how do you setup seamless roaming with WDS?

RouterOS Wireless Networking
1

Ok, let me start off by saying what I don’t want to do. I am not interested in seting up a mesh were one would install single radio hotspots all over the place and roam using the single radio for backhaul and AP. This is what everyone else is doing on the forms and my scenario is quite different in my opinion.

I already have a countywide routed backhaul setup in place and I want to add an AP to each of my existing sites that will be the “mobile clients” ap only and use the existing backhaul.

Now I realize that i need to have each of these AP’s (for the mobile clients) setup with the same SSID and FREQ in order for the seemless roaming. Since my network is routed i will setup NAT on all of these AP’s and put them all on the same subnet so that these clients can immediately switch to another AP without worrying about dhcp issues (clients will have fixed IP’s)

This all sounds pretty simple setup this way but the problem is that the clients would stay connected way to long to an AP and wouldn’t connect to the next strongest AP until they compleately loose connection to the first one.

So from what I’ve been figuring out is that WDS can solve this issue of the AP handing off the connection to the next strongest AP.

My questions are the following

  1. What WDS settings do i need on the AP’s to make this work the way I just said?
  2. Do the cleints all need to be mikrotik? (I’m hoping not)
  3. What is RSTP bridge and does it apply to me?
  4. What would happen if 1 of the AP’s and a different freq.?
2

+1 looking for some tips on this also.

3

Its getting to the point if i can’t find out how to do this that I’m going to have to go with the Alvarion mobile 900mhz since it already does the hand-offs between AP’s seemlessly.

4
  1. You’ll either need to setup static or dynamic WDS links between the APs.
  2. No the clients do not need to be Mikrotik.
  3. You will need to put the WDS and WLAN interfaces in an RTSP or HWMP+ bridge. Read about RTSP http://en.wikipedia.org/wiki/Spanning_tree_protocol and HWMP+ http://wiki.mikrotik.com/wiki/Layer-2_routing_for_Mesh_networks
  4. All the APs will have to be on the same freq for the WDS links. If you want to use different freqs you’ll have to use more than one radio card in that particular AP.
5

thanks, does this include how it get the AP’S to push the bandwidth across the backhauls rather than going through the WDS ap’s for traffic?

6

Will each AP have it’s own backhaul? For example AP1 and AP2 each have their own wired internet connection and when the client roams from AP1 to AP2 the traffic should transfer over to the backhaul on AP2? Are you using public or private IPs for the client?

7

each AP already has a designated 5ghz backhaul coming in and out of it. Everything is already routed. Clients will be on “private fixed” IP’s that will be “masqueraded” behind the mesh so then can roam without problems on the routed network.

8

this is correct

9

Do you have a network diagram? I’d make the WDS links over the wireless backhaul. Then your other radio, I’m guessing 2.4GHz, is free for the clients and you can use different channels. You’ll have to change to a bridge setup.

10

Here is my network diagram right now. As of right now the PURPLE 900mhz AP’s are not there but this is so you can get the idea of what I want to do. Basically I already have a 5ghz infastructure I just want to add the 900mhz for roaming and utilize my backbone already.
WDS.GIF

11

Shoot,
I really hate reviving this thread since it is a bit old, but my situation is very similar to kblazk’s and his network diagram is very similar to mine.

I was wondering if there was any follow-up to his questions? I’ve got an application which will roam from AP to AP and I’m trying to get the best method to allow for this (be it WDS or not..)


Thanks,
scube

12

I ended up giving up on this project.

13

Seamless Roaming cost Eriksson billions for mobile phones.

It can be done theoretically, but not with stock Linux stuff like Mkrotik.

You need to spend lots of money on programmers etc to even give it a chance.

The main Hurdle is the time it takes for a wifi Client to swap from one AP to another.

Adrian Robinson at ADR Communications (www.ineedbroadband.co.uk) in the UK once said to me that he had solved it.

I was/am sceptical, but maybe he has an answer.

I certainly don’t.

14

Somebody else asked about this in a more recent thread.

How about bridging all the APs back to a central ‘server’ using EoIP ?

All the same subnet, so no IP-swap issue.

Maybe with a long DHCP timeout so avoiding that delay.

You still would have the Time it takes to disassociate from one AP and associate with another, but maybe setting minumum signal strengths would help.

These are just ideas that have occured to me - i have not tried it.