Refer to the exhibit.
Which two statements about the VPN solution are true? (Choose two.)
A.
Customer A and customer B will exchange routes with each other.
B.
R3 will advertise routes received from R1 to R2.
C.
Customer C will communicate with customer A and B.
D.
Communication between sites in VPN1 and VPN2 will be blocked.
E.
R1 and R2 will receive VPN routes advertised by R3.
+ VPN1 exports 10:1 while VPN3 imports 10:1 so VPN3 can learn routes of VPN1.
+ VNP1 imports 10:1 while VNP3 export 10:1 so VNP1 can learn routes of VPN3.
-> Customer A can communicate with Customer C
+ VPN2 exports 20:1 while VPN3 imports 20:1 so VPN3 can learn routes of VPN2.
+ VPN2 imports 20:1 while VPN3 exports 20:1 so VPN2 can learn routes of VPN3.
-> Customer B can communicate with Customer C
Therefore answer C is correct.
Also answer E is correct because R1 & R2 import R3 routes.
Answer A is not correct because Customer A & Customer B do not import routes which are
exported by other router. Customer A & B can only see Customer C.
Answer B is not correct because a router never exports what it has learned through importation. It
only exports its own routes.
Answer D is correct because two VPN1 and VPN2 cannot see each other. Maybe in this question
there are three correct answers.
QUESTION NO:
Well done snoopy 🙂
D is not a correct answer. It says communication between “VPN1” and “VPN2” is blocked. Since R3 is importing 20:1, Customer B (VPN1) can “see” routes from Customer C (VPN2).
Additionally, if Customer C is advertising a default route (or customer A & Customer B have a static default route upstream), I believe traffic between Customer A (VPN1) and Customer B (VPN2) would work. Traffic from Customer A to Customer B would follow the default route to R3. When R3 does a route lookup, it sees the traffic is destined for Customer B and forwards it, thus allowing communication between all the sites.
A is incorrect because they do not import each others routes due to VRF restrictions. They are set to only import their own route-targets.
B is incorrect because of the rules of iBGP route advertisement. R3 will advertise to R1 and R2 only what it learns from Customer C. It will not advertise routes received from R1 to R2 or R2 to R1 unless it is a Route Reflector and they do not tell us that it is. R1, R2 and R3 are all in AS100.
D is not necessarily true. It depends on what is happening at Customer C who imports routes from both VPN1 and VPN2.