0

                            +------------+
                            |            |
               +------------|  tester    |<-------------+
               |            |            |              |
               |            +------------+              |
               |                                        |
               |            +------------+              |
               |            |            |              |
               +----------->|    DUT     |--------------+
                            |            |
                            +------------+

Hey guys. in our scenario we have one DUT and one TRex traffic generator with following configurations.

# /etc/trex_cfg.yaml 

- version: 2
  interfaces: ['03:00.1', '05:00.1']
  port_info:
      - ip: 10.0.0.1
        default_gw: 10.0.0.2
      - ip: 10.0.0.5
        default_gw: 10.0.0.6

  platform:
      master_thread_id: 0
      latency_thread_id: 1
      dual_if:
        - socket: 0
          threads: [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23]
# cap2/dns.yaml

- duration : 10.0
  generator :  
          distribution : "seq"
          clients_start : "16.0.0.1"
          clients_end   : "16.0.1.255"
          servers_start : "48.0.0.1"
          servers_end   : "48.0.0.255"
          clients_per_gb : 201
          min_clients    : 101
          dual_port_mask : "1.0.0.0" 
          tcp_aging      : 1
          udp_aging      : 1
  cap_info : 
     - name: cap2/dns.pcap
       cps : 1.0
       ipg : 10000
       rtt : 10000
       w   : 1

In our case we run following command for creating traffic :

./t-rex-64 -f cap2/dns.yaml -d 10

We have two pair interfaces in tester and DUT and we turned them on. traffic generated and transferred from client to server but RX pkts are more that TX pkts! But why ? In wrong scenario we have packet drop, but in this case we have extra packets in server interface. We sent 18 pkts but received 92 pkts. How can I fix it ?

------------                               
 opackets                                 : 9                                                                                                                                  
 obytes                                   : 837                                                                                                                                
 ipackets                                 : 51                                                                                                                                 
 ibytes                                   : 3264                                                                                                                               
 Tx :     363.39  bps                                                                  
 Cpu Utilization : 0.1  %                                                              
 Platform_factor : 1.0                                                                 
 Total-Tx        :     664.27  bps                                                     
 Total-Rx        :       4.54 Kbps                                                     
 Total-PPS       :       0.98  pps                                                                                                                                             
 Total-CPS       :       0.49  cps                                                     
                                           
 Expected-PPS    :       2.00  pps                                                     
 Expected-CPS    :       1.00  cps                                                     
 Expected-BPS    :       1.36 Kbps                                                     
                                           
 Active-flows    :        0  Clients :      511   Socket-util : 0.0000 %                                                                                                       
 Open-flows      :        9  Servers :      255   Socket :        0 Socket/Clients :  0.0 
 drop-rate       :       0.00  bps                                                     
 summary stats                             
 --------------                            
 Total-pkt-drop       : 0 pkts                                                         
 Warning : number of rx packets exceeds 101% of tx packets!                                                                                                                    
 Total-tx-bytes       : 1530 bytes                                                     
 Total-tx-sw-bytes    : 0 bytes                                                        
 Total-rx-bytes       : 5888 byte                                                      
                                           
 Total-tx-pkt         : 18 pkts                                                        
 Total-rx-pkt         : 92 pkts                                                        
 Total-sw-tx-pkt      : 0 pkts                                                         
 Total-sw-err         : 0 pkts                                                                                                                                                 
 Total ARP sent       : 4 pkts                                                         
 Total ARP received   : 2 pkts                                                         

For troubleshooting I used wireshark on DUT interfaces. right side is about server interface with 48.0.0.0/8 route and 10.0.0.6 ip and left side is about client interface with 16.0.0.0/8 route and 10.0.0.2 ip. Following picture is result of ./t-rex-64 -f cap2/dns.yaml -d 1 with following result.

 summary stats 
 -------------- 
 Total-pkt-drop       : 0 pkts 
 Warning : number of rx packets exceeds 101% of tx packets!
 Total-tx-bytes       : 170 bytes 
 Total-tx-sw-bytes    : 0 bytes 
 Total-rx-bytes       : 512 byte 
 
 Total-tx-pkt         : 2 pkts 
 Total-rx-pkt         : 8 pkts 
 Total-sw-tx-pkt      : 0 pkts 
 Total-sw-err         : 0 pkts 
 Total ARP sent       : 4 pkts 
 Total ARP received   : 2 pkts 

enter image description here

2
  • For the packet capture to show meaningful results you need to filter the packets so that you only see TRex packets. Your capture shows only unrelated packets from ARP, DNS, ICMP. What kind of device is the DUT?
    – Zac67
    Jan 10 at 12:54
  • I filtered only TRex packets. I have two interfaces for TRex and wireshark capture just enp6s0f1 and enp3s0f1. TRex send ARP and ICMP packets ... Jan 11 at 5:49

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