JNCIS-DC key terms

A data center overlay architecture that uses BGP Ethernet VPN (EVPN) as the control plane to advertise MAC and IP reachability, while VXLAN provides the data-plane encapsulation over an IP underlay.

A network device or virtual switch interface that originates and terminates VXLAN tunnels, encapsulating original Ethernet frames into UDP packets and mapping frames to a VNI.

VXLAN Network Identifier, a 24-bit value carried in the VXLAN header that identifies which virtual network a frame belongs to, allowing roughly 16 million isolated segments across a shared IP fabric.

An EVPN route that advertises a MAC address together with its associated IP address and VNI, enabling remote VTEPs to learn end-host location and populate bridging and ARP/ND tables.

An EVPN IP Prefix route used to advertise subnets or host prefixes across the fabric, supporting symmetric routing without requiring every prefix to be carried as a MAC/IP route.

A configuration where every leaf switch uses the same virtual MAC and IP address for a distributed gateway, so hosts keep one default gateway while traffic is forwarded locally on the attached leaf.

Integrated routing and bridging design in which the Layer 2 VNI and Layer 3 VNI are the same on both ingress and egress leaf switches, so routing happens once at the ingress VTEP and the packet stays in one VNI.

Integrated routing and bridging design in which the ingress leaf routes into the destination VNI before encapsulation, requiring the egress leaf to hold Layer 2 and Layer 3 state for every VNI.

A VTEP function that bridges frames between a local VLAN and a VNI without performing IP routing, typically used for Layer 2 extension or when routing is handled elsewhere in the fabric.

A VTEP function that performs IP routing for a VNI, acting as the default gateway for hosts and resolving next hops through the overlay or underlay.

The physical IP-routed fabric that transports VXLAN-encapsulated packets between VTEPs, typically built with Layer 3 ECMP links and a routing protocol such as OSPF or BGP.

A logical network built on top of the underlay using tunnels, providing Layer 2 and Layer 3 connectivity and segmentation independent of the physical topology beneath it.

Equal-Cost Multipath, a forwarding behavior that load-balances traffic across multiple equal-cost next hops, commonly used in data center fabrics to increase bandwidth and resilience.

Multichassis Link Aggregation Group, a technique where two switches present a single logical Link Aggregation Group to a server or downstream device, providing redundancy without spanning tree blocking.

Link Aggregation Control Protocol, an IEEE 802.3ad standard that negotiates and maintains bundling of multiple physical links into one logical link, detecting misconfigurations and link failures.

Ethernet Segment Identifier, an EVPN attribute that identifies a set of links attached to the same multihomed device or network, enabling all-active multihoming and split-horizon handling.

A behavior where the VTEP answers ARP requests locally using IP-to-MAC bindings learned from EVPN routes, reducing broadcast flooding across the VXLAN fabric.

Broadcast, Unknown unicast, and Multicast traffic, which must be flooded to multiple VTEPs; in EVPN fabrics it is typically distributed using ingress replication or multicast underlay trees.

A method of distributing BUM traffic in which the ingress VTEP replicates each frame and sends a copy to every remote VTEP that participates in the VNI, avoiding reliance on multicast in the underlay.

A Juniper feature that combines multiple physical switches into a single logical device with one management IP and a shared control plane, simplifying operations and improving resiliency.

A Juniper spine-and-leaf architecture built from multiple devices managed as one logical fabric, using a centralized control plane while forwarding traffic over a Layer 2 or Layer 3 underlay.

Juniper's family of data center switches, ranging from fixed-form-factor leaf switches to modular spine platforms, supporting VXLAN, EVPN, and high-density 100/400 Gigabit Ethernet interfaces.

Juniper Networks' network operating system, configured through a hierarchical configuration tree and committed atomically, with support for commit scripts, rollback, and candidate configurations.

A Junos commit option that applies a configuration temporarily and automatically reverts to the previous configuration unless the change is confirmed within a specified timeout, protecting remote management access.

A Junos operation that restores a previously committed configuration from the numbered rollback history, letting administrators quickly undo disruptive changes.

A Junos construct that creates a separate routing table and protocol context on a device, used to isolate tenants, VRFs, or virtual networks on shared hardware.

Virtual Routing and Forwarding, a technology that allows multiple independent routing tables to exist on the same device, keeping tenant or service traffic isolated from one another.

A BGP extended community attached to EVPN or VPN routes that controls which VRFs import the routes, providing controlled distribution of reachability between routing instances.

Border Gateway Protocol, the path-vector routing protocol used in data center fabrics and EVPN as the control plane to exchange reachability information between leaf and spine devices.

A BGP device that receives routes from clients and reflects them to other clients, removing the need for a full mesh of iBGP sessions in larger fabrics.

Zero Touch Provisioning, an automated onboarding process in which a new Juniper device boots, obtains an IP address, downloads software and configuration from a server, and joins the network without manual setup.

An open-source automation tool that uses declarative playbooks to configure and manage network devices, commonly used with Juniper modules to deploy and validate data center configurations at scale.

Streaming, high-frequency export of operational data such as interface counters and sensor values from network devices, enabling near-real-time monitoring and analytics in modern data centers.

Simple Network Management Protocol, a polling-based standard for monitoring and managing network devices, used for metrics, traps, and basic configuration operations.

A Layer 2 loop-prevention protocol that builds a loop-free logical topology by blocking redundant links, though modern data center fabrics often replace it with Layer 3 routing.

A feature that monitors broadcast, multicast, or unknown unicast traffic on an interface and drops or limits it when a configured threshold is exceeded, protecting the network from broadcast storms.

Class of Service, a set of Junos mechanisms for classifying, queuing, and scheduling traffic to provide differentiated treatment such as low latency for storage or voice flows.

Packet Forwarding Engine, the hardware and microcode component of Juniper devices that performs actual packet lookups, filtering, and forwarding, separate from the routing control plane.