> As the one who initially made this hack, the basic probblem (and the reason
> for the bisdnd -- pppd connection) is that there (was / is ) no sane way
> of openeing a network device for reading. If we could bind a socket to 
> an interface (BELOW any real network stack!!) (or fake a character device for 
> it) we could avoid the communictation between the userland deamons.
> It is only needed to relay the PPP controlpackts (which in async ppp continue
> to be send/received through /dev/ttyxx) to the pppd daemon and to issue the 
> ioctls for ppp state-changes.

Since there are other uses of an hdlc link than just sppp, we need a way
to tell the port what to stack on top. We don't have a way to do this with
network interfaces at the moment (they assume that all attachable protocols
work at once). With tty's, we have line disciplines.

My thought for the hdlc device was to add a character device (seperate
from any async tty character device) on the port and give it line
disciplines. The character side of the interface would be much like
the char side of a tun interface (read and write whole packets).
In ppp mode, control packets could come down this interface.

What other ioctls are needed?

Take care,

Bill