A client that won't roam between APs.

[ranz]

Hi all, my first post here, hopefuly I'll be able to get some insights about some issues I'm having...

So we all know that if we were asked to expend WLan coverage of a certain area we would use one of the following options naturally:
1. Wired AP or router that acts as AP only.
2. WDS.

With a few APs (wired or WDS) spreaded in the area that have the same SSID and Encryption, a computer/PDA that has a "profile" with the SSID/Encryption of the APs will probably "roam" between them only differentiating them by MAC address of their wireless interface, though he will not really roam, he will just check which of the APs he's seeing has the best reception and connect to that one. so far so good, our facility is covered and computers can move from desk to desk without disconnecting from the application or the internet.

BUT, what if we were to talk about a device that only connects to a new AP when the current one is REALLY weak, or when it loses the AP completely - only then will he check and see that its actually standing right next to another AP with great reception (or when you reboot it).
How can we make such a client move around without disconnecting in order to find a new AP?

Is my only option playing around in the first layer? i.e 2.4GHz amps and high gain antennas and only using one active transciever (router/AP)?

Naturally I tried WDS as a replacement for wired AP but they actually behave the same in that matter.

I saw a new repeater option on DD-WRT24 Beta, could that help? the fact that it has to use another IP segmant is kinda problematic, but I might be able to work my system around that one (maybe another router...) if it means that connecting a few APs in repeater mode will make the device able to move around them.

Will accept any advice! thanks in advance.

[golfnut]

The decision to roam is within the device itself and you'll see this problem more often with PDA's because most, not all, will wait until the signal is really weak before roaming. It probably won't help to add other AP's.

Besides using different client devices, I don't think there's much you can do although it's a good idea to make sure you have the latest drivers installed.

Greg

[M/Q]

You have one of two choices to obtain true seamless roaming.
1. Use intelligent AP's (i.e., Cisco) that talk to each other and pass clients between APs.
2. Use a wireless managed switch and thin AP's. This is where the switch is controlling the network and will move clients to the appropriate AP, based on predetermined configuration settings.

[umdivx]

I see this "roaming" issue all the time with the devices I have to support at work. What I have are scanning devices that run on the windows mobile platform, they use an off brand, proprietary wifi compact flash card, and what I have found is that with the higher number of access points in a given area, all using the same SSID, and on the same network you litterally have to drive the signal into the ground before the devices will roam to the next strongest signal.

But what is weird is that Laptops, other PDA devices (that aren't running WM5) roam just fine in our environment.

So What I've gathered is that its either the poorly written drivers for the wifi cards, or that Windows Mobile just plain ****s when it comes to wifi/roaming support.

So what I would recommend is try working with the manufacture of the devices, get the latest greatest drivers, and go from there, if it still doesn't work you might be SOL like I am with my devices.

- Josh

[golfnut]

Josh it right, it's more of a driver/manufacture issue.

I've got a Dell PDA with built-in wireless that literally will not roam until the signal is to the point where it won't communicate. A friend has an HP IPAQ that roams whenever it finds another AP with the same SSID and stronger signal.

I think it's a question of active or passive scanning for the devices. Active scanning probably takes more battery power.

Greg

[ranz]

You have one of two choices to obtain true seamless roaming.
1. Use intelligent AP's (i.e., Cisco) that talk to each other and pass clients between APs.
2. Use a wireless managed switch and thin AP's. This is where the switch is controlling the network and will move clients to the appropriate AP, based on predetermined configuration settings.

Both those solutions are available from cisco right? are they available ONLY from cisco? I haven't seen such products anywhere else. can you point me in a direction of such a product?

[umdivx]

yes both are from cisco, however I can tell you that in my enviornment we are 100% Cisco, WLSE, and doing managed roaming with the wireless management system cisco has.

and we still have the roaming issue.

- Josh

[ranz]

Wait, are you talking about Cisco 2100 series with "lightweight" clients?
That setup still has roaming issues? with what? PDAs?

[golfnut]

The client device always makes the decision when to roam. That decision is baked into the firmware of the adapter.

If a WLAN switch controlled this, it would have to dis-associate the device, block its mac from the AP, which would then force the device to associate with another AP. If someone where using a wireless VOIP phone, that would be a dropped call.

Greg

[DjBlaze]

Greg, so if your client device did not effectively support roaming very well is it right to assume that there is no need to purchase a shiny, expensive Cisco appliance/AP for the sake of seamless roaming?

Also, am i correct in assuming that seamless roaming is not a mature technology at this point?

[golfnut]

Correct. There isn't a standard for roaming so it's really a mixed bag (Vista is another story).

WLAN switches will help with this as M/Q mentioned but they are spendy.

Greg