From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-x234.google.com (mail-ob0-x234.google.com [IPv6:2607:f8b0:4003:c01::234]) (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 5EA8021F3A5 for ; Wed, 20 Aug 2014 15:05:58 -0700 (PDT) Received: by mail-ob0-f180.google.com with SMTP id uy5so6731905obc.25 for ; Wed, 20 Aug 2014 15:05:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=se2GCtZ+EscRKYVnoOlFKsmkih4LDnpOT7zHfDgTmd4=; b=MZQ64RmEun6Y9sS1fl8j3qrxexjgQ1pOBwixlyZLFCohbhHWkpzI8r3H6C4Y/b88Xs E8tS/Ux9cChjClz0HWv+Ov5iQomwTY6sSueqcQZPhqwtMmXW2B30gExC6BaP8QfwlMM1 ArWwANyID2f7SPibg9t+FHb6BIvHoLNmXVE/29YYkFDx+UynN/IQPpge2lx33dUVoBI9 Xos56mqDdrzr1cBpCDocL2+AxigjfashpNYAVTEF4nIoIygLd7+JEgmGqTC/ne+/Z2lh xLvn9k3e4tRuiZBPMDVM45ucEpndCU5gjbaT6ocl95dM07lXNTe6YGT47oU3u0Z1q5Se X84A== MIME-Version: 1.0 X-Received: by 10.60.52.5 with SMTP id p5mr50884478oeo.55.1408572357241; Wed, 20 Aug 2014 15:05:57 -0700 (PDT) Sender: gettysjim@gmail.com Received: by 10.76.124.72 with HTTP; Wed, 20 Aug 2014 15:05:57 -0700 (PDT) In-Reply-To: <91696A3A-EF44-4A1A-8070-D3AF25D0D9AC@netapp.com> References: <91696A3A-EF44-4A1A-8070-D3AF25D0D9AC@netapp.com> Date: Wed, 20 Aug 2014 18:05:57 -0400 X-Google-Sender-Auth: 3pHFr7Dxg202cGGldhpm-2pxNOc Message-ID: From: Jim Gettys To: "Eggert, Lars" Content-Type: multipart/alternative; boundary=001a11332c8efef012050116cefa Cc: bloat Subject: Re: [Bloat] sigcomm wifi X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 20 Aug 2014 22:05:58 -0000 --001a11332c8efef012050116cefa Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Wed, Aug 20, 2014 at 3:12 AM, Eggert, Lars wrote: > On 2014-8-19, at 18:45, Dave Taht wrote: > > I figured y'all would be bemused by the wifi performance in the sigcomm > > main conference room this morning... > > > > http://snapon.lab.bufferbloat.net/~d/sigcomm_tuesday.png > > There is a reason we budgeted a 1G uplink for SIGCOMM Helsinki and made > sure we had sufficient AP coverage... > =E2=80=8BAnd what kinds of AP's? All the 1G guarantees you is that your bo= ttleneck is in the wifi hop, and they can suffer as badly as anything else (particularly consumer home routers). The reason why 802.11 works ok at IETF and NANOG is that: o) they use Cisco enterprise AP's, which are not badly over buffered. I don't have data on which enterprise AP's are overbuffered. o) they do a good job of placing the AP's, given a lot of experience o) they turn on RED in the router, which, since there is a lot of aggregated traffic, can actually help rather than hurt, and keep TCP decently policed. o) they play some interesting diffserv marking tricks to prioritize some traffic, getting part of the effect the fq_codel gives you in its "new flow" behavior by manual configuration. Fq_codel does much better without having to mess around like this. Would be nice if they (the folks who run the IETF network) wrote a BCP on the topic; I urged them some IETF's ago, but if others asked, it would help= . If you try to use consumer home routers running factory firmware and hack it yourself, you will likely lose no matter what you backhaul is (though you might do ok using current CeroWrt/OpenWrt if you know what you are doing. -- Jim > Lars > > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat > > --001a11332c8efef012050116cefa Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable



The reason why 802.11 works ok= at IETF and NANOG is that:
=C2=A0 o) they use Cisco enterprise AP's, which are not badly over buff= ered. =C2=A0I don't have data on which enterprise AP's are overbuff= ered.

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