From mboxrd@z Thu Jan 1 00:00:00 1970 From: Damien Clabaut Subject: Issue with pktgen-dpdk replaying >1500bytes pcap on MCX4 Date: Mon, 25 Sep 2017 13:19:23 -0400 Message-ID: <5f5aba8a-0dd2-fd64-891b-569d2a4627c8@corp.ovh.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit To: Return-path: Received: from 1.mo301.mail-out.ovh.net (1.mo301.mail-out.ovh.net [137.74.110.64]) by dpdk.org (Postfix) with ESMTP id 8A14B2C2A for ; Mon, 25 Sep 2017 19:22:21 +0200 (CEST) Received: from EX2.OVH.local (gw1.corp.ovh.com [51.255.55.226]) by mo301.mail-out.ovh.net (Postfix) with ESMTPS id 4F31F232C0 for ; Mon, 25 Sep 2017 19:22:21 +0200 (CEST) Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hello DPDK devs, I am sending this message here as I did not find a bugtracker on the website. If this is the wrong place, I would kindly apologize and ask you to redirect me to the proper place, Thank you. Description of the issue: I am using pktgen-dpdk to replay a pcap file containing exactly 1 packet. The packet in question is generated using this Scapy command: pkt=(Ether(src="ec:0d:9a:37:d1:ab",dst="7c:fe:90:31:0d:52")/Dot1Q(vlan=2)/IP(dst="192.168.0.254")/UDP(sport=1020,dport=1021)/Raw(RandBin(size=8500))) The pcap is then replayed in pktgen-dpdk: ./app/app/x86_64-native-linuxapp-gcc/pktgen -l 0-7 -- -m [1-7].0 -s 0:pcap/8500Bpp.pcap When I run this on a machine with Mellanox ConnectX-4 NIC (MCX4), the switch towards which I generate traffic gets a strange behaviour #sh int et29/1 | i rate   5 seconds input rate 39.4 Gbps (98.4% with framing overhead), 0 packets/sec A capture of this traffic (I used a monitor session to redirect all to a different port, connected to a machine on which I ran tcpdump) gives me this: 19:04:50.210792 00:00:00:00:00:00 (oui Ethernet) > 00:00:00:00:00:00 (oui Ethernet) Null Unnumbered, ef, Flags [Poll], length 1500 19:04:50.210795 00:00:00:00:00:00 (oui Ethernet) > 00:00:00:00:00:00 (oui Ethernet) Null Unnumbered, ef, Flags [Poll], length 1500 19:04:50.210796 00:00:00:00:00:00 (oui Ethernet) > 00:00:00:00:00:00 (oui Ethernet) Null Unnumbered, ef, Flags [Poll], length 1500 19:04:50.210797 00:00:00:00:00:00 (oui Ethernet) > 00:00:00:00:00:00 (oui Ethernet) Null Unnumbered, ef, Flags [Poll], length 1500 19:04:50.210799 00:00:00:00:00:00 (oui Ethernet) > 00:00:00:00:00:00 (oui Ethernet) Null Unnumbered, ef, Flags [Poll], length 1500 The issue cannot be reproduced if any of the following conditions is met: - Set the size in the Raw(RandBin()) to a value lower than 1500 - Send the packet from a Mellanox ConnectX-3 (MCX3) NIC (both machines are indentical in terms of software). Is this a known problem ? I remain available for any question you may have. Regards, -- Damien Clabaut R&D vRouter ovh.qc.ca