In BIG-IP architecture, link aggregation and redundancy at Layer 2 are implemented using Trunks, not virtual servers or pools.
According to BIG-IP Administration Data Plane Concepts:
Interfaces are the physical network ports on the BIG-IP device
A Trunk is a logical grouping of multiple interfaces
Trunks can be configured to use LACP (Link Aggregation Control Protocol) to:
Provide link redundancy
Increase aggregate bandwidth
Allow automatic detection of link failures
VLANs are then assigned to the trunk, not directly to individual interfaces, once aggregation is in place
Correct Design for the Scenario:
To connect BIG-IP to two upstream switches with LACP:
One physical interface from BIG-IP connects to Switch A
Another physical interface from BIG-IP connects to Switch B
Both interfaces are placed into the same trunk
LACP is enabled on the trunk and on the switches
This configuration allows:
Traffic to continue flowing if one interface or switch fails
Proper LACP negotiation between BIG-IP and the upstream switches
Clean separation of responsibilities (Layer 2 handled by trunking, Layer 4–7 by virtual servers)
Why Option D Is Correct:
A Trunk containing an interface connected to each switch is exactly how BIG-IP implements LACP-based interface binding
The trunk handles link state, load distribution, and failover at the data plane
Why the Other Options Are Incorrect:
A & B – Virtual servers operate at Layers 4–7 and have nothing to do with physical link aggregation or LACP
C – VLAN IDs and MAC addresses are not configured inside a trunk definition; trunks aggregate interfaces, and VLANs are applied to trunks
Key Data Plane Concept Reinforced:
On BIG-IP systems, LACP is always configured on a Trunk, which aggregates physical interfaces to provide Layer 2 resiliency and bandwidth aggregation. Virtual servers and pools are not involved in physical interface binding.
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