Subject: Re: autoconfiguration question
To: Martin Husemann <>
From: None <>
List: tech-kern
Date: 05/25/1997 18:10:45
>>>>> "Martin" == Martin Husemann <> writes:

Bill> Letting the hdlc stuff do syncronous PPP is one reason I want to
Bill> make a different device. Adding a sync PPP and a LocalTalk (and
Bill> an X.25?)  line discipline would be very gross.

I tend to agree with that last statement. However, I was thinking more
along the lines of moving most of the PPP code into user-land, and
using if_tun to pass up protocol packets (after LCP & NCP have been
handled in the user-land code). I'm not terribly happy about the way
the PPP line discipline (de-) multiplexes packets between if_ppp &

This sort of thing makes sense for PPP, but it probably isn't sensible
for LocalTalk.

Martin> FreeBSD has sys/net/if_sppp.h and sys/net/if_spppsubr.c, which
Martin> I'm about to port to NetBSD. They use it for three different
Martin> HDLC card drivers and we just started using it for SyncPPP
Martin> over ISDN in the FreeBSD version of BISDN.

That would be nice. However, I'm a little worried about this approach
- the sync PPP if_sppp* code is a separate PPP stack to the async PPP
if_ppp* code from Paul Mackerras. I would rather have one PPP stack
that can handle both sync and async.

The underlying problem is that we have hardware devices that can act
as both network interfaces and character mode interfaces (besides the
zs, most ISDN cards can do both sync PPP (over HDLC), as well as async
character-at-a-time mode (using V.120 or V.110)). I'm not entirely
comfortable with the approach of attaching 2 or more different device
drivers (one network, one character) to the same physical device.

- S