A VLAN logically segments an Ethernet network. A subnet cuts the IP address space. They are often associated, but they belong to two different layers.
In brief….The clearest design is usually to associate a VLAN with a separate subnet and then control the routing between them.
Solution A….
VLAN
A VLAN creates several logical diffusion domains on the same switching infrastructure.
Key points…
- Commonly identified by a VLAN number
- Transported between equipment with marking 802.1Q
- Separate Ethernet Streams
Solution B….
Sub-network
A subnet defines a range of IP addresses using a network address and a mask.
Key points…
- Example: 192.168.10.0/24
- Determine which addresses are local
- Requires routing to communicate with another sub-network
Comparative table….
| Criterion…. | VLAN | Sub-network |
|---|---|---|
| Layer | Ethernet, layer 2 | IP, layer 3 |
| Identifier | VLAN ID | Network address and prefix |
| Main equipment | Administerable | Router or firewall |
| Usual association | One VLAN per logical area | A subnet by VLAN |
Choose VLAN if…
You need to logically isolate ports and limit the domains of diffusion on the Switches.
Choose Subnetwork if…
You need to organize IP addresses and define routes between different beaches.
Key takeaways
The clearest design is usually to associate a VLAN with a separate subnet and then control the routing between them.
Deepening the two notions….
← Back to all comparison…