Voyage AP and bridging

All this wireless talk prompts me to write about something
that has been
puzzling me for a while.

Steve and others who may be able to help, I have a voyage AP
(in an old
laptop) and currently the wireless stuff is on a separate
subnet
(10.1.10.x) from the wired stuff (192.168.1.x).

The main problem with this is that broadcasting/scanning
does not work for
stuff like samba shares, cups printers etc (because
broadcasts will not
cross the subnet boundaries).

The voyage docs talk about setting up bridging like this:

"3.6 Bridging
======================
The most common way to bridge wireless (ath0) and LAN (eth1)
as follow:
iwpriv ath0 mode 3
iwconfig ath0 mode master
iwconfig ath0 essid <my essid>
iwconfig ath0 txpower auto
iwconfig ath0 enc off
iwconfig ath0 rate auto
ifconfig ath0 0.0.0.0 up

ifconfig eth1 0.0.0.0 up

brctl addbr br0
brctl addif br0 eth1
brctl addif br0 ath0
ifconfig br0 up

You may also include the above commands in
/etc/network/interface."

Will this result in the eth0 lan and the ath0 lan being ion
the same
subnet? Is that what bridging is all about? Does anyone else
run an AP
like that?

At a deeper lever, do the wireless clients then get a dhcp
address from a
(different) box on the wired lan? At present wired boxes get
their dhcp
from ipcop and wireless get theirs from the voyage box.

Or am I totally off the wall on what the result of bridging
will be?

Nick.

On Mon, 12 Mar 2007 13:54:08 +1300 (NZDT)
nickrout.co.nz wrote:

> All this wireless talk prompts me to write about
something that has been
> puzzling me for a while.
> 
> Steve and others who may be able to help, I have a
voyage AP (in an old
> laptop) and currently the wireless stuff is on a
separate subnet
> (10.1.10.x) from the wired stuff (192.168.1.x).
> 
> The main problem with this is that
broadcasting/scanning does not work for
> stuff like samba shares, cups printers etc (because
broadcasts will not
> cross the subnet boundaries).
> 
> The voyage docs talk about setting up bridging like
this:
> 
> "3.6 Bridging
> ======================
> The most common way to bridge wireless (ath0) and LAN
(eth1) as follow:
> iwpriv ath0 mode 3
> iwconfig ath0 mode master
> iwconfig ath0 essid <my essid>
> iwconfig ath0 txpower auto
> iwconfig ath0 enc off
> iwconfig ath0 rate auto
> ifconfig ath0 0.0.0.0 up
> 
> ifconfig eth1 0.0.0.0 up
> 
> brctl addbr br0
> brctl addif br0 eth1
> brctl addif br0 ath0
> ifconfig br0 up
> 
> You may also include the above commands in
/etc/network/interface."
> 
> Will this result in the eth0 lan and the ath0 lan being
ion the same
> subnet? Is that what bridging is all about? Does anyone
else run an AP
> like that?
In effect, yes. There are still two subnets, but they are
joined at the ethernet frames level, so all services running
on them are visible to all. Routing is at the IP level, so
traffic destined for the other subnet will be routed there.

Using the ISO model, routing takes place at level 3
(network) layer, whereas bridging is on level 2 (data)
layer.
> 
> At a deeper lever, do the wireless clients then get a
dhcp address from a
> (different) box on the wired lan? At present wired
boxes get their dhcp
> from ipcop and wireless get theirs from the voyage
box.
If you have a dhcp server on each subnet, then either is
able to answer over a bridge.
> 
> Or am I totally off the wall on what the result of
bridging will be?
Smack on
> 
> Nick.
> 
> 

In short - yes.  Bridging will connect ath0 to eth0 with a
"patch cable" so
broadcasts will broadcast.

APs work like that all the time - simply moving the ethernet
frames on wires
to wireless and back again.

All traffic would be in the wired subnet of
192.168.XX.whatever/24  DHCP
could be served by a wired host to wireless laptops fine. 
Your
understanding is perfect.

Dooes the voyage give you WPA encryption?



-----Original Message-----
From: nickrout.co.nz [mailto:nickrout.co.nz] 
Sent: Monday, 12 March 2007 1:54 p.m.
To: linux-usersit.canterbury.ac.nz
Subject: Voyage AP and bridging


Will this result in the eth0 lan and the ath0 lan being ion
the same subnet?
Is that what bridging is all about? Does anyone else run an
AP like that?

At a deeper lever, do the wireless clients then get a dhcp
address from a
(different) box on the wired lan? At present wired boxes get
their dhcp from
ipcop and wireless get theirs from the voyage box.

Or am I totally off the wall on what the result of bridging
will be?

Nick.