Internal Port 0 Test – Selects the Internal loopback connections for testing Port 0.

Internal Port 1 Test – Selects the Internal loopback connections for testing Port 1.

Internal Port 2 Test – Selects the Internal loopback connections for testing Port 2.

External Port 0 Test – Selects the External loopback connections for testing Port 0.

External Port 1 Test – Selects the External loopback connections for testing Port 1.

External Port 1 Test – Selects the External loopback connections for testing Port 2.