From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ondar.cablelabs.com (ondar.cablelabs.com [192.160.73.61]) by huchra.bufferbloat.net (Postfix) with ESMTP id 4E69221F17B for ; Wed, 28 Nov 2012 11:21:33 -0800 (PST) Received: from kyzyl.cablelabs.com (kyzyl [10.253.0.7]) by ondar.cablelabs.com (8.14.5/8.14.5) with ESMTP id qASJLW8j015192; Wed, 28 Nov 2012 12:21:32 -0700 Received: from srvxchg.cablelabs.com (10.5.0.15) by kyzyl.cablelabs.com (F-Secure/fsigk_smtp/407/kyzyl.cablelabs.com); Wed, 28 Nov 2012 12:21:32 -0700 (MST) X-Virus-Status: clean(F-Secure/fsigk_smtp/407/kyzyl.cablelabs.com) Received: from srvxchg.cablelabs.com ([10.5.0.15]) by srvxchg ([10.5.0.15]) with mapi; Wed, 28 Nov 2012 12:21:32 -0700 From: Greg White To: =?iso-8859-1?Q?Toke_H=F8iland-J=F8rgensen?= , "bloat@lists.bufferbloat.net" Date: Wed, 28 Nov 2012 12:21:41 -0700 Thread-Topic: [Bloat] [Cerowrt-devel] FQ_Codel lwn draft article review Thread-Index: Ac3NnZKd0QbLPnjzQMm90kM/TKq4qQ== Message-ID: In-Reply-To: <87d2yymtxi.fsf@toke.dk> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Microsoft-MacOutlook/14.2.5.121010 acceptlanguage: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [Bloat] [Cerowrt-devel] FQ_Codel lwn draft article review 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, 28 Nov 2012 19:21:33 -0000 Jitter on its own is not useful for estimating VoIP quality. For (c), I've used: =09 =09 =09 =09 =09 =09 =09 =09 Cole, Robert G., and Joshua H. Rosenbluth. "Voice over IP performance monitoring." ACM SIGCOMM Computer Communication Review 31, no. 2 (2001): 9-24. Which I generally simplify to: =09 =09 =09 =09 =09 =09 =09 =09 R=3D 94.2 - 0.024*Latency - 0.11*max(0,Latency-177.3 ms) - 30*log(1 + 15*Loss). =09 =09 =09 =09 where Loss is mean packet loss rate (counting packets with latency > (min_latency + 60ms) as lost), Latency is mean latency for packets not counted as lost. =09 =09 =09 =09 You can then translate R into an estimate of MOS using Eq.1 in the above reference. -Greg On 11/27/12 5:51 PM, "Toke H=F8iland-J=F8rgensen" wrote: >Oliver Hohlfeld > writes: > >> The jitter measurements you have in mind will give you an idea on the >> jitter specific to the chosen traffic scenario, nothing more --- and >> in particular not the VoIP quality (although low vs. high jitter could >> /indicate/ certain /possible/ quality degradations). > >Well no, in this sense the only "real" test for voip quality is picking >up the (soft)phone and talking to someone. However, since the context >here is automated measuring tools (preferably generating solid >quantitative, comparable data), that is hardly feasible. > >I guess the goal of a comprehensive testing suite is to gather as many >indicators of quality degradations (in the widest possible sense) as >possible and testing for them under a variety of traffic conditions. I >am by no means an expert on VoIP, but someone suggested measuring jitter >could be useful, and I've proposed a possible way to do that (using >iperf udp flows at a low-ish bandwidth). > >Since for the purpose of this particular discussion I seem to be in the >test tool building business (at least for the time being), what I really >need before going forward with this is someone to comment on (a) if >using iperf udp flows is a valid way to measure jitter, (b) if measuring >jitter is actually something someone wants to do and (c) if there are >other tests that would be useful for testing VoIP (or general) >conditions instead of / in addition to the jitter measurements. > >So far I don't have an answer to (a), only negative answers to (b) and >nothing concrete for (c). So for the time being I'm shelving the idea, >and will just note that it seems quite feasible to return to it should >someone change their mind on (b) :) > > >-Toke > >--=20 >Toke H=F8iland-J=F8rgensen >toke@toke.dk