**1.3 MPLS**

In 1996, companies like Nokia, Cisco, IBM and Toshiba, among others, introduced proprietary solutions to the problem of multilayer switching. This was not only a solution to integrate ATM with IP, but offered brand new services. Unfortunately, these solutions were not compatible despite the large number of aspects in common. MPLS (Multi-Protocol Label Switch) came up from the work of the IETF in 1997 to standardise the proprietary multilayer switching technologies mentioned above. The main feature of MPLS is the combination of layer 3 routing and the simplicity of level 2 switching.

Another important feature of MPLS is that it provides a good balance between connectionoriented technologies to improve non-IP connection-oriented mechanisms (they can only deliver a Best Effort level of service). On the other hand, MPLS adds labels to the packets, so no routing is based on layer 3 addresses but in label switching. This allows interoperability between IP and ATM networks. It also increases the speed of the packets traversing the network because they do not run complex routing algorithms at every hop; they are forwarded considering the packet's label only. This labelling system is also very useful to classify the incoming traffic according to its higher or lower QoS requirements contracted or required.

Since MPLS is a standard solution, it also reduces the operational complexity between IP networks and gives IP advanced, routing capabilities in order to use traffic-engineering techniques that were only possible on ATM.
