Re: Long range test

From: Jouni Malinen (
Date: 2002-04-05 05:50:51 UTC

On Thu, Apr 04, 2002 at 05:01:28PM -0800, Kristian Hoffmann wrote:

> I think the stations we use are, well, stupid, and don't drop the
> duplicate frames. We have 11mbit lucent stations at one or two places and
> they have little to no dupliactes.

> This is pinging from the AP to the station. The duplicate replies are all
> 2-3ms higher than the last.

Good.. Well, at least, from my view point ;-), since this does not sound like a bug in Host AP driver.

> We didn't have any problems at close range with a small number of
> stations. I've been looking over the code trying to find a way to prevent
> frame retransmission by setting the SHORTRETRYLIMIT and LONGRETRYLIMIT
> RIDs to 0 or 1. Something smaller in any case. I'm hoping that the
> higher layers (IP) will take care of retransmitting frames that were
> actually lost in transit.

Setting retry limit (i.e., the number of retries) is not supported in current station firmware. Those RIDS (FD48 and FD49) are readonly. There is a field in TX descriptor for setting the retry limit on packet by packet basis. However, it is not yet implemented in firmware..

I'm going to make a workaround for this by using alternative retry count. It won't have support for separate short/long retry limit, but at least it will allow one to configure retry limit for cases where the default values (8 for short and 5 for long) are not suitable. I have used alt. retry count for disabling retries completely for some TX packets. However, this is not used in the current driver version, so alt. retry count can be used for all TX frames.

> There is actually an acktime setting on the XWL-450 that
> you can only set on the serial interface. Does something like this exist
> in the station firmware in the form of a RID?

Not that I know of. There might also be some other BBP settings that could help in different environments. I have added 'writemif' command for the next version of the Host AP driver so that it is easier to experiment with different settings.

Jouni Malinen                                            PGP id EFC895FA

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