Hi Edward, I was trying to configure a rxe device on the lo interface and although some tests (e.g. ib_send_bw) work fine and some of the python tests run correctly many do not. This is useful for testing because I can generate loopback traffic that actually traverses the IP stack after disabling the internal loopback path in rxe. This a more realistic test case. The problem occurs somewhere in libibverbs in the call to ibv_resolve_eth_l2_from_gid(). I'd be interested if the problem is obvious. There are at least a couple of issues. First the default gid_index in tests is 0 and the MAC address based GID[0] for lo is all zeros which breaks things. If you set it to 1 which gives you the IPV6 mangled version of 127.0.0.1 you get further but a netlink message exchange fails and I haven't been to figure it out. Regards, Bob Pearson