LWAPP discovery - what's in the APs list of controllers
I know the AP goes through a series of steps to discover a controller. I've read that it checks DHCP Option 43 **BEFORE** checking DNS for CISCO-LWAPP-CONTROLLER.localdomain. And, the AP compiles a list of candidate controllers.
My question is:
Does it use BOTH the set of controllers given in DHCP Option 43 -AND- in DNS? Or, if it sees an Option 43, does the discovery end there?
Re: LWAPP discovery - what's in the APs list of controllers
Excellent question! The LWAPP Discovery does not end there as it essentially wants as many candidate Contollers as possible. Have a look;
The LWAPP Layer 3 WLC discovery algorithm repeats until at least one WLC is found and joined.
Note: During the LWAPP Layer 3 WLC discovery, the AP **always completes all steps 1 through 5 (discovery type: broadcast, configured, OTAP, dhcp server and dns)
in this section in order to build a list of candidate WLCs. After the AP has completed the LWAPP WLC discovery steps, the AP selects a WLC from the candidate WLC list on the basis of certain criteria, and then sends that WLC an LWAPP join request.
The LWAPP AP goes through this process on startup for Layer 3 mode:
The LAP boots and DHCPs an IP address if it was not previously assigned a static IP address.
The LAP sends discovery requests to controllers through the various discovery algorithms and builds a controller list. Essentially, the LAP learns as many management interface addresses for the controller list as possible via:
DHCP option 43 (
DNS entry for âcisco-lwapp-controllerâ
Management IP addresses of controllers the LAP remembers previously
Transferring Crash file from standby:
Login to the Active WLC in HA.
(Cisco Controller) >transfer upload datatype crash
(Cisco Controller) >transfer upload filename <Desired filename>
(Cisco Controller) >transfer up...
This is the start of a display filter cross reference between Wireshark and OmniPeek.
The 1st installment is a table of advanced filters. More filters will be added as time allows.
It is a living doc, so check back for changes every so often
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I have created a Powershell script to automatically add a Wireless Guest User on Cisco WLCs. (tested on 2500 Series)
The script should be completely self explanatory.
Powershell SNMP Module (Install-Module -Name SNMP)
SNMP Write Access to...