Solved: LWAPP AP finds controller without benefit of option 43

john.preves · ‎07-13-2007

This is quite the head scratcher. I have installed about 7 AP's that pulled a DHCP address from a scope that (accidentally) had no DHCP option 43 associated to it.

It is my impression this should not of worked. The LWAPP firmware is 4.0.179.11

but is full of AP's that did not find the controller with out option 43.

How could this be?

rupert.wever · ‎07-13-2007

LWAPP AP's discover controller thru other methods as well. DHCP Option 43 is only one of those methods.

> Pre-Configured (aka Primed) AP's will remember their previously joined controller's Mgmt IP address in NVRAM

> DHCP Option 43

> DNS entry 'CISCO-LWAPP-CONTROLLER.localdomain' lookup

> Local broadcast domain (same subnet)

> OTAP - Messages from neighboring AP's

Your AP's must have found the controller thru one of these methods.

Does this help (feel free to rate this response).

View solution in original post

ericgarnel · ‎07-13-2007

Is the dhcp server residing in the same network as the APs & ap-management interface? My guess is that it probably is

john.preves · ‎07-13-2007

Actually, no they arent.

AP clients come out of various ranges associted with the ap-manager interface.

AP's get assigned addresses depending on what VLAN the switchport is in, which is directly predicated on what closet the switch is in.

DHCP is on yet a different network altogether.

Still scratching head...but thanks for the response.

rupert.wever · ‎07-13-2007

LWAPP AP's discover controller thru other methods as well. DHCP Option 43 is only one of those methods.

> Pre-Configured (aka Primed) AP's will remember their previously joined controller's Mgmt IP address in NVRAM

> DHCP Option 43

> DNS entry 'CISCO-LWAPP-CONTROLLER.localdomain' lookup

> Local broadcast domain (same subnet)

> OTAP - Messages from neighboring AP's

Your AP's must have found the controller thru one of these methods.

Does this help (feel free to rate this response).

john.preves · ‎07-13-2007

Thank you for your response.

It must have been number one or three since 2,4 and 5 do not apply. (This was a new LWAPP install- no other AP's to grab from.)

I did pre-configure them, but I have had that fail before...

This means that I have to update the scope to include option 43, in the event of something changing in a couple of months and there will be no option 43 to fix it.

I will do more research on these methods and try and track it down.

Thank you again- 5 points from me!