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

Solution Verified - Updated -


  • 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.


  • Red Hat Enterprice Linux (RHEL) 7
  • Red Hat OpenStack Platform (RHOSP) 10
  • Red Hat OpenStack Platform (RHOSP) 11
  • Red Hat OpenStack Platform (RHOSP) 12

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