Introduction to VLANs
1. What's a VLAN ?
- VLAN means Virtual Local Area Network
- It is a logical segmentation of a local network.
- Allows network traffic to be separated between different user groups, even if they are physically connected to the same switch.
Pros
- Security: Users in different VLANs cannot communicate directly with each other.
- Management: Facilitates network administration.
- Performance: Reduces the broadcast domain.
2. Key concepts to know
| VLAN ID | Unique identifier for each VLAN (1 to 4094) |
| VLAN Name | Name associated with a VLAN |
| Port Access | Port associated with a single VLAN |
| Broadcast domain | A VLAN is a separate broadcast domain |
3. Creating VLANs on a switch
1. Create and manage a VLAN
| vlan 10 |
Create the vlan with the identifier 10 Access (config-vlan) mode |
| name Accounting |
Name the vlan Accounting In (config-vlan) mode |
| show vlan brief | List VLANs with their identifier, name, and interfaces |
2. Assign a port to a VLAN
| interface fastethernet 0/1 or interface fa0/1 |
Select an interface Access (config-if) mode |
| switchport mode access | Force the switch port into access mode (only carry traffic for one VLAN as opposed to trunk) |
| switchport access vlan 10 | Assign the port to the VLAN |