Inter-VLAN Routing, VLANs, and Switch Configuration

Flashcards covering Inter-VLAN routing techniques, VLAN types and configuration, trunking protocols, switch boot sequences, physical interface modes, and remote management security based on Cisco CCNA modules.

Inter-VLAN Routing

The process of forwarding network traffic from one VLAN to another VLAN using a router or a Layer 3 switch.

Legacy Inter-VLAN Routing

An early inter-VLAN routing solution that relied on using a router with multiple physical Ethernet interfaces, each connected to a separate switch port assigned to a distinct VLAN.

Router-on-a-Stick

An inter-VLAN routing method where a single physical Ethernet interface on a router is configured as an 802.1Q trunk link with subinterfaces to route traffic between up to 50 VLANs.

Subinterface

A software-based virtual interface associated with a single physical Ethernet interface on a router, independently configured with its own IP address and VLAN assignment.

Switched Virtual Interface (SVI)

A virtual Layer 3 interface configured on a switch for a specific VLAN to perform routing and packet processing functions for that VLAN.

Layer 3 Switch

A device (also called a multilayer switch) capable of hardware-based Layer 2 switching and Layer 3 routing between VLANs using SVIs or routed ports.

Routed Port

A physical port on a Layer 3 switch that has been converted into a Layer 3 interface by disabling switchport features using the no switchport command.

Virtual Local Area Network (VLAN)

A logical partition of a Layer 2 switched network that segments groups of devices into separate broadcast domains.

Default VLAN

VLAN 1 on Cisco switches; it serves as the default data, native, and management VLAN, and cannot be deleted or renamed.

Data VLAN

A VLAN configured specifically to carry user-generated network traffic such as email and web browsing traffic.

Native VLAN

A VLAN assigned to an 802.1Q trunk link to carry all untagged traffic across the link.

Management VLAN

A VLAN configured specifically for remote switch administration traffic (such as SSH/Telnet VTY traffic) using a Switched Virtual Interface (SVI).

Voice VLAN

A dedicated VLAN requiring guaranteed bandwidth, high QoS priority, congestion avoidance, and source-to-destination latency under $150\,m/s$ to support VoIP traffic.

VLAN Trunk

A point-to-point Layer 2 link between two network devices that carries traffic for multiple VLANs across the network using 802.1Q encapsulation.

IEEE 802.1Q Header

A 4-byte VLAN tag field inserted into an Ethernet frame header, containing a 2-byte Tag Protocol ID (0x8100), 3-bit User Priority, 1-bit Canonical Format Identifier, and 12-bit VLAN ID.

Normal Range VLANs

VLAN IDs ranging from 1 to 1005 used in small-to-medium business networks, whose configurations are stored in the vlan.dat file in switch flash memory.

Extended Range VLANs

VLAN IDs ranging from 1006 to 4095 used primarily by service providers, saved directly within the switch running-config file.

Dynamic Trunking Protocol (DTP)

A Cisco proprietary protocol operating at Layer 2 that automatically negotiates trunking states and encapsulation modes between neighboring switch ports.

DTP Dynamic Auto Mode

A switchport DTP mode in which the interface automatically becomes a trunk link if the neighboring interface is configured in trunk or dynamic desirable mode.

DTP Dynamic Desirable Mode

A switchport DTP mode in which the interface actively sends negotiation frames to convert the link into a trunk link with neighboring auto or desirable interfaces.

Switch Boot Sequence

The five-step initialization process of a switch consisting of POST, loading the boot loader, low-level CPU initialization, flash file system initialization, and loading the IOS image into memory.

Switch LED Mode Indicators

Status indicator lights on a Cisco switch front panel showing System (SYST), Redundant Power Supply (RPS), Port Status (STAT), Duplex (DUPLX), Speed (SPEED), and PoE status.

Full-Duplex Communication

A bidirectional data transmission method allowing simultaneous sending and receiving of data across a link without collision domains.

Half-Duplex Communication

A unidirectional data transmission method where data can flow in only one direction at a time, requiring collision detection.

Microsegmentation

A network topology state achieved when a switch port connects to only a single device operating in full-duplex mode, eliminating collisions.

Runt

An Ethernet frame that is discarded because its length is smaller than the minimum required size of $64\,\text{bytes}$.

Giant

An Ethernet frame that is discarded because its total size exceeds the maximum permitted size of $1518\,\text{bytes}$.

Cyclic Redundancy Check (CRC) Error

An interface counter error generated when the calculated frame checksum does not match the checksum value received by the destination device.

Late Collision

A frame collision error that takes place after the first $512\,\text{bits}$ of an Ethernet frame have already been transmitted.

Secure Shell (SSH)

A secure remote management protocol operating on TCP port 22 that encrypts authentication credentials and session data.

Telnet

An unsecure legacy management protocol operating on TCP port 23 that transmits authentication details and command data in plain unencrypted text.

Loopback Interface

A software-based logical interface internal to a router that remains continuously in an up state, used for testing, management, and process emulation.