Layer 3 Roaming
What if a wireless network grows even more, such that the WLAN interfaces on each controller are assigned to different VLANs and subnets? Breaking a very large WLAN up into individual subnets seems like a good idea from a scalability viewpoint. However, when a wireless client roams from one controller to another, it could easily end up on a different subnet than it started with.
Clients will not usually be able to detect that they have changed subnets. They will be aware of the AP roam but little else. Only clients that aggressively contact a DHCP server after each and every roam will continue to work properly. But to make roaming seamless and efficient, time-consuming processes such as DHCP should be avoided.
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