JN0-682 Data Center Professional (JNCIP-DC) Question and Answers

In an EVPN environment, VRF (Virtual Routing and Forwarding) import policies along with community values can be used to selectively accept certain MAC advertisement routes. These policies can be configured to include or exclude specific routes based on community values, allowing for granular control over the routes accepted from EVPN peers.

References:

• Juniper Networks - EVPN for VXLAN Configuration Guide

A. In a multi-site data center design using EBGP (External Border Gateway Protocol), using the same AS (Autonomous System) number across all devices in all data centers can simplify the design and routing policies.

C. Private AS numbers can be used for an EBGP IP fabric in a multi-site data center environment. This is a common practice as these AS numbers are not intended to be used on the public internet and are suitable for internal network use.

The MAC mass withdrawal feature in EVPN-VXLAN environments significantly improves network convergence during link failures. When a link failure occurs, instead of individually withdrawing each MAC address learned on the failed link, EVPN can send a single, consolidated message indicating that all MAC addresses associated with the Ethernet Segment Identifier (ESI) of the failed link are no longer reachable. This accelerates the convergence process by reducing the amount of control plane traffic needed to update the network state.References:Juniper Networks EVPN-VXLAN Technical Documentation.

In a scenario where RSVP and LDP are restricted, and routes are not appearing in the inet table, the use of "bgp family inet labeled-unicast per-group-label" becomes necessary. This setting is crucial in environments where label distribution protocols like RSVP or LDP are not used. It enables the use of MPLS labels in BGP without relying on these protocols, which is essential for integrating L3VPN with EVPN over WAN links that do not support RSVP or LDP. The “per-group-label” option ensures that a single label is used for all routes exchanged with a BGP neighbor, which simplifies label management and conserves label space.References:

• Junos OS Routing Protocols Library for Routing Devices

Edge-routed bridging architecture fits all the criteria: routing occurs on leaf devices, VTEPs terminate on the leaf devices, facilitates inter-VLAN communication, and provides lower latency for East-West traffic due to its distributed nature.

When a packet is encapsulated by VXLAN, a VXLAN Network Identifier (VNI) is placed in the VXLAN header. This VNI is crucial as it maps to the VLAN-ID, ensuring that the packet is correctly identified and routed within the overlay network.

References:

• Juniper Networks - VXLAN Overview

In ZTP, the image storage service and the DHCP server can be running on different server hosts, allowing for flexibility in network design. When a switch is booted, DHCP requests are sent through both the management interface

and attached revenue ports. This ensures that the switch can retrieve its configuration from the network regardless of how it's connected.References:

• Zero Touch Provisioning Guide

For a Data Center Interconnect (DCI) over an IP network, Layer 2 data needs to be encapsulated. This encapsulation, typically using VXLAN or similar technologies, allows Layer 2 traffic to traverse an IP network while preserving the Layer 2 information.

References:

• Juniper Networks - Data Center Interconnect Solutions

In Zero Touch Provisioning (ZTP), the process is streamlined to simplify the deployment of new switches in the network. When a switch that supports ZTP boots and does not find a configuration file, it attempts to acquire one using DHCP. If the switch is already running the firmware image specified by the DHCP server (if mentioned), it proceeds to the next step without re-downloading the image. DHCP Option 43 suboption 01 is used by the DHCP server to provide the URL of the configuration file to the switch.

References

• Zero Touch Provisioning

The Contrail Command user interface supports various functions including configuring management domains and creating virtual networks. It provides an integrated platform for managing and configuring network resources in a centralized manner.

References:

• Juniper Networks - Contrail Networking Documentation

In an EBGP setup with different AS numbers for spine and leaf devices, all BGP routes advertised by a leaf device will be accepted on the spine devices as they are considered external routes. Additionally, a leaf device will accept all BGP routes received from the spine that were originated from another leaf device, enabling full connectivity within the fabric.References:

• EBGP Configuration for IP Fabric

A. GPB (Google Protocol Buffers) and C. JSON are two common formats supported for streaming network analytics data.

ICCP (Inter-Chassis Control Protocol) is the protocol used to replicate forwarding information between MC-LAG (Multi-Chassis Link Aggregation Group) peers. It ensures coordination and consistency of state between the MC-LAG devices.

