Network+ 10-009 Objective 2.2: Configure Switching Technologies and Features

September 9, 2025•32 min read•CompTIA Network+ Certification

Network+ Exam Focus: This objective covers the configuration and management of switching technologies including VLANs, interface settings, spanning tree protocols, and MTU configurations. Understanding these concepts is essential for network design, implementation, and troubleshooting in modern switched networks. Master these technologies for both exam success and real-world network administration.

Introduction to Switching Technologies

Switching technologies form the foundation of modern local area networks, providing intelligent forwarding of network traffic based on MAC addresses. Understanding how to configure and manage switching features is crucial for network administrators, as switches are the primary devices connecting end-user devices in most networks.

Key Switching Concepts:

MAC Address Learning: Switches learn device locations automatically
Frame Forwarding: Intelligent forwarding based on destination MAC
Broadcast Domains: VLANs control broadcast traffic scope
Collision Domains: Each switch port is a separate collision domain
Loop Prevention: Spanning tree protocols prevent switching loops
Traffic Segmentation: VLANs provide logical network separation

Virtual Local Area Network (VLAN)

VLANs are logical networks created within a physical network infrastructure, allowing network administrators to segment traffic and improve security, performance, and management. VLANs enable multiple logical networks to coexist on the same physical infrastructure.

VLAN Benefits:

Security: Isolate traffic between different groups
Performance: Reduce broadcast traffic scope
Flexibility: Logical grouping independent of physical location
Management: Easier network administration and troubleshooting
Cost Savings: Reduce need for additional hardware
Scalability: Easy to add/remove devices from VLANs

VLAN Types:

Static VLANs: Port-based VLAN assignment
Dynamic VLANs: MAC address-based assignment
Protocol VLANs: Protocol-based assignment
Voice VLANs: Dedicated VLANs for VoIP traffic
Management VLANs: VLANs for device management
Native VLANs: Untagged traffic VLAN

VLAN Configuration Best Practices:

VLAN Naming: Use descriptive names for VLANs
VLAN Numbering: Use consistent numbering schemes
Documentation: Document VLAN purposes and assignments
Security: Implement VLAN access controls
Monitoring: Monitor VLAN traffic and performance
Backup: Backup VLAN configurations regularly

VLAN Database

The VLAN database stores information about all VLANs configured on a switch, including VLAN IDs, names, and status. Understanding VLAN database management is essential for maintaining consistent VLAN configurations across network devices.

VLAN Database Components:

VLAN ID: Unique identifier (1-4094)
VLAN Name: Descriptive name for the VLAN
VLAN Status: Active or suspended state
VLAN Type: Static, dynamic, or voice
Port Assignments: Ports assigned to the VLAN
VLAN Trunking: Trunk port configurations

VLAN Database Management:

VLAN Creation: Add new VLANs to the database
VLAN Modification: Change VLAN properties
VLAN Deletion: Remove unused VLANs
Database Synchronization: Sync across multiple switches
Backup and Restore: Save and restore configurations
Version Control: Track VLAN configuration changes

VLAN Database Commands:

vlan database: Enter VLAN configuration mode
vlan [id]: Create or modify VLAN
name [name]: Assign name to VLAN
show vlan: Display VLAN information
show vlan brief: Brief VLAN status
copy running-config startup-config: Save configuration

Switch Virtual Interface (SVI)

A Switch Virtual Interface (SVI) is a virtual interface that provides Layer 3 routing capabilities for VLANs on a multilayer switch. SVIs enable inter-VLAN routing and provide a gateway for devices within a VLAN.

SVI Characteristics:

Virtual Interface: Logical interface for VLAN routing
Layer 3 Capability: Provides routing functionality
VLAN Gateway: Default gateway for VLAN devices
IP Address Assignment: Requires IP address configuration
Inter-VLAN Routing: Routes traffic between VLANs
Management Interface: Can be used for switch management

SVI Configuration:

Interface Creation: Create interface vlan [id]
IP Address Assignment: Configure IP address and subnet mask
Interface Activation: Enable the interface (no shutdown)
Routing Protocol: Configure routing protocols if needed
Access Lists: Apply security policies
QoS Configuration: Configure quality of service

SVI Benefits:

Inter-VLAN Routing: Route between different VLANs
Centralized Routing: Single device for routing and switching
Cost Effective: Eliminates need for separate router
Performance: High-speed routing within switch
Management: Single point of management
Scalability: Easy to add new VLANs

Interface Configuration

Switch interface configuration involves setting up various parameters that control how the interface operates, including VLAN assignments, speed and duplex settings, and special VLAN configurations for voice and native traffic.

