You are deploying an IP fabric with an oversubscription ratio of 3:1. In this scenario, which two statements are correct? (Choose two.)
Correct Answer: C,D
Adding leaf devices increases the edge bandwidth (workload-facing ports), which lowers the oversubscription ratio because the amount of bandwidth facing the workloads increases relative to the fabric bandwidth. However, the oversubscription ratio itself remains the same when you add leaf devices if the fabric design and spine capacity remain unchanged because the ratio is a function of edge bandwidth to spine bandwidth. Adding leaf devices without changing spine devices keeps the ratio at the same level. Removing leaf devices would increase the oversubscription ratio because the amount of edge bandwidth decreases while spine bandwidth remains the same.
Question 17
In a Junos EVPN-VXLAN fabric, which underlay routing protocol is most commonly recommended for a large-scale IP fabric due to its scalability and fast convergence?
Correct Answer: C
External BGP (EBGP) is the most commonly recommended underlay protocol for large-scale Clos-based IP fabrics because it scales well with a large number of devices, provides granular routing policy control, and offers predictable, fast convergence when each device is assigned its own autonomous system number in a single-hop EBGP design between leaf and spine devices.
Question 18
Exhibit. You have implemented an EVPN-VXLAN data center. Device served must be able to communicate with device server2. Referring to the exhibit, which two statements are correct? (Choose two.)
Correct Answer: C,D
* Understanding the Exhibit Setup: * The network diagram shows an EVPN-VXLAN setup, a common design for modern data centers enabling Layer 2 and Layer 3 services over an IP fabric. * Leaf1 and Leaf2 are the leaf switches connected to Server1 and Server2, respectively, with each server in a different subnet (172.16.1.0/24 and 172.16.2.0/24). * Spine1 and Spine2 are part of the IP fabric, interconnecting the leaf switches. * EVPN-VXLAN Basics: * EVPN (Ethernet VPN) provides Layer 2 and Layer 3 VPN services using MP-BGP. * VXLAN (Virtual Extensible LAN) encapsulates Layer 2 frames into Layer 3 packets for transmission across an IP network. * VTEP (VXLAN Tunnel Endpoint) interfaces on leaf devices handle VXLAN encapsulation and decapsulation. * Integrated Routing and Bridging (IRB): * IRB interfaces are required on leaf1 and leaf2 (where the endpoints are directly connected) to route between different subnets (in this case, between 172.16.1.0/24 and 172.16.2.0/24). * The IRB interfaces provide the necessary L3 gateway functions for inter-subnet communication. * Traffic Flow Analysis: * Traffic from Server1 (172.16.1.1) destined for Server2 (172.16.2.1) must traverse from leaf1 to leaf2. * The traffic will be VXLAN encapsulated on leaf1, sent over the IP fabric, and decapsulated on leaf2. * Since the communication is between different subnets, the IRB interfaces on leaf1 and leaf2 are crucial for routing the traffic correctly. * Correct Statements: * C. An IRB Interface must be configured on leaf1 and leaf2:This is necessary to perform the inter-subnet routing for traffic between Server1 and Server2. * D. Traffic from server1 to server2 will transit the VXLAN tunnel between leaf1 and leaf2: This describes the correct VXLAN operation where the traffic is encapsulated by leaf1 and decapsulated by leaf2. Data Center References: * In EVPN-VXLAN architectures, the leaf switches often handle both Layer 2 switching and Layer 3 routing via IRB interfaces. This allows for efficient routing within the data center fabric without the need to involve the spine switches for every routing decision. * The described traffic flow aligns with standard EVPN-VXLAN designs, where direct VXLAN tunnels between leaf switches enable seamless and scalable communication across a data center network.
Question 19
Click the Exhibit button. You want to enable the border leaf device to send Type 5 routes of local networks to the border leaf device in another data center. What must be changed to the configuration shown in the exhibit to satisfy this requirement?
Correct Answer: C
For EVPN Type 5 route advertisement and full inter-data center connectivity, the EVPN configuration must specify the encapsulation type, especially if VXLAN is used as the data-plane overlay. The parameter encapsulation vxlan must be added under the protocols evpn hierarchy to ensure border leaf devices can advertise and exchange IP prefix routes (Type 5) properly between data centers. The option to move vrf-target under the EVPN hierarchy is not valid, as that statement is only supported within the routing instance or vni-options section, but not directly under protocols evpn.
Question 20
Due to heavy congestion, some VXLAN packets are being lost. In this scenario, which two statements are correct? (Choose two.)
Correct Answer: A,C
VXLAN encapsulation is carried over UDP and does not include any built-in acknowledgement or retransmission mechanism. When packets are lost in transit, recovery is handled by the transport/application behavior of the endpoints (for example, TCP at the hosts detects loss and triggers retransmission).
