On 13-Nov-18 7:16 AM, Sam wrote:
Hi all,
As we know, ethernet frame must longer then 64B.
So if I create rte_mbuf and fill it with just 60B data, will
rte_eth_tx_burst add padding data, let the frame longer then 64B
If it does, where is the code?
Others can correct me if i'm wrong here, but specifically in case of
64-byte packets, these are the shortest valid packets that you can send,
and a 64-byte packet will actually carry only 60 bytes' worth of packet
data, because there's a 4-byte CRC frame at the end (see Ethernet frame
format). If you enabled CRC offload, then your NIC will append the 4
bytes at transmit. If you haven't, then it's up to each individual
driver/NIC to accept/reject such a packet because it can rightly be
considered malformed.
In addition, your NIC may add e.g. VLAN tags or other stuff, again
depending on hardware offloads that you have enabled in your TX
configuration, which may push the packet size beyond 64 bytes while
having only 60 bytes of actual packet data.
--
Thanks,
Anatoly
