AP 3500 with 5508 Error messsage - query

[janesh_abey]

Hi Team,

I'm troubleshooting a DHCP issue between a 3500 and a 5508.During the investigations we discovered two error messages one on the controller and the one on the AP.I could not find this error on any of the doco and if someone could elaborate on the error mesages I will be able  to figure out the solution.

on  3500 AP

%CAPWAP-3-ERRORLOG: Invalid event 38 & state 2 combination.

What is event 32 and state 2

on the 5508

*DHCP Socket Task: Sep 08 14:55:56.263: 11.aa.bb.cc.dd.ee DHCP dropping packet from AP e8:b7:48:aa:bb:cc received on port 13, vlan 412

*DHCP Socket Task: Sep 08 14:55:56.269: 11.aa.bb.cc.dd.ee DHCP received op BOOTREPLY (2) (len 319,vlan 412, port 13, encap 0xec00)

*DHCP Socket Task: Sep 08 14:55:56.269: 11.aa.bb.cc.dd.ee DHCP dropping packet (no mscb) found - (giaddr 1.2.3.4, pktInfo->srcPort 67, op:

What is mscb? is that some kind of a data store where the controller stores the binding details?

We are running 7.0.116.0 code.

Thanks,

J

[pcroak]

Hello,

I want to first mention that the internal DHCP scope on the WLC was not designed to provide DHCP to wired network devices, and I would strongly recommend using another DHCP server for your wired devices.

Regarding the error messages you are seeing:

MSCB (Mobile Station Control Block) -- this is the database for the client devices on the WLC. Since the AP is not a client, there is no entry in the database so the packet is dropped.

-Patrick Croak

Wireless TAC

[janesh_abey]

Hi Patrick,

Thanks for your reply. We have not configured an internal DHCP server on the controller.DHCP server is an external device and the DHCP server IPs are configured under the interfaces.Pretty stock standard setup :-). basically IPs for the APs  and clients are allocated through DHCP .we have configured the DNS  method and option 43 for controller discovery. DNS method is working fine but we seem to be having few challenges around  getting option 43 to work and as part of troubleshooting came across the above error messages.

About the MSCB, I'm wondering how would the controller distinguish between a dhcp request coming from a wlan client device and an AP as we do not have option 60 configured.Does it look athe OUI and figure itout that is a Cisco AP?

I also did some debugging on the service port and it seems that the DHCP is failing.

*DHCP Client Task: Sep 08 15:30:39.833: DHCP TX from 0.0.0.0 ---> 255.255.255.255

*DHCP Client Task: Sep 08 15:30:39.833: DHCP State DHCPSTATE_INIT ===> DHCPSTATE_SELECTING

*DHCP Client Task: Sep 08 15:30:44.096: DHCP State DHCPSTATE_SELECTING ===> DHCPSTATE_FAILED

*DHCP Client Task: Sep 08 15:30:59.136: DHCP State INVALID ===> DHCPSTATE_INIT

*DHCP Client Task: Sep 08 15:30:59.137: 68:ef:bd:8f:04:21 ---------DHCPSTATE_INIT sending:

If all fails, I'm going to do reboot the controller and see whether it fixes the issue.

cheers,

Janesh

[pcroak]

Hi Janesh,

I want to be sure that I understand your current problem -- your 3500 APs are unable to discover your WLC using DHCP option 43, is that correct?

What type of server are you using for DHCP? Here are the instructions for option 43 and the 3500 series:

http://www.cisco.com/en/US/docs/wireless/access_point/3500/quick/guide/ap3500getstart.html#wp37440

-Pat

[janesh_abey]

Hi Janesh,

I  want to be sure that I understand your current problem -- your 3500 APs  are unable to discover your WLC using DHCP option 43, is that correct?

>>Yeap. That is correct

What type of server are you using for DHCP? Here are the instructions for option 43 and the 3500 series:

>> We are using a solution by infoblox as the dhcp server.Packet capture on the DHCP server side shows that option 43 is sent out.However on the controller I can't see option 43 received when I do a debug dhcp mess enable.

As the next step I'm going to look at the option 43 hex string and compare it with the string  I inted to receive, it could be that there is some padding  inserted by the DHCP server  which prevents WLC from seening it.

WIll let u know how it goes.

cheers,

Janesh

[janesh_abey]

Hi Peter,

As we thought the problem was due to a mismatch on how the hexstring is represented within the dhcp server and thus it was rejected by the controller. So we entered the hex string with colons and that fixed the issue.

cheers,

Janesh

[jesav]

Hi,

What did you use as DHCP option in Infoblox?  Option 43 (string) but with the HEX value?

Thanks,