On 18/12/2012 09:27, Dave Liquorice wrote:
On Tue, 18 Dec 2012 02:44:13 +0000, John Rumm wrote:

For certain values of dynamically...

If you open up a laptop and connect to the strongest access point
signal, then its fine. What it does not do is actually allow roaming.
i.e. move that same machine from close to one access point to the
other, and it will still try to talk to the original connection point
even when there is another that offers a much better signal strength.
Only when you explicitly break the connection (or it goes out of range)
will windows look for an alternative.

My iPAQ (Windows Mobile 5) has a WiFi roaming setting of "Poor Signal" or
"No Signal" it does not say what constitues a "Poor Signal". This is not
a setting I have seen in more recent devices.

Firstly "windows mobile" != "windows" - so behaviour will be different.

Roaming is something very difficult to do well - having said that its
not something you often actually need when it comes down to it.

The trend has been to make windows less hop happy rather than more.
While it would be nice if it could roam, its actually even more annoying
when it decides to jump to another network that momentarily has a
stronger signal (especially when that network for example lacks internet
access or access to your LAN etc). So the current behaviour makes some
sense.

You then have a secondary problem that the router injecting internet
connectivity into the APs won't have any way of being told that the
connection point has changed - hence it will still be using the MAC
address of the previous point.

Hum, my routers ARP table shows the MAC address of the end point not the
MAC address of the intermediate wireless AP (in bridge mode). How long

It depends somewhat on at what layer your AP is working. If it truly is
operating in bridge mode (i.e. layer 2 routing based on MAC addresses
rather than layer 3 IP routing), the non roaming endpoint of a
connection should have the MAC of the actual laptop cached in its ARP
table. If its working as an IP level router, then the routers MAC
address will be cached.

the unmanaged switch between the router and AP takes to notice the move
is another matter but I've never experienced any noticable delay when
physically moving things on switch ports.

Most switches will spot the change fairly quickly IME.


--
Cheers,

John.

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