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WLAN Controllers and the Difference Between Layer 2 and 3 Transport Mode
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Q:
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In the deployment of Wireless LAN controllers, what is the difference between Layer 2 and Layer 3 Transport Mode?
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A:
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In a nutshell, when lightweight APs first boot up, their only mission in life is to find their controller. When the controller and APs are on the same subnet or VLAN, the APs can find the controller with a simple Layer 2 broadcast. That’s easy Layer 2 deployment. But, what if the APs and controller are on different subnets or VLANs? Then, a layer 2 broadcast won’t cut it. Now, Layer 3 transport mode is required. This means the APs must acquire an IP address (usually through DHCP) and then proceed to be routed over to the subnets where the controllers reside. In layer 2 mode, the APs do not have an IP address. It is also strongly advised to avoid mixed deployments of layer 2 and layer 3 transport mode controllers. Either deploy them ALL as layer 2 or ALL as layer 3. When lightweight APs boot up, they first try Layer 2 broadcast and, upon failing to find a controller, switch over to Layer 3 and DHCP for an IP address.
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To learn more, contact GigaWave Technologies at 210.375.0085 or info@giga-wave.com
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