MPLS for Beginners – A Simplified Explanation for Non-Technical Audiences

Multi-Protocol Label Switching (MPLS) is a tried and true networking technology that speeds up data flow by eliminating the need to look up complex routing tables at each network router. Instead, packets are routed along predetermined pathways based on a unique identifier.

Operating at OSI Layer 2.5, between the data link and network layers, MPLS is designed to converge traffic and enable QoS metrics while allowing for automatic failover during an outage.

What is MPLS?

MPLS is a packet-labeling technique that prioritizes data types and reduces network congestion. Rather than routing each packet of data to its destination IP address at the layer 2 (data link) switching level, it sends them on a predetermined path based on labels. This means routers do not have to spend time crawling through the information in each packet to determine its destination – much like looking inside every letter and package at the post office when sending mail.

Each packet is given a label when it enters an MPLS network through a label edge router (LER). The LER assigns the packet to a specific forwarding equivalence class based on its type and destination. Once the packet has been assigned a label, it is encapsulated in an LSP and then passed on to other routers throughout the MPLS domain.

The other routers on the path know that a specific label is associated with a particular destination prefix – they have a list of such associations in a label information base (LIB) database. When a packet arrives at a router with an LSP matching its label, it simply removes the label and then routes the packet to its final destination as usual. This process is much faster than traditional routing because it bypasses the need to examine the entire packet and its source and destination address to determine how it should be routed.

The Process

How does MPLS works? Each packet gets a data label predetermining its destination path in MPLS networks. The first router to intercept the packet will attach the label, and then other devices can read it to know where to send the packet next without conducting an IP lookup. This process speeds up data transfer because it removes the delay caused by the need to determine the best route for the packet.

Another feature of MPLS is traffic shaping. This allows network administrators to prioritize different types of data, which improves performance and helps keep employees productive. For example, you can limit employee web browsing to reduce bandwidth consumption and protect your organization from malware that could harm your business.

Finally, MPLS networks offer scalability, which makes it easy for businesses to connect new locations quickly and efficiently. This can be important for companies with multiple office locations that need to share files and applications simultaneously.

MPLS also offers several other benefits, including reduced expenses and improved productivity. 

What are the Benefits of MPLS?

When MPLS first came onto the market two decades ago, organizations welcomed it as a way to connect remote offices to their primary data centers and support real-time traffic like video conferencing. Today, those same organizations are wrestling with whether to keep MPLS or move away from it toward more agile and flexible options such as SD-WAN and VPNs running over commodity broadband.

When MPLS is deployed, each packet has metadata appended to it in labels containing a 32-bit value, a time-to-live field, and a stack bit that indicates relative quality of service (QoS). MPLS routers look up these labels at every hop to determine if the packet is being rerouted and to create a predetermined path to the final destination. This provides scalability, high performance, better bandwidth utilization, and reduced network traffic congestion for a better end-user experience.

In addition, consistent network performance across locations helps to boost productivity and reduce the need for support calls. This can also reduce the money required to maintain and manage the infrastructure. Finally, an MPLS VPN protects the data from unauthorized users as it is isolated from the public Internet, making it a secure transport mode. One drawback of MPLS is that it needs to provide encryption, which is an issue that is becoming increasingly important as more organizations move their applications and data to the cloud.

What are the Drawbacks of MPLS?

While MPLS provides several advantages, it can be expensive and complicated to set up. The dedicated paths needed by an organization can also slow down network connections. Lastly, it does not encrypt traffic, which can be problematic as organizations increasingly rely on cloud applications. This has given rise to newer, more agile alternatives like SD-WAN.

An advantage of using MPLS is data delivery’s excellent reliability and predictability compared to traditional IP routing. Instead of performing a hop-by-hop route lookup, MPLS determines the complete path to a destination and appends that information to packets. This allows routers to decide on the best path for each packet. This helps to eliminate network congestion and reduce latency.

In addition, using MPLS can help improve the performance of certain types of data. Organizations can prioritize specific data and provide high-quality service (QoS) by applying specific labels to each packet. This can be useful for streaming videos or saving retail customers who use point-of-sale systems time as they dial in to make credit card payments.

However, using MPLS can be challenging for organizations not used to operating with transport networks. This type of networking uses a command line interface (CLI) for all its provisioning and troubleshooting, which can be challenging for network engineers who are used to point-and-click/GUI-based tools.