ND_NA_FLAG_OVERRIDE
ND_NA_FLAG_OVERRIDE, 1, NULL);
flags &= ~ND_NA_FLAG_OVERRIDE;
((anycast || proxy || !tlladdr) ? 0 : ND_NA_FLAG_OVERRIDE) |
((anycast || proxy || !tlladdr) ? 0 : ND_NA_FLAG_OVERRIDE) |
is_override = ((flags & ND_NA_FLAG_OVERRIDE) != 0);