First I want to note that I do like openwrt and my asterisk box on it is working gracefully.

But the thing is that I have been using dd-wrt as a wireless "BRIDGE" for years with Fonera. Since I've moved to openwrt, people say Athores (or was it madwifi driver?) is not capable of such thing. (I mean, setting the same network subnet with ath0(client connection to other wi-fi router) and eth0)

Everybody is taking this 'can't do wireless bridge' so naturally, there isn't really any explanation anywhere.
I understand both distributions are actively developed and one of them done this wireless bridge thing with Fonera years ago, why can't openwrt do this as well? Is this so, because it’s a bug, a to-do, or unnecessary?

BTW, I am not criticizing anything here. I am just genuinely curious. We are so used to ask how here, and in the process we stop asking why or even why not.

Hi.

A wireless client bridge requires arp-nat to perform a kind of layer 2 masquerading between ethernet and wifi.
This is needed because 802.11 wireless uses a three-mac-address-format in station mode while bridging requires a four-mac-address-format for ethernet frames.

Due to the missing fourth mac address, the ap can't determine the actual sender of a frame on the stations lan side and only sees the stations wireless interface as sender. Therefore the reply frames are sent to the wrong destination mac and the host on the lan side can't receive them.

Iirc, a while ago, some users requested the inclusion of arpnat patches into OpenWrt but it was refused since it degrades bridging performance.

~ JoW

(Last edited by jow on 25 Mar 2009, 12:28)

So, basically if one needs wireless bridge, dd-wrt is the answer.

I just reinstalled dd-wrt and its wireless bridge works quite well. Not really thinking about the throughput performance, since it's just for a network printer client.  It would be good to have that with openwrt as a module or something though.

The latest Gargoyle firmware (www.gargoyle-router.com) now allows wireless client bridging too.

Thanks for the info.
I hope openwrt will keep up with the trend.

But isn't gargoyle just OpenWRT with a dedicated web GUI, like X-Wrt? So why gargoyle can do it, but OpenWRT can't?

It's mostly a web GUI, but in order to enable some features several back-end programs as well as kernel modules have been added as well.  One of the added kernel modules makes this possible.