Question 1

What are EVPN inclusive multicast Ethernet tag (IMET) routes used for?

Accepted Answer

C

Explanation: The EVPN Inclusive Multicast Ethernet Tag (IMET) route, also known as EVPN Route Type 3, is used for the auto-discovery of Provider Edge (PE) routers participating in the same EVPN Instance (EVI) or VPLS service. Each PE advertises an IMET route to signal its membership in a specific VPLS. Other PEs in the same service receive this route and add the originating PE to their flood list. This mechanism is fundamental for establishing the necessary ingress replication tunnels to forward Broadcast, Unknown Unicast, and Multicast (BUM) traffic to all participating PEs within that service instance.

Question 2

Which of the following statements about multi-homing for a Layer-2 service is TRUE?

Accepted Answer

C

Explanation: In an EVPN multi-homing all-active mode, a Customer Edge (CE) device is connected to multiple Provider Edge (PE) routers, and all the links are active and can be used for forwarding traffic. This setup provides both load balancing and redundancy. All PEs attached to the same Ethernet Segment (ES) advertise the same Ethernet Segment Identifier (ESI) and can forward traffic to and from the CE for a given service. This is the fundamental operational principle of all-active multi-homing.

Question 3

In the exhibit, the EVPN-IRB is using the interface-ful unnumbered model and is fully operational. Which of the following statements is FALSE? https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/NOKIA_4A0-115/page_27_img_1.jpg

Accepted Answer

C

Explanation: Statement C is false. PE3 is a standard VPRN PE, not an EVPN-IRB gateway. When PE3 receives the VPN-IPv4 route for 10.10.1.0/24 from the EVPN domain (advertised by PE1/PE2), it resolves this route using a standard VPRN mechanism. This involves finding a transport tunnel (e.g., an MPLS LSP) to the BGP next-hop (PE1 or PE2). The concept of resolving a route to a "MAC-OI" (MAC Overlay Index) is an internal data plane function specific to an EVPN-IRB PE. The IRB PE uses this to forward Layer 2 traffic to the correct destination VTEP after IP-to-MAC resolution. A remote VPRN-only PE like PE3 has no awareness of the EVPN Layer 2 constructs.

Question 4

Which of the following statements about EVPN auto-discovery per EVPN instance (A-D per EVI) routes is FALSE?

Accepted Answer

D

Explanation: Statement (D) is false because it incorrectly describes the scope and primary purpose of the EVPN Auto-Discovery (A-D) per EVI route. The discovery of all PEs attached to an Ethernet Segment (ES) for functions like Designated Forwarder (DF) election is the specific role of the A-D per ES route. The A-D per EVI route, as its name implies, is scoped to a specific EVPN Instance (EVI) or service. It is used to discover other PEs on the same ES that are also part of that specific service. Its primary functions are to enable aliasing (for all-active multi-homing) and mass MAC withdrawal for that service. It cannot be used to discover a PE on the ES that does not participate in that particular EVI.

Question 5

Examine the exhibit. https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/NOKIA_4A0-115/page_25_img_1.jpg Which of the following configuration is NOT required to enable Layer-2 communication between CEI and CE2?

Accepted Answer

C

Explanation: The topology depicts a BGP-signaled Virtual Private Wire Service (VPWS) using EVPN signaling, which is a modern approach for establishing Layer 2 point-to-point services. In this model, BGP is used for both service discovery (EVPN routes) and for establishing the transport tunnels (BGP Labeled Unicast). Service Distribution Points (SDPs) are transport tunnels used in legacy VLL/VPLS services that are signaled using Targeted LDP (T-LDP). When BGP is used for both service and transport signaling (as implied by the MP-BGP sessions for EVPN and labeled routes), the concept of a manually configured SDP is obsolete. The router automatically resolves the BGP next-hop of the remote PE over a labeled path learned via BGP-LU, eliminating the need for SDP configuration.

