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Unexpected TCP retransmissions


I am trying to debug a network using wireshark. I have a few VMs running on virtualbox. One of the VM is connected to the host using a "host only" interface. The host runs OVS through which all the VMs communicate. I ran wireshark on one of the VMs and the corresponding port on OVS and I see a number of TCP retransmissions. What can cause this?

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asked 13 Aug '12, 17:13

Abhishek%20Chanda's gravatar image

Abhishek Chanda
accept rate: 0%

One Answer:


I see the following, possible reasons:

  • a bug in the OpenFlow dissector (see also error message in the screenshot)
  • a bug in Open vSwitch
  • some kind of overload in your virtual environment, leading to drops within the Open vSwitch or one of the VMs
  • a bug in yor OS/application that handles the HTTP connection
  • any other strange problem, wich is unpredictable without further information about your system and software versions used.


answered 14 Aug '12, 03:28

Kurt%20Knochner's gravatar image

Kurt Knochner ♦
accept rate: 15%

This turned out to be a problem with Virtualbox. I changed to KVM and its gone.

(23 Aug '12, 16:06) Abhishek Chanda