Explanation/Reference:
Explanation: With such an arrangement there is no complex mesh of access points & controllers.
Link: http://www.cisco.com/web/learning/le31/le46/cln/qlm/CCDA/design/understanding-wireless- network- controller-technology-3/player.html N+N WLC Redundancy
With N+N redundancy, shown in Figure 5-14. an equal number of controllers hack up each other. For example, a pair of WLCs on one floor serves as a backup to a second pair on another floor. The top WLC is primary for API and AP2 and secondary for AP3 and AP4. The bottom WLC is primary for AP3 and AP4 and secondary for API and AP2. There should be enough capacity on each controller to manage a failover situation.

N+N+1 WLC Redundancy
With N+N+1 redundancy, shown in Figure 5-15, an equal number of controllers back up each other (as with N+N), plus a backup WLC is configured as the tertiary WLC for the APs. N+N+1 redundancy functions the same as N+N redundancy plus a tertiary controller that backs up the secondary controllers. The tertiary WLC is placed in the data center or network operations center

Exam B