Question 6

Examine the exhibit. https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/NOKIA_4A0-115/page_23_img_1.jpg Which of the following statements about the operation of EVPN VPWS 4 is FALSE?

Accepted Answer

B

Explanation: The statement that is FALSE is B. The P-flag (Proxy-ARP/ND flag) is an attribute carried within the EVPN BGP Extended Community. Its purpose is to signal that the advertising Provider Edge (PE) router is capable of and willing to perform proxy-ARP/ND functions for hosts within the EVPN instance. This functionality is specific to Integrated Routing and Bridging (IRB) interfaces in EVPN VLAN-based services. The service in the exhibit is an EVPN-VPWS (Virtual Private Wire Service), which is a point-to-point Layer 2 service. EVPN-VPWS does not involve Layer 3 routing or ARP/ND processing within the service. Therefore, the P-flag is not applicable, and PE3 would not set it to 1.

Question 7

Which of the following statements about EVPN Layer-3 services that utilize the interface-ful model is TRUE?

Accepted Answer

B

Explanation: In the EVPN Layer-3 interface-ful model, each subnet is configured as a separate VPLS service with an associated Integrated Routing and Bridging (IRB) interface within a VPRN. To handle inter-subnet (routed) traffic between different PEs, a special VPLS instance known as the Supplementary Broadcast Domain (SBD) is used. The SBD acts as a transport VPLS that interconnects all the IRB interfaces belonging to the same VPRN service across the participating PEs. When a packet needs to be routed from one subnet to another on a remote PE, it is forwarded over the SBD tunnels to the IRB interface on the destination PE.

Question 8

A Layer-3 EVPN service is configured to use the interface-ful unnumbered forwarding model. Which of the following statements is FALSE?

Accepted Answer

B

Explanation: In the interface-ful unnumbered forwarding model for Layer-3 EVPN, IP-Prefix routes (EVPN Route Type 5) are advertised with the Gateway IP address field in the NLRI set to 0.0.0.0. The router's MAC address, which is essential for forwarding, is carried in the BGP Router's MAC Extended Community attribute, not directly in the NLRI as a primary field. While the MAC address is used by the receiving PE to forward traffic, referring to it as an "overlay index" can be misleading. The primary overlay index is the VNI (VXLAN Network Identifier), which identifies the forwarding context (the SBD). The statement that the route includes a non-zero MAC address as an overlay index is the most imprecise and therefore considered false in the context of strict terminology where the VNI is the primary index.

Question 9

Which of the following statements about the operation of a single-homed EVPN VPWS is TRUE?

Accepted Answer

C

Explanation: In a single-homed EVPN VPWS (Virtual Private Wire Service), when the local attachment circuit (AC) becomes operationally active, the Provider Edge (PE) router signals the service availability to remote PEs. It does this by advertising an Ethernet Auto-Discovery (A-D) per EVI route (Type 1). This route must contain two critical pieces of information: a non-zero Ethernet Tag ID, which uniquely identifies the service instance on the advertising PE, and a non-zero, downstream-assigned MPLS label. The remote PE uses this advertised label to encapsulate and forward traffic destined for the local AC, thus establishing the data plane for the point-to-point service.

Question 10

In the exhibit, the EVPN-IRB is configured to use the interface-ful unnumbered model. Which of the following statements regarding the route advertisement is FALSE? https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/NOKIA_4A0-115/page_26_img_2.jpg

Accepted Answer

D

Explanation: Statement D is false because PE4 is a VPRN-only Provider Edge (PE) router and is not part of the EVPN domain. Therefore, it has no EVPN functionality and cannot originate or advertise EVPN route types, such as an IP-Prefix route (Route Type 5). Furthermore, the network topology shows no BGP peering session between PE4 and PE2. PE4 advertises its locally attached prefixes to PE3 using standard VPN-IPv4 BGP updates within the VPRN service. The entire premise of the statement is architecturally incorrect.

Free Nokia 4A0-115 Actual Exam Questions