Network Controller

The controller is a key part of the software defined WAN as it provides centralized intelligence for the WAN. In a Talari SD-WAN, any appliance can be designated as the controller, and is referred to as the Network Control Node or NCN. The appliance designated as the controller is usually in a location with sufficient bandwidth and connectivity to establish a connection with each Talari appliance in the network – generally either the data center, a colocation facility or the cloud.

Because of the importance of the NCN, it is possible to run the NCN as a high availability pair so that there is an active standby in case the primary NCN fails. And a second appliance or high availability pair in a geographically separate location can be designated as a backup NCN, which will take over in case of a complete failure of the primary NCN pair. These levels of redundancy ensure that the controller function is highly available. Even with those measures, it is possible in a WAN to experience periods where the controller is not accessible. The Talari software defined WAN is designed to continue to function even when the NCN is temporarily unavailable.

Control Functions

  • Learn topology and push to clients appliances
  • Synchronize time between appliances
  • Arbitrate bandwidth reservation
  • Establish dynamic connections
  • Synchronize one-touch push of OS upgrades

Centralized Policy Functions

Policies that control the behavior of a Talari software defined WAN are defined in a single location – not on every appliance. The NCN is responsible for centrally storing the application and traffic handling policies and pushing changes to the client appliances.

Controller Location

  • Can be a physical or virtual appliance. All Talari appliances with the exception of the T510 can be designated as the controller.
  • Can reside in the cloud, co-lo or on premises.
  • Can be installed inside of a client appliance or stand-alone.
  • Can be deployed in HA pairs and in a geo-redundant location. The form factor of the geo-redundant locations do not have to be the same, so that, for example, a cloud controller can be backed up with an on premises controller.