RoCE Configuration for Arista switches

Version 4

    This post provides a configuration example for Arista switches running RoCE over a lossy or a lossless network in PCP/DSCP-based QoS mode.



    • Configuration was derived and tested on DCS-7050QX-32, EOS-4.12.4



    Step 1 - configure buffers

    platform trident mmu queue profile RoCELosslessProfile

       ingress threshold 1/16

       egress unicast queue 3 threshold 8

    platform trident mmu queue profile RoCELosslessProfile apply

    Step 2 - configure load balancing

    port-channel load-balance trident fields mac src-mac dst-mac

    port-channel load-balance trident fields ip source-ip destination-ip source-port

    Step 3 - per port configuration

    Enable PFC and configure ECN:

    interface Ethernet1/1-1/32

       priority-flow-control mode on

       priority-flow-control priority 3 no-drop

       tx-queue 3

          random-detect ecn minimum-threshold 150 kbytes maximum-threshold 1500 kbytes

          bandwidth guaranteed 20000000

    [If trust DSCP] Set trust layer

    interface Ethernet1/1-1/32

       qos trust dscp

    [If trust PCP] Set trust layer and configure vlan access

    interface Ethernet1/1-1/32

       qos trust cos

       switchport access vlan [vlan-id]

       switchport trunk allowed vlan [vlan-id]

    [Optional] Enable DCBX LLDP

    Note: This is required in case the adapter card relies on LLDP configuration in the switch for setting priority for PFC.

    interface Ethernet1/1-1/32

       dcbx mode ieee

    Step 4 - QoS mapping - needed only if trust DSCP

    qos map dscp 0 to traffic-class 0

    qos map dscp 26 to traffic-class 3

    qos map dscp 48 to traffic-class 7

    qos map traffic-class 0 to dscp 0

    qos map traffic-class 3 to dscp 26

    qos map traffic-class 7 to dscp 48