Virtual Local Access Networks (vLAN)

Logical subdivision of a given network that segments into separate broacdcast domains. Acheived through a sowfware configuration.

using VLANs different switchports can be used for different VLANs.

When a switch is configured to utilized a vlan it will tag each frame of data with a VLAN ID as it passes through the swithc.

enhanced securety

improved performcnae - reduces the sie of a broadcast domain to

increased management - providing greatoer control over the managemtn of the networks to implement the policy changes and troubleshoot

improved cost efficency - breaking the exisgin network into smaller logica lsegments, less hardware is needed.

Effective VLANs must maintain a VLAN databse that contains all the VLAN info fro the switch

VLAN ID

vlan NAME

VLAN.DAT

SWITCH VIRTUAL INTERFACE - svi allows switchigng to route traffic between VLANs without needing a separate router. can handle the routing descisions for a vlan

Virtual LANs (VLANs) (N10-009)

Definition

Logical subdivision of a physical network.
Segments a switch into separate broadcast domains using software configuration.
Achieved via VLAN tagging (IEEE 802.1Q standard).

How VLANs Work

Switchports can be assigned to different VLANs.
Each VLAN = separate broadcast domain.
Switch adds a VLAN ID (tag) to Ethernet frames so traffic stays in the correct VLAN.
VLAN database (VLAN.dat):
- VLAN ID
- VLAN Name
- Stored on switch for persistence.

Benefits of VLANs

Security: Users/devices segmented, traffic isolated.
Performance: Reduces size of each broadcast domain.
Management: Easier policy enforcement, troubleshooting.
Cost Efficiency: One switch can serve multiple VLANs → less hardware required.

Switch Virtual Interface (SVI)

Logical interface on a switch that allows it to route traffic between VLANs.
Provides Layer 3 functionality (routing) without needing a separate router.
Used in Inter-VLAN routing.
Example: VLAN 10 and VLAN 20 on same switch can communicate through the SVI.

✅ Must-Know Exam Points

VLAN = logical broadcast domain.
802.1Q = VLAN tagging standard.
SVI = enables inter-VLAN routing on a Layer 3 switch.
VLANs provide segmentation, security, performance, and management.

⚡ Flashcard Drill

Q: What standard is used for VLAN tagging?

A: IEEE 802.1Q.
Q: Each VLAN is its own…?

A: Broadcast domain.
Q: What allows inter-VLAN routing on a switch?

A: Switch Virtual Interface (SVI).