This concept explains how static IP client mobility enables seamless connectivity for wireless clients that use static IP addresses as they roam across controllers within the same mobility group.
Static IP client mobility is a wireless network capability that
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allows clients with static IP addresses to maintain connectivity when roaming between controllers
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tunnels client traffic to controllers that support the client’s original subnet, and
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ensures reliable service across controllers within the same mobility group.
Behavior and configuration details for static IP client mobility
Wireless networks sometimes require clients to use static IP addresses. When these clients move within the network, they may attempt to associate with different controllers.
If a client tries to connect to a controller that does not support the subnet that matches the static IP address, the connection fails. The controller inspects ARP requests from the client to determine whether the IP address was assigned by DHCP or was statically configured.
If the ARP request contains an IP address that is not present on any of the controller’s Switched Virtual Interfaces (SVIs), the client is disconnected with a VLAN_FAIL error. In this case, client traffic is backhauled without explicit disconnection. The disconnection behavior that results from a VLAN mismatch was introduced in the 17.9.1 release.
Example of static IP client mobility in action
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If a wireless client with a static IP address moves to a controller that does not support the client’s subnet, the controller analyzes the ARP request. If the subnet is not recognized, the controller disconnects the client, and the client traffic is backhauled.
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When the client moves to a controller within the same mobility group that supports the correct subnet, the traffic is tunneled to the appropriate controller. As a result, the client remains connected to the network even when subnet support varies across controllers.