VLT is a proprietary layer-2 link aggregation protocol developed by Force10 which allows users to setup aggregated links between end devices (servers) to two different physical switches. The main property is that after enabling VLT, the two physical switches will act as a single logical switch. This offers redundancy for the connection from server and balanced traffic to the core network eliminating packet loops.
In dynamic link aggregation protocol like LACP, the connections from a server can be only be terminated to a single logical switch (it can be a single physical switch or multiple switches in a single stacked switch setup). There wont be any redundancy if the aggregated links terminate to a single physical switch and the disadvantage of a switch stack is that incase of maintenance or firmware update the whole stack needs to be taken offline causing downtime which is not practical in a production environment.
The VLT peers exchange and synchronize layer-2 related table details (MAC tables, IGMP states etc) among the whole VLT domain. Devices connected to the VLT domain could be either servers or switches as long as they support port channel (LAG, LACP etc). It is recommended to enable RSTP and configure bridge priorities. Prefer static LAG between VLT peers and LACP towards hosts/ switches.
Configuration steps:
1.Enable RSTP and configure bridge priority on peer VLT switches
2.Configure VLT interconnect (VLTi), static LAG between VLT switches
3.Configure VLT domain
4.Configure LACP for the connected device
5.Verify status
References: Dell TechCenter, Niktips blog
