Imagine A sending frames to X over the A-S2 link 1. We’ll keep using the same network topology with two switches and five hosts, and assume our system tries its best to implement hot-potato switching (sending the frames toward the destination MAC address on the shortest possible path). This post focuses on a major building block of the layer-2 data plane functionality: MAC learning. In the first blog post of the MLAG Technology Deep Dive series, we explored the components of an MLAG system and the fundamental control plane requirements.