title: DPDK-Pktgen from DPDK NIC to directly connected non-DPDK NIC (different servers) not working
body: <p><br />
  I've been playing around with DPDK and trying to create the following scenario.
  I have 2 identical servers with 2 different NICs each. The goal is from server1 to send packets in different rates (up to the link maximum using DPDK), and capture the packets on the other side where an app will be running.</p>
  <p>On server1 one NIC (Netronome) is taken by DPDK, but on server 2 it's not. The NICs are directly connected with fiber.
  On server1 I run
  <code>./dpdk-devbind.py --bind=vfio-pci 0000:05:00.0</code>
  and then pktgen. It appears to be working (packets are being reported as sent by pktgen). However on the other side (server2), the inteface goes down the moment I devbind. From:</p>
  <pre><code>Settings for enp6s0np1:
      Supported ports: [ FIBRE ]
      Supported link modes:   Not reported
      Supported pause frame use: Symmetric
      Supports auto-negotiation: No
      Supported FEC modes: None
      Advertised link modes:  Not reported
      Advertised pause frame use: Symmetric
      Advertised auto-negotiation: No
      Advertised FEC modes: None
      Speed: 40000Mb/s
      Duplex: Full
      Auto-negotiation: off
      Port: Direct Attach Copper
      PHYAD: 0
      Transceiver: internal
      Link detected: yes
  </code></pre>
  <p>it goes to:</p>
  <pre><code>ethtool enp6s0np1
  Settings for enp6s0np1:
      Supported ports: [ FIBRE ]
      Supported link modes:   Not reported
      Supported pause frame use: Symmetric
      Supports auto-negotiation: No
      Supported FEC modes: None
      Advertised link modes:  Not reported
      Advertised pause frame use: Symmetric
      Advertised auto-negotiation: No
      Advertised FEC modes: None
      Speed: Unknown!
      Duplex: Unknown! (255)
      Auto-negotiation: off
      Port: Other
      PHYAD: 0
      Transceiver: internal
      Link detected: no
  </code></pre>
  <p>It thinks that there is no physical connection between the two NICs and obviously this is not the case.</p>
  <pre><code> enp6s0np1: &lt;NO-CARRIER,BROADCAST,MULTICAST,UP&gt; mtu 1500 qdisc mq state DOWN group default qlen 1000
      link/ether 00:15:4d:13:30:5c brd ff:ff:ff:ff:ff:ff
  </code></pre>
  <p>The pktgen output:</p>
  <pre><code>\ Ports 0-1 of 2   &lt;Main Page&gt;  Copyright(c) &lt;2010-2021&gt;, Intel Corporation
    Flags:Port        : P------Sngl       :0
  Link State          :           &lt;--Down--&gt;     ---Total Rate---
  Pkts/s Rx           :                    0                    0
         Tx           :               14,976               14,976
  MBits/s Rx/Tx       :                 0/10                 0/10
  Pkts/s Rx Max       :                    0                    0
         Tx Max       :               15,104               15,104
  Broadcast           :                    0
  Multicast           :                    0
  Sizes 64            :                    0
        65-127        :                    0
        128-255       :                    0
        256-511       :                    0
        512-1023      :                    0
        1024-1518     :                    0
  Runts/Jumbos        :                  0/0
  ARP/ICMP Pkts       :                  0/0
  Errors Rx/Tx        :                  0/0
  Total Rx Pkts       :                    0
        Tx Pkts       :            2,579,072
        Rx/Tx MBs     :              0/1,733
  TCP Flags           :               .A....
  TCP Seq/Ack         :  305419896/305419920
  Pattern Type        :              abcd...
  Tx Count/% Rate     :        Forever /0.1%
  Pkt Size/Tx Burst   :            64 /  128
  TTL/Port Src/Dest   :       10/ 1234/ 8000
  Pkt Type:VLAN ID    :      IPv4 / UDP:0001
  802.1p CoS/DSCP/IPP :            0/  0/  0
  VxLAN Flg/Grp/vid   :     0000/    0/    0
  IP  Destination     :          192.168.0.2
      Source          :          192.168.0.1
  MAC Destination     :    00:15:4d:13:30:5c
      Source          :    00:15:4d:13:30:81
  PCI Vendor/Addr     :    19ee:4000/05:00.0
  </code></pre>
  <p>when I try to capture with <code>tcpdump -i enp6s0np1</code>, it doesn't record anything. Are those issues related and if yes, is there any workaround? Shouldn't some packets be captured by tcpdump on server2?</p>