References:

• Juniper Networks - Understanding MC-LAG

B. Configure virtual-gateway-accept-data under the IRB interface. This configuration is necessary to ensure that the IRB interfaces on the spine devices can handle traffic destined to the virtual gateway IP address.

D. Configure proxy-macip-advertisement under the IRB interface. This enables the advertisement of proxy MAC/IP routes to remote VTEPs. This is essential in a CRB (Centralized Routing and Bridging) topology to ensure that all hosts, including those connected to the spine devices, have reachability to all IRB interface addresses.

References:

• Juniper EVPN Configuration Guide

For building an IP fabric underlay network in a data center, it is recommended that all spine devices are identical models, including the same installed line cards, to ensure uniformity and predictable performance. Additionally, each leaf device should have an identical uplink to every spine device to ensure consistent

and predictable load-balancing behavior across the network. This uniformity in spine and leaf configurations helps in achieving optimal and predictable data paths, thereby enhancing overall network efficiency and stability.References:Juniper Networks Technical Documentation, Data Center Design Considerations.

A. If BGP multipath is not configured, traffic may not be load-balanced across multiple paths. B. Without proper load-balancing policies, traffic distribution might not be optimal. D. Insufficient bandwidth between spine and leaf can lead to congestion and affect load balancing.

To enable ECMP (Equal-Cost Multi-Path) routes in the Routing Information Base (RIB) in an EBGP-based IP fabric, you should enable the 'multipath multiple-as' BGP parameter. This setting allows the use of multiple paths for BGP routes even when they come from different autonomous systems, which is key in a typical EBGP deployment in a data center IP fabric.References:

• BGP and Multipath Routing

To enable communication between VXLANs in different data centers across a WAN connection using an MX Series router, Integrated Routing and Bridging (IRB) interfaces must be configured. IRB interfaces provide Layer 3 routing capabilities within a VXLAN overlay network, allowing for inter-VXLAN routing. By configuring IRB interfaces on the MX router, you enable it to act as a Layer 3 gateway, routing traffic between the different VXLANs across the data centers.References:Juniper Networks MX Series Documentation - VXLAN and EVPN Configuration.

https://www.juniper.net/documentation/us/en/software/junos/ovsdb-vxlan-qfx/topics/example/overlay-ping-traceroute-vxlan.html

A MAC-VRF (MAC Virtual Routing and Forwarding) instance with a VLAN-bundle service type is used in EVPN-VXLAN architectures. It can be implemented in a bridged overlay architecture where Ethernet segments are bridged across the EVPN-VXLAN network. This setup supports multiple VLAN IDs per Ethernet VPN Instance (EVI), enabling the segregation and transport of traffic from different VLANs over the same EVPN-VXLAN infrastructure.

References

• [EVPN-VXLAN Configuration Guide](https://www.juniper.net/documentation/us/en/software/en/software/junos/evpn-vxlan/topics/topic-map/evpn-overview.htm

In an EVPN-VXLAN environment, to ensure that multicast traffic is delivered only to leaf devices with interested receivers, IGMP snooping is required. IGMP snooping enables the leaf devices to listen to IGMP report and leave messages from hosts and make forwarding decisions based on this information. This way, multicast traffic is only forwarded to ports with interested multicast group members, optimizing bandwidth and resource utilization.References:

• EVPN-VXLAN Configuration Guide

BGP Additional Paths in EVPN-VXLAN environments enable the advertisement of multiple paths through BGP, which provides faster network convergence in the event of a leaf node link failure. This is especially important in large-scale networks with thousands of MAC addresses.

If not all routers show up in the routing tables despite formed adjacencies in an EBGP setup, it's likely due to the lack of configuration of the 'multipath multiple-as' parameter. This parameter allows the use of multiple paths for BGP routes even when they originate from different ASes.

References:

• Juniper Networks - BGP Multipath