Low throughput between vmWare hosts in vxlan topology - spurious retransmissions.
Got this weird case of low throughput between hosts. Seems to me, the problem starts when there are 3 outstanding packets in flight that are not full size. The receiver seems to acknowledge them first, then the rest of the packets. By that time the receiver has generated 3 duplicate ACK packets which triggers the sender re-transmit packets that were already acknowledged. Took a capture at both sides while running iperf. Throughput from A to B is low (around 1Gbps), B to A is ok. If we remove one leg of the port-channel on B side, throughput improves significantly. download packet captures
Have you ever tried to use the port-channel on B-side as an active-backup configuration instead of a load balancing configuration?
BTW you are facing real packet loss here, too!
Thanks Christian, we are not using active-standby port channels. Where do you see the packet loss? I see exactly the same number of sent and received packets at both sides:
yes you are right no loss, I was missled by my wireshark. -> Different story
But then I think you should try an active-standby setup as the out of order arrivals are slowing down your session. Or you can post the trace, where you disconnected one leg, so I can proof my assumption.
Captures with one of the port channel legs down.