VPLS / Layer-2 VPN
Remote sites share one broadcast domain as if on the same switch.
How widely is it used?
Still around, but being replacedLegacy layer-2 stretching; VXLAN overlays have taken over new deployments.
How it works
Instead of routing between subnets, the provider or overlay bridges Ethernet frames between sites, so hosts in different buildings sit on the same layer-2 segment.
Connects
LAN segment ↔ LAN segment
Protocols
VPLS, L2TPv3, VXLAN, EoIP
Typical users
Enterprises with legacy layer-2 applications, Carriers
Main use case
Stretching a VLAN across locations.
Advantages
- Applications that assume one LAN keep working
- No re-addressing needed
Limitations
- Broadcast storms travel too
- Often unencrypted unless layered over IPsec