Wireless LAN Controller

Question

I have a Cisco 2500 series WLC, and a 1700 series LWAP.

1. In this case, what provides the AP the DHCP IP address, my router or the WLC??
2. There is already a PoE port in the WLC, yet when I connect my LWAP to the WLC, it does not get a DHCP IP address and the LWAP keeps searching for the controller. Why is it so?
3. I know that the only way to have the routing done in the controller is via VLAN using the switches. Please suggest me how to create VLANs and do the routing via it.

Answer 1

The LWAP will get its IP address from the DHCP server for the VLAN to which its management interface is attached, just like any other host on a VLAN.

The LWAP should also get option 43 from the DHCP server to indicate which WLC it should use. You can read about it in DHCP OPTION 43 for Lightweight Cisco Aironet Access Points Configuration Example:

3. Add the Option 43 line with this syntax:

option 43 hex <hexadecimal string>

The hexadecimal string in step 3 is assembled as a sequence of the TLV values for the Option 43 suboption: Type + Length + Value. Type is always the suboption code 0xf1. Length is the number of controller management IP addresses times 4 in hex. Value is the IP address of the controller listed sequentially in hex.

For example, suppose there are two controllers with management interface IP addresses, 192.168.10.5 and 192.168.10.20. The type is 0xf1. The length is 2 * 4 = 8 = 0x08. The IP addresses translate to c0a80a05 (192.168.10.5) and c0a80a14 (192.168.10.20). When the string is assembled, it yields f108c0a80a05c0a80a14. The Cisco IOS command that is added to the DHCP scope is:

option 43 hex f108c0a80a05c0a80a14

The WLC doesn't do routing, and neither do switches. Routing is handled in a router (a layer-3 switch includes a router). You must trunk the VLANs to a router for it to route between the VLANs.

VLANs and routing are very fundamental networking. An answer on how to do these is far too broad, and the possible answer far too large, to be answered here.

I would strongly suggest that you hire someone who knows what to do to accomplish what you want done.

You can connect WLCs and LWAPs like you do with users. In the diagram below, users can connect to any of the switches, as can WLCs and APs. Each switch can have one or more VLANs, or you could have a single switch with one or more VLANs.

Answer 2

The WLC does not physically sit between the AP and the rest of the LAN. In your scenario, your router should connect directly to the switch ("normal switch"). The WLC and AP should also have their own individual connections to the switch.

To answer your questions:

1. The router will provide an address to the AP.
2. Connecting the AP to the PoE port is not currently supported by Cisco.
3. In this small network, there is no need for multiple VLANs. The AP will find the controller because they are on the same VLAN. If youwere to have them on different VLANs, you could use either DHCP options (as @ronmaupin explains) or use DNS (my preference).