I’m trying to send a frame that has two VLAN tags (two 0x8100 tags) out of a Mellanox ConnectX-3 40G NIC.
When tx-vlan-offload is turned on (which it is by default), I see the inner VLAN tag is missing when I sniff the frame on the wire, despite being present when the frame is sent out to the interface (as seen in tcpdump).
When I turn tx-vlan-offload off, then both VLAN tags are present on the wire as expected.
I’m using version 3.1-1.0.4 of the mlx4 driver.
Does anyone know why this is happening? Is it a bug in the driver? Is it a known issue?