What is the function of NSP Cross-Connections in the usage of a 6400 in a production network. (multiple answer)

A.
NSP cross connections can be used as conventional PVC cross-connection when both associated physical ports are external.

B.
NSP cross connections can be use to convert IGP protocols.

C.
NSP cross connections as a PVC part of a subscriber downlink or service uplink if one of the physical ports is internal

D.
NSP cross connections can function as IPSec aggregator in a VPN enviornement.

E.
NSP cross connections performs node protection using FRR.