>>222 docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Technical_Notes/ar01s04s02.html > A change in the 2.6.31 Linux kernel made the net.ipv4.conf.default.rp_filter = 1 more strict in the I/O that is accepted. > Consequently, in Red Hat Enterprise Linux 6, if there are multiple interfaces on the same subnet and I/O is sent to the one that is not the default route, the I/O will be dropped.