Bill Studenmund (wrstuden@loki.stanford.edu) wrote:
: Howdy, everyone!
: 
: As part of the LocalTalk design, I've been snooping around in the
: network source, and have some questions.
: 
: What are the packet reading & writing routines in
: src/usr.sbin/pppd/sys-bsd.c for? It looks to me like our ppp keeps
: packets in the kernel, so why are they going out? Or am I missing
: something, and the packets really do cross the blood- brain barrier
: twice?

No.

The real payload packets (that is, currently, only IP) are handled
inside the kernel.

However, everything not recognized is still output (rather: input) via
the read() system call. The pppd uses this to access the link control
protocol, the authentication protocols and the IP control protocol, and
would use it for other protocol control protocols once we support them
via PPP.

When pppd decides that some protocol should pass-through in the kernel, it
issues an ioctl to make it pass (or block); the corresponding data are
short-circuited to, say, ipinput().

Regards,
	Ignatios Souvatzis