Xeta Group
(Multi-Protocol Label Switching)
Multi-protocol label switching (MPLS) is a way to ensure reliable connections for real-time applications, but it's expensive, leading enterprises to consider SD-WAN as a way to limit its use. The thing about MPLS is that it's a technique, not a service — so it can deliver anything from IP VPNs to metro Ethernet. It's expensive, so with the advent of SD-WAN enterprises are trying to figure out how to optimize its use vs. less expensive connections like the internet.

What Is MPLS And How
Does It Work?

What Is MPLS?
MPLS (Multiprotocol Label Switching) is a routing technique in telecommunications networks that directs data from one node to the next based on short path labels rather than long network addresses, thus avoiding complex lookups in a routing table and speeding traffic flows. The labels identify virtual links (paths) between distant nodes rather than endpoints. MPLS can encapsulate packets of various network protocols, hence the "multiprotocol" reference on its name. MPLS supports a range of access technologies, including DSL, T1, DS3, Ethernet Over Copper (EoC), Ethernet Over T1 or DS3, Ethernet Over Fiber (Metro Ethernet), and Ethernet Over Fixed Wireless. Other access technologies you may have heard of are 4G Cellular, Business-Class Cable and A-Synchronous Ethernet. Although these are all fantastic, inexpensive backup Internet access technologies for your MPLS connection, you won't find providers offering true MPLS over connections like these.

The beauty of MPLS is that it's not tied to any underlying technology. It was designed back in the days of ATM and frame relay as an overlay technique designed to simplify and improve performance -- that's the "multi-protocol" part. ATM and frame relay are distant memories, but MPLS lives on in carrier backbones and in enterprise networks. The most common use cases are branch offices, campus networks, metro Ethernet services and enterprises that need quality of service (QoS) for real-time applications.

How MPLS Works.
With MPLS, the first time a packet enters the network, it's assigned to a specific forwarding equivalence class (FEC), indicated by appending a short bit sequence (the label) to the packet. Each router in the network has a table indicating how to handle packets of a specific FEC type, so once the packet has entered the network, routers don't need to perform header analysis. Instead, subsequent routers use the label as an index into a table that provides them with a new FEC for that packet.

This gives the MPLS network the ability to handle packets with particular characteristics (such as coming from particular ports or carrying traffic of particular application types) in a consistent fashion. Packets carrying real-time traffic, such as voice or video, can easily be mapped to low-latency routes across the network — something that's challenging with conventional routing.

With MPLS, the first time a packet enters the network, it's assigned to a specific forwarding equivalence class (FEC), indicated by appending a short bit sequence (the label) to the packet. Each router in the network has a table indicating how to handle packets of a specific FEC type, so once the packet has entered the network, routers don't need to perform header analysis. Instead, subsequent routers use the label as an index into a table that provides them with a new FEC for that packet.
What Is MPLSHow It works
MLPLS Network
Is MPLS Layer 2 or Layer 3?
There's been a lot of confusion about whether MPLS is a Layer 2 or Layer 3 service. But MPLS doesn't fit neatly into the OSI seven-layer hierarchy, and is sometimes classified as Layer 2.5. In fact, one of the key benefits of MPLS is that it separates forwarding mechanisms from the underlying data-link service. In other words, MPLS can be used to create forwarding tables for any underlying protocol.

Specifically, MPLS routers establish a label-switched path (LSP), a predetermined path to route traffic in an MPLS network, based on the criteria in the FEC. It is only after an LSP has been established that MPLS forwarding can occur. LSPs are unidirectional which means that return traffic is sent over a different LSP. When an end user sends traffic into the MPLS network, an MPLS label is added by an ingress MPLS router that sits on the network edge. The MPLS Label consists of four sub-parts:

The Label: The label holds all of the information for the MPLS routers to determine where the packet should be forwarded.

Experimental: Experimental bits are used for Quality of Service (QoS) to set the priority that the labeled packet should have.

Bottom-of-Stack: The Bottom-of-Stack tells the MPLS Router if it is the last leg of the journey and there are no more labels to be concerned with. This usually means the router is an egress router.

