[Winpcap-users] WinPcap, VMWare and Packet Loss

Max WhoTheHellCares krakazzyabra at gmail.com
Mon Mar 2 11:59:56 PST 2009


Hi everybody!

I have recently stumbled upon a problem, which renders my project
nearly useless....

I have 2 VMs on two physical servers, each one runs Win2k3 Server. My
server-side program sends packets using WinPcap, the client-side gets
them using WinPcap (lets call them Tx and Rx respectively).
Up till now i worked without VMs - Win2k3 Server was installed on both
physical servers. My project worked like it should - without losses
during packet transfer from server to client.

Now, as i started using VMs (Virtual NIC is BRIDGED to physical), i
get packet loss ~11% in case Tx AND Rx are installed on VMs.
If i install only one side (Tx OR Rx) on VM and the other one on
physical disk(on another server), packet loss is still present, but
varies depending on which side (Tx or Rx) is installed on VM. It goes
like this:

Transmitter      Receiver      %packet loss
-------------------------------------------------------------
TX                  RX               0%
TX                  VM_RX        10%
VM_TX            RX              0.1%
VM_TX            VM_RX        11%

where TX, RX - installed on physical machines
         VM_TX, VM_RX - installed on virtual machines.

How it works: having done extensive debug on the Tx side,
pcap_sendpacket(...) sends everything without errors. However the Rx
side still registers packet loss. BTW, WinPcap version is 3.1beta.

Please, if someone has a clue of why this happens, share your
thoughts, my project is on-hold ATM.

Thanks in advance.


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