Juniper JN0-683 Data Center Professional Exam Practice Test

Answer : C

Understanding the Scenario:

In an EVPN-VXLAN environment, when using multi-homing in active/active scenarios, there's a risk that a multihomed server might receive duplicate copies of Broadcast, Unknown unicast, and Multicast (BUM) traffic. This is because multiple VTEPs might forward the same BUM traffic to the server.

EVPN Route Types:

Type 4 Route (Ethernet Segment Route): This route type is used to advertise the Ethernet Segment (ES) to which the device is connected. It is specifically used in multi-homing scenarios to signal the ES and its associated Ethernet Tag to all the remote VTEPs. The Type 4 route includes information that helps prevent BUM traffic duplication in active/active multi-homing by using a split-horizon mechanism, which ensures that traffic sent to a multihomed device does not get looped back.

The Type 4 route is crucial for ensuring that in a multi-homed setup, particularly in an active/active configuration, BUM traffic does not result in duplication at the server. The route helps coordinate which VTEP is responsible for forwarding the BUM traffic to the server, thereby preventing duplicate traffic.

Data Center Reference:

Type 4 routes are essential for managing multi-homing in EVPN to avoid the issues of BUM traffic duplication, which could otherwise lead to inefficiencies and potential network issues.

Answer : A

Understanding VPN Route Table Association:

In MPLS/VPN and EVPN networks, the route-target community is a BGP extended community attribute used to control the import and export of VPN routes. It associates received routes with the appropriate VPN route tables on the PE (Provider Edge) routers.

Function of Route-Target Community:

The route-target community tag ensures that routes are imported into the correct VRF (Virtual Routing and Forwarding) instance, allowing them to be correctly routed within the VPN.

Conclusion:

Option A: Correct---The route-target community is used to associate received routes with a local VPN route table.

Answer : C

Understanding DCI (Data Center Interconnect) Schemes:

DCI schemes are used to connect multiple data centers, enabling seamless communication and resource sharing between them. The choice of DCI depends on the specific requirements, such as isolation, VNI translation, or routing domain separation.

VXLAN Stitching:

VXLAN stitching involves connecting multiple VXLAN segments, allowing VNIs (VXLAN Network Identifiers) from different segments to communicate with each other while maintaining separate routing domains.

This approach is particularly effective for keeping routing domains isolated while supporting VNI translation, making it ideal for scenarios where you need to connect different data centers or networks without merging their control planes.

Other Options:

A . MPLS DCI label exchange: This option typically focuses on MPLS-based interconnections and does not inherently support VNI translation or isolation in the context of VXLAN.

B . Over the top (OTT) with VNI translation enabled: This could support VNI translation but does not inherently ensure routing domain isolation.

D . Over the top (OTT) with proxy gateways: This typically involves using external gateways for traffic routing and may not directly support VNI translation or isolation in the same way as VXLAN stitching.

Data Center Reference:

VXLAN stitching is a powerful method in multi-data center environments, allowing for flexibility in connecting various VXLAN segments while preserving network isolation and supporting complex interconnect requirements.

Answer : A

Telemetry in Data Centers:

Telemetry allows for real-time monitoring of network devices by collecting and exporting data such as interface statistics, routing table updates, and other key metrics.

Option A: JTI (Junos Telemetry Interface) OpenConfig sensors use a vendor-neutral data model, which is important for ensuring compatibility across different network devices and systems. OpenConfig is an industry-standard model, which facilitates integration with various telemetry collection systems.

Conclusion:

Option A: Correct---OpenConfig sensors provide a vendor-neutral solution for telemetry, ensuring broad compatibility and flexibility in data center environments.

Answer : B, D

Clos IP Fabric Design:

A Clos fabric is a network topology designed for scalable, high-performance data centers. It is typically arranged in multiple stages, providing redundancy, high bandwidth, and low latency.

Three-Stage Clos Fabric:

Option B: A three-stage Clos fabric, consisting of leaf, spine, and super spine layers, is widely used in data centers. This design scales well and allows for easy expansion by adding more leaf and spine devices as needed.

Super Spines for Scalability:

Option D: Using high-capacity devices like the QFX5700 Series as super spines can handle the increased traffic demands in large data centers and support future growth. These devices provide the necessary bandwidth and scalability for large-scale deployments.

Conclusion:

Option B: Correct---A three-stage Clos fabric is a proven design that addresses growth and scalability concerns in large data centers.

Option D: Correct---QFX5700 Series devices are suitable for use as super spines in large-scale environments due to their high performance.

Answer : D

Collapsed Fabric Architecture:

A collapsed fabric refers to a simplified architecture where the spine and leaf roles are combined, often reducing the number of devices and links required.

In this architecture, the spine typically handles core switching, while leaf switches handle both access and distribution roles.

Understanding Border Gateway Functionality:

Border gateway functions include connecting the data center to external networks or other data centers.

In a collapsed fabric, these functions are usually handled at the leaf level, particularly on border leaf devices that manage the ingress and egress of traffic to and from the data center fabric.

Correct Statement:

D . Border gateway functions occur on border leaf devices: This is accurate in collapsed fabric architectures, where the border leaf devices take on the role of managing external connections and handling routes to other data centers or the internet.

Data Center Reference:

The collapsed fabric model is advantageous in smaller deployments or scenarios where simplicity and cost-effectiveness are prioritized. It reduces complexity by consolidating functions into fewer devices, and the border leaf handles the critical task of interfacing with external networks.

In conclusion, border gateway functions are effectively managed at the leaf layer in collapsed fabric architectures, ensuring that the data center can communicate with external networks seamlessly.

Answer : A, D

Understanding BGP Configuration in the Exhibit:

The exhibit shows a BGP configuration on spine1 with a group named underlay, configured to peer with directly connected interfaces of other devices in the network.

Multipath multiple-as: This statement allows the router to install multiple paths in the routing table for routes learned from different ASes, facilitating load balancing.

Key Statements:

A . The multihop statement is not required to establish the underlay BGP sessions: In this case, the BGP peers are directly connected (as indicated by their neighbor IP addresses), so the multihop statement is unnecessary. Multihop is typically used when BGP peers are not directly connected and packets need to traverse multiple hops.

D . Load balancing for the underlay is configured correctly: The multipath { multiple-as; } statement in the configuration enables load balancing across multiple paths from different autonomous systems, which is appropriate for underlay networks in data center fabrics.

Incorrect Statements:

C . The multihop statement is required to establish the underlay BGP sessions: This is incorrect because the peers are directly connected, making the multihop statement unnecessary.

B . Load balancing for the underlay is not configured correctly: This is incorrect because the configuration includes the necessary multipath settings for load balancing.

Data Center Reference:

BGP configurations in EVPN-VXLAN underlay networks are crucial for ensuring redundancy, load balancing, and efficient route propagation across the data center fabric.