Setup: Assume I have 3 VMs. VM1 VM2 and VM3. VM2 has two interfaces, say eth1 and eth3. eth1 is connected to VM1 physically and eth3 to VM3. I create a bridge on VM2 using brctl with eth1 and eth3.
When VM1 pings VM3, it needs MAC address of VM3. It will send ARP request to VM2. According to this, a bridging decision must be taken based only on the basis of destination MAC address (which will be roadcast ff:ff:ff:ff:ff:ff...). What should happen now. Why does it go on the forward chain?