Users Guide

• Downlinks — An edge port link that connects the access switches to the access layer. For example,

servers or ToR elements.

• Fabric Interlinks (Fabric Links) — The fabric interlink bandwidth is fixed: 10 GB or 40 GB.

– For a one-tier fabric, fabric interlinks connect a pair of aggregation switches.

– For a two-tier fabric, fabric interlinks connect the aggregation switches to the access switches.

– For a three-tier fabric, fabric interlinks connect the core, aggregation, and access switches

together.

VLT Components

VLT peer switches have independent management planes. A VLT interconnect (VLTi) between the VLT

chassis maintains synchronization of Layer 2 and Layer 3 control planes across the two VLT peer

switches. The VLTi uses either 10 GB or 40 GB ports on the switch.

A separate backup link maintains heartbeat messages across an out-of-band (OOB) management

network. The backup link ensures that node failure conditions are correctly detected and are not

incorrectly identified as VLTi failures by the software. VLT ensures that local traffic on a chassis does not

traverse the VLTi and takes the shortest path to the destination using direct links.

Figure 10. VLT Components

Typical VLT Topology

The VLT domain uses VLTi links between VLT peers and VLT port-channels to connect to a single access

switch, a switch stack, a server supporting LACP on its NIC, or another VLT domain. The backup-link

connects through the OOB management network. Some hosts can connect through the non-VLT ports.

Key Considerations for Designing a Layer 2 VLT Fabric

Use the Layer 2 VLT fabric for workload migration over virtualized environments. When designing the

Layer 2 VLT fabric, consider the following:

• You can deploy up to 10 fabrics. However, the fabrics do not communicate with each other.

• For a VLT fabric, AFM manages Dell Networking S4810 and S55 switches.

Supported Fabric Types