Hi there, Santa brought me a huge pile of useless crap, but also new network equipment: a Cisco 20-port managed switch (SRW2016-K9) I'm currently trying to set up a new network environment. For better performance I want the designated server (a Mac Mini 2011 running 10.8.2) to use link aggregation on two ports (the native ethernet port and one via a Thunderbolt adapter). Both connections receive their IP addresses through DCHP from another router when plugged in > connection established. I then created a network bond in sysprefs/network ('manage virtual interfaces' > 'new link aggregate' with both ports. No problems so far. On the switch I set port speed to 1000Mbit and full duplex mode for both ports (Port Management/Port Settings). Then I added both ports to one LAG enabling LACP. However, only one member - the Thunderbolt Ethernet - was recognized and went green (OS X/sysprefs/advanced). The light for the native port is blinking, changing between red and orange. The error messages 'Invalid Link' ('The link state was not valid, i.e. down, half-duplex, or wrong speed') and 'No Partner' ('The port on the switch that the device is connected to doesn't seem to have 802.3add Link Aggregation enabled.') are changing accordingly. The port on the switch in which the native ethernet is plugged into is 'down' (no LED). I checked the physical connections, exchanged cables and used different ports - no avail. When I connect two Macs (one of which is the above mentioned Mini) with two patch cables directly, the connection works just fine. I further tested link aggregation in a similar setup (Mini 2012 and Display Ethernet and a Retina MBP with two Thunderbolt Ethernet adapters). > no problems AT ALL! Any ideas? Any hints are greatly appreciated!