User Manual
TRex 96 / 113
+----+------+---------++-------------------------------+-----------+-
| 9 | 1 | 87:00.0 || MT27700 Family [ConnectX-4] | mlx5_core | #
v
1
+----+------+---------++-------------------------------+-----------+-
| 10 | 1 | 87:00.1 || MT27700 Family [ConnectX-4] | mlx5_core | #
v
2
+----+------+---------++---------------------------------------------
v
1
ConnectX-4 port 0
v
2
ConnectX-4 port 1
Config file example
### Config file generated by dpdk_setup_ports.py ###
- port_limit: 2
version: 2
interfaces: [’87:00.0’, ’87:00.1’]
port_info:
- ip: 1.1.1.1
default_gw: 2.2.2.2
- ip: 2.2.2.2
default_gw: 1.1.1.1
platform:
master_thread_id: 0
latency_thread_id: 1
dual_if:
- socket: 1
threads: [8,9,10,11,12,13,14,15,24,25,26,27,28,29,30,31]
7.8.4 TRex specific implementation details
TRex uses flow director filter to steer specific packets to specific queues. To support that, we change IPv4.TOS/Ipv6.TC LSB to
1 for packets we want to handle by software (Other packets will be dropped). So latency packets will have this bit turned on (This
is true for all NIC types, not only for ConnectX-4). This means taht if the DUT for some reason clears this bit (change TOS LSB
to 0, e.g. change it from 0x3 to 0x2 for example) some TRex features (latency measurement for example) will not work properly.
7.8.5 Which NIC to buy?
NIC with two ports will work better from performance prospective, so it is better to have MCX456A-ECAT(dual 100gb ports)
and not the MCX455A-ECAT (single 100gb port).
7.8.6 Limitation/Issues
For some reason the mlx5 driver is special and while working, integrating and running regression 24/7 we found a few issues
with how TRex utilized it. TRex uses special RSS configurations and filters and this might bring up the issues that otherwise
were not observed (e.g. Simple DPDK l3 application). The list of the issues can be seen here open issues Mellanox is aware of
those issues.
for example: * In ASTF mode there is an out of order of TCP packets see out-of-order * Stateless mode “per stream statistics”
feature is handled in software (No hardware support like in X710 card). * Latency issue * Statful RX out of order * CX-5
performance issue