Throughput drop, TCP out-of-order packets and re-transmissions when crossing veth device

Issue

• Standard network performance tooling displays remarkable drops in throughput (~50%), along with high number of retransmissions, drastic reduction in TCP Congestion Window (Cwnd), and out-of-order packets on a single TCP network stream traffic between two instances running on different compute nodes (East-West traffic).
• The problem can also be reproduced on physical nodes by directly using interfaces that have to cross a veth device.