Currently, some tests use udp.xml/tcp.xml, which may bind to NICs other than loopback (127.0.0.1).
Change this to always bind to 127.0.0.1 and (in case of UDP or MPING), use a multicast address in the 224.0.0.0/4 range, so we don't need to add routes to other mcast addresses to the routing table.