howto determine which access point a mobile client is using?

[florian]

Hello,

My problem is:
How can I determine which access point a mobile client is using from a server-side application?

My setup is:
Several access points
One web server
Several mobile clients
(All on the same subnet)

When a mobile client connects to a specific page on my web server, I want to find out which access point the mobile client is using to connect. The aim is to deliver location-based content to the mobile client depending on which access point the client is using.

My ideas range from doing a traceroute to querying the access points tables. Maybe the solution is much easier and I just don't realize.

Has anyone had this problem before and can give me a hint on how to solve this problem the most elegant way?


Florian

[jwfox]

Depending on what you're using for your layer 2 aggregation (of your access points) the following might work :

If your using a switch (or switches in a switch fabric) with each AP on a seperate switch port (i.e. AP's aren't connected to hubs) then the switch table(s) will contain the clients MAC address and the corresponding switch port -

Comparing the MAC address to an ARP table (at router level, server level (or if you switch is layer 3 capable), switch level) would determine which switch port a given IP address if coming in from.

You should be able to query both the switch table & arp caches via SNMP (on most network devices). Could get a bit messy if your using a trunked switching fabric (you have to filter out trunk ports in the switch table(s) - but it seems to me it would work.

Hope this helps.