Native VLAN

The native VLAN is the VLAN that carries untagged traffic on a trunk port. Understanding native VLAN configuration is crucial for proper trunk operation and security in VLAN environments.

Native VLAN Characteristics:

Untagged Traffic: Carries traffic without VLAN tags
Default VLAN: Usually VLAN 1 by default
Trunk Ports: Only applies to trunk connections
Security Risk: Can be security vulnerability if misconfigured
802.1Q Standard: Defined in IEEE 802.1Q standard
Configuration Required: Must match on both ends of trunk

Native VLAN Best Practices:

Change Default: Change from default VLAN 1
Dedicated VLAN: Use dedicated VLAN for native traffic
Consistent Configuration: Match on all trunk ports
Security: Apply security policies to native VLAN
Documentation: Document native VLAN assignments
Monitoring: Monitor native VLAN traffic

Native VLAN Configuration:

Trunk Configuration: Configure trunk port first
Native VLAN Assignment: Set native VLAN ID
Verification: Verify configuration on both ends
Testing: Test connectivity through native VLAN
Security Review: Review security implications
Documentation: Document configuration changes

Voice VLAN

Voice VLANs are dedicated VLANs configured specifically for VoIP traffic, providing quality of service and security for voice communications. Voice VLANs ensure that voice traffic receives priority treatment and is isolated from data traffic.

Voice VLAN Benefits:

Quality of Service: Priority treatment for voice traffic
Security: Isolation from data network traffic
Performance: Dedicated bandwidth for voice
Management: Easier voice network management
Troubleshooting: Simplified voice troubleshooting
Compliance: Meet voice quality requirements

Voice VLAN Configuration:

VLAN Creation: Create dedicated voice VLAN
Port Configuration: Configure access port for voice
QoS Settings: Configure quality of service
Power Settings: Configure PoE if needed
Security Policies: Apply voice-specific security
Monitoring: Monitor voice VLAN performance

Voice VLAN Features:

Auto-Detection: Automatic voice device detection
Priority Queuing: High priority for voice traffic
Bandwidth Allocation: Reserved bandwidth for voice
Traffic Shaping: Control voice traffic flow
Call Admission Control: Limit concurrent calls
Emergency Services: Priority for emergency calls

802.1Q Tagging

802.1Q tagging is the IEEE standard for VLAN tagging that allows multiple VLANs to be carried over a single physical link. Understanding 802.1Q tagging is essential for trunk configuration and inter-switch communication.

802.1Q Tagging Characteristics:

VLAN Tag: 4-byte tag inserted into Ethernet frame
VLAN ID: 12-bit field for VLAN identification
Priority Bits: 3-bit field for QoS priority
Canonical Format: 1-bit field for frame format
Trunk Ports: Used on trunk connections
Interoperability: Standard across vendors

802.1Q Tag Structure:

TPID (Tag Protocol ID): 0x8100 identifies 802.1Q frame
TCI (Tag Control Information): Contains priority and VLAN ID
Priority (PCP): 3-bit priority field (0-7)
CFI (Canonical Format Indicator): 1-bit format indicator
VLAN ID: 12-bit VLAN identifier (1-4094)
Frame Size: Increases frame size by 4 bytes

802.1Q Configuration:

Trunk Mode: Configure port as trunk
Allowed VLANs: Specify allowed VLANs on trunk
Native VLAN: Configure native VLAN
Pruning: Configure VLAN pruning
Encapsulation: Specify encapsulation type
Verification: Verify trunk configuration

Link Aggregation

Link aggregation combines multiple physical links into a single logical link, providing increased bandwidth, redundancy, and load balancing. Understanding link aggregation is essential for designing high-performance and resilient networks.

