Dell PowerConnect W-IAP92 Dell Instant 6.2.0.0-3.2.0.0 User Guide - Page 109

Chapter 9 Virtual Controller Dell W-Instant does not require an external Dell PowerConnect W-Series Mobility Controller to regulate and manage the Wi-Fi network. Instead, one W-IAP in every network assumes the role of virtual controller. It coordinates, stores, and distributes all the settings required to provide a centralized functionality to regulate and manage the Wi-Fi network. The Virtual Controller (VC) is the single point of configuration and firmware management. When configured, the virtual controller sets up and manages the VPN tunnel to a Dell PowerConnect W-Series mobility controller in the data center. The VC also functions like any other AP with full RF scalability. It also acts as a node, coordinating DHCP address allocation for network address translated clients ensuring mobility of the clients when they roam between different W-IAPs. Master Election Protocol The Master Election Protocol enables the Dell W-Instant network to dynamically elect a W-IAP to take on a VC role, allow graceful failover to a new Virtual Controller when the existing VC is down, and avoid race conditions. This protocol ensures stability of the network during initial startup or when the VC goes down by allowing only one W-IAP to self-elect as a VC. Preference to an IAP with 3G/4G Card The Master Election Protocol prefers the Instant AP (W-IAP) with a 3G/4G card, when electing a VC for the Dell W-Instant network during initial startup. The VC is selected as follows: l If there are more than one W-IAP with 3G/4G cards, one of these W-IAPs is dynamically elected as the VC. l When a W-IAP without 3G/4G card is elected as the VC but is up for less than 5 minutes, another W-IAP with 3G/4G card in the network will be elected as the VC to replace it and the previous VC reboots. l When a W-IAP without 3G/4G card is already elected as the VC and is up for more than 5 minutes, the VC will not be replaced until it goes down. NOTE: W-IAP135 is preferred over W-IAP105 when a VC is elected. Preference to a W-IAP with Non-Default IP The Master Election Protocol prefers the W-Instant AP (W-IAP) with non-default IP, when electing a VC for the Dell W-Instant network during initial startup. If there are more than one WIAPs with non-default IPs in the network, all W-IAPs with default IP will automatically reboot and the DHCP process is used to assign new IP addresses. Dell PowerConnect W-Series Instant Access Point 6.2.0.0-3.2.0.0 | User Guide 109 | Virtual Controller