Juniper JN0-683 Data Center Professional Exam Practice Test

Answer : B

Understanding the Problem:

Host1 (10.1.1.1) is failing to communicate with Host2 (10.1.2.1) within an EVPN-VXLAN environment using ERB architecture.

Analysis of the Exhibit:

The provided output includes information from the show route forwarding-table matching command for IP 10.1.2.1. The next hop is shown as vtep.32769, which indicates that the traffic destined for 10.1.2.1 is being forwarded into the VXLAN tunnel with the correct VTEP (VXLAN Tunnel Endpoint).

Conclusion:

Option B: Correct---The traffic from Host1 is entering the VXLAN tunnel, as evidenced by the next hop pointing to a VTEP. However, the issue could lie elsewhere, possibly with the remote VTEP, routing configurations, or the receiving leaf/spine devices.

Answer : A, D

Understanding the Output:

The show evpn database command output shows the MAC address, VLAN, active source, timestamp, and IP address associated with various hosts in the EVPN instance.

Analysis of the MAC Address:

Option A: The MAC address 40:00:dc:01:00:04 is associated with the IP address 10.4.4.5, as indicated by the output in the IP address column. This confirms that this host has been assigned the IP 10.4.4.5.

Option D: The active source for the MAC address 40:00:dc:01:00:04 is listed as 00:02:00:00:00:04:00:04:00:00:04:00:04, which indicates that the host is connected via an ESI (Ethernet Segment Identifier) LAG (Link Aggregation Group). This setup is typically used in multi-homing scenarios to provide redundancy and load balancing across multiple physical links.

Conclusion:

Option A: Correct---The host with MAC 40:00:dc:01:00:04 is assigned IP 10.4.4.5.

Option D: Correct---The host is originating from an ESI LAG, as indicated by the active source value.

Answer : B, D

Understanding the Configuration:

The exhibit shows configurations for two VRFs (Customer_A and Customer_B) with specific VLANs and VNIs assigned. Each VRF has interfaces (IRBs) associated with particular VLANs.

Communication Between VLANs and Routing Instances:

Option B: VLAN 400 (irb.400) is part of Customer_B, and there is no direct connection or routing between Customer_A and Customer_B in the configuration provided. Therefore, devices in irb.400 cannot communicate directly with devices in the Customer_A routing instance.

Option D: Since irb.400 (VLAN 400) and irb.800 (VLAN 800) are part of the same routing instance (Customer_B), they can communicate over the fabric using VXLAN encapsulation.

Conclusion:

Option B: Correct---There is no direct communication between devices in irb.400 (Customer_B) and routing instance Customer_A.

Option D: Correct---Devices in VLAN 400 and VLAN 800 can communicate within the Customer_B routing instance over the fabric.

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 : 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 : B, D

Issue Overview:

The leaf devices in an IP fabric using eBGP are advertising and receiving all routes, but the routes are not being installed in the routing table and are marked as hidden. This typically indicates an issue with the BGP configuration, particularly with next-hop handling or AS path concerns.

Corrective Actions:

B . You need to configure a next-hop self policy: This action ensures that the leaf devices modify the next-hop attribute to their own IP address before advertising routes to their peers. This is particularly important in eBGP setups where the next-hop may not be directly reachable by other peers.

D . You need to configure multipath multiple-as: This setting allows the router to accept multiple paths from different autonomous systems (ASes) and use them for load balancing. Without this, the BGP process might consider only one path and mark others as hidden.

Incorrect Statements:

A . You need to configure as-override: AS-override is used to replace the AS number in the AS-path attribute to prevent loop detection issues in MPLS VPNs, not in a typical eBGP IP fabric setup.

C . You need to configure loops 2: There is no specific BGP command loops 2 relevant to resolving hidden routes in this context. It might be confused with allowas-in, which is used to allow AS path loops under certain conditions.

Data Center Reference:

Proper BGP configuration is crucial in IP fabrics to ensure route propagation and to prevent routes from being marked as hidden. Configuration parameters like next-hop self and multipath multiple-as are common solutions to ensure optimal route installation and load balancing in a multi-vendor environment.