[ovs-discuss] gratuitous arp replies on behalf of virtual machine

Ben Pfaff blp at nicira.com
Wed Mar 18 14:59:06 UTC 2015

On Wed, Mar 18, 2015 at 03:35:53PM +0100, Stefan Kooman wrote:
> Hi All,
> I'm trying to achieve the following: I would like to send gratuitous arp
> replies on a OpenvSwitch (tagged) virtual machine (VM) interface (vnet5) from
> the host itself (Ubuntu 14.04, OVS 2.0.2) (to update upstream switch(es) their
> mac-address-tables after a live-migration of the VM). Therefore I made a little
> python script that utilizes Scapy, relevant part:
> sendp(Ether(src=args.macaddress,dst="ff:ff:ff:ff:ff:ff") / ARP(op=2,
> hwsrc=args.macaddress, psrc=args.ipaddress, hwdst="ff:ff:ff:ff:ff:ff",
> pdst=""), iface=args.vnet, count=4, inter=0.2)
> The gratuitous arp replies do come in one the Virtual Machine itself, but never
> make it out of the bridge (uplink), bond (bond1) and physical interface(s)
> (eth2, eth5): 

I think that this sends the packet in the wrong direction (toward the
VM).  I don't know how to inject a packet in the direction that you

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