ppp_send_config
ppp_send_config(0, mtu, (u_int32_t) 0, 0, 0);
ppp_send_config(f->unit, mtu,
ppp_send_config(f->unit, mtu, 0xffffffff, 0, 0);
ppp_send_config(unit, mtu, 0xffffffff, 0, 0);
extern void ppp_send_config __P((int, int, u_int32_t, int, int));