Virtual Link Trunking (VLT) | 1065Enhanced VLTAn enhanced VLT (eVLT) configuration creates a port channel between two VLT domains by allowingtwo different VLT domains, using different VLT Domain ID numbers, connected by a standard LACPLAG to form a loop-free Layer 2 topology in the aggregation layer. This configuration supports amaximum of four (4) nodes per eVLT domain, increasing the number of available ports and allowing fordual redundancy of the VLT.Additionally, a VLT domain that is a member of one eVLT can be used in another eVLT configurationwith a different VLT domain. Routing protocols such as OSPF are not compatible with eVLT; however,VLT domains can be used for routing. A separate Layer 3 router is not required for inter-VLANcommunication.The following figure shows how the core/aggregation port density in the Layer 2 topology is increasedusing eVLT. For inter-VLAN routing and other Layer 3 routing, a separate Layer 3 router is required.VLT Concepts TerminologyThe following are some key VLT terms.Virtual link trunk (VLT) - The combined port channel between an attached device and the VLT peerswitches.VLT backup link - The backup link monitors the vitality of a VLT peer switch. The backup link sendsconfigurable, periodic keep alive messages between VLT peer switches.VLT interconnect (VLTi) - The link used to synchronize states between the VLT peer switches. Bothends must be on 10Gor 40G interfaces.
