Users Guide

Enhanced VLT
An enhanced VLT (eVLT) configuration creates a port channel between two VLT domains by allowing two
different VLT domains, using different VLT domain ID numbers, connected by a standard link aggregation
control protocol (LACP) LAG to form a loop-free Layer 2 topology in the aggregation layer.
This configuration supports a maximum of four switches, increasing the number of available ports and
allowing for dual redundancy of the VLT. The following example shows how the core/aggregation port
density in the Layer 2 topology is increased using eVLT. For inter-VLAN routing and other Layer 3 routing, you
need a separate Layer 3 router.
Figure 129. Enhanced VLT
VLT Terminology
The following are key VLT terms.
• Virtual link trunk (VLT) — The combined port channel between an attached device and the VLT peer
switches.
• VLT backup link — The backup link monitors the vitality of VLT peer switches. The backup link sends
configurable, periodic keep alive messages between the VLT peer switches.
• VLT interconnect (VLTi) — The link used to synchronize states between the VLT peer switches.
Virtual Link Trunking (VLT) 1029