From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oa0-x22c.google.com (mail-oa0-x22c.google.com [IPv6:2607:f8b0:4003:c02::22c]) (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 0244421F6B2 for ; Thu, 31 Jul 2014 13:44:15 -0700 (PDT) Received: by mail-oa0-f44.google.com with SMTP id eb12so2451101oac.3 for ; Thu, 31 Jul 2014 13:44:15 -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=OBECZd1qWh7GWNvULKNSXsh7bLv9gZTkmL5lU/5Jr90=; b=UexsqtmRnib+jwn3rNathf8UpqWnsaXpKgunRbiORVBQXhXY/PLMKsjEr0wsPz9baC M49NNaFCZq5NqU+HmjDe7qUHssz0BvplT7GnVRcpuacHbzqg8KJ6UpeWp5k52Klvat0p gwdQt9W251ToXXIwc/TqlemmlIhQ4w7LY/L0qsTRhsbabgsQ47G7GmHZuqKRflhosjwW chH9KQUAqt6GFWz272gaeZ6P9X9JYRqWw7aD8fSfUIAs17rcQzOHD74PlDAfoRVnLGmq rzRPoJt/AEYHVGSC2v2QFVrw9PoKwIEF9NpwPftSa4bZSVq4qnpJ2m/cEWfOQSsZMF4N pqyg== MIME-Version: 1.0 X-Received: by 10.60.146.228 with SMTP id tf4mr1093932oeb.37.1406839455097; Thu, 31 Jul 2014 13:44:15 -0700 (PDT) Sender: gettysjim@gmail.com Received: by 10.76.124.72 with HTTP; Thu, 31 Jul 2014 13:44:15 -0700 (PDT) In-Reply-To: References: Date: Thu, 31 Jul 2014 16:44:15 -0400 X-Google-Sender-Auth: IErD6RX9pO-VS9LPfSbsSBAkEYQ Message-ID: From: Jim Gettys To: Wes Felter Content-Type: multipart/alternative; boundary=047d7b5d98effa28d604ff8355fe Cc: bloat Subject: Re: [Bloat] is there no RED at level3? 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: Thu, 31 Jul 2014 20:44:16 -0000 --047d7b5d98effa28d604ff8355fe Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Thu, Jul 31, 2014 at 4:13 PM, Wes Felter wrote: > On 7/30/14, 5:49 PM, Dave Taht wrote: > >> I have been following the level3 vs verizon debate with some interest, >> trying to sort out fact from fiction. It does appear that once they >> saturate a core interconnect they end up with nearly 100ms of latency in >> it. Is RED not available on 10GigE interconnects or any other mediation >> means to increase packet loss in exchange for getting better latency? >> > > Wasn't CoDel created because nobody understands how to configure RED? > =E2=80=8BMore or less.... Dave Oran noted at one IETF meeting that RED tun= ing (at least on Cisco gear) might not even be stable between different versions of their operating system. CoDel's goal was to be a "do no harm" aqm safe enough to always have turned on (according to Kathie and Van). But RED mistuned can hurt you (or so I gather).... And testing your tuning under load is not something you want to do, even if you can arrange it. =E2=80=8B > > If you've built a network under the assumption that congestion won't > happen, why enable RED? > =E2=80=8BBackhoe events, tsunamis, and peering disputes show that congestio= n does happen. And it takes time to lay more fiber, particularly in backbone networks. Crystal ball gazing goes only so far on avoiding congestion in the core. But see above... =E2=80=8B > > If you're in an adversarial public pissing match, is your incentive to > make the situation look better or worse? =E2=80=8BIt's commonplace, and given RED's difficulty, hardly surprising to= me that many peering points run without it. Also note that the *actual* bottleneck may not even be in a device where you have (W)RED present; switches are widespread... - Jim =E2=80=8B > > > -- > Wes Felter > > > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat > --047d7b5d98effa28d604ff8355fe Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Thu= , Jul 31, 2014 at 4:13 PM, Wes Felter <wmf@felter.org> wrote:
On 7/30/14, 5:49 PM, Dave Ta= ht wrote:
I have been following the level3 vs verizon debate with some interest,
trying to sort out fact from fiction. It does appear that once they
saturate a core interconnect they end up with nearly 100ms of latency in it. Is RED not available on 10GigE interconnects or any other mediation
means to increase packet loss in exchange for getting better latency?

Wasn't CoDel created because nobody understands how to configure RED?

=E2=80=8BMore or less.... =C2=A0Dave Oran noted at one IETF meeti= ng that RED tuning (at least on Cisco gear) might not even be stable betwee= n different versions of their operating system.

CoDel's goal was to be a &= quot;do no harm" aqm safe enough to always have turned on (according t= o Kathie and Van).

But RED mistuned can hurt you = (or so I gather).... =C2=A0And testing your tuning under load is not someth= ing you want to do, even if you can arrange it.
=E2=80=8B
<= blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px= #ccc solid;padding-left:1ex">
If you've built a network under the assumption that congestion won'= t happen, why enable RED?

=E2=80=8BBackhoe events, tsunamis, and= peering disputes show that congestion does happen. =C2=A0And it takes time= to lay more fiber, particularly in backbone networks. =C2=A0Crystal ball g= azing goes only so far on avoiding congestion in the core. =C2=A0But see ab= ove...
=E2=80=8B

If you're in an adversarial public pissing match, is your incentive to = make the situation look better or worse?

=E2=80=8BIt's commonpla= ce, and given RED's difficulty, hardly surprising to me that many peeri= ng points run without it.

Also note that the *actual* bo= ttleneck may not even be in a device where you have (W)RED present; switche= s are widespread...
=C2=A0 =C2=A0 =C2=A0= =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0- Jim
=E2=80=8B


--
Wes Felter


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