Trex opackets drop seen

[Amar K Hrishikesh]

Hey Team,

in stateless mode while sending bidirectional or unidirectional traffic seeing packet drop,

at low rate itself issue seen

iam using trex v2.96

installed on

Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz

Architecture:          x86_64

CPU op-mode(s):        32-bit, 64-bit

Thread(s) per core:    2

Core(s) per socket:    18

Socket(s):             2

NUMA node(s):          2

along with 2 Mellanox MT27800 connect x5 single port installed in same NUMA node

5e:00.0 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5] 86:00.0 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5]

### Config file generated by dpdk_setup_ports.py ###

- version: 2  

interfaces: ['5e:00.0', '86:00.0'] 

port_info:      

    - dest_mac: 00:0a:35:3a:9b:62       

      src_mac:  04:3f:72:c7:c5:8a      

    - dest_mac: 00:0a:35:8a:f4:b7      

      src_mac:  04:3f:72:e9:6b:36

#####################################

say i am sending traffic from port 0 of trex  .

so if i take Trex statistics from Trex console )

opackets value is 397681765 (outgoing packet from Trex to dut)

ipackets value is 397569500( incoming packets from dut to trex)

there is a loss of 112265 packets for say 25gbps (seen at all rates lower rate, drop very less)  this 112265 packets never reached our DUT  ingress

is there any way to find out why drop rate ,  on outgoing packets from trex because it never reached out DUT ( connection from TREX to DUT is directly connected and i'am testing stateless  traffic )

##################################

Earlier i was using trex v2.89 with dual port mellanox that time i didn't face this issue,

can you suggest any way to resolve this

would be great if we get any input on the same

Thanking you in advance

regards

Amar

[Besart Dollma]

Hi Amar, 

These values that you are talking about, are they taken when the traffic has finished sending or while there is still ongoing traffic?

Also, what is your topology, usually what you TX (opackets) in port 0 should Rx in port 1 (ipackets), so are these values indeed from two different ports?

Thanks, 

[Amar K Hrishikesh]

Hi Besart

Yes these values are taken once traffic has been completely stoped 

I have checked status of trex console manually &  stateless scripts aswell both shows the same difference 

Topology is Trex is directly connected to my dut. So from port 0 egress (opackets) of trex and port 1(ipackets) ingress of trex is what iam comparing 

Dut side there is no drop, but there is a  difference in packets reaching the dut 

Like i mentioned above :

there is a loss of 112265 packets for say 25gbps (seen at all rates lower rate, drop very less)  this 112265 packets never reached our DUT  ingress 

so like i mentioned i have around 120 stateless scripts with different traffic patern all were working with my old trex setup (v2.89 and dual port nic mellanox installed in a different server  )

Now i have moved to latest version 2.96 and single port mellanox 2 nic card installed in same numa node in a new server details have been mentioned in above thread, now i see this issue with rate difference between opackets of port 0 and ipackets port 1 

Thanks 

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[Besart Dollma]

Hi,

Can you provide the output of stats -x?

Thanks,

[Amar K Hrishikesh]

Hi Besart,

sorry for the late reply, i am on holidays please expect some delay

thanks

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[Amar K Hrishikesh]

Hey Besart ,

sorry for the delayed response,

so was checking the same  stats -x output

so TX out from TREX = 31589343

RX ingress on our DUT = 31566950

in between there is a loss of packets. cable is 100g, tried changing cables still the same , did not change the mellanox card yet !

is there any chance packet can be still dropped at port 0 of TREX?

thanks

[Besart Dollma]

Hi Amar, 

Your problem is not with the Tx but rather with the Rx. You are not receiving all the transmitted packets. As such, I asked you to provide the xstats for the RX port (port 1), so we can see if there are any discards at the NIC level.

Please provide the xstats for port 1 (you provided for port 0).

Thanks,