Juniper JN0-683 Data Center Professional Exam Practice Test

Answer : C, D

In the provided network configuration, Host A is in VLAN 100 and Host B is in VLAN 200. The issue arises because these two hosts are unable to communicate, which indicates that either the interfaces are not properly linked to their respective VLANs, or there is a missing static route required for inter-VLAN routing.

Step-by-Step Analysis:

VLAN Assignment:

The exhibit shows that irb.200 is correctly associated with VLAN 200 in the configuration. However, there is no corresponding irb.100 for VLAN 100. Without irb.100, the network lacks the logical interface to handle routing for VLAN 100. Thus, adding irb.100 to VLAN 100 is necessary.

Command to solve this:

set vlans vn100 13-interface irb.100

Static Route Configuration:

For inter-VLAN routing to occur, a static route needs to be configured that allows traffic to pass between different subnets (in this case, between VLAN 100 and VLAN 200). The command set routing-options static route 0.0.0.0/0 next-hop 192.168.200.10 would add a static route that directs all traffic from VLAN 100 to the correct gateway (192.168.200.10), which is necessary to route traffic between the two VLANs.

Command to solve this:

set routing-options static route 0.0.0.0/0 next-hop 192.168.200.10

Explanation of Incorrect Options:

Option A (delete vlans vn200 13-interface irb.200): This would remove the logical interface associated with VLAN 200, which is not desired because we need VLAN 200 to remain active and properly routed.

Option B (set interfaces irb unit 100 family inet address 192-168.100.1): This command would incorrectly assign an IP address that does not correspond with the subnet of VLAN 100 (192.168.200.1/24). This could create a misconfiguration, leading to routing issues.

Data Center Reference:

For a Data Center, proper VLAN management and static routing are crucial for ensuring that different network segments can communicate effectively, especially when dealing with separated subnets or zones like in different VLANs. This aligns with best practices in DCIM (Data Center Infrastructure Management) which stress the importance of proper network configuration to avoid downtime and ensure seamless communication between all critical IT infrastructure components.

Ensuring that the correct interfaces are associated with the correct VLANs and having the proper static routes in place are both essential steps in maintaining a robust and reliable data center network.

This detailed analysis reflects best practices as noted in standard data center design and network configuration guides.

Answer : C, D

Load Balancing in VXLAN:

VXLAN uses UDP encapsulation to transport Layer 2 frames over an IP network. For load balancing across Equal-Cost Multi-Path (ECMP) links, various fields in the packet can be used to ensure even distribution of traffic.

Key Load Balancing Fields:

C . The source port in the UDP header is used to load balance VXLAN traffic: This is correct. The source UDP port in the VXLAN packet is typically calculated based on a hash of the inner packet's fields. This makes the source port vary between packets, enabling effective load balancing across multiple paths.

D . The inner packet fields are used in the hash for load balancing: This is also correct. Fields such as the source and destination IP addresses, source and destination MAC addresses, and possibly even higher-layer protocol information from the inner packet can be used to generate the hash that determines the ECMP path.

Incorrect Statements:

A . The inner packet fields are not used in the hash for load balancing: This is incorrect as the inner packet fields are indeed critical for generating the hash used in load balancing.

B . The destination port in the UDP header is used to load balance VXLAN traffic: This is incorrect because the destination UDP port in VXLAN packets is typically fixed (e.g., port 4789 for VXLAN), and therefore cannot be used for effective load balancing.

Data Center Reference:

Effective load balancing in VXLAN is crucial for ensuring high throughput and avoiding congestion on specific links. By using a combination of the source UDP port and inner packet fields, the network can distribute traffic evenly across available paths.

Answer : D, D

Understanding the Configuration:

The exhibit shows a BGP configuration on a Border-Leaf device. The BGP group UNDERLAY is used for the underlay network, OVERLAY for EVPN signaling, and PROVIDER for connecting to the provider network.

The OVERLAY group has the accept-remote-nexthop statement, which is designed to accept the next-hop address learned from the remote peer as is, without modifying it.

Problem Identification:

The BGP session to Border-Leaf-2 is not established. A common issue in EVPN-VXLAN environments is related to next-hop reachability, especially when accept-remote-nexthop is configured.

