EPLD (Erasable Programmable Logic Device) upgrades are used to patch known hardware issues or enhance functionality on modular Cisco Nexus 9000 Series switches. These upgrades affect programmable logic components on hardware modules. GIR (Graceful Insertion and Removal) is used for maintenance without traffic disruption. SMU (Software Maintenance Upgrade) addresses software bugs. POAP (Power-On Auto Provisioning) automates initial switch configuration, not hardware functionality.