Wireless Access

If I have two controllers in redundancy mode while all APs should get the IP address through DHCP on the controllers, I understand that DHCP server should be splitted between the controllers but what happens when one controller fails ?

Lets say I have a class C subnet used for the APs, while there is atleast 200 APs connected to the controllers.

By splitting DHCP each controller will provide 127 IP Addresses only, so if one of the controllers went down as soon as the APs restart and request a new IP address what would happen as the other controller is out of IPs ? 

They will not get an ip address.  Use an external DHCP server for the best results.

Some good options u might consider:

• Ubuntu Server will give u good results.

https://help.ubuntu.com/community/dhcp3-server

https://help.ubuntu.com/10.04/serverguide/dhcp.html

• Windows Server (DHCP)

http://community.arubanetworks.com/aruba/attachments/aruba/115/3411/1/DHCP_Microsoft_Option43-v1.1.pdf

http://technet.microsoft.com/en-us/library/cc732584.aspx

http://technet.microsoft.com/en-us/library/cc732075.aspx

http://www.arubanetworks.com/techdocs/ArubaOS_60/UserGuide/DHCP_Option_43.php

• Router/GW with DHCP server

You may find other good options via Google.

Me.

Thank you guys, I guess providing DHCP using the core switch would be a good option.

I would strongly advise a server-based DHCP solution and not use network gear to provide those services. A majority of the DHCP solutions are free.

Most DHCP features provided by network gear are meant for small deployments and do not scale well or provide HA capability.