Lesson 6: VLAN (Virtual Local Area Network)

VLAN (Virtual Local Area Network)

A logical subnetwork grouping devices from different physical LANs.

Flat Network

The network where all devices share a single broadcast domain (limited scalability).

VLANs

This network reduce cost, improve flexibility, and support future growth.

Default VLAN (VLAN 1):

All ports belong to it unless reassigned. Cannot be changed/deleted (security risk if used for data).

Native VLAN

Carries untagged traffic on trunk ports (for legacy devices). Used for control protocols (e.g., CDP, STP).

Creating VLAN syntax

#vlan 300  
#name SALES  

Assigning IP in VLAN

#interface vlan 300  
#ip address 192.168.0.1 255.255.255.0  

Assigning Ports in VLAN

#switchport access vlan 10  

Inter-VLAN Routing Traditional Option

Router with multiple interfaces (limited scalability).

Inter-VLAN Routing Router-on-a-Stick Option

Single trunk link to router.

Inter-VLAN Routing Multilayer Switch Option

Combines switching/routing (uses SVIs).