I am trying to redeploy Cisco 1242 LAPs on new Cat4507R+E switches, which means the IP address of the WLC is changing for that LAP. For some reason, I have to configure
ip helper-addresses on my LWAP vlan to jumpstart communication between my Cisco AP1242 LAPs and the WLC; I have DHCP (with Option 43) on the LAP Vlan, but I don't know why the LAP is ignoring the DHCP Option.
DHCP runs on Cisco 4507R+E switches... The switches are configured with DHCP Option 43 (Single WLC address: 10.19.3.209 / hex: 0a13.03d1) and Option 60...
ip dhcp pool lwap_v99 network 10.1.1.0 255.255.255.0 default-router 10.1.1.254 dns-server 10.19.26.225 option 43 hex f104.0a13.03d1 option 60 ascii "Cisco AP c1240" !
The LWAP is getting a DHCP address...
WL-DST2#sh ip dhcp bind Bindings from all pools not associated with VRF: IP address Client-ID/ Lease expiration Type Hardware address/ User name 10.1.1.17 0158.8d09.03ec.de Jun 28 2013 03:07 AM Automatic WL-DST2#
Using wireshark on Supervisor 7, I can see that the LAPs are ignoring Option 43; instead, the LAPs (for example, 10.1.1.17) are broadcasting CAPWAP packets and never send a unicast request...
WL-DST2#sh monitor capture file bootflash:mycap.pcap | i CAPWAP 681 597.979997 10.1.1.17 -> 10.19.26.225 DNS Standard query A CISCO-CAPWAP-CONTROLLER 684 600.977998 10.1.1.17 -> 10.19.26.225 DNS Standard query A CISCO-CAPWAP-CONTROLLER 689 603.977998 10.1.1.17 -> 10.19.26.225 DNS Standard query A CISCO-CAPWAP-CONTROLLER 705 615.975999 10.1.1.17 -> 255.255.255.255 CAPWAP CAPWAP-Control - Discovery Request 715 625.974001 10.1.1.17 -> 255.255.255.255 CAPWAP CAPWAP-Control - Discovery Request 728 635.970995 10.1.1.17 -> 255.255.255.255 CAPWAP CAPWAP-Control - Discovery Request
I validated that DHCP is offering Option 43 in the DHCP Offer message...
Option: (t=43,l=13) Vendor-Specific Information Option: (43) Vendor-Specific Information Length: 13
I tried setting both
option 43 ascii "10.19.3.209" and
option 43 hex f104.0a13.03d1... both of these are ignored by the LWAP. I also tried hard-resetting the LAP with the mode button.
Workaround for non-functional DHCP Option 43 & 60
At this point, the only thing that makes the AP talk to the WLC is a helper-address (for udp/5246 & udp/5247) on the Vlan...
! interface Vlan99 ip address 10.1.1.252 255.255.255.0 ip helper-address 10.19.3.209 <------ no ip redirects no ip unreachables no ip proxy-arp standby 99 ip 10.1.1.254 ! ip forward-protocol udp 5246 <------ ip forward-protocol udp 5247 <------
How do I use DHCP to make these LAPs use unicast packets to initiate CAPWAP with the WLC? FWIW, I don't want to use DNS to direct the APs to the WLC.
Version information for the LAP / WLC system...
(Cisco Controller) >show ap config general AP588d.0903.ecde ... S/W Version .................................... 126.96.36.199 Boot Version ................................... 188.8.131.52
The 4507R+E switches are running IOS-XE 3.4.0SG