Users Guide

• Provides a loop-free topology.
• Uses all available uplink bandwidth.
• Provides fast convergence if either the link or a device fails.
• Optimized forwarding with virtual router redundancy protocol (VRRP).
• Provides link-level resiliency.
• Assures high availability.
CAUTION: Dell Networking does not recommend enabling Stacking and VLT simultaneously. If you
enable both features at the same time, unexpected behavior occurs.
As shown in the following example, VLT presents a single logical Layer 2 domain from the perspective of
attached devices that have a virtual link trunk terminating on separate chassis in the VLT domain. However,
the two VLT chassis are independent Layer2/Layer3 (L2/L3) switches for devices in the upstream network.
L2/L3 control plane protocols and system management features function normally in VLT mode. Features
such as VRRP and internet group management protocol (IGMP) snooping require state information
coordinating between the two VLT chassis. IGMP and VLT configurations must be identical on both sides of
the trunk to ensure the same behavior on both sides.
The following illustration shows VLT deployed on S5000 switches. The switches appear as a single virtual
switch from the point of view of the switch or server supporting LACP.
Figure 145. Virtual Link Trunking on S5000 Switches
Virtual Link Trunking (VLT) 1126