Cisco 300-515 SPVI Service Provider VPN Practice Exam

Correct: B — the route distinguisher. The RD is prepended to the customer IPv4 prefix to form a globally unique 96-bit VPNv4 address, which is what allows two customers with overlapping address space to be advertised independently through MP-BGP.

Why not the others: The route target (A) controls which VRFs import and export a route — it governs VPN membership, not uniqueness. The VPN label (C) is a forwarding-plane construct that tells the egress PE which VRF to use; it does not disambiguate the advertisement itself. The VRF name (D) is locally significant to one router and is never carried in BGP.

Correct: D — the label switched path. When the control plane is healthy but forwarding fails, the fault is in the underlay transport. MPLS LSP ping and traceroute send MPLS echo request and reply messages down the label stack to validate the LSP and isolate the failing hop.

Why not the others: RT policy (A) and the route distinguisher (B) are control-plane constructs, and the question already states routes are present and VRFs populated. The PE-CE adjacency (C) governs the customer edge, not the provider core where the traffic is being dropped.

Correct: A — control-plane MAC learning via MP-BGP. EVPN replaces the data-plane flood-and-learn behaviour of VPLS with control-plane MAC learning, which is what enables all-active multihoming with per-flow load balancing.

Why not the others: MAC addresses are still learned (B) — the change is where and how. The core still needs an IGP and label distribution (C); EVPN is a service overlay, not a replacement for the underlay. Broadcast and BUM traffic still exist (D), which is precisely why EVPN defines designated forwarder election and split-horizon filtering.

Correct: B — the Ethernet Segment Identifier. An Ethernet segment is the set of links connecting a multihomed device, and it is assigned a unique non-zero ESI that must match on the peering PEs so they recognise the shared segment and can elect a designated forwarder.

Why not the others: The EVI (A) identifies the EVPN instance, not the segment, and multiple segments can exist within one EVI. The bridge domain name (C) is locally significant. The route distinguisher (D) makes advertisements unique per PE and should generally differ, not match.

Correct: A — Ethernet CFM. CFM is a service-level OAM protocol providing proactive connectivity monitoring, fault verification, and fault isolation per VLAN, and its frames traverse the entire end-to-end Ethernet network rather than a single link.

Why not the others: BFD (B) gives fast failure detection but is a per-link or per-session mechanism without service-level fault isolation. LLDP (C) is a neighbour discovery protocol confined to a single link. STP notifications (D) signal topology changes for loop prevention and are not a monitoring or fault-isolation tool.

Correct: B — Inter-AS Option B. In Option B the ASBRs peer using eBGP and exchange VPNv4 routes together with VPN labels; the ASBR does not hold customer VRFs but carries the VPNv4 routes that must cross to the other autonomous system, kept unique by route distinguisher and filtered by route target.

Why not the others: Option A (A) uses back-to-back VRF connectivity with a subinterface and BGP session per VPN, so the ASBRs do hold VRFs and the traffic between them is IP rather than labelled. Option C (C) pushes VPNv4 exchange to the route reflectors or PEs with the ASBRs carrying only labelled IPv4 loopbacks. CSC (D) is a different architecture where one carrier provides transport to another carrier.

Correct: C — selective route-target import and export. Extranet and shared-services designs work by controlling which route targets each VRF imports and exports, optionally refined with route policy, so the shared prefixes leak into every customer VRF while customer prefixes never leak between customers.

Why not the others: A shared RD (A) does not create reachability and would defeat the uniqueness the RD exists to provide. A single VRF with ACLs (B) collapses the isolation that VRFs supply and does not scale. Static routes without MP-BGP (D) abandons the VPN control plane entirely and still would not enforce customer-to-customer isolation.

Correct: D — an MLDP-based profile. With MLDP, customer multicast packets are encapsulated in MPLS labels and forwarded over label switched paths in the same manner as unicast, which removes the requirement for PIM in the provider core.

Why not the others: Rosen GRE (A) encapsulates customer multicast into provider multicast packets and specifically requires PIM enabled in the core — the opposite of the stated requirement. Unicast replication (B) does not scale and is not an mVPN profile. Extending the customer PIM domain into the core (C) breaks the separation that mVPN exists to preserve.

Correct: C — MP-BGP reachability over the existing IPv4 MPLS LSPs. 6PE and 6VPE reuse the existing MPLS IPv4 core for IPv6 transport, relying on multiprotocol BGP extensions on the dual-stacked PE routers to exchange IPv6 reachability together with an MPLS label for each prefix.

Why not the others: Dual-stacking every P router (A) is exactly the disruptive core upgrade 6VPE is designed to avoid — only the edge routers are dual-stacked. Protocol translation (B) is not part of the 6VPE model. CE-to-CE GRE tunnels (D) would bypass the provider VPN service altogether.

Correct: C — EVPN IRB. Integrated routing and bridging combines Layer 2 bridging within a bridge domain and Layer 3 routing between bridge domains on the same PE, which is what the requirement for both intra-subnet and inter-subnet forwarding describes.

Why not the others: EVPN VPWS (A) delivers point-to-point pseudowire service with no routing function. E-Tree (B) enforces a root-and-leaf forwarding restriction and is about traffic policy rather than routing between subnets. EVPN native with split-horizon filtering (D) addresses loop and duplicate prevention on multihomed segments, not inter-subnet routing.