Deployment
MPLS is currently (as of March 2012) in use in IP-only networks and is standardized by the IETF in RFC 3031. It is deployed to connect as few as two facilities to very large deployments. For example, in the retail sector, it is not uncommon to see deployments of 2000 to 5000 locations to communicate transaction data to a headquarters data center.
In practice, MPLS is mainly used to forward IP datagrams and Ethernet traffic. Major applications of MPLS are telecommunications traffic engineering and MPLS VPN.
Read more about this topic: Multiprotocol Label Switching