On Wed, Nov 28, 2018 at 7:40 PM Cong Wang <xiyou.wangc...@gmail.com> wrote: > > On Wed, Nov 28, 2018 at 4:07 PM Eric Dumazet <eduma...@google.com> wrote: > > > > A NIC is supposed to deliver frames, even the ones that 'seem' bad. > > A quick test shows this is not the case for mlx5. > > With the trafgen script you gave to me, with tot_len==40, the dest host > could receive all the packets. Changing tot_len to 80, tcpdump could no > longer see any packet. (Both sender and receiver are mlx5.) > > So, packets with tot_len > skb->len are clearly dropped before tcpdump > could see it, that is likely by mlx5 hardware.
Or a router, or a switch. Are your two hosts connected back to back ?
