JNCIE-ENT flashcards

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

Commit Confirmed

Junos command that activates a configuration for a limited period (default 10 minutes) unless confirmed with commit confirmed, automatically reverting to the prior configuration if no confirmation occurs.

Rescue Configuration

A saved known-good Junos configuration stored on the device; request system configuration rescue save creates it and rollback rescue restores it, useful after failed changes.

Configuration Groups

Junos feature that applies shared statements to multiple interfaces, protocols, or routing instances; apply-groups inherits values and explicit lower-level statements override them.

Traceoptions

Junos debugging mechanism configured under a protocol or routing-options hierarchy; it writes selected events to a file in /var/log with configurable size and flags.

NETCONF Service

XML-based management interface enabled with set system services netconf ssh; it listens on port 830 and supports atomic commit per session with YANG-modeled data.

Syslog Host Configuration

Junos system syslog statements specifying host address, facility, severity level, and match conditions to control which log messages are exported to remote collectors.

Commit History Rollback

Junos retains the last 50 commits; rollback N loads revision N into the candidate configuration, and show system commit lists revisions with user and timestamp.

Trunk Native VLAN

On an 802.1Q trunk port, native-vlan-id designates the single VLAN whose frames are sent untagged, while all other VLANs are tagged.

RSTP Edge Port

Access-facing port configured with set protocols rstp interface X edge; it transitions immediately to forwarding and should be paired with BPDU protection.

BPDU Protection

Feature that err-disables or blocks an edge port when a BPDU is received, preventing user devices from injecting spanning-tree topology changes into the network.

Q-in-Q Tunneling

Provider bridging where an outer 802.1Q tag is added to customer frames; Junos uses vlan-id for the outer tag and inner-vlan-id-list for customer VLANs.

MAC Limiting

Interface feature restricting learned MAC addresses with interface-mac-limit; packet-action drop or shutdown determines behavior when the limit is exceeded.

Storm Control

Per-interface thresholds limiting broadcast, multicast, or unknown-unicast traffic by percentage or rate, protecting the switching fabric from flooding loops.

LACP Aggregated Ethernet

802.3ad link aggregation configured on ae interfaces with lacp active or passive; fast timers (1 second) detect failures faster than slow timers (30 seconds).

MSTP Instances

802.1s spanning tree maps VLANs to multiple instances, each with its own topology, enabling load sharing across redundant links rather than a single blocked path.

IRB Interface

Integrated routing and bridging interface that provides Layer 3 gateway addressing for a VLAN; the VLAN references it via l3-interface irb.N.

VRRP Preempt

VRRP option allowing a higher-priority backup to take over the master role; without preempt, the current master retains control until it fails.

OSPF NSSA

Not-so-stubby area that blocks Type 5 external LSAs but permits Type 7 LSAs originated within the area, which the ABR translates to Type 5.

BGP Next-Hop-Self

iBGP configuration that rewrites the next hop to the advertising router's address, required when the original eBGP next hop is unreachable inside the AS.

Junos Route Preference

Tie-breaking value where lower wins: direct 0, static 5, OSPF internal 10, RIP 100, OSPF external 150, BGP 170; used when multiple protocols offer the same prefix.

DHCP Relay Helper

forwarding-options helpers bootp statement that forwards client DHCP requests to a configured server address; the relay needs reachability to that server.

BFD Timers

Bidirectional forwarding detection uses minimum-interval and multiplier; detection time equals interval times multiplier, commonly three times the negotiated interval.

Filter-Based Forwarding

Firewall filter action routing-instance that directs matching traffic into a specific routing instance, enabling policy-based paths independent of the main routing table.

EVPN Type 2 Route

EVPN MAC/IP advertisement route carrying a MAC address and optional IP; it enables MAC learning across VTEPs and host route distribution for Layer 3.

EVPN Type 3 Route

Inclusive multicast route that signals a VTEP's participation in a VNI and builds the ingress replication list used for BUM traffic delivery.

VXLAN VNI Mapping

Configuration binding a VLAN to a VXLAN network identifier; the VTEP encapsulates frames with the VNI, and the underlay transports only IP packets.

EVPN Ethernet Segment

ESI-based multihoming construct identifying links to the same customer device; all-active mode enables per-flow load sharing with designated forwarder election.

Symmetric IRB EVPN

Layer 3 EVPN design where each VTEP routes into a shared L3 VNI using a common router MAC, allowing inter-VNI routing without per-VRF peering.

MAC Mobility Sequence

EVPN attribute in Type 2 routes that orders MAC moves; a higher sequence number indicates a more recent move and resolves duplicate MAC conflicts.

BA Classifier

Behavior aggregate classifier maps a code point such as DSCP, IP precedence, or 802.1p to a forwarding class and loss priority at ingress.

Strict-High Scheduler

CoS scheduler priority that drains its queue before all others; it can starve lower queues unless the transmit rate or shaping limits its bandwidth.

Rewrite Rules

CoS rules that mark egress DSCP or 802.1p bits according to forwarding class and loss priority; without one, incoming markings are forwarded unchanged.