Major typo in 1.9.1

[skysurf76]

I configured a couple routers tonight in wireless bridge mode and next to bridge IP is says "must be outside AP range" or something to that effect, when I'm fairly certain it should say "must be in AP range".

[Lantis]

Outside is correct.
Behaviour was changed between the versions.

[skysurf76]

Ok well then I need to report the following behavior...

I configured three WR841N's tonight in a building about 400 feet long. I configured the middle router as a standard AP, nothing special.

I configured the other two routers on opposite sides of the AP as wireless bridges.

Middle AP was 192.168.1.1, outside bridges were 192.168.1.2, and 192.168.1.3.

After positioning them and powering them all on the DHCP server on the middle AP was assigning them DHCP IP's. I couldn't access them from 192.168.1.2 or 192.168.1.3, but I could find their DHCP IPs from their MACs from the connected clients list from the AP and get to their webgui's that way.

They were working just fine as bridges at this point. This was verified by signal strengths as I moved around with a laptop.

What I ended up doing was setting static IPs in the DHCP server on the AP such that the outside bridges were 192.168.1.2. and 192.168.1.3. With these settings I could access the AP at 192.168.1.1, and the two bridges at 192.168.1.2, and 192.168.1.3. And that was with both bridges being assigned those IPs. Everything worked fine.

Perhaps the bridge IPs don't have to be in AP subnet, but I can definitely say that it works if they are.

Now that I think about it its almost as if the IP you assign to the bridge has no effect. It seems that the AP they connect to handles their IP assignments. Its as if while in bridge mode they wait to be assigned IPs even if you have an IP entered into the bridge IP text box.

Anyway, its all working wonderfully now. I just wanted to report what I saw to be a good citizen

[Lantis]

The address from outside the AP is used as a "dummy" address. A relay client is established at this address which allows DHCP and other traffic to traverse to its clients, allowing them to establish an IP address on the AP subnet.
Effectively, all clients end up on the one subnet and the "dummy" subnet disappears.

The router can be accessed initially (at setup) on the "dummy" address. Once connected to the AP, it is given an IP address from the AP and it assigns this address to a dummy bridge interface, allowing you to access it at this address also.

Please see the following diagram, and if you have further questions please ask.



In short, what you describe (although slightly confusing) is expected.

[skysurf76]

Wow thats confusing.

I've read the previous post several times, and the way I'm interpreting it the "bridge" IP seems like its only used when a client initially connects to the bridge.

Actually I'll admit I'm completely lost. Why does a "dummy" address have to be present at all? The whole point of a wireless client bridge is so everything remains on the same subnet. Why is an IP outside of the subnet that is being used by clients and the AP even used?

There has to be a good reason or function for this "dummy" address outside the AP/bridge subnet.

More to that point, I configured both my bridges with IP's in the same subnet as the AP subnet, and its working great. Granted I had to put static mappings for the IPs in the APs DHCP configuration for these two bridges, but once I did that both the bridges show up in the APs connection list with the IPs that I assigned.

So if you enter static mappings in the AP for the bridge IPs, and put IPs in at the bridges in the same subnet as the AP it works fine. They don't "have" to be outside the APs subnet to work.

If you don't enter static mappings at the AP for the bridge IPs though then the AP DHCP will assign them IPs from the DHCP pool no matter what is entered into the "bridge IP" box.

I have a feeling it may be for programming reasons. If that is the case then we have left my area of understanding and I'll just nod my head and say "OK".

The main reason I can't get my head around it is that I come from a networking background and things just don't mix that are on separate subnets. Different subnets just shouldn't interact at all without a router in between them.

[Lantis]

That's where the relayd client gets setup.

I'm not confident enough in my own understanding of how it works in order to give you a perfect answer.
Relayd is one of the easiest ways to establish routed wireless bridge. I switched to this method from the previous arpNAT method to reduce code and complexity (in my opinion).
Relayd is also well supported by openwrt, whereas arpNAT was not and was patched in to the kernel.
(That being said, i think we currently still use arpNAT for guest network separation)

You can experiment if you like. But everything ends up on the one subnet once the relay has fired up and established itself.

[skysurf76]

After some thought I realized that after setting the bridge IPs in the same subnet as the AP I can't say for sure if I ever rebooted the laptop or did anything to require a new DHCP address on the laptop from one of the bridges, so maybe the bridge IP does need to be outside the AP subnet. If my laptop had a DHCP address from the AP the whole time I was messing around with stuff then it never needed to use the bridge IP outside AP subnet magic. I'll have to check tomorrow.

It sounds like its mainly for programming reasons. So at this point I'll just smile and take your word that its for the best.

I really really appreciate you taking the time to respond and trying to explain it!