sppp_dladdud
mp = sppp_dladdud(uqs, mp, uqs->sps_sap, B_FALSE);
mp = sppp_dladdud(uqs, mp, uqs->sps_sap, B_FALSE);
extern mblk_t *sppp_dladdud(spppstr_t *, mblk_t *, t_scalar_t, boolean_t);
dmp = sppp_dladdud(sps, dmp, proto, B_TRUE);