High-speed SLIP/PPP

[Rich Braun]

There has been some discussion of CTS/RTS in comp.unix.sysv386, and I'm
in the midst of specifying a SLIP interface for a product under
development.  One of the requirements is the ability to communicate with
SLIP running on virtually any Unix system.

SCO's TCP product includes a caveat that SLIP won't work faster than
2400 baud for Unix 3.2.0 or earlier; presumably they've made some fixes
to the serial port driver so it will handle faster data rates without
flow control.

The engineering veep here shudders at the thought of hardware flow
control.  I'm claiming one should support CTS/RTS in the interest of
providing better performance.  But he does have a point:  I've spent
many an hour tearing out my hair making RS-232 interfaces work against
odd flavors of equipment, and we don't want our customers to go bald
too.

So, I pose the question to the net.  When designing a new product which
supports SLIP, what kind of performance can I expect without flow
control against various flavors of Unix?  Will I have to get into the
business of writing device drivers and/or OEMing "smart" serial cards?
Am I crazy to consider developing an interface without RTS/CTS?  Is
the half-duplex hardware flow control supported by SCO widespread enough
that I need to worry about supporting it?

Finally, PPP (Point to Point Protocol) seems to address many inadequacies
in SLIP.  For example, it's possible to use XON/XOFF flow control with
PPP, because it remaps control characters out of the range 01-1F.  Is
PPP catching on quickly, and is it generally expected that new products
supporting serial-line IP should also support PPP?  (And, can I get a
public-domain C implementation?)

-rich