ppp_recv_config
ppp_recv_config(0, PPP_MRU, (u_int32_t) 0, 0, 0);
ppp_recv_config(f->unit, (go->neg_mru? MAX(wo->mru, go->mru): PPP_MRU),
ppp_recv_config(f->unit, PPP_MRU,
ppp_recv_config(unit, PPP_MRU, 0xffffffff,
void ppp_recv_config(int, int, u_int32_t, int, int);