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Vlan Select Feature

I am pending to deploy wireless controller in my new office. I will have 20 Vlans for different departments or functional staff. For previous setup experience, we will use two 21xx WLC and map each VLAN to each WLAN.

This few days, I read there is a new feature in latest IOS (v7.2) call "Vlan Select" / "Interface Group" so I would want to ask is it mean I can group all the VLAN to one interface group. Then assign this interface group to on WLAN but I don't understand how the WLC can correctly assign a end point with corresponding VLAN. For example, a guy should be assigned to VLAN 5, how can WLC assign it to VLAN 5 if this guy access a WLAN with the interface group which include VLAN 1~20?

Thanks very much.

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Vlan Select Feature


When using interface groups the vlan assignment will be in round robin. If VLANs in the the interface gropu belong to VLANs from 1 - 20 then first client to connect will be mapped to VLAN 1, second to VLAN 2, Third to VLAN3........ Twenth to VLAN 20, 21st clietn will go to VLAN 1 back again....etc.



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Vlan Select Feature

Expanding on the above,

         If you need to have a particular user put into a particular VLAN, you would need to use dynamic VLAN assignement from your AAA server.  IETF attributes 64/65/81, would need to be configured in the group the user(s) belong to, so that it sends this to the WLC when teh 802.1x authentication happens.


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HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered

Re: Vlan Select Feature

You ate right Steve.

Vlan override is mentioned in the doc i posted. I did not mention it in my post because vlan override can be used even without utilizing vlan select feature.

Sent from Cisco Technical Support iPad App

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Cisco Employee

Re: Vlan Select Feature

On wireless clients get ip in round robin fashion and not on 7.2 initially.

On 7.2, the same wireless client will get an ip assigned from same vlan, however it fallback to round robin if the interface continue to be dirty.

Community Member

Re: Vlan Select Feature

ON 7.2, how is the ip assignment for wireless client?

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Re: Vlan Select Feature

Here is a link:

The new algorithm is based on the Client’s MAC address and operates in this way:

  • When a client associates to a WLAN on a controller, an index is calculated based on the MAC address of the client and the number of interfaces in the interface group using a hashing algorithm.

  • Based on this index, an interface is assigned to the client.

  • Whenever this client joins the controller, the hashing algorithm always returns the same index and the client is assigned to the same interface.

  • If the interface is “dirty”, then a random index is generated and the interface is assigned based on that random index.

  • If that interface is still dirty, then a fall back to round robin implementation occurs.

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Re: Vlan Select Feature

newer and  are having same algorithm as 7.2.

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