Multiprotocol Label Switching, also known as MPLS, is a method that is widely used in high-performance telecommunication networks to transmit data from one node on a network to another. This protocol was designed mainly to improve on the weaknesses inherent in the ATM or Asynchronous Transfer Mode architecture. The ATM approach to networking required the development of permanent virtual circuits between the source and destination. Whereas this is advantageous in that it guarantees performance for any virtual circuit that has been established, it presents a lot of overhead in the form of increased setup costs. This is due to the increased need to lay cables to handle the increased load. On the other hand, MPLS takes advantage of high-speed transmission media such as fiber optic cables to manage and maintain virtual connections between nodes.
In this node, instead of messages possessing an address that would determine the route, packets of data are assigned labels. With the label, there is no need to define the type of data, thus allowing this data to form any route over any media to its destination. Thus, it can be used to transmit either packet or frame-based data, thus allowing the transmission of various forms of data over the same media. This is made possible since the speed offered on media such as fiber optic cables is unlikely to cause any delays due to switching and routing of data. It is also possible to transmit a variety of data over the same media in this protocol owing to variable packet size. The overhead incurred by the router of inspecting the IP to determine the shortest route is avoided, and the messages are pushed along from source to destination over available routes. The only data inspected is the source label and destination label.