sppp_down_event
sppp_down_event(sp, xcp);
static void sppp_down_event(struct sppp *, void *);
sppp_up_event, sppp_down_event, sppp_ipcp_open,
sppp_up_event, sppp_down_event, sppp_ipv6cp_open,
sppp_up_event, sppp_down_event, sppp_open_event,
sppp_up_event, sppp_down_event, sppp_chap_open,