What is VLAN (Virtual Local Area Network)
A virtual LAN or VLAN is any broadcast domain that is segregated and isolated at the data link layer OSI layer 2. VLANs reduce the load on a network by keeping local traffic within a VLAN. However, because each type VLAN its own domain, a mechanism is needed for VLANS to pass data to other VLANS without passing the data through a router.
The solution is SVI networking i.e. switched virtual interface.
Related – VLAN vs Subnet
What is SVI (Switched Virtual Interface)
An SVI interface is usually found on Layer 3 switches. With SVIs the switch recognizes the packet destinations that are local to the sending VLAN and then routes packets destined for different VLANs.
An SVI interface can be created for each VLAN that exists but only one SVI can be mapped to each VLAN. An SVI is virtual and has no physical port defined and performs the same functions for the VLAN as a router interface. SVI is also called Interface VLAN.
Comparison Table: VLAN vs SVI
Below table summarizes the differences between the two:
| PARAMETER | SVI | VLAN |
|---|---|---|
| Abbreviation for | Switched Virtual Interface | Virtual Local Area Network |
| Platform support | Only configurable on Layer 3 devices. | Can be configured on Layer 3 and Layer 2 devices |
| Routing across IP subnets | SVI can perform routing across IP subnets | Cannot perform Routing between VLANs |
| Configuration | Interface VLAN (VLAN ID) | Can be enabled via following command: VLAN (VLAN ID) |
| OSI Layer | Works on Layer 3 of OSI Model | Works on Layer 2 of OSI Model |
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