In the last two decades, applications have evolved from single monoliths to the highly distributed microservices model. The scale of the traffic supported in a modern-day infrastructure is huge. All new applications demand a greater network bandwidth, and the interconnect speeds are increasing at a rapid pace. To provide non-stop services, modern data centers require high availability (HA) designs for providing non-stop services. The HA concept should be followed in both software and hardware designs.
For software design, the software should communicate and synchronize data with the connected Top-of-Rack (ToR) or leaf switch. This way, if one of the switches goes down, either due to planned maintenance or outage, the other switch will take over. For hardware design, hosts with two NICs should be dual-attached with one link to two leaf switches in a port-channel. Dell Technology calls this protocol Virtual Link Trunking or VLT. In this protocol, the end host functions as if it were connected to a single switch with a bond.
VLT enables networks with high availability and resiliency. VLT has been deployed at various locations, and customers are satisfied with its seamless functionality for the traffic flow and their business needs.
This document explains the dual-node VLT deployment strategies with its associated network reference architecture with an emphasis on best practices and references for network scenarios. This document also covers the configuration and troubleshooting of VLT using relevant show commands and different outputs.