From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: want to randomly drop packets based on percent Date: Mon, 17 Apr 2006 10:32:11 -0700 Message-ID: <20060417103211.24115952@localhost.localdomain> References: <444345F9.4090100@cmu.edu> <20060417091915.67e28361@localhost.localdomain> <4444171B.90507@cmu.edu> <20060417094634.7191fea5@localhost.localdomain> <4443CAD1.9050701@cmu.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.4]:36571 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1751184AbWDQRcP (ORCPT ); Mon, 17 Apr 2006 13:32:15 -0400 To: George Nychis In-Reply-To: <4443CAD1.9050701@cmu.edu> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org O > >>>>I wanted to insert artificial packet loss based on a percent so i found: > >>>>network emulab qdisc could do it, so i compiled support into the kernel > >>>>and tried: > >>>>tc qdisc change dev eth0 root netem loss .1% > >>>> > >>>> > > ^^^^^^ > > > >You need to do add not change. Add will set the queue discipline > >to netem (default is pfifo_fast). Change is for changing netem parameters > >after it is loaded. > > > > > > > bahhh I see... the wiki has "change" instead of add. Now i'm running > into another problem, I have an XCP qdisc that I have already added via: > tc qdisc add dev ath0 root xcp capacity 54Mbit size 500 > Wiki reads as a set of examples. First uses, "add" after that "change". > therefore when I also try to incorperate loss: > tcq disc add dev ath0 root netem loss .1% > > I get: > RTNETLINK answers: File exists > > Is it possible to use two qdiscs on the same interface? > No, but netem is "classful" so you can put xcp inside netem. Look at the token bucket example on the wiki.