Link Aggregation Benefits:

Increased Bandwidth: Combines multiple link speeds
Redundancy: Automatic failover if link fails
Load Balancing: Distributes traffic across links
Cost Effective: Better than single high-speed link
Scalability: Easy to add more links
Transparency: Appears as single link to upper layers

Link Aggregation Protocols:

LACP (Link Aggregation Control Protocol): IEEE 802.3ad standard
PAgP (Port Aggregation Protocol): Cisco proprietary
Static Aggregation: Manual configuration without protocol
Dynamic Aggregation: Automatic negotiation
Cross-Stack Aggregation: Aggregation across multiple switches
Multi-Chassis Aggregation: Aggregation across chassis

Link Aggregation Requirements:

Same Speed: All links must have same speed
Same Duplex: All links must be full duplex
Same Media: All links must use same media type
Same VLAN: All links must be in same VLAN
Same Configuration: Consistent configuration on all links
Compatible Equipment: Both ends must support aggregation

Speed and Duplex

Speed and duplex settings control the data transmission rate and communication direction on network interfaces. Proper configuration of these settings is essential for optimal network performance and avoiding connectivity issues.

Speed Settings:

10 Mbps: 10 Megabits per second
100 Mbps: 100 Megabits per second (Fast Ethernet)
1000 Mbps: 1 Gigabit per second (Gigabit Ethernet)
10 Gbps: 10 Gigabits per second
25 Gbps: 25 Gigabits per second
40 Gbps: 40 Gigabits per second
100 Gbps: 100 Gigabits per second

Duplex Settings:

Half Duplex: Communication in one direction at a time
Full Duplex: Simultaneous bidirectional communication
Auto Negotiation: Automatic speed and duplex detection
Manual Configuration: Explicit speed and duplex setting
Mismatch Issues: Problems when settings don't match
Performance Impact: Duplex affects network performance

Speed and Duplex Best Practices:

Auto Negotiation: Use auto-negotiation when possible
Consistent Settings: Match settings on both ends
Full Duplex: Use full duplex for better performance
Documentation: Document speed and duplex settings
Monitoring: Monitor for speed/duplex mismatches
Troubleshooting: Check settings when troubleshooting

Spanning Tree Protocol

Spanning Tree Protocol (STP) prevents switching loops in redundant network topologies while maintaining redundancy for fault tolerance. Understanding spanning tree is crucial for designing resilient networks and troubleshooting connectivity issues.

Spanning Tree Benefits:

Loop Prevention: Prevents switching loops
Redundancy: Maintains backup paths
Automatic Recovery: Automatic failover on link failure
Network Stability: Prevents broadcast storms
Load Balancing: Some variants support load balancing
Standards Based: IEEE 802.1D standard

Spanning Tree Variants:

STP (802.1D): Original spanning tree protocol
RSTP (802.1w): Rapid Spanning Tree Protocol
MSTP (802.1s): Multiple Spanning Tree Protocol
PVST+: Per-VLAN Spanning Tree (Cisco)
Rapid-PVST+: Rapid Per-VLAN Spanning Tree
MST: Multiple Spanning Tree (Cisco)

Spanning Tree Port States:

Blocking: Port blocks traffic to prevent loops
Listening: Port listens for BPDUs
Learning: Port learns MAC addresses
Forwarding: Port forwards traffic normally
Disabled: Port is administratively disabled
Alternate: Backup port (RSTP)
Backup: Backup port for same segment (RSTP)

Spanning Tree Roles:

Root Bridge: Central reference point for STP
Root Port: Port with best path to root bridge
Designated Port: Port that forwards traffic on segment
Blocked Port: Port that blocks traffic to prevent loops
Alternate Port: Backup root port (RSTP)
Backup Port: Backup designated port (RSTP)

Maximum Transmission Unit (MTU)

The Maximum Transmission Unit (MTU) defines the largest packet size that can be transmitted over a network interface. Understanding MTU configuration is important for network performance and avoiding fragmentation issues.

