Loopback
- EthTrcv — Loopback Modes for Testing and Diagnostics
How internal, external, and remote loopback work inside the Ethernet PHY, how EthTrcv drives them, and why they are indispensable for end-of-line testing and fault isolation.
- EthSwt — Diagnostics, Loopback & Test Modes on Switch Ports
The surprising fact-check finding: most of EthSwt's port diagnostic APIs are pure forwarders to the referenced EthTrcv instance, not switch-native functionality.