From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail2.tohojo.dk (mail2.tohojo.dk [IPv6:2a01:4f8:200:3141::101]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 8F80821F23A for ; Mon, 12 May 2014 13:21:48 -0700 (PDT) X-Virus-Scanned: amavisd-new at mail2.tohojo.dk Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id D99E122E3B; Mon, 12 May 2014 22:21:39 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toke.dk; s=201310; t=1399926100; bh=+q7cX4OLb0cM7gt4VFnMh36NSnkj6wCF74eYe61V/hM=; h=From:To:Cc:Subject:References:Date:In-Reply-To; b=hyqsA+mGSpa4mxpf073mNjwwpDpUSwVX8JO9Rv2wrMpgGfaPjMLZguXHyZJsm533x FG3KPrpN5K6LpnqHlJsqA9qimhZt8LTuWW12bocNTdxMSLNlTDKNe5Xa334UKEGu3Z 1LtcoLvgVrxwLrS5JSXOgsppaJMyflJbd3+5UCxo= From: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= To: Forums1000 References: Date: Mon, 12 May 2014 22:21:37 +0200 In-Reply-To: (Forums's message of "Mon, 12 May 2014 09:11:10 +0200") Message-ID: <87ha4u3fzi.fsf@toke.dk> Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Cc: bloat Subject: Re: [Bloat] How is bufferbloat prevented/fixed for UDP? 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: Mon, 12 May 2014 20:21:49 -0000 --=-=-= Content-Type: text/plain Forums1000 writes: > 1) With UDP, you cannot uniquely identify a flow? This prevents an > AQM-algorithm to drop packets for an (several) offending UDP flow(s). For most cases UDP flows are determined by port number pairs, same as TCP. Multiple flows can be multiplexed over one "connection", but this is no different from TCP. > 2) Unlike TCP, UDP does not back down when encountering packet loss This is true; i.e. not back-off mechanism is built into the protocol. However, it is quite possible to build in such a mechanism in whatever protocol is running *on top of* UDP. Indeed this is done for things like real-time media protocol, and also bittorrents uTP protocol runs on top of UDP. So I guess the answer is "it all depends". As an aside, if you *do* have an unresponsive UDP flow (whether misconfigured or malignant), having a flow queueing mechanism like that of fq_codel helps a lot; the bad UDP flow is then isolated and only hurts itself, so to speak. :) -Toke --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQEcBAEBCAAGBQJTcS1RAAoJEENeEGz1+utPtuEH/1ti21/Y4lqgVGefCvF50gVf BdD8loRvEo2aHq4rdrDfS5mqkF78lKvC9fFJ9eLewtLCv35rWN+gIz2G+gbVl2up 554QhwI17+Y/u/VbtLTW7pb2ELcZgfJQshNjyRpMqsIbdcEFAXo0y9l1K/Xj+YIL AKfVUlZGrzC7qfV7RscqLmY+y/xBWOGrXeNd3iFRWMCKrv8+RJv6KFS5j1yEW7jv 6qLSLtqMYxyiUigxGHyn4lIR0Dj+ionnW4n6PnAMn5ANJsq4Kp/uAGrZkvW5A0IZ dbn/bz8EHC/CkIWlClmHMNnDuiAl5rQgVjLgcOdlFa7DhutJFBNWFU6xl3YBao4= =s25H -----END PGP SIGNATURE----- --=-=-=--