about tty line discipline and pppd

Hi all, I need your advice, please.

Situation:
I have two ppc processors with their SMC2 ports connected to each
other port. Saying 'y' to SMC2 support on kernel 2.4, I can "echo foo

quoted

/dev/ttyS1" in one processor while "cat /dev/ttyS1" on the other

and the "foo" text appears.

Question:
I want to exchange data between these two processors through sockets
interface. The right way to do that is writing a "tty line discipline"
driver?

Another question:
I tried without sucess to setup pppd on this line, the more close to a
working pppd I got was issuing "stty -F /dev/ttyS1 -echo raw", so the
pppd appears to send the LCP packets and the other peer receive them
while I watch through "cat /dev/ttyS1" but pppd itself doesn't work.
Do you have some advice on this situation too?

Thanks in advance,
Evandro Clivatti Dall'Agnol