What is the role of a route distinguisher via a VRF-Lite setup implementation?

What is the role of a route distinguisher via a VRF-Lite setup implementation?
A . It extends the IP address to identify which VFP instance it belongs to.
B . It manages the import and export of routes between two or more VRF instances
C . It enables multicast distribution for VRF-Lite setups to enhance EGP routing protocol capabilities
D . It enables multicast distribution for VRF-Lite setups to enhance IGP routing protocol capabilities

View Answer

Answer: A

Explanation:

In VRF-Lite, Route distinguisher(RD) identifies the customer routing table and ”allows customers to be assigned overlapping addresses”.

The below example shows overlapping IP addresses configured on two interfaces which belong to two different VPNs:

Router(config) #ip vrf VRF_BLUE

Router(config-vrf) #rd 100:1

Router(config-vrf) #exit

Router(config) #ip vrf VRF_GREEN

Router(config-vrf) #rd 100:2

Router(config-vrf) #exit

Router(config) #interface GigabitEthernet 0/ 1

Router(config-if) #ip vrf forwarding VRF BLUE

Router(config-if) #ip address 10.0.0.1 255.0.0.0

Router(config-vrf) #exit

Router(config) #interface GigabitEthernet 0/ 2

Router(config-if) #ip vrf forwarding VRF GREEN

Router(config-if) #ip address 10.0.0.1 255.0.0.0

In this example, the RD will be added to the beginning of the IP address. For example with VRF_BLUE (rd 100:1), anIP addresswillbeseenlikethis:100:1:10.0.0.1/8 so that it is unique in the routing table.