1522 getting ip address

Unanswered Question
May 14th, 2008

Hi all!

I'm a bit confused in understanding of getting ip address by 15xx LAPs.

Is that possible somehow to get ip address during first time startup if neither WLC nor DHCP accessible though the network with 15xx's broadcasts.

Is WLC or DHCP mandatory for getting initial ip address?

How can I get IP address if LAP15xx and WLC/DHCP are in diffirent broadcast domains (separated by router)? Helper address?

Thanks for clarification.

Michael

I have this problem too.
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jeromehenry_2 Wed, 05/14/2008 - 09:18

Your AP will request an IP address via a DHCP discover broadcast just like any other DHCP device (if it doesn't have any static IP yet). ip helper on the local router will redirect the query to your DHCP server if it is on another subnet.

DHCP option 43 can return a WLC IP address along with DHCP IP address, follow this step by step to configure the option:

http://www.cisco.com/univercd/cc/td/doc/product/wireless/airo1130/1130hig5/113h_g.htm#wp1008661

Tx

Jerome

dennischolmes Wed, 05/14/2008 - 14:20

You could also configure a DNS server to resolve the controller to an IP address or prime the AP before deploying by sticking it on a switch within the same network segment that the WLC management interface is on. That segment will still need a dhcp scope advertised on it or you could setup the internal dhcp on the controller for configuring of APs only.

Oh, and this is a biggy, make sure to enter the mac address of the AP into the controller under mac filtering. If you don't do this then the AP will never fully register to the controller.

kozharov Wed, 05/14/2008 - 23:27

Thank you all,

So, there are no means to configure initial static IP address on 15xx APs w/o DHCP, so we need external DHCP or internal DHCP running on WLC.

If DHCP and AP are separated by the router I should

1) use helper address on local router or

2) once connect AP to the same segment with DHCP and WLC, get IP address and save it on AP permanently (statically). So booting next time I'll not need to have AP and DHCP and WLC on the same subnet because I'm alresdy have IP address assigned.

Please corrert me if I'm wrong.

Michael

jeromehenry_2 Thu, 05/15/2008 - 02:34

Hi Michael,

Yes, you first have to get the AP somehow on a controller, you can't pre-configure a static IP.

Both your methods work. Keep in mind that the AP needs to get an IP address, but also to discover the controller. This is what the option 43 is for (or DNS option). With your second option, the AP has an IP address, but if it is not in the same subnet as the controller, it might not be able to discover it (if it is the same controller on which you had the AP to configure its IP address, this series, in code 4.1.191-24M, usually remembers the last controller IP address, so it might work).

Cheers

Jerome

kozharov Thu, 05/15/2008 - 02:51

Thank you for clarification,

I think it's a good idea ones somehow accessed to WLC, assign permanent (static) IP address to AP and specify primary controller IP address.

Then moving AP to new location and restarting it should be able to discover WLC (even for L3 LWAPP mode) because AP has it's own IP address and primary controller IP address already assigned.

Michael

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