WLC5520 and DHCP for APs

[Rafael Jimenez]

Hello experts,

I have a 5520 WLC with several 3802E APs with a weird issue with the ip assignment. The dhcp is windows server 2008.

my problem is that if a put the WLC and AP in the same vlan, the AP dont get the ip.

if I move the AP to a different vlan, the AP gets its ip without problem.

I dont know if its necessary a special config if the APs are in the same vlan of the wlc.

please help me.

the config: 

I have a L3 SW with several vlans:

- servers (dhcp, radius, etc) vlan.

- WLC and APs vlan

- wi-fi users vlans.

the sw configuration is the following:

#show ip int br
Interface IP-Address OK? Method Status Protocol
Vlan1 unassigned YES NVRAM administratively down down
Vlan4 10.0.3.254 YES NVRAM up up
Vlan906 172.16.16.254 YES NVRAM up up
Vlan907 172.16.63.254 YES manual up up
Vlan908 172.16.95.254 YES manual up up

#sh vlan
4 servers active Fa0/13, Fa0/14, Fa0/15
906 WLC & APs active Fa0/1, Fa0/2, Fa0/4
907 EST active Fa0/3
908 FUN active

#sh run
!
interface Vlan4
ip address 10.0.3.254 255.255.255.0
!
interface Vlan906
ip address 172.16.16.254 255.255.255.0
ip helper-address 10.0.3.50
!
interface Vlan907
ip address 172.16.63.254 255.255.224.0
ip helper-address 10.0.3.50
!
interface Vlan908
ip address 172.16.95.254 255.255.224.0
ip helper-address 10.0.3.50
!

#show cdp ne de  (((( working fine )))))
-------------------------
Device ID: AP3890.A55E.28BA
Entry address(es):
IP address: 172.16.32.2
Platform: cisco AIR-AP3802E-A-K9, Capabilities: Router Trans-Bridge
Interface: FastEthernet0/3, Port ID (outgoing port): GigabitEthernet0
Holdtime : 169 sec

Version :
Cisco AP Software, ap3g3-k9w8 Version: 8.2.166.0
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2014-2015 by Cisco Systems, Inc.

advertisement version: 2
Duplex: full
Management address(es):

-------------------------
Device ID: wlc-usb
Entry address(es):
IP address: 172.16.16.5
IPv6 address: UNKNOWN (link-local)
Platform: AIR-CT5520-K9, Capabilities: Host
Interface: GigabitEthernet0/1, Port ID (outgoing port): TenGigabitEthernet0/0/1

[Leo Laohoo]

---

@Rafael Jimenez wrote:

my problem is that if a put the WLC and AP in the same vlan, the AP dont get the ip. 

---

Check the VLAN if there is a valid IP helper address. 

Check the DHCP if there is a valid scope for this VLAN subnet.

And check the configuration of the VLAN.  Maybe it's disabled or there is no VLAN database in one of the switches?

Maybe allowed-VLAN is not configured?

[Rafael Jimenez]

Thanks Leo,

Your answer confirms that there is nothing special about the parameters of the WLC.
I have reviewed these configurations again and again and I can not find the error. Maybe it's in front of my nose and I do not see it.
Thank you.

[Leo Laohoo]

If you can console into one of the APs, can you post the complete output to the command "sh capwap client rcb"?

[Rafael Jimenez]

AP3890.A55E.28BA#sh capwap client rcb[*02/27/2018 21:35:34.8801] Resetting wired0 and[02/27/2018 21:35:34.9100] wired0: stopped
restart DHCP client

AdminState : ADMIN_ENABLED
OperationState : DISCOVERY
Name : AP3890.A55E.2....
SwVer : 8.5.120.0
HwVer : 1.0.0.0
MwarApMgrIp : ::
MwarName :
MwarHwVer : 0.0.0.0
Location : default location
ApMode : Local
ApSubMode : Not Configured
CAPWAP Path MTU : 576
CAPWAP UDP-Lite : Enabled
IP Prefer-mode : IPv4
AP Link DTLS Encryption : OFF
AP TCP MSS Adjust : Disabled
LinkAuditing : disabled
AP Group Name : default-group
Cisco Trustsec Config
AP Inline Tagging Mode : Disabled
AP Sgacl Enforcement : Disabled
AP Override Status : Disabled
Now the with the wlc, ap, and dhcp on the same vlan, work fine. The wireless clients on another vlan get its ip only if I change the DHCP Proxy Mode to Enabled, wich means the wlc is the dhcp relay instead of the ip helper on the L3 switch.  

I think the problem is a non cisco switch in the middle of the path to the dhcp server.

[Rafael Jimenez · Accepted solution]

Solved. The problem is a no dhcp service on the L3 4500 switch.
The result, no (dhcp server -> client) traffic (also tftp).
I posted the problem in wrong way....
Work if wlc, aps and dhcp server are in the same vlan.
dont work if the dhcp server is in a differente vlan.