[Cerowrt-devel] Managed to break 802.11n (on a 3800)

Dave Taht dave.taht at gmail.com
Thu Jan 16 17:35:27 EST 2014


On Thu, Jan 16, 2014 at 2:08 PM, Aaron Wood <woody77 at gmail.com> wrote:
>
>>> Sebastian, after sorting out the router, it's still biased, but far
>>> less
>>> so, about a 2:1 ratio between upload and download.
>>
>> So I See offen 10:1 and worse @165Mbit/s raw wireless rate
>
> I get mixed results, but they aren't good.  IIRC, apple really changed something about the media access in 10.8, I'll look into that.  And see if my wife will let me install netperf on her laptop (I think it's still running 10.7)
>
>
>>> Also, my understanding was that with rts/cts, the router was in control
>>> of
>>> that aspect of things?
>>
>>      That is what I thought AS well, but it is not what I See with osx 10.8.
>>
>
> It may be a case of the station aggressively asking to send, and the AP granting instead of sending data to the station that's waiting.

Um, probably not. Both station and AP are doing EDCA scheduling, (I'd
hope) which was originally a p2p style protocol. So it
is kind of overly "fair" to both. The client is doing better
aggregation since it is only going one way, the AP has trouble with
aggregation due to lack of per station queueing.

folk have done work to try and give the APs more priority and looking
at that has also long been on the todo list.

> It should be clear in a monitor-mode tcpdump (or a statistical summary of packets).

but do check. I generally get terrible results from macos, and the
intel wifi chip in the laptop. the ath9k in another laptop is
considerably better, and ath10k (on the nuc) is not horrible. It's
terrible on both ends, on this test and both the clients and the APs
need a ton of work...

> --Aaron
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-- 
Dave Täht

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html



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