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

An EVPN Type-4 route, also known as an Ethernet Segment (ES) route, is generated when a new Ethernet Segment Identifier (ESI) is configured. The ESI represents an Ethernet segment for multi-homing purposes in EVPN. When a new ESI is configured on an interface, it triggers the generation of an EVPN Type-4 route to advertise the Ethernet segment's existence and its multi-homed state to other VTEPs in the EVPN instance. This helps in providing redundancy and load balancing in a multi-homed EVPN environment.

References:

• EVPN Type 4 Route (Ethernet Segment Route) Explanation

VXLAN (Virtual Extensible LAN) is an overlay technology designed to support large-scale, multi-tenant environments. Unlike traditional VLANs which are limited to 4096 unique network identifiers, VXLANs can support up to 16 million unique network segments, providing significantly greater scalability. This is achieved through a 24-bit VXLAN Network Identifier (VNI). Additionally, being an overlay technology, VXLAN allows for the creation of virtualized Layer 2 networks over an existing Layer 3 infrastructure.References:Juniper Networks Documentation, VXLAN Overview.

Setting the Virtual Chassis as auto-provisioned (A) and configuring the auto-sw-update parameter (D) are key to enabling plug-and-play functionality for line card switches in an active VCF. This ensures that new line cards are automatically recognized and updated to the correct Junos version without manual intervention.

References:

• Juniper Networks - Virtual Chassis Fabric Configuration Guide

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

To accommodate the extra header information added by VXLAN, which can be 50 to 54 bytes, it's necessary to increase the MTU (Maximum Transmission Unit) on the physical interfaces connected to the VXLAN network. This ensures that the larger frames can be transmitted without fragmentation, maintaining efficient network performance.

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 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.

By configuring all spines in a POD to share the same ASN, it simplifies the BGP routing and ensures that more optimal paths are used in a 5-stage EVPN-VXLAN IP fabric.

Mesh groups in EVPN environments can control BUM (Broadcast, Unknown unicast, Multicast) flooding. This is particularly useful in scenarios where the network is expanding, as it helps manage the flood of BUM traffic more efficiently.

Among the listed protocols, External Border Gateway Protocol (EBGP) provides the highest degree of scalability for an IP fabric underlay. EBGP is designed for inter-autonomous system routing and thus is well-suited to handle large-scale network environments with robustness and scalability. It is commonly used in data center fabrics due to its ability to efficiently manage routing information and scale with the network as it grows.References:Juniper Networks Data Center Design - IP Fabric.

A. In EVPN based VXLAN implementations, MAC addresses are propagated through BGP updates, which helps in efficient and scalable MAC address dissemination across the network.

C. The movement of a virtual host in an EVPN VXLAN environment triggers the dynamic remapping of the VTEP (VXLAN Tunnel Endpoint), ensuring that traffic is always routed to the current location of the host.

References:

• Juniper Networks - EVPN VXLAN Configuration Guide

A. Scaling limitations are a critical factor in selecting spine devices as they determine how well the network can grow and adapt to increasing demands. C. Port density is another key consideration, as it impacts the number of connections that the spine devices can handle, which is crucial for supporting a large number of leaf devices in an IP fabric.

B. service-type vlan-aware allows for multiple VLANs to be associated with a single bridge domain. D. instance-type virtual-switch is used for creating a single bridge domain to accommodate multiple VLANs.

Configuring Proxy ARP on leaf devices in an EVPN overlay network enables them to respond to ARP requests on behalf of other hosts. When the leaf device knows the MAC of the intended destination, it can reply to ARP requests with its own MAC address, thus facilitating local resolution and avoiding unnecessary ARP traffic across the overlay.

When connecting two data centers on different subnets using EVPN, MAC addresses need to be advertised between the data centers to maintain Layer 2 connectivity. Using different subnets implies the need for Layer 3 gateways at each site, which typically involve exchanging type-5 routes in an EVPN context.References:

• EVPN for Data Center Interconnect

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

ICCP (Inter-Chassis Control Protocol) is used to replicate forwarding information between MC-LAG (Multi-Chassis Link Aggregation Group) peers. It coordinates the state and roles ofthe MC-LAG peers and ensures consistent forwarding state between them.

B. Virtual Router Redundancy Protocol (VRRP) ensures high availability by allowing multiple routers to work together to provide network resilience.

C. Graceful Routing Engine switchover (GRES) allows for the seamless transition of control plane functions between Routing Engines, ensuring continuous operation of the network.

D. Dual Routing Engines provide a hardware-based high-availability solution, where a backup Routing Engine takes over in case the primary fails, ensuring uninterrupted network service.

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 VXLAN domains, when dealing with Layer 2 traffic, the original VLAN ID of the packet can be either transmitted within the VXLAN packet or discarded, depending on the specific implementation and configuration. When the VLAN ID is preserved, it allows for VLAN transparency, enabling the VXLAN to transport VLAN-tagged frames across the network. On the other hand, discarding the VLAN ID can simplify the encapsulation process but removes the original VLAN information from the packet.References:Juniper Networks VXLAN Implementation 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

The Ethernet segment router in EVPN is responsible for preventing BUM traffic from looping back to a multi-homed host. It ensures that BUM traffic is properly handled in scenarios where hosts are connected to multiple leaf nodes.