[Gllug] Bridging/routing

Adrian McMenamin adrian at mcmen.demon.co.uk
Thu Jun 16 13:51:51 UTC 2011

On Wed, June 15, 2011 4:39 pm, john walker wrote:
> Hi Adrian
> I'd be interested to know how you got on. Sorry about earlier when I mixed
> up routing with bridging. Is there a kind of picture you could draw of the
> network ( ascii art maybe ). It might help me understand.

No problem. I have got it working - though it died on me after about 36
hours because of some issue which I haven't fully investiagted (reported
over full buffers then fell over):  network is like this

ADSL ------- Router (commodity) ------ Wireless AP
               | (Ethernet)
            |   |   |
     PC-----|   |   |
                |   |
     PC---------|   |--------PC (bridged) ----- Wireless AP

I need to tidy up the admin on it so the bridge comes back automatically
on reboot/restart which may eliminate the problem described above.

The key thing is that the Wireless AP on the remote machine is on the same
subnet as the other interfaces on the network - eg if a wireless machine
sends out a DHCP discovery packet it goes straight back to the router
(which is running a DHCP daemon) - I don't need to have a second DHCP
daemon running or worry about routing packets across the bridge (in the
sense that the softwar bridge does all that for me). Hope this is clear.

I did have to use an old 802.11b card for the second AP though - aiui more
modern ones need firmware changes to properly handle the layer 2 routing.

(again apologies if this turns up twice - keep forgetting to switch
accounts from the default to reply to GLLUG emails)

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