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New Member

LWAPP AP - DHCP Option 43

Hi,

I am working to deploy a group of 1242AG APs with a 4402-12. I am looking to use LWAPP and run the WC in layer 3 mode with the APs deployed on a different subnet.

I have been trying to allocate an address (and DHCP option 43 for the WC management IP address) via the Cisco IOS DHCP server but so far this has not been successful.

I have been unable to provide the DHCP option 43 to the APs. Below is the configuration I have tried to use.

Router DHCP Config

ip dhcp pool WLAN

network 192.168.1.0 255.255.255.0

Option 43 hex f1:07:c0:2e:a8:2e:01:2e:c8 (TLV = 241 7 192.168.1.200)

….

Can anybody possibly assist me?

Thx. Jon

  • Getting Started with Wireless
1 ACCEPTED SOLUTION

Accepted Solutions

Re: LWAPP AP - DHCP Option 43

Try this...

ip dhcp pool

network

default-router

dns-server

option 60 ascii "VCI string"

option 43 hex

----------------------------------------

assuming your management interface of 192.168.1.200 TLV

ex: option 43 hex f104c0a801c8 (no colons)

----------------VCI Strings--------------

Cisco Aironet 1130 Series = "Cisco AP c1130"

Cisco Aironet 1240 Series = "Cisco AP c1240"

Cisco Aironet 1200 Series = "Cisco AP c1200"

6 REPLIES
Super Bronze

Re: LWAPP AP - DHCP Option 43

Hi

Is the IP you are putting in the option your ap-manager or management interface?

It should be the management interface.

Additionally, 1000 series APs use a string for this option (apparently) whereas converted 1200s etc use a TLV style option - see this quote from a doc:

======================================

The IP address that should be configured as DHCP option 43 or be resolved from

CISCO-LWAPP-CONTROLLER is the IP address of the controller Management IP address. Consult the

specific documentation for the DHCP or DNS platform for details on configuring these parameters

correctly.

Cisco 1000 series access points use a string format for DHCP option 43, whereas Cisco Aironet access

points use the type-length-value (TLV) format for DHCP option 43. DHCP servers must be programmed

to return the option based on the access point’s DHCP Vendor Class Identifier (VCI) string (DHCP

option 60).

======================================

TRy adding it as a string if you only have 1000-series..

Aaron

Please rate helpful posts

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
New Member

Re: LWAPP AP - DHCP Option 43

Hi,

Thanks for the quick reply.

I am using the management interface address of the WC.

I am using a 1242AG shipped in LWAPP configuration. The setup documentation appears to indicate I need to use a TLV value.

I have tried using an ascii string however a DHCP debug on the AP would appear to show this approach does not work. I will try this approach again tomorrow.

Jon

Re: LWAPP AP - DHCP Option 43

Captured by Ethereal with WLC management address of 151.102.96.50 TLV format.

Option 43: Vendor-Specific Information (6 bytes)

f1 04 97 66 60 f0

Super Bronze

Re: LWAPP AP - DHCP Option 43

Hi

The format should be like this:

The format of the TLV block is:

Type: 0xf1 (decimal 241)

Length: Number of controller IP addresses * 4

Value: List of WLC management interfaces

So I think you have the Type (first bit right), the length wrong, and the iP address right.

Acording to the to text above, you need 04 for length, not 07:

Option 43 hex f1:04:c0:2e:a8:2e:01:2e:c8 (TLV = 241 7 192.168.1.200)

Regards

Aaron

Please rate helpful posts

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
New Member

Re: LWAPP AP - DHCP Option 43

Hi all,

Thx for all your replies. I am afraid to say the problem still persists. I have tried the following configs.

option 43 hex f1:04:c0:a8:01:c8

&

Option 43 hex f1:04:c0:2e:a8:2e:01:2e:c8

Both of these have no affect on the APs even though I can see the option being delivered by a dhcp debug and using ethereal.

Any ideas as I assume this is only a syntax issue?

Jon

Re: LWAPP AP - DHCP Option 43

Try this...

ip dhcp pool

network

default-router

dns-server

option 60 ascii "VCI string"

option 43 hex

----------------------------------------

assuming your management interface of 192.168.1.200 TLV

ex: option 43 hex f104c0a801c8 (no colons)

----------------VCI Strings--------------

Cisco Aironet 1130 Series = "Cisco AP c1130"

Cisco Aironet 1240 Series = "Cisco AP c1240"

Cisco Aironet 1200 Series = "Cisco AP c1200"

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