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MPLS -A Cram Guide

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MPLS stands for Multiprotocol Label Switching, which is a technique used in computer networking to improve the speed and efficiency of data transfer. MPLS works by attaching a label to each data packet that identifies the packet’s destination and priority level.

When a packet enters an MPLS network, it is assigned a label that is used to route the packet through the network. This label-based routing is much faster than traditional IP-based routing because it does not require each router along the way to inspect the packet’s header and make a forwarding decision based on the destination IP address.

MPLS is commonly used by Internet Service Providers (ISPs) to provide Virtual Private Network (VPN) services to their customers. MPLS VPNs allow multiple customers to share a single physical network infrastructure while maintaining the privacy and security of their data.

MPLS also supports Quality of Service (QoS) features, which allow network administrators to prioritize certain types of traffic (such as voice or video) over others to ensure that critical applications receive the necessary bandwidth and low latency to function properly. This article covers detailed knowledge of  Multiprotocol Label Switching (MPLS).


Types of MPLS

Several types of MPLS (Multiprotocol Label Switching) are used in different network environments. Here are a few of the most common types:

  • MPLS Layer 3 VPN (L3VPN): This is the most common type of MPLS for connecting multiple sites or users via a Virtual Private Network (VPN). L3VPNs provide secure, private connections over a shared network infrastructure and are typically used by enterprises to connect remote offices, data centers, and cloud environments.
  • MPLS Layer 2 VPN (L2VPN): This type of MPLS connects multiple sites over a Layer 2 (Ethernet) network. L2VPNs provide a transparent connection between sites, allowing them to appear as if they are on the same local network. Service providers typically use L2VPNs to offer Ethernet services to their customers.
  • MPLS Traffic Engineering (MPLS-TE): This type of MPLS is used to optimize network performance and reduce latency by directing traffic along predetermined paths. MPLS-TE allows network operators to manage congestion and improve QoS by prioritizing traffic and balancing network loads.
  • MPLS Quality of Service (MPLS-QoS): This type of MPLS prioritizes traffic based on its label, ensuring that critical applications receive the necessary bandwidth and priority. MPLS-QoS is typically used in enterprise networks to ensure the quality of voice, video, and other real-time applications.
  • MPLS Multicast VPN (MVPN): This type of MPLS distributes multicast traffic across a VPN. MVPN allows network operators to optimize network performance and reduce bandwidth usage by sending multicast traffic only to the intended recipients.
  • MPLS Layer 2 Tunneling Protocol (L2TPv3): This type creates a secure tunnel over a Layer 2 network. L2TPv3 allows network operators to connect remote sites or users over an existing Layer 2 infrastructure.

What are the Components of an MPLS Network?

An MPLS network typically consists of the following components:

  • Provider Edge (PE) Routers: These are the routers that connect customer sites to the MPLS network. They are responsible for adding and removing labels from packets entering and exiting the network.
  • Provider (P) Routers: These core routers within the MPLS network forward packets based on their labels. They do not participate in routing protocols; their only function is forwarding packets based on label information.
  • Label Distribution Protocol (LDP): This protocol is used by MPLS routers to exchange label information with each other. It ensures that each router has a consistent view of the labels being used within the network.
  • Routing Protocols: MPLS networks often use standard routing protocols, such as OSPF or BGP, to determine the best path for traffic within the network.
  • Control Plane: The control plane manages the configuration and operation of the MPLS network. It handles label distribution, routing protocol exchanges, and network management functions.
  • Data Plane: The data plane is responsible for forwarding packets within the MPLS network. It uses labels to determine the path that packets should take through the network.
  • Virtual Private Networks (VPNs): MPLS networks can be used to create VPNs, which provide secure, private connections between different sites. VPNs can connect different branches of a company, for example, or provide remote access for employees.

MPLS Routing Terminologies

Label edge routers (LERs) – Edge cutters with labels. When an LSR is labeled the first or last router in a network, LERs are the ingress or egress routers or nodes. LSRs mark incoming data (the ingress node) or pop the label off the packet.


Label-switched Ports (LSPs) – LSPs are the paths through which packets are directed. An LSP enables service providers to determine the best method to route specific types of traffic within a private or public network.

Label switch routers (LSRs) – LSRs read the labels and transmit labeled data along predetermined pathways. If a packet data link needs to be corrected, intermediate LSRs are accessible.

Pop – This mechanism is typically done by the egress router, removing a label.

Push – This mechanism, which adds a label, is usually done by the ingress router.

Swap – This mechanism replaces labels and is typically done by LSRs between ingress and egress routers.

How Does MPLS Work?

