Hi all, This mail is intended to warn people from mac address issues, and determine the best way to handle it. When you create a new VM using the engine core, its MAC address is being selected from a range of allowed addresses in the the DB. (MacPoolRanges in vdc_options table). As developers and users, you must verify the range does not conflict in anyway with existing machines (both physical and virtual), or this may lead to networking issues. _So before running a VM, please make sure it will not create issues._ The default range is 00:1A:4A:16:01:51-00:1A:4A:16:01:e6, which belongs to Qumranet and we may move to some unassigned prefix. We'd still need a way to randomize this, to prevent colleagues on the same network from collision. Here's a sample on how this is documented and used in qemu-kvm: http://www.linux-kvm.org/page/Networking#private_virtual_bridge (look for 'Generate a MAC address'). -- /d "This message will self destruct in the future. Or not."