Subject: VLAN + bridging problems
To: None <tech-net@netbsd.org>
From: Dobromir Montauk <dmontauk@rescomp.berkeley.edu>
List: tech-net
Date: 11/30/2002 16:20:15
I've found a lot of information about bridging a VLAN with a regular LAN
(both on the same netcard), but can't find anything specific to NetBSD
1.6.  Perhaps someone can help?  Here's my problem:

Packets comming in on the regular LAN (fxp0) get bridged to the VLAN fine
-- the VLAN header is automatically added & they go out to the correct
computer (who gets them w/o the VLAN header, since our switches take them
off correctly as well).
But packets comming in FROM the VLAN do NOT get their header taken off &
correctly bridged to the regular LAN.  Instead, they get another header
tacked on!  It looks pretty funky: here's the tcpdump:

17:53:44.914785 hal.Rescomp.Berkeley.EDU >
man-97-238.Reshall.Berkeley.EDU: icmp: echo request

17:53:44.914794 802.1Q vlan#95 P0 hal.Rescomp.Berkeley.EDU >
man-97-238.Reshall.Berkeley.EDU: icmp: echo request

17:53:44.915153 802.1Q vlan#95 P0 man-97-238.Reshall.Berkeley.EDU >
hal.Rescomp.Berkeley.EDU: icmp: echo reply

17:53:44.915163 802.1Q vlan#95 P0 802.1Q vlan#95 P0
man-97-238.Reshall.Berkeley.EDU > hal.Rescomp.Berkeley.EDU: icmp: echo
reply

I'm pinging from a host called hal to the host man-97-238 (which is
sitting on a VLAN port).  Clearly, the ping gets routed all the way to
man-97-238 just fine, since it gets it & responds.  But the response,
comming in on VLAN#95 (the third packet above) and supposedly going to
fxp0, instead has ANOTHER "802.1Q vlan#95 P0" tag attached.

Needless to say, this prevents man-97-238 from communicating with the
outside world.

The Linux people say that for THEIR version of the VLAN driver, there
exists an option to remove this header, just the way I want.  But I can't
find any info for such options in NetBSD.

This seems to be a bug...  Or do I have something misconfigured?  Any help
most appreciated!

Dobromir