A-MPDU transmission in net80211 on FreeBSD 8

[Sam Leffler]

Alexander Egorenkov wrote:
> Sorry, i posted the wrong comment.
> Here is the comment which i don't understand:
> 
> /*
>              * NB: don't assign a sequence # to potential
>              * aggregates; we expect this happens at the
>              * point the frame comes off any aggregation q
>              * as otherwise we may introduce holes in the
>              * BA sequence space and/or make window accouting
>              * more difficult.
>              *
>              * XXX may want to control this with a driver
>              * capability; this may also change when we pull
>              * aggregation up into net80211
>   */
> 
> Thanks.

What is unclear?

	Sam

> 
> 
> On Wed, Jan 27, 2010 at 8:04 PM, Alexander Egorenkov <
> egorenar at googlemail.com> wrote:
> 
>> Hi,
>>
>> i'm implementing a device driver for a 802.11n NIC under FreeBSD 8
>> und experimented with A-MPDU transmission. I looked into net80211 code
>> and there is some code which implements this feature but it worked not very
>> well for me.
>> I noticed e.g. that sequence numbers are not assigned to A-MPDU frames
>> and found this comment in file ieee80211_output.c :
>>
>>
>> /*
>>          * Check if A-MPDU tx aggregation is setup or if we
>>          * should try to enable it.  The sta must be associated
>>          * with HT and A-MPDU enabled for use.  When the policy
>>          * routine decides we should enable A-MPDU we issue an
>>          * ADDBA request and wait for a reply.  The frame being
>>          * encapsulated will go out w/o using A-MPDU, or possibly
>>          * it might be collected by the driver and held/retransmit.
>>          * The default ic_ampdu_enable routine handles staggering
>>          * ADDBA requests in case the receiver NAK's us or we are
>>          * otherwise unable to establish a BA stream.
>>  */
>>
>> Can somebody elaborate this description to me please.
>>
>> Thanks.
>>
>> ALex.
>>
>>
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