Simple problem: fully wireless L2 bridge to secondary AP using 2 radios (1 trunk, 1 distribution). Is it even possible?

RouterA: eth1.2+wlan0 in br-wlan. wlan0 must be in AP mode.

RouterB: no ethernet, 2 radios. Need 1 AP.

How to make one single collision domain out of the two routers, and possibly without using any additional software? I need the wireless terminals to be handed over as soon as the user walks from one room to the other...

I've been messing around for two days before writing. It used to be possible long time ago. Now I can't find the proper setup.

Yesterday I got a kind-of-working setup by setting RouterA's AP in WDS, then bridging a WDS client and a normal AP on RouterB; but (a) handover was not working properly and (b) bandwidth was ... 500kbit/s (routers at less than 3 meters LOS, N-radios, 40MHz channels).

Today I dismantled the working setup and made some other tests; and seems to be unable to go back to the previous setup. A normal non-bridged client works; as soon as I set the WDS flag on the wireless interface, I get the client to connect but I can't ping RouterA.

Any clue?

If you mean clients then it's their devices that control which AP they connect to. You can't control this from the AP side other than to drop clients.

If you mean the APs themselves are mobile then you want 892.11s / mesh or BATMAN adv

No, the APs are stuck in place. Don't need any mesh. Just a way to have a single collision domain; join the two network segments at l2 (ie: no routing).

Docs online are about single radio solutions; I tried to use WDS for linking the two routers, and the second radio for AP, to avoid bandwidth halving. It looks simple but ... I can't do it.

I have been doing this for a few years now based on these docs:

I use the 5GHz band for the trunk. On the downstream AP, I also added the LAN to the relay so the nas and streaming box have one less wireless link - that made a huge improvement to consistency. The downstream AP also got upgraded antennas from ebay - they are at least 4000db gain :slight_smile:

That doesn't make a single collision domain and it is based upon additional software. The major issue would be breaking the dhcp...

It looks like kmod-trelay may be the solution, but I can't figure out how to make it work.

config trelay
        option enabled  1
        option dev1     wlan1
        option dev2     wlan2

Where wlan1 is sta to main AP and wlan2 is local AP. In theory trelay should repeat all traffic across the two interfaces, in practice it doesn't.

I used WDS at one point and found it was rather flaky. For me it would work fine for a few days and then one of the devices would just get disconnected... Required a reboot. If you got it working but only got very low speed it's probably working as designed but you should look at things like the radio environment. Which band was back haul? Which band was AP? What other APs are there? How were you testing speed? Etc

The whole network is complicate. It's something similar to this diagram linked from this wiki page.

I need to add one router without ethernet and having 2 N radios, to extend the wireless signal to another room.

Yes and you set it up as WDS and it worked! Except your throughout was crap. So why was the throughout crap? Perhaps you can stand in the region where the extra device was added and show snapshots of the channel graphs in wifi analyzer (android app)? Both the 2.4GHz and all three 5GHz screens. That would help us understand your difficulties.

Here's and example from my house

1 Like

I use the same app on my phone to setup the proper channel spacing on every router and band. The radio spectrum in my place is clear; I'm the only one using it.

I use the 2.4GHz band, 802.11N, disable legacy 'b' rates and force the 40MHz channel size. The main AP (RouterA) is on ch1, the extender (RouterB) is on ch11.

It wasn't a radio problem; it's more likely to have been some kind of l2 problem, I didn't enable STP but I had no circular network / double links. The problem is I changed that setup to try different solutions and haven't been able to go back and test it further.

Where's the WDS backhaul? If the "WDS client" is connecting to RouterA then it can't be on a different channel than RouterA. If you're doing the backhaul on 5GHz what's that spectrum look like? Can you show some sort of configs. Basically it's impossible to really help you unless you show us some specific and technical information about what you tried.

RouterB have 2 radios. Radio1 is sta to RouterA (same channel, ch1); Radio2 is the second AP (different channel, ch11). There's no frequency overlapping.

Ok if I understand correctly you have:

RouterA: eth1.2 + wlan0 in WDS AP mode on channel 1
RouterB: one radio in AP mode on Channel 11, a second 2.4GHz radio on WDS client mode on channel 1

You connect to RouterB on channel 11, and get a proper connection with DHCP and all that but "only 500kbps" which you still haven't explained how you measured that. Can you give some details of your measurement? Was it just running a speedtest on a website? Were speeds the same symmetrically for up and download?

Then you say

But you're using 1 and 11 which overlap in the region of channel 6 when both using 40MHz channel widths. So the router B has two radios which are interfering with each other.

I would strongly recommend to try things out without forcing 40MHz channels. in north america you should never use 40MHz channels on 2.4GHz it's just an interference disaster. In other parts of the world you can use channel 1 and 13 to do two nonoverlapping 40MHz channels so it becomes somewhat viable.

No buddy, they are not interfering. As I wrote: the radio spectrum is clear and I'm spacing correctly. I wrote ch11 to not give information about my location but indeed I usually configure DFS to be in JP, so I can use ch14 which is a few MHz far from ch13 (not contiguous in band).
And I force the use of 40MHz in order to keep the channel width at 40Mhz even on edge channels.

Give up the radio issues... it's a logic problem in the tcp/ip protocol stack.

ok, so you're lying to us about what you're doing, and then you're askingn for help, but providing no actual details. I guess someone else will have to help you.


Damn kid. Tying up the phone line again. They're all alike...

I haven't been able to use trelay for joining client and ap devices. Without any macaddr option to clone the other interface, a few icmp echo request/reply work then stops working. With mac cloning nothing works.

So I reset both devices and went back to WDS:

RouterA(AP-WDS on ch1) <-> RouterB(STA-WDS on ch1 + AP on ch11) <-> station

STA-WDS and AP on RouterB are bridged.

Performance are strange. I use iperf3 on the named devices:

  • RouterA - RouterB: 70 Mbits, it is kind of ok given the radio specs and the distance.
  • RouterB - station: 20 Mbits, this is strange as the station is very close to the radio.
  • RouterA - station: 10 to 0.5 Mbits, looks broken.

Switching to 20MHz channels, changing channels, enabling/disabling STP, doesn't change anything. The CPU isn't maxed, plenty idle time.

No idea what's going on.