Live migration moves running VMs between hosts without downtime.
Network requirements:
Layer adjacency. VM keeps its IP. Both hosts need same broadcast domain, or use overlays.
Low latency. Target under ms between hosts.
High bandwidth. A GB VM needs significant capacity.
Dedicated network. Isolate migration from production.
After migration: VM announces new location via gratuitous ARP. Switches update MAC tables.
With VXLAN, migration can cross Layer boundaries.