From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yk0-x232.google.com (mail-yk0-x232.google.com [IPv6:2607:f8b0:4002:c07::232]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id DFC5C21FCAA; Thu, 13 Aug 2015 15:14:38 -0700 (PDT) Received: by ykaz130 with SMTP id z130so54213622yka.0; Thu, 13 Aug 2015 15:14:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=Y0BGwAL32l+BlcgFR97rsL5pp7v1M5HQfrQjAk/j8LA=; b=0K/0ZS0efrAFsxnw0Irf6qvtZqwUIOYNezDwtSA2FMzInrboX/iAKH62fpBhF9ggAk bu9yzTSFmn6YR7lL800t6Sgc3HjQgh0h+kOn+NGSiQ/x/JxmZcaFJ+Rhf1UarUjReJyO FI/o99nAStXUWTznPG04Czc5L2nc1kODttdrIYkABg1wfFcmrmAbe+NvfZBbVK3Os2uA jvTLSPQ9L1sIJc1t1oXl62K70vpuJaOAlD32qJcgPXyLXwImXZrzg8P1XwkvOYDcH4h+ snMroxobIcHY214w7WuMcojoTF5VDkTPrB0Fymu6O5RIsCeiFWOdp51+ef4mGQNidGUM dvXA== MIME-Version: 1.0 X-Received: by 10.129.117.4 with SMTP id q4mr37409130ywc.15.1439504077249; Thu, 13 Aug 2015 15:14:37 -0700 (PDT) Received: by 10.37.214.203 with HTTP; Thu, 13 Aug 2015 15:14:37 -0700 (PDT) Received: by 10.37.214.203 with HTTP; Thu, 13 Aug 2015 15:14:37 -0700 (PDT) In-Reply-To: References: <356F5FEE-9FBD-4FF9-AC17-86A642D918A4@gmail.com> <5CC1DC90-DFAF-4A4D-8204-16CD4E20D6E3@gmx.de> <4D24A497-5784-493D-B409-F704804326A7@gmx.de> <1438361254.45977158@apps.rackspace.com> <6E08E48D-5D53-48E5-B088-2D1DB5E566AD@gmail.com> <1438983998.16576420@apps.rackspace.com> <1439066765.7348311@apps.rackspace.com> Date: Fri, 14 Aug 2015 01:14:37 +0300 Message-ID: From: Jonathan Morton To: David Lang Content-Type: multipart/alternative; boundary=001a1147e5382d65c1051d38a9e7 Cc: make-wifi-fast@lists.bufferbloat.net, cerowrt-devel@lists.bufferbloat.net Subject: Re: [Make-wifi-fast] [Cerowrt-devel] [tsvwg] Comments on draft-szigeti-tsvwg-ieee-802-11e X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 13 Aug 2015 22:15:01 -0000 --001a1147e5382d65c1051d38a9e7 Content-Type: text/plain; charset=UTF-8 The only mandatory form of aggregation in 'n' is of the one-checksum type, even though other types are permitted. The overhead at the data layer is slightly less, and checksum failure handling on receive is simpler (just throw the whole thing out and nak it), as is handling the nak at the transmitter (just retransmit the whole aggregate at the next opportunity). Most 'n' hardware thus caters only to this lowest common denominator. I'm not sure whether soft-MAC type hardware (like ath9k) can also support the more flexible type via driver support - I would hope so - but hard-MAC hardware almost certainly can't be retrofitted in this way. However, since 'ac' hardware is required to support individual-checksum aggregation, a dual-band 'ac' card running on 2.4 GHz will effectively be an 'n' card with such support, even if it's a hard-MAC. - Jonathan Morton --001a1147e5382d65c1051d38a9e7 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

The only mandatory form of aggregation in 'n' is of = the one-checksum type, even though other types are permitted.=C2=A0 The ove= rhead at the data layer is slightly less, and checksum failure handling on = receive is simpler (just throw the whole thing out and nak it), as is handl= ing the nak at the transmitter (just retransmit the whole aggregate at the = next opportunity).=C2=A0 Most 'n' hardware thus caters only to this= lowest common denominator.

I'm not sure whether soft-MAC type hardware (like ath9k)= can also support the more flexible type via driver support - I would hope = so - but hard-MAC hardware almost certainly can't be retrofitted in thi= s way.

However, since 'ac' hardware is required to support = individual-checksum aggregation, a dual-band 'ac' card running on 2= .4 GHz will effectively be an 'n' card with such support, even if i= t's a hard-MAC.

- Jonathan Morton

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