Hi, I'vrecently started using neteto simulate a network carrying primarily UDP traffic. All of thfeatures seeto work well except for th"corrupt" option. If I seup netewith the following string tc qdisc add dev eth0 roonetecorrupt 50% and observthtraffic leaving eth0 i can see many packets being corrupted however all of therrors appear in thheader of the packet and nothpayload. I havobserved thstream for some time using arbitrarily large or small packets and noobserved any payload corruption. Is this intended functionality? How would i forcbierrors within the payload? All experiments havbeen donusing Ubuntu 10.04 Kernel 2.6.32-24, I'notoo sure what version of netem is included with this distribution. Thanks Matt Frolaurent.mariat thomson-networks.com Thu Aug 19 02:07:22 2010 From: laurent.mariathomson-networks.com (Marie Laurent) Date: Thu, 19 Aug 2010 11:07:22 +0200 Subject: Whercan I find thnetem distribution? In-Reply-To: <0D8D27B39DF07F4A9098E500C751C3B416F313B3B0@xxxxxxxxxxxxxxxxxxx> References: <0D8D27B39DF07F4A9098E500C751C3B416F313B3B0@xxxxxxxxxxxxxxxxxxx> Message-ID: <E55CA8ECFBA85E4CB8E8173566B9EFEB0163DD0A@xxxxxxxxxxxxxxxxxxxxxxxxxx> Hello, Neteis divided into two parts thawork together. A kernel modulwhich is delivered along with any 2.6 kernel. You may download ifrohttp://kernel.org You will download thsourcarchive that match the kernel version of your LINUX PC (gethversion with uname -a command). Once you have decompressed tharchive, thkernel module netem source file is located into linux/net/sched/sch_netem.c Othother hand, the user interface of netem is part of iproute2 project: http://devresources.linuxfoundation.org/dev/iproute2/download/ You will download thsourcarchive that match the kernel version of your LINUX PC (gethversion with uname -a command). Once you have decompressed tharchive, thnetem user sources are in iproute2/tc/q_netem.c If you add new functionalities to netem, you will havto patch files both akernel and user levels. Yours sincerely, Mr LaurenMARIE ------------------------------------------------------------------------ -------------------------------- Cayou pleassend me a link to the site where I can download netem? Froshemminger avyatta.com Thu Aug 19 14:23:33 2010 From: shemminger avyatta.co(Stephen Hemminger) Date: Thu, 19 Aug 2010 14:23:33 -0700 Subject: netecorrupand UDP In-Reply-To: <AANLkTimdeAP7BdQkGO_EGCwQQbBUWMz878o1dtT1gP99@xxxxxxxxxxxxxx> References: <AANLkTimdeAP7BdQkGO_EGCwQQbBUWMz878o1dtT1gP99@xxxxxxxxxxxxxx> Message-ID: <20100819142333.37ee4986@nehalam> OTue, 17 Aug 2010 09:11:48 +0100 Matthew Clifford <matthew.clifford agmail.com> wrote: > Hi, > > I'vrecently started using neteto simulate a network carrying > primarily UDP traffic. All of thfeatures seeto work well except > for th"corrupt" option. > > If I seup netewith the following string > tc qdisc add dev eth0 roonetecorrupt 50% > > and observthtraffic leaving eth0 i can see many packets being > corrupted however all of therrors appear in thheader of the packet > and nothpayload. > > I havobserved thstream for some time using arbitrarily large or > small packets and noobserved any payload corruption. Is this > intended functionality? How would i forcbierrors within the > payload? > > All experiments havbeen donusing Ubuntu 10.04 Kernel 2.6.32-24, > I'notoo sure what version of netem is included with this > distribution. Corrupis only ablto change the part of the data that is in the unshared portioof thpacket buffer. When a UDP packet is created, itypically has two parts in thsocket buffer: a kernel buffer and a fragmenthacontains the data from the user. This socket buffer thepasses on down to netem. Neteis only ablto corrupt the kernel buffer, it is not allowed to modify thfragmenportion. Theris a simplworkaround, the packet fragmentation depends on thunderlying ethernedevice supporting Scatter/Gather DMA operations. So if you turoff Scatter/Gather with ethtool, then thpacket will bin all-one-buffer when iis passed to netem. sudo ethtool -K eth0 sg off Froaakhter acisco.com Tue Aug 31 08:08:49 2010 From: aakhter acisco.co(Aamer Akhter (aakhter)) Date: Tue, 31 Aug 2010 10:08:49 -0500 Subject: hiearchrical netem Message-ID: <7F298ACC76CC154F832B6D02852D169F02826FC4@xxxxxxxxxxxxxxxxxxxxx> Folks, I'trying to creata set of netem structures that act multiple times oa packet. I had thoughthat if I used HTB, this might be possible. However, ilooks likonly the single leaf netem is performed on the traffic rather thathentire chain of netems. Thoughts welcome... # creattop level htb tc qdisc add dev eth1.3500 roohandl1: htb default 10 tc class add dev eth1.3500 paren1: classid 1:1 htb rat1000mbit # creatchild class off of handl1: ( 1:10 takes all traffic by default) tc class add dev eth1.3500 paren1: classid 1:10 htb rat1000mbit tc qdisc add dev eth1.3500 paren1:10 handl2: netem delay 50ms 20ms distributionormal # creatchild of #2, to add delay tc class add dev eth1.3500 paren2: classid 2:10 htb rat1000mbit tc qdisc add dev eth1.3500 paren2:10 handl3: netem delay 100ms # creatchild of #2, to add delay tc class add dev eth1.3500 paren3: classid 3:10 htb rat1000mbit #tc qdisc add dev eth1.3500 paren3:10 handl4: netem loss 50%
