ppp_send_config
ppp_send_config(0, PPP_MRU, (u_int32_t) 0, 0, 0);
ppp_send_config(f->unit, MIN(ao->mru, (ho->neg_mru? ho->mru: PPP_MRU)),
ppp_send_config(f->unit, PPP_MRU, 0xffffffff, 0, 0);
ppp_send_config(unit, PPP_MRU, 0xffffffff, 0, 0);
void ppp_send_config(int, int, u_int32_t, int, int);