MTU Characteristics:

Frame Size Limit: Maximum frame size for transmission
Layer 2 Concept: Applies to data link layer
Path MTU: Smallest MTU in path to destination
Fragmentation: Large packets may be fragmented
Performance Impact: Affects network performance
Protocol Dependent: Different protocols have different MTUs

Standard MTU Sizes:

Ethernet: 1500 bytes (standard)
Token Ring: 4464 bytes
FDDI: 4352 bytes
ATM: 9180 bytes
PPP: 1500 bytes
Frame Relay: 1500 bytes
Jumbo Frames: 9000+ bytes

MTU Configuration Considerations:

End-to-End Consistency: MTU must be consistent across path
Performance vs. Compatibility: Balance performance and compatibility
Fragmentation Overhead: Consider fragmentation costs
Application Requirements: Some applications require specific MTUs
Network Monitoring: Monitor for MTU-related issues
Testing: Test MTU changes before deployment

Jumbo Frames

Jumbo frames are Ethernet frames larger than the standard 1500-byte MTU, typically 9000 bytes. Jumbo frames can improve network performance by reducing the number of frames needed to transmit large amounts of data.

Jumbo Frame Benefits:

Reduced Overhead: Fewer frame headers per data
Improved Throughput: Higher effective bandwidth
Lower CPU Usage: Fewer interrupts per data transfer
Better Performance: Improved performance for large transfers
Efficiency: More efficient use of network bandwidth
Scalability: Better performance in high-speed networks

Jumbo Frame Considerations:

End-to-End Support: All devices must support jumbo frames
Memory Requirements: Higher memory requirements
Latency Impact: May increase latency for small packets
Compatibility Issues: Not all devices support jumbo frames
Configuration Complexity: Requires careful configuration
Testing Required: Thorough testing before deployment

Jumbo Frame Implementation:

Network Assessment: Assess network for jumbo frame support
Device Configuration: Configure all devices consistently
Testing: Test jumbo frame transmission
Monitoring: Monitor performance improvements
Documentation: Document jumbo frame configuration
Rollback Plan: Plan for rollback if issues occur

Switching Technology Comparison

Technology	Purpose	Benefits	Use Case
VLAN	Traffic Segmentation	Security, Performance	Network Segmentation
SVI	Inter-VLAN Routing	Cost Effective	Layer 3 Switching
Link Aggregation	Bandwidth Increase	Redundancy, Performance	High Availability
Spanning Tree	Loop Prevention	Network Stability	Redundant Topologies
Jumbo Frames	Performance	Higher Throughput	High-Speed Networks

Common Configuration Scenarios

Network+ exam questions often test your understanding of switching technologies in practical scenarios. Here are common configuration scenarios:

Scenario-Based Questions:

VLAN Configuration: Setting up VLANs for different departments
Trunk Configuration: Configuring inter-switch connections
Voice VLAN Setup: Implementing VoIP networks
Link Aggregation: Increasing bandwidth between switches
Spanning Tree Tuning: Optimizing STP for faster convergence
MTU Configuration: Setting appropriate MTU sizes

Switching Technology Best Practices

Configuration Best Practices:

VLAN Design: Plan VLAN structure before implementation
Naming Conventions: Use consistent naming for VLANs and interfaces
Documentation: Document all configuration changes
Security: Implement proper VLAN security policies
Monitoring: Monitor switch performance and traffic
Backup: Regular backup of switch configurations
Testing: Test configurations in lab before production
Change Management: Follow proper change management procedures

Study Tips for Network+ Objective 2.2

Key Study Points:

VLAN Concepts: Understand VLAN benefits and configuration
Trunking Protocols: Know 802.1Q tagging and native VLANs
Interface Settings: Understand speed, duplex, and MTU configuration
Spanning Tree: Know STP variants and port states
Link Aggregation: Understand LACP and aggregation benefits
Voice VLANs: Know voice VLAN configuration and benefits
Troubleshooting: Practice troubleshooting switching issues

Conclusion

Switching technologies form the backbone of modern networks, providing intelligent traffic forwarding, network segmentation, and high availability. Understanding how to configure VLANs, trunking, spanning tree protocols, and interface settings is essential for network design, implementation, and troubleshooting.

Proper configuration of switching technologies enables network administrators to create secure, high-performance networks that can scale with organizational needs. From basic VLAN segmentation to advanced features like link aggregation and jumbo frames, these technologies provide the foundation for reliable network operation.

Next Steps: Practice configuring VLANs, trunking, and spanning tree protocols in lab environments. Understanding these switching technologies will help you design efficient networks and troubleshoot connectivity issues effectively. Focus on hands-on experience with different switch vendors and their specific configuration commands.