Seamless Layer 3 Roaming Configuration
A customer currently is migrating the old wireless infrastructure to a new Cisco IOS XE-based solution and wants a mobility group configured between a Cisco AireOS WLC and an IOS XE WLC. During the migration phase from AireOS to IOS XE, the Layer 3 roaming between the WLCs must be seamless. Which action meets the requirements?
Community Votes
100% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
Layer 3 inter-controller roaming requires the same SSID to allow seamless client transition, but different VLANs and subnets to trigger the Layer 3 mobility tunnel.
Seamless Layer 3 roaming between Cisco WLCs requires clients to maintain their wireless connection across different subnets. This page establishes that for Layer 3 roaming to occur, the SSIDs must be identical while the VLANs and subnets must differ.
Choosing option A because it seems intuitive for seamless roaming, but using the same VLAN IDs and subnets results in Layer 2 roaming, not Layer 3.
Community Discussion (5 comments)
Comments & Corrections
No comments yet — spotted an error or have a note? Share it below.
Expert Analysis
Why the Answer Is Correct
For seamless inter-controller roaming, the client must associate to the same SSID on both wireless LAN controllers; otherwise, the client would disconnect and reassociate rather than roam. Because the requirement specifies Layer 3 roaming, the client must move to a different subnet on the foreign controller, which necessitates different VLAN IDs and subnets. Option D correctly identifies this combination of same SSIDs with different VLANs and subnets.Why the Other Options Are Wrong
Option A describes Layer 2 roaming, where the client stays in the same subnet across both controllers, contradicting the Layer 3 requirement. Options B and C suggest using different SSIDs, which prevents seamless roaming entirely because the client would see them as distinct networks and drop its connection before reassociating. Option C also incorrectly suggests using the same VLANs and subnets, which would force Layer 2 roaming.Community Comment Notes
The community correctly emphasizes that the distinction hinges on the Layer 3 requirement, noting that "if the same VLAN and subnet then it is not Layer 3 roaming". Another user pointed out that different SSIDs eliminate roaming altogether, stating "If different SSID then there's no roaming at all". The consensus highlights that Layer 3 roaming inherently requires different subnets.Official Reference
Exam Strategy
When analyzing roaming questions, first determine if the roaming is Layer 2 or Layer 3. Layer 2 roaming uses the same subnet and VLAN, while Layer 3 roaming requires different subnets. Always remember that seamless roaming fundamentally requires the same SSID; different SSIDs force a full reassociation.
Layer 3. It they are roaming in Layer 3, each WLC will be in a different subnet