Hi Michael, You don't have to add aliased interfaces on the device level. You can use the routing mechanism of lnet (see e.g. http://wiki.lustre.org/manual/LustreManual20_HTML/ConfiguringLNET.html and http://wiki.lustre.org/manual/LustreManual20_HTML/ManagingLNET.html) You would have a fabric containing your lustre servers and some routers for cluster A and some routers for cluster B. The routers are nothing else than servers equipped with two infiniband cards (or dual port cards), with one port in the server-fabric, the other port in the cluster fabric. You have to enable forwarding on the routers. On the servers you add the routes to the lnets in the clusters and on the clients you have to add the routes towards the server fabric. lnet in conjunction with ofed 2 uses the ip addresses (together with the lnet id) as a name for the client. It doesn't actually use ipoib. When the routes are set up correctly (back and forth) you can lctl ping the clients from the servers and vice versa, whereas ip pings can not pass trough the routers (which can be seen as an lnet connection from one fabric to the other one). Using lnet routing you shouldn't run into address conflicts on the ip level, because there is no routing between the networks on the level of the ip stack. kind regards, Martin On 05/30/2014 03:59 PM, Michael Di Domenico wrote: