Aruba Switching Expert (Written) flashcards

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

Broadcast domain boundary

A broadcast domain ends at a Layer 3 boundary such as a router or routed port; every port in the same VLAN shares one broadcast domain.

Store-and-forward switching

The switch buffers the whole frame, checks the frame check sequence, and discards errored frames before forwarding. Higher latency but error filtering.

Oversubscription ratio

Downstream access bandwidth divided by uplink bandwidth. A 20:1 ratio means 20 Gbps of access capacity shares 1 Gbps of uplink capacity.

802.1Q tag fields

Four bytes: TPID 0x8100, a 3-bit priority code point, a 1-bit drop eligible indicator, and a 12-bit VLAN identifier usable from 1 to 4094.

Native VLAN behavior

Frames in the native VLAN cross a trunk untagged. A mismatch between the two ends leaks traffic between VLANs and can create connectivity faults.

Private VLAN port types

Promiscuous ports reach every port, isolated ports reach only promiscuous ports, and community ports reach each other plus promiscuous ports.

Voice VLAN

A dedicated VLAN for IP phone traffic, often advertised to phones by LLDP-MED, keeping voice separate from data for QoS and security.

Root bridge election

The switch with the lowest bridge ID becomes root. Bridge ID combines a configurable priority, default 32768 in steps of 4096, with the system MAC.

RSTP port roles

Root port toward the root bridge, designated port forwarding toward a segment, alternate port as backup for the root port, backup port for a designated port.

BPDU Guard

A feature that err-disables an edge port if it receives a bridge protocol data unit, protecting the topology from unauthorized or misconfigured switches.

MSTP region match

Switches must share the same region name, revision number, and VLAN-to-instance mapping to belong to the same multiple spanning tree region.

LACP active vs passive

Active mode initiates negotiation by sending LACPDUs; passive mode only responds. Two passive ports never form a bundle because neither initiates.

Aggregation member requirements

All links in one bundle must match speed, duplex, MTU, and VLAN membership; any mismatch keeps the link out of the bundle.

Per-flow load balancing

Hashing on source and destination addresses or ports sends one flow over one member link, so a single flow cannot exceed one link's bandwidth.

Multi-chassis aggregation

Two switches present one logical bundle to a server or downstream device, combining link redundancy with device redundancy without spanning tree blocking.

Stack split risk

If stack links fail, members can become independent switches with duplicate addresses and loops; split detection and redundant management paths mitigate this.

Stack commander election

Members elect a commander or master using configured priority first, then MAC address as a tiebreaker; the result determines the control plane.

Virtual switching pair

Two switches keep separate control planes but synchronize forwarding state, providing device redundancy without the single-control-plane risk of a stack.

Switch virtual interface

A logical Layer 3 interface bound to a VLAN, used for inter-VLAN routing. It requires an IP address and an active VLAN.

Longest prefix match

When multiple routes match a destination, the router selects the most specific prefix; administrative distance and metric only break ties within equal prefixes.

DHCP relay operation

The switch forwards client DHCP broadcasts as unicast to a configured server, inserting the gateway address so the server selects the correct pool.

VRRP virtual gateway

Routers share a virtual IP and MAC; the highest priority router forwards, and preemption controls whether a recovered router reclaims the role.

802.1X roles

The supplicant is the endpoint, the authenticator is the switch port, and the authentication server is RADIUS; EAPoL carries authentication to the switch.

DHCP snooping trust

Only trusted uplink ports may offer DHCP; untrusted ports cannot respond, and the binding table feeds dynamic ARP inspection and IP source guard.

Dynamic ARP Inspection

The switch validates ARP packets against the DHCP snooping binding table, dropping replies that do not match a known IP-to-MAC binding.

Port security violations

Protect silently drops offending frames, restrict drops and logs them, and shutdown err-disables the port until it is manually recovered.

IGMP snooping

The switch listens to IGMP joins and leaves and forwards multicast only to ports that requested the group, instead of flooding to the whole VLAN.

DSCP EF value

Expedited Forwarding uses DSCP 46 and is the recommended marking for voice, giving low latency and low loss treatment in queues.

Shaping versus policing

Shaping buffers and delays excess traffic to smooth bursts; policing drops or re-marks excess traffic immediately without buffering.

Late collisions

Collisions detected after the first 64 bytes, typically caused by a duplex mismatch or an over-long cable segment, and they indicate a physical or configuration fault.

Port mirroring

A copy of traffic from one or more source ports is sent to a monitor port for analysis; remote mirroring carries the copy in a dedicated VLAN.

NTP for operations

Accurate time synchronization lets logs from multiple devices correlate and supports time-based access control lists and certificate validation.