Recommended Settings for PTP WDS Bridge

Installing and Using OpenWrt Network and Wireless Configuration
1

When creating a dedicated point-to-point network bridge using WiFi WDS (meaning the devices will not allow any direct client connectivity, they are solely there for bridging purposes to extend a Layer 2 network) are there any other settings people would recommend to make the connection more robust/reliable?

I'm thinking in general any settings that are geared towards client roaming, multi-client access, bandwidth sharing, broadcasting etc could be turned off as there will only ever be two devices (the AP in WDS mode and the STA in WDS mode).

My thoughts so far are:

  • Hide SSID (obvious one)
  • MAC Filter to only STA Mac addr
1 Like
2

Never done WDS.

Are you planning on extending more than one layer 2 network over the link?
i.e. a tunnel over the point to point link?

Only thing I can think of is make sure you increase the MTU so you can send vlan's, use vxlan etc.

If this is a point to point link. What's the distance? Are you planning on doing custom antennas? Make sure you are getting your EIRP, indoor/outdoor bands correct, and DFS channel switch event isn't going to make you illegal.

I've normally set 802.11s if I don't need the AP to be used by normal stations. Just in case I plan on extending from doing a point to point link.

1 Like
3

No tunnel, need to extend 2 VLANs and plan to use a bridge/radio for each independently so they will be sent untagged.

Is it possible to send tagged traffic over a WDS link?

It's only 15 meters, but there is no viable way to run a cable. Hoping to achieve it with standard antennas, will most likely just lock it to a single 5G channel.

I did consider 802.11s but seemed overkill for this situation, unless there are other benefits I'm overlooking?

4

You need gretap tunnels.

1 Like
5

No WLAN hardware so far will allow you to run two STA interfaces on the same radio, nor does WLAN offer VLANs. brada4's suggestion above is a workaround for this.

1 Like
6

So your initial plan was two WDS links? One for each layer 2 network?

you could tunnel one off the vlan's whilst having the other vlan be the native one for the WDS link? Main thing is get your MTU right. But I haven't used WDS so that's a big disclaimer there.

If you have radios/spectrum to spare the two WDS on different channels certainly is an easy method.

If you're already talking sending data over two 5ghz links between two or four AP's. Perhaps a more elegant solution is using batman iv with vlans and going for a mesh topology. You can set the routing to load balance or alternate between the radios etc.

No worries. As long as your RF environment is good and you have enough channels, no need to cut down on the interference with directional antennas. 15M as long as it isn't through reinforced concrete or double brick should be fine?

I'm biased but I've only done wireless links when I needed a expedient, inexpensive solution. Or when I had to bring the wired link down.

As an aside. I've used flat network cable and flat trunking on walls and to get cables where it wasn't easy to get a cable.

You have up to 100M on gbase-t to play with so you can be quite inventive in going around skirting, wall corners, through doors etc. Going through doors is easy if you have carpet. But can always cause issues with damaging paint worst case I guess. Lots of blu-tack. Or you just use the adhesive tabs for hanging pictures but the ones with cable clips instead if you don't mind an ugly solution =P.

Similarly, fibre media converters are relatively inexpensive and pre terminated fibre doesn't cost too much, and it's thin enough to put in very thin trunking.

Benefit of fibre is most places allow you to get it pulled through in the same place as your electrical cables as you're not going to get induced voltages. Keep in mind your fire barriers I guess, plus all the other cabling stuff for wherever you are.

Edit:
I neglected to mention MOCA if you have existing 75ohm coax, nor powerline networking but those are also wired solutions. MOCA should be fine but powerline networking I'd avoid.

2 Likes
7

Yep, I plan to use the 5GHz radio for the main network and the 2.4GHz radio for the management network.

8

Thanks for the insights. It's 15m outdoors to another building, and it goes across a parking lot and there is no appetite to dig that up and can't fly the cable overhead due to the height of potential vehicles driving through. It's a charity project so cost is key. It's only to allow the local after-school group to get access to the web so performance is not critical as such.

9

Is that strictly true? You might be right in practice, but as far as the config is concerned STA mode and WDS for that matter is set at the wifi interface level (not the adapter level) and you can have multiple interfaces (SSIDs) per radio as in the typical LAN SSID + Guest SSID setup.

EDIT: I was getting confused, it would work on the AP side but not the STA side. You're right.

10

Mm. Must the first link be 2.4ghz? Are you reusing existing hardware? If so, what is it?

I'd need to test with some spare hardware how much of a speed imbalance actually affects this. I guess if you run directional antennas you might be able to get 40mhz on 2.4ghz working properly. I still favour the batman with vlans approach rather than WDS.

https://www.open-mesh.org/projects/batman-adv/wiki/Multi-link-optimize.

Do you want an excuse to put in speed humps? =P I'd explore industrial outdoor cable covers and flat / ramped conduit :stuck_out_tongue:. But yeah surplus / used wifi AP's are cheap. You can also get deals on outdoor cisco / HP antennas / insert vendor here. Outdoor weatherproofing can be challenging though.

Understood. So 20-200Mbps probably sufficient? You'll probably be able to do that even with 40mhz channels and wifi 5 hardware.

OK so outdoor. 2.4ghz fine. 5ghz just check regdb and don't do a no-outdoor channel?
IMO it'd be good practice to do directional antennas and lower the transmit power until you get a good link margin but no more whilst staying within EIRP limits.

STA is the "client" device. The other end that is the "AP" is the one transmitting the beacons with the SSID? just making sure we're not getting confused here?

11

The management network is rarely used it's just for the SSH interfaces of the APs to keep them off the public network away from wannabe hackers. Speed is not an issue at all for that network.

I've got some Extreme Networks 7632i AC Wave 2 devices from a business liquidation, so they were as good as free. They seem to be fairly robust devices ($400+ new). I will test it all before deploying.

You're right, I was getting confused, it's early :slight_smile: So it will/may work on the AP end but you'd need two receivers on the STA end.

Plan to put them in a plastic weatherproof project box like this:

61PbPG49cEL.AC_SL1500-3586482071
61PbPG49cEL.AC_SL1500-35864820711390×1410 52.2 KB

Should be fairly transparent to WiFi signals?

1 Like
12

Are they supported by Openwrt?

13

I wouldn't have come this far if I hadn't checked that :slight_smile: However it uses an image designed for another Extreme device so it will need some testing to ensure it works functionally.

14

thank you, both device pages are missing from the Openwrt wiki, so I'll get that sorted out later:
https://openwrt.org/toh/extreme_networks/start

15

You're welcome. I'll be starting this project this evening so let me know if I can dump any device data to help you build the Wiki page.

16

bootlogs would be appreciated if you have time.

1 Like
17

DM'd you. Let me know if you need anything else.

18

Yeah wifi transparency will be OK. Haven't looked at the gain /pattern/polarisation etc of the ap but 2x2 on both 2.4 and 5? Those probable have enough CPU performance to run the bridge fast enough.

Is it going to be a condensing or freezing environment? Do you need a heater, or a way to keep them out of the sun? I've had issues with condensation inside the enclosure. Proper cable glands and desiccant sachet's should be a good enough solution but eh.

Do these have a temperature sensor? I melted the enclosure of one of my AP's leaving it in the sun. Like literally warped the plastic =P How hot are these going to get? Are you going to be able to get to them to inspect regularly? Are you mounting at height?

More with the 2.4ghz, could also use it for load balancing to eke out some more performance depending on how you configure the routing, or you go for multiple AP's, per the batman load balancing etc. But yeah speed no worries.