Refer to the partial Cisco IOS XR PE router configuration exhibit for supporting a Layer 3 MPLS
VPN customer using BGP as the CE-to-PE routing protocol.

The service provider AS number is 64500, the customer AS number is 64501, and the customer
CE router is 10.1.1.1. What is missing in the configuration?

A.
The route distinguisher has not been configured under router bgp 64500 vrf Customer_A.

B.
The import and export route targets have not been configured under router bgp 64500 vrf
Customer_A.

C.
The 10.1.1.1 BGP neighbor has not been activated for IPv4 unicast routing.

D.
The 10.1.1.1 BGP neighbor has not been activated for the VPNv4 address family.

Explanation:

http://www.cisco.com/en/US/docs/ios/12_2sr/12_2sra/feature/guide/srbgprid.html
Route Distinguisher
A router distinguisher (RD) creates routing and forwarding tables and specifies the default route
distinguisherfor a VPN. The RD is added to the beginning of an IPv4 prefix to change it into a
globally unique VPN-IPv4prefix. An RD can be composed in one of two ways: with an autonomous
system number and an arbitrarynumber or with an IP address and an arbitrary number. You can
enter an RD in either of these formats:
•Enter a 16-bit autonomous system number, a colon, and a 32-bit number. For example:
45000:3
•Enter a 32-bit IP address, a colon, and a 16-bit number. For example:
192.168.10.15:1