RTF_PROTO1
flags |= RTF_PROTO1;
{ RTF_PROTO1, '1' },
(RTF_LLINFO | RTF_PROTO1 | RTF_PROTO2 | RTF_PROTO3 | RTF_BLACKHOLE | \
#define RTF_PROBEMTU RTF_PROTO1
#define RTF_USETRAILERS RTF_PROTO1 /* use trailers */
{ RTF_PROTO1, '1' },
RTFLAG("1", RTF_PROTO1);