Hi, Can you attach a basic topology diagram, showing the ports with the performance problem, and how they are connected?
Are the inter-switch ports showing any discards or errors?
Are the inter-switch ports part of a port channel? Is there mlag configured on these inter-switch ports?
"When the same 40G port sends traffic to a 10G port located on the same switch, the performance is very good, nearly line speed (9.9Gb/s)."
Did you do this same test on "both" switches?
The issue has been resolved via support. The config was missing the following:
interface port-channel 1 vlan map-priority 0 traffic-class 1
dcb priority-flow-control priority 0 enable
It may be worth updating the community MLAG how-to's with these lines as I don't believe this is in there.
With that in, everything is now working well.
Great - thanks for the update.