From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from rcdn-iport-7.cisco.com (rcdn-iport-7.cisco.com [173.37.86.78]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "rcdn-iport.cisco.com", Issuer "HydrantID SSL ICA G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 999CE21F317; Tue, 3 Mar 2015 10:00:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=2916; q=dns/txt; s=iport; t=1425405644; x=1426615244; h=from:to:cc:subject:date:message-id:references: in-reply-to:mime-version; bh=qb6U/qDebyNjZ4JuxVQ4iCHDiyjP3e0wi79v56lCwEI=; b=FzML2Lrb5ELkzj2VV0d4jtWPvOrkWDMlJ0h8kmOS6liAvs7zo9frX9i8 X6GPbrN5dUJSCXkxeuSYvyD9NnnbTfXkFDhpWFadL6Gxn/8mcn/sfGYk3 byCeEiikalBZ95U7QwEmn/cy7V8xseoLp+WBYvvSgtVHgwpkYUNsnORLL 8=; X-Files: signature.asc : 487 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: A0BXBgC89fVU/4YNJK1agwKBLASDB8QtAoEoTQEBAQEBAXyEDwEBAQMBI1YFCwIBBgIOCicDAgIhERQRAgQOBQ6IDQMJCJ8XnGyVDw2FHgEBAQEBAQEBAQEBAQEBAQEBAQEBAReLEoJEgioHgmgvgRQBBI95gWGBLoRygUgBjVKGDCODbm+BRH8BAQE X-IronPort-AV: E=Sophos;i="5.09,682,1418083200"; d="asc'?scan'208";a="400494557" Received: from alln-core-12.cisco.com ([173.36.13.134]) by rcdn-iport-7.cisco.com with ESMTP; 03 Mar 2015 18:00:15 +0000 Received: from xhc-aln-x07.cisco.com (xhc-aln-x07.cisco.com [173.36.12.81]) by alln-core-12.cisco.com (8.14.5/8.14.5) with ESMTP id t23I0FYn021417 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=FAIL); Tue, 3 Mar 2015 18:00:15 GMT Received: from xmb-rcd-x09.cisco.com ([169.254.9.149]) by xhc-aln-x07.cisco.com ([173.36.12.81]) with mapi id 14.03.0195.001; Tue, 3 Mar 2015 12:00:15 -0600 From: "Fred Baker (fred)" To: Wesley Eddy Thread-Topic: [aqm] [Bloat] ping loss "considered harmful" Thread-Index: AQHQVdvmDWBYEA2CWkyvb8nphm+1ug== Date: Tue, 3 Mar 2015 18:00:14 +0000 Message-ID: References: <54F5EF7B.4000006@mti-systems.com> In-Reply-To: <54F5EF7B.4000006@mti-systems.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: yes X-MS-TNEF-Correlator: x-originating-ip: [10.19.64.116] Content-Type: multipart/signed; boundary="Apple-Mail=_B6E8299E-53E0-4F4C-BE1F-5FCE73074BD1"; protocol="application/pgp-signature"; micalg=pgp-sha1 MIME-Version: 1.0 Cc: bloat , "cerowrt-devel@lists.bufferbloat.net" , "aqm@ietf.org" Subject: Re: [Bloat] [aqm] ping loss "considered harmful" 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: Tue, 03 Mar 2015 18:00:45 -0000 --Apple-Mail=_B6E8299E-53E0-4F4C-BE1F-5FCE73074BD1 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On Mar 3, 2015, at 9:29 AM, Wesley Eddy wrote: >=20 > On 3/3/2015 12:20 PM, Fred Baker (fred) wrote: >>=20 >>> On Mar 1, 2015, at 7:57 PM, Dave Taht >> > wrote: >>>=20 >>> How can we fix this user perception, short of re-prioritizing ping = in >>> sqm-scripts? >>=20 >> IMHO, ping should go at the same priority as general traffic - the >> default class, DSCP=3D0. When I send one, I am asking whether a = random >> packet can get to a given address and get a response back. I can = imagine >> having a command-line parameter to set the DSCP to another value of = my >> choosing. >=20 > I generally agree, however ... >=20 > The DSCP of the response isn't controllable though, and likely the = DSCP > that is ultimately received will not be the one that was sent, so it > can't be as simple as echoing back the same one. Ping doesn't tell = you > latency components in the forward or return path (some other protocols > can do this though). >=20 > So, setting the DSCP on the outgoing request may not be all that = useful, > depending on what the measurement is really for. Note that I didn=E2=80=99t say =E2=80=9CI demand=E2=80=9D=E2=80=A6 :-) I share the perception that ping is useful when it=E2=80=99s useful, and = that it is at best an approximation. If I can get a packet to the = destination and a response back, and I know the time I sent it and the = time I received the response, I know exactly that - messages went out = and back and took some amount of total time. I don=E2=80=99t know = anything about the specifics of the path, of buffers en route, or delay = time in the target. Traceroute tells me a little more, at the cost of a = more intense process. In places I use ping, I tend to send a number of = them over a period of time and observe on the statistics that result, = not a single ping result. --Apple-Mail=_B6E8299E-53E0-4F4C-BE1F-5FCE73074BD1 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="signature.asc" Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQEVAwUBVPX2rZ9ieig10VPpAQIiHQf9EAnDNTFElc0bSlEPO1UaR2MIRPL3pogf I5AivFJXHox7saxf+oTAUToBLxAr+SIQycxRW0vIj5PsBz/Dw3udX1UF4H+0movD CH1kxj0CG0QE13XGtq+YuBHyawgd922WnBoV0dqwJZ4vOdxblpIRU2HV99QOJYEI dtAykP0y+RtnxovcDjfGGj2jd4/R9t4UrTpY6CyOjN7rUqyi5cWeHtf5VyVtKWPW 5QP0sTUbfvxQWErl3OhAdJyo0Zi7UzywnHvbfPpHz0X6QbuPIzWbbFzjXiQ8IKnp 7uYeudDETGBRLDHF1+Ly66k9wPg+mxhZVpSb+hTF0SmGUX0kS7sm2w== =Yzpk -----END PGP SIGNATURE----- --Apple-Mail=_B6E8299E-53E0-4F4C-BE1F-5FCE73074BD1--