Dell W-Series 207 Instant 6.5.1.0-4.3.1.0 User Guide - Page 70

Master Election and Virtual Controller Instant does not require an external Mobility Controller to regulate and manage the Wi-Fi network. Instead, one W-IAP in every network assumes the role of VC. It coordinates, stores, and distributes the settings required for providing a centralized functionality to regulate and manage the Wi-Fi network. The VC is the single point of configuration and firmware management. When configured, the VC sets up and manages the Virtual Private Network (VPN) tunnel to a mobility controller in the data center. The VC also functions like any other W-IAP 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 Instant network to dynamically elect a W-IAP to take on a VC role and allow graceful failover to a new VC when the existing VC is not available. 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 a W-IAP with 3G/4G Card The Master Election Protocol prefers the W-IAP with a 3G/4G card when electing a VC for the Instant network during the initial setup. The VC is selected based on the following criteria: l If there is 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 is 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. 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 a W-IAP with non-default IP when electing a VC for the Instant network during initial startup. If there are more than one W-IAPs 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. Viewing Master Election Details To verify the status of a W-IAP and master election details, execute the following commands: (Instant AP)# show election statistics (Instant AP)# show summary support Manual Provisioning of Master W-IAP In most cases, the master election process automatically determines the best W-IAP that can perform the role of VC, which will apply its image and configuration to all other W-IAPs in the same W-IAP management VLAN. When the VC goes down, a new VC is elected. Provisioning a W-IAP as a Master W-IAP You can provision a W-IAP as a master W-IAP by using the Instant UI or the CLI. 70 | Customizing W-IAP Settings Dell Networking W-Series Instant 6.5.1.0-4.3.1.0 | User Guide