Question: How to understand the Aruba Instant Architecture?
Environment: This article applies to all the IAPs and all the OS versions.
The easiest way to understand any WLAN architecture is to know how the Management, Control and Data Planes of the WLAN solution function. Below are the details of how these three planes are divided for Instant.
Management PlaneFor Instant the Management Plane is Centralized. The self-elected Virtual Controller (VC) acts as the single point of configuration for an IAP cluster. The GUI interface to the VC provides local configuration and monitoring of an IAP cluster. Cloud based configuration and management options are also available using Aruba Central (public cloud) or AirWave (private cloud).
Control PlaneThe Control Plane for IAPs is completely Distributed. All functions like Adaptive Radio Management (ARM) - Auto Channel/Power assignment, IDS/IPS, client handover etc. are handled by the individual IAPs. The Virtual Controller AP is not involved in any of these functions. For Example: The client database is completely maintained in the AP the clients are connected to. When a client roams, the new AP figures out the last associated AP for the client and requests all the client info from that AP. The other IAPs send updates to VC IAP periodically only for management plane reporting.
Data PlaneThe Data plane for Instant is also fully distributed except for certain corner cases. Each individual IAP handles the traffic for the clients associated to that IAP. The firewall policies and bandwidth control also gets applied on a per IAP basis. There is no centralized flow of all user traffic to the VC. The exception to this rule is for Guest VLAN or VC assigned VLAN in which case all IAPs forward the traffic to the VC and VC NATs the traffic out of its uplink port. This is done in order to allow L2 mobility for VC assigned VLAN.