MPLS works by adding a label to each packet as it enters the network. This label is used to forward the packet through the network based on predetermined paths rather than being routed on a hop-by-hop basis. Here’s a simplified step-by-step breakdown of how MPLS works:

  • A packet enters the MPLS network at the Provider Edge (PE) router.
  • The PE router adds a label to the packet based on the packet’s destination address.
  • The label contains information about the path that the packet should take through the network. This path is predetermined based on the network topology and is known as the Label Switched Path (LSP).
  • The packet is forwarded to the first Provider (P) router, which reads the label and forwards the packet to the next router in the path.
  • Each P router along the LSP reads the label and forwards the packet to the next router in the path until the packet reaches the destination PE router.
  • The destination PE router removes the label from the packet and forwards it to its intended recipient.
  • MPLS also supports Quality of Service (QoS) by allowing routers to prioritize packets based on their label. This allows for better network traffic management and ensures critical applications, such as voice and video, receive the necessary bandwidth and priority.

What are the Benefits of MPLS?

MPLS (Multiprotocol Label Switching) provides several benefits over traditional IP-based routing:

  • Faster Packet Forwarding: MPLS uses labels to forward packets through the network, which speeds up packet processing and reduces network congestion.
  • Improved Network Performance: MPLS allows for better traffic engineering, which can help optimize network performance and reduce latency.
  • Quality of Service (QoS) Support: MPLS supports QoS, allowing for better network traffic management and prioritization of critical applications.
  • Scalability: MPLS is highly scalable and can handle large amounts of network traffic without affecting performance.
  • Security: MPLS can be used to create Virtual Private Networks (VPNs), which provide secure, private connections between different sites or users.
  • Simplified Network Management: MPLS provides a centralized control plane, simplifying network management and reducing the risk of configuration errors.

Challenges of MPLS

While MPLS (Multiprotocol Label Switching) provides several benefits, it also presents several challenges that must be addressed:

  • Complexity: MPLS is a complex technology that requires specialized skills and knowledge to design, implement, and manage. This can lead to higher costs and long deployment times.
  • Cost: MPLS can be expensive, particularly for small and mid-sized businesses, due to the need for specialized equipment and dedicated network resources.
  • Vendor lock-in: MPLS is typically implemented by service providers, which can lead to vendor lock-in and limit the ability of organizations to switch providers or change network configurations.
  • Lack of Standardization: While MPLS is an industry standard, different vendors and service providers have variations in how it is implemented, which can lead to interoperability issues.
  • Security Concerns: While MPLS can be used to create VPNs, it is not inherently secure and must be configured and managed appropriately to ensure data privacy and protection.
  • Limited Support for New Technologies: MPLS is a mature technology and may not support newer network technologies or protocols, such as Software-Defined Networking (SDN) or IPv6, without additional configuration or upgrades.
  • Limited Visibility: MPLS makes packet forwarding more efficient by reducing the number of hops. However, this can also limit visibility into network traffic and make it more difficult to troubleshoot issues.

When is MPLS used?

When speed and dependability are critical, MPLS can be used. Real-time applications are those that demand near-instant data delivery. Voice and video calls are two typical instances of real-time applications.

MPLS can also be used to create wide-area networks. (WANs). However, as previously stated, MPLS-based WANs are costly and challenging to scale up. Cloudflare Magic WAN replaces these MPLS connections with a cloud-based network that is simple to set up and does not depend on expensive hardware appliances.



SD-WAN is a solution that allows end-to-end enterprise connectivity across vast geographical distances. It combines the flexibility and economics of multiple WAN links, including MPLS, wireless, broadband, Virtual Private Networks (VPNs), and the internet, to give users in remote offices access to corporate apps, cloud services, and workloads, enabling them to work from anywhere. SD-WAN monitors the performance of WAN connections and intelligently manages traffic based on these metrics to maintain high speeds and optimize connectivity. SD-WANs provide businesses with agility and cost savings when compared to an MPLS infrastructure, which is expensive and difficult to change. Centralized administration, which is frequently cloud-managed, simplifies configuring and provisioning networks at scale and speed, significantly reducing operational complexity.


MPLS Networks and the Cloud

When businesses migrate to the cloud, the MPLS-based hub-and-spoke model becomes inefficient because it routes traffic through corporate offices (hubs), which serve as central choke points. It is more efficient to transmit traffic straight to the cloud. Furthermore, the increased use of cloud services, video, and mobile apps has raised bandwidth requirements, and MPLS services are difficult to scale on demand.

MPLS was a great innovation at the time, but there are newer technologies that better handle today’s network architectures. SD-WAN is designed with cloud connectivity in mind. Therefore, many companies have replaced or supplemented their MPLS networks with SD-WAN.



MPLS is a powerful technology that provides several benefits over traditional IP-based routing, including faster packet forwarding, improved network performance, QoS support, scalability, security, and flexibility.

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