RoCE Configuration for MLNX-OS Switches in DSCP-Based QoS Mode

Version 5

    This post provides a configuration example of RoCE over lossy network for MLNX-OS switches in DSCP-based QoS mode.

    This post assumes MLNX-OS version 3.6.5000 and above. For manual buffer configuration and older versions see:

    For other configuration modes, see Getting Started with RoCE Configuration.








    1. Enable ECN for RoCE traffic that runs over traffic class 3:

    switch (config) # interface ethernet 1/1-1/32 traffic-class 3 congestion-control ecn minimum-absolute 150 maximum-absolute 1500


    Note: For a fair sharing of switch buffer with other traffic classes, it is recommended to configure ECN on all other traffic classes.


    2. Configure the pool for RoCE

    switch (config) # traffic pool roce type lossy

    switch (config) # traffic pool roce memory percent 50.00
    switch (config) # traffic pool roce map switch-priority 3

    3. Set a strict priority to CNPs over traffic class 6

    switch (config) # interface ethernet 1/1-1/32 traffic-class 6 dcb ets strict


    4. Set trust layer to L3

    switch (config) # interface ethernet 1/1-1/32 qos trust L3


    For end to end configuration example and troubleshooting,  HowTo Configure RoCE over a Lossy Fabric (ECN) End-to-End Using ConnectX-4 and Spectrum (Trust L3)