In typical EVPN-VXLAN setups, the next-hop address should be reachable within the overlay network. However, the accept-remote-nexthop can cause issues if the next-hop IP address is not directly reachable or conflicts with the expected behavior in the overlay.

Corrective Action:

Answer : D, D

Understanding VRF and Routing Instances:

In an EVPN-VXLAN overlay network, multiple tenants are separated using unique VRF (Virtual Routing and Forwarding) instances. Each VRF instance maintains its own routing table, allowing for isolated routing domains within the same network infrastructure.

Role of Route Distinguisher:

Route Distinguisher (RD): The RD is a unique identifier used in MPLS and EVPN environments to distinguish routes belonging to different VRFs. The RD is prepended to the IP address in the route advertisement, ensuring that routes from different tenants remain unique even if they use the same IP address range.

Correct Property:

Answer : C

Scenario Overview:

Converting an MX Series router from a VXLAN Layer 2 gateway to a VXLAN Layer 3 gateway involves transitioning the router's functionality from simply bridging traffic within a VXLAN segment to routing traffic between different segments.

Key Configuration Requirement:

IRB (Integrated Routing and Bridging) Interface: An IRB interface allows for both Layer 2 switching and Layer 3 routing. To enable routing for a specific VNI (VXLAN Network Identifier), the IRB interface must be associated with the routing function in the corresponding bridge domain.

Correct Command:

C . set bridge-domains VLAN-100 routing-interface irb.100: This command correctly binds the IRB interface to the bridge domain, enabling Layer 3 routing functionality within the VXLAN for VNI 100. This effectively transitions the device from operating solely as a Layer 2 gateway to a Layer 3 gateway.

Data Center Reference:

This configuration step is essential when converting a Layer 2 VXLAN gateway to a Layer 3 gateway, enabling the MX Series router to route between VXLAN segments.

Answer : A, D, E

MAC Move Limiting:

MAC move limiting is a security feature used in network switches to detect and mitigate rapid changes in MAC address locations, which could indicate a network issue or an attack such as MAC flapping or spoofing.

When a MAC address is learned on a different interface than it was previously learned, the switch can take various actions to prevent potential issues.

Available Actions:

A . drop: This action drops packets from the MAC address if it violates the move limit, effectively blocking communication from the offending MAC address.

D . log: This action logs the MAC move event without disrupting traffic, allowing network administrators to monitor and investigate the event.

E . shutdown: This action shuts down the interface on which the MAC address violation occurred, effectively stopping all traffic on that interface to prevent further issues.

Other Actions (Not Correct):

B . filter: Filtering is not typically associated with MAC move limiting; it generally refers to applying ACLs or other mechanisms to filter traffic.

C . enable: This is not an action related to MAC move limiting, as it does not represent a specific reaction to a MAC move event.

Data Center Reference:

MAC move limiting is crucial for maintaining network stability and security, particularly in environments with dynamic or large-scale Layer 2 networks where MAC addresses might frequently change locations.

Answer : C, E

Issue Analysis:

The problem in the exhibit suggests a mismatch in configuration parameters between Leaf-1 and Leaf-2, leading to communication issues between hosts connected to these leaf devices.

Configuration Mismatches:

Service-ID: Leaf-1 has service-id 1 configured, while Leaf-2 does not have this parameter. For consistency and proper operation, the service-id should be the same across both leaf devices.

VRF Target: Leaf-1 is configured with vrf-target target:65000:1, while Leaf-2 is configured with vrf-target target:65000:2. To allow proper VRF import/export between the two leafs, these should match.

Corrective Actions:

C . Configure the set switch-options vrf-target target:65000:1 parameter on Leaf-2: This aligns the VRF targets between the two leaf devices, ensuring they can correctly import and export routes.

E . Configure the set switch-options service-id 1 parameter on Leaf-2: This ensures that both Leaf-1 and Leaf-2 use the same service ID, which is necessary for consistency in the EVPN-VXLAN setup.

Data Center Reference:

Correct configuration of VRF targets and service IDs is critical in EVPN-VXLAN setups to ensure that routes and services are correctly shared and recognized between different devices in the network fabric.