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advantages/disadvantages of kernel pppoe(4) vs userland pppoe(8)?
- To: misc_(_at_)_openbsd_(_dot_)_org
- Subject: advantages/disadvantages of kernel pppoe(4) vs userland pppoe(8)?
- From: Jonathan Thornburg <jthorn_(_at_)_aei_(_dot_)_mpg_(_dot_)_de>
- Date: Fri, 21 Apr 2006 14:30:00 +0200 (CEST)
- Cc: Jonathan Thornburg <jthorn_(_at_)_aei_(_dot_)_mpg_(_dot_)_de>
I'm about to setup up ADSL at home for the first time, using the
following network topology:
ADSL +-------+ +----------+ +----------+
to <-----> | DSL |<-------> | firewall | <-----> | ethernet |
ISP | modem | pppoe | + router | | switch |
+-------+ | + nat | +----------+
+----------+ | | |
V V V
to other computers
The firewall/router/nat box is (will be when I get this setup)
an old 486 laptop with 2 pcmcia ethernet cards, running 3.9-stable.
(Yes, I've ordered a CD; until it arrives I'm using 3.8-stable.)
I already have the (external) DSL modem, and from talking to other
Unix-savvy customers of my ISP (arcor.de), their setup is that the
DSL modem talks pppoe to me (in this case to my firewall/router/nat
box). From looking at the FAQ section 6, it seems I have two basic
options available doing this in OpenBSD: pppoe(4) in the kernal, and
pppoe(8) in userland. My question is, what are the relative
advantages/disadvantages of these?
The obvious tradeoff is performance: I expect pppoe(8) to be slower
due to the extra kernel/user-space crossings for each packet. My
ADSL is 6M bits/sec downstream, 0.5M upstream.
But are there other significant differences in
* support for pppoe features?
* ease of configuration?
-- "Jonathan Thornburg (remove -animal to reply)" <jthorn_(_at_)_aei_(_dot_)_mpg-zebra_(_dot_)_de>
Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut),
Golm, Germany, "Old Europe" http://www.aei.mpg.de/~jthorn/home.html
"Washing one's hands of the conflict between the powerful and the
powerless means to side with the powerful, not to be neutral."
-- quote by Freire / poster by Oxfam