When should a service provider deploy a Layer 2 MPLS VPN rather than another VPN technology?

The simplest case is when the service provider’s customer is already using a Layer 2 VPN. Migration is fairly straightforward in this case. Other situations where a Layer 2 MPLS VPN is preferable are when a service provider is using non-IP protocols or has a large number of routes in its network. An important factor to note in contrasting Layer

2 and Layer 3 MPLS VPNs is that Layer 2 MPLS VPNs usually require the provider’s customer to have more routing expertise.