Networking & Internet

What is Multiprotocol Label Switching (MPLS)?

Mehedi Hasan Masum | July 16, 2019 | 53 views | 0 People said helpful.

What is MPLS?

Multiprotocol Label Switching (MPLS) is a routing technique that defines the shortest path of complex long network address, avoids complex lookup and speeds up the data flow between two nodes. MPLS can encapsulate different types of network protocols and make it a single protocol which refers to “Multiprotocol” as its name and provide a label on its data packets which refers to “Label Switching” for faster transmission of data packets.

How Does Multiprotocol Label Switching (MPLS) Work?

In a normal networking system, when a data packet is passing through a router, the router looks inside every packet to check the data type and its destination. So if a data packet passes through 10 routers, then it will check 10 times for its packet type and destination which is time-consuming. It’s like a postal delivery system where every post office will open the package, check the package type and its destination.

But with MPLS networking system, MPLS uses label switching and set a label with a packet of its end destination router. So the routers only read the packet label and deliver the packet to the final destination without opening it, that is why it is much faster and reliable. Routers don’t look up for an IP address because the destination is already on the label.

In MPLS network, ingress router also called Label edge router (LER) which gives a label in each packet on the entry of network by any service providers. This router also devices the LSP (Label Switched Path) of the packet until it reaches the destination. Packets with MPLS labels forwarded to following Label switching routers(LSRS), those routers never check those packet as it’s labeled. At last, the egress router discards those labels and forwards the original IP packet to the final destination.

Following diagram describe the simple MPLS network workflow

Multiprotocol Label Switching (MPLS) Network Diagram

In which Layer does MPLS work?

MPLS does not fit with standard seven layers hierarchy of OSI Model. MPLS works between OSI Layer 2 (Data link Layer) and Layer 3 (Network Layer) and it’s often known as a layer of 2.5 protocol. Data Link Layer works over simple LANs or point to point connectivity which transmits only IP packets. On the other hand, Network Layer works over internet-based connectivity like addressing and IP protocol based routing. MPLS works in between them by adding additional features for transmitting the packet over the network and separate forwarding technique from the data link service.

Benefits of MPLS (Multiprotocol Label Switching)

Faster Packet Processing

MPLS was designed to make packet processing faster than IP based lookup. Its label switching technology is faster than IP header processing. MPLS is not being used now for fast packet processing although initially it was invented for that.

Improve Uptime

If there are multiple data links with MPLS network, then MPLS can send data over an alternative path which is less time-consuming. It also reduces the manual intervention of multiple networks which reduces the downtime of network and increases the performance.

Scalable VPNs

It’s easy to configure any site to the VPN with MPLS. It is a common and easy approach to configure the VPN as there is no complex tunnel mechanism.

BGP (Border Gateway Protocol) free Core

If BGP is implemented on the network, then it’s needed to run on every device on the networking path. MPLS has totally removed this need as there is no obligation of the protocol with MPLS.

Increased user experience

MPLS can prioritize sensitive traffic by its multiple classes of service that can separate different types of traffic and set the priority of the traffic which in turn improves user experience.

Proper Utilisation of Bandwidth

When different types of traffic pass through the same data link, then it’s not possible to prioritize real time-sensitive traffic to gain maximum bandwidth. Both lower and higher priority traffic use the same type of bandwidth. MPLS can set priority on traffic as users need the maximum capacity of bandwidth when needed.

Minimize Network Complexity

MPLS can be configured as a Virtual Private LAN service which can hide all the hops between two connections and work as a single long ethernet connection.

Minimize Network Congestion

We know that the shortest path of the network reduces network congestion but what to do if the shortest path has congestion? MPLS has a traffic engineering mechanism that can choose a secondary connection for the time being to reduce the latency and it can avoid the congested connection with its secondary connection.

Is MPLS dead?

In 2013, Gartner made a prediction about MPLS with the question “Is MPLS Dead?” People are thinking that WAN is the main reason for MPLS dying. SD-WAN companies are claiming that SD-WAN is the main reason for this. But can SD-WAN really replace MPLS technology? The answer is no. SD-WAN is an overlying technology which has Quality of Service(QoS), advanced routing, software controlled management, lower service plan which create a virtual layer over physical layer whereas MPLS is an underlying technology which works in the physical layer of the network. As MPLS runs on Local private networks, it’s more secure and still works for most of the data centers and big corporates.

Although internet usage is increasing day by day, it does not mean that WAN is not necessary. There are lots of new technologies available which can work like MPLS and also can provide internet over the cloud with advanced features which can be named as Hybrid WAN models. Today, many Internet bonding solutions are providing this type of services.