Which four statements about the Carrier Supporting Carrier (CSC) feature are true?
(Choose four)

A.
MPLS is required between the PE and CE routers that connect the backbone carrier to the
customer carrier.

B.
The backbone carrier must enable the PE router to check that the packets it receives from the
CE router contain only the labels that the PE router advertised to the CE router.

C.
Every packet that crosses the backbone carrier must be encapsulated so that the packet
includes MPLS labels

D.
AII PE routers that link the backbone carrier to the customer carrier must run Route Target
Rewrite.

E.
A routing protocol is required between the PE and CE routers that connect the backbone carrier
to the customer carrier. The routing protocol enables the customer carrier to exchange IGP routing
information with the backbone carrier.