Tunnel Concentrator supports tunnel redundancy and failover between multiple instances of the application. Redundancy ensures that tunneling services remain active even if a Tunnel Concentrator instance fails, or if the server on which the application is installed goes down.
Redundant Tunnel Concentrator instances must be in the same network segement with layer 2 connectivity so that services are not affected by a server failure. As a best practice, use instances that are installed on different physical Universal Compute Platform boxes so that a server failure affects only a single instance.
Redundancy configuration and functionality depend on whether you use ExtremeCloud IQ Controller or ExtremeCloud IQ as the management entity.
Configure redundancy on ExtremeCloud IQ Controller by configuring GRE tunneling mode for a VLAN with multiple Tunnel Concentrator instances (up to three). You can then assign the VLAN to one or more WLAN networks.
The AP attempts to send traffic for that VLAN to the highest ranked Tunnel Concentrator instance. If that connection fails, the AP attempts to connect to the second higest ranked instance, and if that connection fails, the AP attempts the third instance. The priority ranking depends on whether you also select load balancing:
If load balancing is selected—The priority ranking of the three Tunnel Concentrator instances is selected randomly to ensure that the traffic load gets balanced evenly across the instances.
If load balancing is not selected—The first Tunnel Concentrator instance in the list is given the highest priority ranking followed by the second instance and then the third instance.
Note
ExtremeCloud IQ Controller must be configured to allow an ICMP ping between the access point and the controller. The ping is required for tunnel failover to work.See Figure 2 for a redundancy setup example that uses ExtremeCloud IQ Controller as the management application. This example uses three Tunnel Concentrator instances that are spread across three Universal Compute Platform boxes.
Configure redundancy on ExtremeCloud IQ by creating redundant pairs of Tunnel Concentrator instances where each instance in an HA pair shares a single VRRP address, and the pair has an active and standby instance.
When APs send data through a tunnel, they send the data to the shared VRRP address of the HA pair, with data being directed to the active Tunnel Concentrator instance in the pair. However, if the active instance goes down or becomes unavailable, the standby instance becomes active so that data can be directed to that instance instead.
You can configure redundancy using the Tunnel Concentrator service and Tunnel Concentrator policy configurations on ExtremeCloud IQ.
See Figure 3 for an example of a redundancy setup with ExtremeCloud IQ. This example uses three redundant pairs of Tunnel Concentrator instances that are spread across two Universal Compute Platform 4120C boxes.
To add load balancing when using ExtremeCloud IQ, create more than one Tunnel Concentrator service under .