JN0-650 Practice Exam Questions | JNCIP-ENT

In a three-stage EVPN-VXLAN fabric (Spine-Leaf architecture) where leaf devices perform the gateway services (Edge-Routed Bridging or ERB):

VTEP Functionality (Option B): Leaf devices act as VXLAN Tunnel End Points (VTEPs). They are responsible for encapsulating Ethernet frames from locally connected hosts into VXLAN packets for transport across the IP fabric and de-encapsulating incoming VXLAN packets.

Fabric Support (Option C): In a standard Juniper IP fabric design, both the leaf and spine devices are typically expected to support VXLAN and EVPN capabilities. While spines in an ERB design might only perform IP forwarding in the underlay, they often participate in the BGP control plane (as Route Reflectors) or provide the ability to transition to Centrally-Routed Bridging (CRB) where spines would act as gateways.

Incorrect Options: Option A is incorrect because the entire fabric infrastructure must be " VXLAN aware " in terms of MTU settings and routing capability to support the overlay. Option D is incorrect because in an ERB design, the spine devices are high-speed transit nodes and do not terminate VXLAN tunnels; only the edge (leaf) devices act as VTEPs.

The exhibit illustrates a standard end-to-end Class of Service (CoS) path consisting of an edge router (R1) and core/intermediate routers (R2 and R3).

Edge Classification (Option B): The scenario specifies that video traffic enters the network without any class-of-service markings. Because there are no DSCP or 802.1p bits to inspect, the ingress router (R1) cannot use simple Behavior Aggregate (BA) classification. Instead, it must use Multifield (MF) classification. MF classification allows the router to look deeper into the packet (Source/Destination IP, Protocol, Port numbers) to identify the video stream and assign it to a specific forwarding class. * Core Classification (Option D): Once R1 has identified the traffic, it will typically apply a rewrite rule on its egress interface to mark the packets with a specific CoS value (like a DSCP code). Consequently, the downstream routers (R2 and R3) do not need to perform expensive deep-packet inspection again. They can use Behavior Aggregate (BA) classification, which simply looks at the markings in the packet header to determine the appropriate forwarding priority.

Option A and C: These are incorrect because BA classification is impossible on unmarked ingress traffic, and performing MF classification in the core is inefficient and not a recommended Juniper design practice for high-speed transit.