This is the free-text interface description that the remote pseudowire endpoint sent during signaling/OAM, letting the local device know what the peer calls its own attachment circuit. It's useful for cross-checking that the pseudowire actually terminates on the interface the admin thinks it does, since VC labels alone don't reveal the peer's physical port name. For instance, this field might read 'GigabitEthernet0/1/2 - Customer XYZ WAN link', confirming the VC lands on the expected remote interface rather than a spare or mis-provisioned port.