-- binary
01 0f # version/type
00 20 # length
00 00 00 02 # xid
ff fd # port_no
01 02 03 04 05 06 # hw_addr
90 ab cd ef # config
ff 11 ff 11 # mask
ca fe 67 89 # advertise
00 00 00 00 # pad
-- python
ofp.message.port_mod(
    xid=2,
    port_no=ofp.OFPP_CONTROLLER,
    hw_addr=[1,2,3,4,5,6],
    config=0x90ABCDEF,
    mask=0xFF11FF11,
    advertise=0xCAFE6789)
-- c
obj = of_port_mod_new(OF_VERSION_1_0);
of_port_mod_advertise_set(obj, 0xCAFE6789);
of_port_mod_config_set(obj, 0x90ABCDEF);
{
    of_mac_addr_t hw_addr = { { 1, 2, 3, 4, 5, 6 } };
    of_port_mod_hw_addr_set(obj, hw_addr);
}
of_port_mod_mask_set(obj, 0xFF11FF11);
of_port_mod_port_no_set(obj, 65533);
of_port_mod_xid_set(obj, 2);