Users Guide

Multiple VLT
A multiple VLT (mVLT) configuration allows two different VLT domains connected by a standard LACP LAG to
form a loop-free Layer 2 topology in the aggregation layer.
This configuration supports a maximum of four (4) units, increasing the number of available ports and
allowing for dual redundancy of the VLT. The following illustration shows how the core/aggregation port
density in the Layer 2 topology is increased using mVLT. For inter-VLAN routing and other Layer 3 routing, a
separate Layer 3 router is required.
Figure 147. Example of a Multiple VLT Configuration
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. Both
ends must be on 10 GbE or 40 GbE interfaces.
• VLT domain — This domain includes both the VLT peer devices, VLT interconnect, and all of the port
channels in the VLT connected to the attached devices. It is also associated to the configuration mode
that you must use to assign VLT global parameters.
Virtual Link Trunking (VLT) 1128