sppp_reopen — notify of physical link loss
int sppp_reopen (struct net_device * dev);
This function informs the synchronous protocol code that the underlying link died (for example a carrier drop on X.21)
We increment the magic numbers to ensure that if the other end failed to notice we will correctly start a new session. It happens do to the nature of telco circuits is that you can lose carrier on one endonly.
Having done this we go back to negotiating. This function may be called from an interrupt context.