How to setup internal DHCP server on 2504 controller?

[Ilya Semenov]

Hello, everybody!

I have 2504 controller and three 2600 APs.

Controller has ip 192.x.x.1(management) and APs have 192.x.x.2, 192.x.x.3, 192.x.x.4. There is only one SSID.

Clients receive IPs from external DHCP server. Everything works fine.

In a few days the controller and APs will be transferred to other building. Now, I have to give them addresses from an internal DCHP Server, because there will no external DHCP in a new location.

I've created a scope 192.x.y.2-192.x.y.254, network 192.x.y.0 in DHCP tab on the controller. Checkmark DHCP proxy is on. Scope is activated. But I have no idea what to next?

How to made APs to give clients IPs from the internal DHCP? Should I have to create new dymanic interface?

There is no step-by-step instructions in manual...

Guys, please help!

Many thanks in advance!!!

[Rasika Nayanajith]

You should have dynamic interface for the WLAN. When configuring DHCP server IP address on that dynamic interface, it should be configured with WLC-mgt interface IP address.

Following deployment guide should help you

http://www.cisco.com/en/US/products/ps11630/products_tech_note09186a0080b8450c.shtml

HTH

Rasika

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[Daniel Ordóñez Flores]

Rasika is right... You need to create a dynamic interface for you WLAN

Here some links that can help you.

http://www.cisco.com/en/US/docs/wireless/controller/7.5/config_guide/b_cg75_chapter_01000101.html

http://www.cisco.com/en/US/docs/wireless/controller/7.5/config_guide/b_cg75_chapter_01000110.html

[Abha Jha]

To configure the controller as a DHCP server, in the controller GUI go to:

CONTROLLER > Internal DHCP Server > New

(Controller is one of the tabs on the horizontal menu).

Also please try to keep the internal DHCP server range belonging to the management network IP subnet.

Here are some sites that may help:

--Cisco guide to Configuring DHCP and DHCP scopes here:

http://www.cisco.com/en/US/docs/wireless/controller/5.1/configuration/guide/c51wlan.html#wp1152559

--For info on the AP to WLC join process here:

http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a00806c9e51.shtml?referring_site=bodynav

--Using DHCP Option 43 (only needed if your AP is on a different subnet than the WLC) here:

http://www.cisco.com/en/US/tech/tk722/tk809/technologies_configuration_example09186a00808714fe.shtml

[kaaftab]

Kindly check the following link for WLC (DHCP)  configuration.

                   http://www.cisco.com/en/US/docs/wireless/controller/5.1/configuration/guide/c51wlan.html#wp1152559

[Ilya Semenov]

Good day, friends!

Many thanks for your help!

Unfortunately, there still no success - Internal DHCP doesn't work. Clients receive nothing but APIPA.

As I told, I've created a scope 192.168.20.2-192.168.20.254, network 192.168.200 in DHCP tab on the controller. Checkmark DHCP proxy is on and scope is activated.

Now, I have created a dynamic interface with values shown below and set it for my WLAN (I have only one).

My general incomprehension and difficulties now are:

1) Which IP address should I set as DHCP Server in my dynamic interface properties?

2) What's DHCP Proxy mode here?

3) Is there any connection between internal DHCP server scope range and dynamic interface address? Should it be the same scope?

4) Which gateway should I set in DHCP scope properties?

5) Are there any additional actions in WLAN properties required?

Guys, please take a look at my screens. What is wrong with my confs? (Management int properties is also included)

Many, many  thanks in advance!!!

[Scott Fella · Accepted solution]

Your configuration is wrong... on your dynamic interface, you have a gateway of 192.168.20.254, then on your DHCP scope, you need to also use 192.168.20.254 as the clients default gateway, not 192.168.20.1, which you currently have.  So the question is, what is your subnets default gateway address, is it 192.168.20.1 or 192.168.20.254? 

Now, I have created a dynamic interface with values shown below and set it for my WLAN (I have only one).

My general incomprehension and difficulties now are:

1) Which IP address should I set as DHCP Server in my dynamic interface properties?

> The management IP of the WLC whcih is 192.168.0.111

2) What's DHCP Proxy mode here?

> DHCP proxy is set to global which meand that in the global configuration, you need to have dhcp proxy enabled.  You might want to enable it there on the interface.

3) Is there any connection between internal DHCP server scope range and dynamic interface address? Should it be the same scope?

> If you create a DHCP scope on the WLC, you also need to have a, interface/dynamic interface in which the clients will obtain the dhcp address from. 

4) Which gateway should I set in DHCP scope properties?

> The gateway in the dhcp scope is the gateway for the subnet defined in the dhcp scope

5) Are there any additional actions in WLAN properties required?

> You need to make sure that the WLAN is mapped to the dynamic interface you created.

Thanks,

Scott

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[Ilya Semenov]

Scott, many thanks to you!

I have applied your recommendations and there is a great progress at the moment. Now, clients receive IP addresses from 192.168.20.0/255.255.255.0 range. The gateway is 192.168.20.254.

But there are several problems:

1) Win8 output of ipconfig command states that ip-address of DHCP server is 1.1.1.1 (It's the vitrual interface on the controller) - it's very strange!

2) From telnet session with controller I can ping only 192.168.20.1 (dynamic interface), but not 192.168.20.254

3) From windows machine I can ping neither 192.168.20.1 or 192.168.20.254

It seems like there is no routing between the interfaces on controller's side...

Do you have any ideas how it could be resolved?

Thank you very much!

[Scott Fella]

Well for one, the virtual interface is used as the dhcp server when dhcp proxy is enabled. Since you are using the WLC as a dhcp server, you need dhcp proxy enabled and the client will show the VIP as the dhcp server. The WLC does not route only bridges. So your router needs do all the routing.

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[Ilya Semenov]

Sorry, Scott, but it sounds incredible!

I think there is kind of misunderstanding...

In the simplest terms, I have lack of free IPs on LAN. So, local administrator has given me only four ip address for controller and three 2600 APs from 10.10.10.0 range. I need to use fake, different range for wi-fi clients, something like 192.168.x.x...

You mean, that 2504 controller can't make NAT between two interfaces like all the countless $30 DLINKs ???

Thank you!!!

[Scott Fella]

Nope... not at all... the WLC only bridges the traffic, you need to have a valid layer 3 interface on the network.

Thanks,

Scott

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[Ilya Semenov]

Hello, Scott!

You were completely right - CISCO conformed, that there is an additional interface at the router side required. 

The only question remains - one computer constantly receives 169.254.x.x address, while others - correct addresses from 192.168.20.x...

At the Monitor>Clients tab it's shown as "Excluded". What most likely could be the problem?

Scott, many thanks to you! Your help are greatly appreciated!

[Scott Fella]

That means the client failed to authenticate. Make sure the wireless authentication is set properly. For example, if your using preshared key, the key could of been entered wrong.

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