WLC - 4402/4 - Vlan Interface Addressing

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Sep 11th, 2009
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I currently have 7 WLCs with the same Vlan interfaces defined across all 7 controllers. Does anyone know the best practice for addressing these interfaces on each of the WLCs. I currently have each unique Vlan interface assigned with the same IP address across all 7 WLCs. This is working. Should I leave it this way or should I assign each controller with a different address for the Vlan interface?

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dancampb Fri, 09/11/2009 - 06:16
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If I read this correctly you have used the same IP address on all the VLAN interfaces across all the controllers? If so I'm surprised this is working. Each controller should have a unique IP address for every interface. The only interface that should have the same IP address as the other controllers is the virtual interface.

Rick Meier Fri, 09/11/2009 - 06:47
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These interfaces are the interfaces that are assigned to the SSIDs. In the manual they are called the Dynamic interfaces. I inherited the network and the addresses were assigned when I got here. It's been working this way for close to a year. The section on the interface config page entitled "Interface Address" with the fields Vlan identifer, IP address,netmask and gateway. Is what I'm talking about.

dancampb Fri, 09/11/2009 - 07:05
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Yes, the dynamic interface on a controller has to have a unique IP address.

Rick Meier Fri, 09/11/2009 - 07:08
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Thanks for your help. I'll change them.

How was it working w/ them being the same? What kind of problems do you think this would have caused?

ehlers.kevin Fri, 09/11/2009 - 14:43
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The controllers, assuming you have it configured as such, act as dhcp relay agents. Presumably, if the router got the wrong mac address in its arp entry, the dhcp message would be lost.

Clients could have taken a while before getting a dhcp addr (race condition for router arp entry) and not been able to work if dhcp was required.

That said, I've seen the controllers work with the dhcp server set to so the ip helper addresses on the routers would pick up the requests.

George Stefanick Sat, 09/12/2009 - 08:48
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