JNCIP-DC flashcards

36 cards. Read the term and the definition here. The deck at the top of this page is optional.

Spine-leaf oversubscription

Ratio of total leaf downlink bandwidth to total leaf uplink bandwidth. A 3:1 ratio means 3 Gbps of server-facing capacity per 1 Gbps of spine-facing capacity.

EVPN-VXLAN ERB

Edge-routed bridging places the Layer 3 gateway on the leaf VTEP, so inter-subnet traffic is routed at the leaf rather than hairpinned to the spine.

ESI-LAG

Ethernet Segment Identifier LAG used in EVPN multihoming. The same ESI is configured on both leaves, and designated forwarder election picks the forwarding leaf per segment.

VXLAN VNI size

The VXLAN Network Identifier is 24 bits, allowing up to 16,777,215 segments, far more than the 12-bit 802.1Q VLAN tag space of 4094 usable VLANs.

EVPN Type 2 route

MAC/IP Advertisement route. It carries a MAC address and optionally an IP address, enabling MAC learning and ARP/ND suppression across the overlay.

Anycast gateway

The same IP and virtual MAC are configured on every leaf IRB for a subnet, so a host's default gateway is always local regardless of which leaf it attaches to.

Junos policer

A traffic conditioner that limits bandwidth using bandwidth-limit and burst-size-limit. It is referenced from a firewall filter action and can discard or mark excess traffic.

DHCP snooping

A Layer 2 security feature that filters DHCP server messages on untrusted ports and builds a binding table used by dynamic ARP inspection to validate ARP packets.

Junos PyEZ

A Python library for Junos automation. It connects over NETCONF, exposes a Device class, and supports CLI commands, configuration loading, and commit operations.

NETCONF port

NETCONF over SSH uses TCP port 830 by default. Enable it on Junos with 'set system services netconf ssh' before programmatic configuration.

EVPN MAC mobility

Type 2 routes carry a sequence number. When a MAC moves between VTEPs, the higher sequence number wins, preventing duplicate MAC entries in the overlay.

Port mirroring

Junos forwarding-options port-mirroring copies traffic from a source interface to a destination interface for analysis, configured with input rate and destination-interface.

Virtual Chassis

Multiple Junos switches managed as one logical device using a ring topology. Members are assigned routing-engine or line-card roles and identified by serial number.

GRES and NSR

Graceful Routing Engine switchover and nonstop active routing keep forwarding and routing sessions alive during a Routing Engine failover, reducing downtime.

Junos ELS syntax

Enhanced Layer 2 Software uses 'interface-mode access|trunk' and 'vlan members' under family ethernet-switching, replacing the older port-mode syntax.

IRB interface

An integrated routing and bridging interface provides Layer 3 gateway services for a VLAN. It is associated with a VLAN using the l3-interface statement.

EVPN route target

A 64-bit BGP extended community that controls which EVPN routes are imported into a VRF or EVPN instance. Typically one RT per VNI.

EVPN Type 5 route

IP Prefix route. It advertises IP prefixes across the EVPN overlay, supporting inter-subnet routing without requiring an IRB on every leaf.

MACsec

IEEE 802.1AE link-layer encryption. Junos configures it with a connectivity association, a cipher suite, and an interface binding for hop-by-hop protection.

Dynamic ARP inspection

A feature that validates ARP packets against the DHCP snooping binding table, dropping spoofed ARP responses on untrusted ports.

Junos commit script

A script that runs during commit to enforce configuration policy. It can emit warnings or errors using xnm:warning and xnm:error elements.

Junos REST API

An HTTP interface enabled with 'set system services rest http' that accepts GET and POST requests with JSON payloads for configuration and operational commands.

Underlay MTU for VXLAN

VXLAN adds outer IP, UDP, VXLAN, and inner Ethernet headers. The underlay MTU must be at least 1600 bytes, typically 9000, to avoid fragmentation.

Path MTU test

Use 'ping <dest> size <n> do-not-fragment' to verify the largest packet that traverses the path without fragmentation, useful for VXLAN underlay validation.

QFX5120 role

A Junos data center switch commonly deployed as a leaf in EVPN-VXLAN fabrics, offering 25G and 100G interfaces for server and spine connectivity.

Nonstop bridging

NSB keeps Layer 2 protocol state, such as LACP and STP, synchronized between Routing Engines so a failover does not disrupt Layer 2 forwarding.

Storm control profile

A Junos profile that limits broadcast, multicast, and unknown-unicast traffic as a percentage of link bandwidth, applied per interface under ethernet-switching.

LACP LAG

A bundle of links using 802.3ad. Members must match speed, duplex, and MTU; at least one side is configured active, and system priority determines selection.

BGP route reflector

A BGP router that reflects routes between iBGP peers, avoiding a full mesh. In EVPN fabrics, spines typically act as route reflectors for leaf-originated routes.

ARP suppression

An EVPN feature that answers ARP requests locally using the EVPN database, reducing broadcast flooding across the overlay. Configured with protocols evpn arp-suppression.

Control-plane protection

A firewall filter applied to the loopback interface that permits only required protocols to the Routing Engine, protecting it from DoS traffic.

ZTP DHCP options

Zero Touch Provisioning relies on DHCP options, including option 43, to deliver the software image URL and configuration file to a new device.

Ansible Junos modules

junos_command, junos_config, and junos_facts automate Junos devices. They require NETCONF or network_cli connections and are commonly used for configuration compliance.

Event script

A Junos script triggered by a system event, configured under event-options with an events list and execute-commands action, used for automated remediation.

EVPN instance command

'show evpn instance' displays EVPN instance state, VTEPs, and route targets; 'show evpn database' lists MAC and IP entries per instance.

Optical diagnostics

'show interfaces diagnostics optics' displays transmit and receive power levels and temperature, helping isolate cabling or transceiver faults.