From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id EFD893B5 for ; Mon, 10 Aug 2015 12:28:21 +0200 (CEST) Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga103.fm.intel.com with ESMTP; 10 Aug 2015 03:28:20 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,644,1432623600"; d="scan'208";a="622561385" Received: from bricha3-mobl3.ger.corp.intel.com ([10.237.208.159]) by orsmga003.jf.intel.com with SMTP; 10 Aug 2015 03:28:18 -0700 Received: by (sSMTP sendmail emulation); Mon, 10 Aug 2015 11:28:18 +0025 Date: Mon, 10 Aug 2015 11:28:18 +0100 From: Bruce Richardson To: Stefan Binna Message-ID: <20150810102817.GA9544@bricha3-MOBL3> References: <55C3573D.9060308@salzburgresearch.at> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55C3573D.9060308@salzburgresearch.at> Organization: Intel Shannon Ltd. User-Agent: Mutt/1.5.23 (2014-03-12) Cc: dev@dpdk.org Subject: Re: [dpdk-dev] TX-packet counter increased when no packets were actually sent X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Aug 2015 10:28:22 -0000 On Thu, Aug 06, 2015 at 02:46:53PM +0200, Stefan Binna wrote: > Hi, > > I have created a little testbed for DPDK testing. > > NIC: Intel Gigabit 82574L (1-port) > > The testbed for DPDK has following structure: > > 1) al40-118 (10.100.40.118/24): DUT running the DPDK application > 2) al40-119 (10.100.40.119/24): Used for sending traffic to al40-118 > 3) al40-111 (10.100.40.111/24): Used to sniff the traffic send on the > network > > All three devices are connected via a hub and use the network > 10.100.40.1/24. > > *Test:* Ping the DUT and review network traffic > The use of ping implies the presence of an IP protocol stack to respond to that ping. Testpmd included no protocol stack support so can't respond to the ping request. > At al40-119 an ARP-Table-Entry was created and the device al40-118 was > pinged: > > arp -s 10.100.40.118 68:05:ca:37:51:75 > ping 10.100.40.118 > > On al40-118 the application testpmd was started with following parameters: > > ./x86_64-native-linuxapp-gcc/build/app/test-pmd/testpmd -c 0xf -n 4 -- -i --portmask=0x1 --nb-cores=2 --port-topology=chained > > After start of the testpmd application the ports were started and after a > while stopped: > > start #wait a while due to testduration > stop > > What's interesting is, that the TX-packet counter in the output of the > "stop" command had the same value as the RX-packet counter. But the actual > traffic on the network sniffed with Wireshark only showed the ping request > but never a response on any layer (not even L2). > > Sample output of the "stop" command: > > Telling cores to stop... > Waiting for lcores to finish... > > ---------------------- Forward statistics for port 0 ---------------------- > RX-packets: 2 RX-dropped: 0 RX-total: 2 > TX-packets: 2 TX-dropped: 0 TX-total: 2 > ---------------------------------------------------------------------------- > > +++++++++++++++ Accumulated forward statistics for all ports+++++++++++++++ > RX-packets: 2 RX-dropped: 0 RX-total: 2 > TX-packets: 2 TX-dropped: 0 TX-total: 2 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > Done. > Stopping port 0...done > > Could you tell me why the TX-packet counter increased when actually no > packets were sent out to the 10.100.40.1 network or in other words, where > have the packets been sent out? Packets were sent out by the DUT. However, those packets weren't ping responses, they were the ping requests themselves being forwarded. That's why they showed up in your wireshark track on the receiving side. /Bruce