Slow or non-working TCP connections over VXLAN with Cisco Systems NICs
Issue
TCP checksums of TCP segments that are encapsulated in VXLAN segments by OVS are incorrect. As a result receiving side is dropping those TCP segments after checking their checksums.
Environment
The issue was found in RHOSP 12, but it is not RHOSP-specific. The following conditions were met:
- kernel-3.10.0-862.3.2.el7.x86_64
- openvswitch-2.7.3-3.git20180112.el7fdp.x86_64
- Cisco Systems Inc VIC 1340 MLOM Ethernet NIC
-
the following NIC settings were configured in Cisco UCS Manager:
- Receive Side Scaling (RSS)
- Accelerated Receive Flow Steering
- Network Virtualization using Generic Routing Encapsulation
- Virtual Extensible LAN
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