You can use the BIG-IP system in an aggregated two-interface load balancing topology. Link aggregation is the process of combining multiple links so that the links function as a single link with higher bandwidth. Aggregating multiple interfaces into a trunk to create a link has the following advantages:
Link aggregation occurs when you create a trunk. A trunk is a combination of two or more interfaces and cables configured as one link.
The examples in this implementation show a trunk that includes two tagged interfaces aggregated together. A tagged interface is an interface that is configured to process traffic for multiple VLANs. A VLAN tag identifies the specific VLAN and enables traffic to pass through that specific VLAN. To cause traffic for multiple VLANs to be passed through a single trunk, you must assign the same trunk to each VLAN.
In the example, we create a trunk (trunk1) that includes two interfaces, 1.1 and 1.2, and then assign trunk1 as a tagged interface to both VLAN external and VLAN internal. Both VLANs (external and internal) reside on the same network, and are combined to form a VLAN group.
With this configuration, inbound and outbound traffic passing between the BIG-IP system and the vendor switch can use either interface. For example, traffic destined for VLAN externall can pass through either interface, 1.1 or 1.2.
Perform the following tasks to configure two interfaces (tagged VLANs) to function as a single link with higher bandwidth. In this implementation, you combine the two tagged VLANs into one VLAN group, where the two VLANs are on the same IP network.