for lightly loaded satellites.
regards,
--
true global communications GmbH
Thomas Giger
In der Au 27, 61440 Oberursel, Germany
fon +49.6171.6381-0, fax +49.6171.6381-19
www.tgnet.de || www.megaspeed-internet.de
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