Which two statements regarding VRF tables are correct? (Choose two.)
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A. B. C. D.AC
VRF (Virtual Routing and Forwarding) tables are used in multi-tenant networks, where multiple virtual networks are running over a single physical infrastructure. Each virtual network or tenant has its own VRF table, which contains the routing information for that specific network. In a service provider network, VRF tables are commonly used in MPLS (Multiprotocol Label Switching) VPNs (Virtual Private Networks).
Now, let's analyze the statements provided in the question and determine which two are correct:
A. A PE router's VRF table stores routes received from directly connected CE devices.
This statement is correct. PE (Provider Edge) routers connect to the CE (Customer Edge) routers of each tenant, and the VRF table on the PE router stores the routes learned from the directly connected CE devices. This is the primary purpose of VRF tables in MPLS VPNs.
B. A PE router's VRF table stores routes received from its IGP from remote PE devices.
This statement is not entirely correct. While it is true that PE routers use an IGP (Interior Gateway Protocol) to exchange routing information with other PE routers, this information is not stored in the VRF table. Instead, the information learned through the IGP is used to build the MP-BGP (Multiprotocol Border Gateway Protocol) routes, which are then stored in the VRF table.
C. A PE router's VRF table stores routes received from MP-BGP from remote PE devices.
This statement is correct. In MPLS VPNs, the PE routers use MP-BGP to exchange routing information with other PE routers. The MP-BGP routes contain the VPNv4 ( VPN version 4) prefixes, which are then stored in the VRF table of the receiving PE router. This allows the PE router to forward traffic to the correct destination within the VPN.
D. A PE router's VRF table stores routes received from all P and PE devices within the same AS.
This statement is not correct. The VRF table on a PE router only stores the routes learned from the directly connected CE devices, as well as the MP-BGP routes learned from other PE routers. The P (Provider) routers in the network do not participate in the VPN routing, and their routing information is not stored in the VRF tables.
Therefore, the correct statements regarding VRF tables are A and C.