Inter-WLC Roaming with Same VLAN and IP Address
A customer has two Cisco wireless controllers named WLC-A and WLC-B. Each controller is in a different building on a campus. The WLCs have different Layer 3 interfaces and broadcast the same SSIDs from their respective APs. Users must remain connected to the same VLAN and maintain their IP addresses during roaming from the APs that are attached to WLC-A and WLC B. Which action accomplishes the requirement?
Community Votes
100% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
This question tests inter-controller L3 roaming where the client must retain its IP address; the common trap is assuming 802.11r or SSO clustering solves L3 subnet persistence instead of mobility anchoring.
When roaming between APs on different Cisco WLCs with distinct Layer 3 interfaces, clients can maintain their IP address and VLAN by using a mobility anchor. This page explains why creating a mobility group for auto-anchoring is the correct solution for seamless inter-controller L3 roaming.
Choosing 802.11r (Option C) because it speeds up roaming, but it only caches the PMK for faster authentication and does not preserve the client's IP address across different WLC interfaces.
Community Discussion (3 comments)
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Expert Analysis
Why the Answer Is Correct
Creating a mobility group between WLC-A and WLC-B allows the controllers to form a mobility tunnel. By configuring auto-anchoring (or static anchoring) for the SSID, a client roamed to WLC-B will have its traffic tunneled back to the original anchor WLC-A, keeping it on the original Layer 3 interface, VLAN, and IP address. This satisfies the requirement of maintaining IP address continuity across different L3 interfaces on the campus.Why the Other Options Are Wrong
SSO clustering (Option B) is a high-availability feature for WLC redundancy, not a mechanism for inter-controller roaming across separate active controllers. 802.11r (Option C) enables fast BSS transition by caching pairwise master keys, but it does not address L3 roaming or IP address retention. AP groups (Option D) simply map APs to specific interfaces locally on a single WLC and do not facilitate inter-WLC subnet persistence.Community Comment Notes
Commenters correctly identified that mobility features are required to solve this roaming scenario. As one user noted, "if you want roaming users to stay within the same Subnet, you need to use auto-anchoring because of the tunnel it creates". Another pointed out that clustering is for "large scale networking" rather than maintaining a specific subnet across two distinct controllers.Official Reference
Exam Strategy
For roaming questions requiring IP address retention across different WLCs or subnets, always look for the mobility anchor (auto-anchoring) option. Fast roaming protocols like 802.11r only reduce authentication time and do not maintain L3 connectivity.