Time-To-Live: This identifies how many hops the packet can make before it is discarded.

Is MPLS Dead?
That question was raised back in 2013 and answered itself by predicting that MPLS would continue to be a fundamental part of the WAN landscape, but that most enterprises would slowly transition to a hybrid environment consisting of both MPLS networks and the public Internet. MPLS will continue to have a role connecting specific point-to-point locations, like large regional offices, retail facilities with point of sale systems, regional manufacturing facilities, and multiple data centers. And it is required for real-time applications. But enterprise WAN architects need to make a risk/reward calculation between the top-notch but expensive performance of MPLS vs. the cheaper but less reliable performance of the Internet. Which brings us to an exciting new technology called SD-WAN.
Pros Of MPLS
Multiprotocol Label Switching or MPLS is very scalable when compared to other options. It has a very highly scalable mechanism. MPLS also ensures high-performance telecommunications that are required by most of the enterprise. Your IT team can easily maintain and optimize the MPLS network. You can potentially scale MPLS to hundreds of different sites.
MPLS has been a reliable technology for over a decade. It has served various enterprises for more than two decades now.
Bandwidth Utilization
The MPLS divides the traffic in various networks. Thus, the bandwidths of your network will automatically increase. You can transverse through the whole network in very little time.
Inter-connectivity Growth
You can connect MPLS to all your networks without buying new hardware. MPLS requires a minimal amount of hardware to connect all your networks.
Remote Connections
The best thing about MPLS is that you can add new remote connections without buying any new hardware. Thus, you can save a lot of your money. MPLS is fully cloud-hosted. Thus, MPLS doesn't require any point to point connectivity.
Improved Up-time
MPLS provides various alternate network paths to a request. Thus, the up-time of your network will automatically improve.
Reduced Traffic Congestion
If you are using old frame-relay networks then you must suffer from high traffic congestions. MPLS divides the requests in various network paths. Thus, it helps in avoiding high traffic congestion.
Traffic Routing
This is one of the best features of MPLS. MPLS works by adding labels on data packets when they are leaving the customer network. In normal technology, the network will read the IP header information to read its element. But, MPLS will directly check the MPLS label to predetermine the network path. This helps in improving the reliability of MPLS. It becomes very easy to predict the traffic of a network. The Label Switched Paths or LSPs are already predetermined. The data packets will travel on the paths which are already pre-determined. This is very different from IP routing where the path of the packet can differ according to the network conditions.
Service Level Agreements
Multiprotocol Label Switching or MPLS services are delivered with Service-level Agreements or SLAs. These SLAs contain various points like guaranteed delivery
Better End-user Experience
MPLS helps in improving the end-user experience. You can choose from different types of services like VoIP. Provides a quality connection that offers a consistent user experience with no packet loss, fixed latency, and low jitter.
Cons Of MPLS
MPLS is also expensive when compared to options like Ethernet. But, it still costs less than technology like T1 lines. MPLS also requires WAN optimization for streamlining its delivery. This will add extra costs on top of the old cost. The cost is high because of limited competition in the marketplace
Network Control
The worst thing about MPLS is that you won't have complete control over your network. Your service provider will configure all the networks. You will only help your provider in dynamic routing.
Cloud Applications
MPLS is optimized for point-to-point connectivity only. They are not perfect for cloud users. You can't directly access your SaaS or cloud application with MPLS. There are very few cloud services in the market that provide this service. But, you have to pay a hefty price to get this service.
If your offices are situated in different countries or states, then MPLS will take a long time to deploy. It can even take more than 6 months to connect all your offices
Flexibility & Scalability
Slow to scale, modifications to infrastructure may take weeks of waiting.


If you listen to the hype, cheap, flexible SD-WAN is going to wipe out MPLS, the slow-footed dinosaur. But, in fact, both technologies have a role to play in modern WANS. SD-WAN is the application of Software Defined Networking (SDN) concepts to the WAN. This means the deployment of SD-WAN edge devices that apply rules and policies to send traffic along the best path. SD-WAN is a transport-agnostic overlay that can route any type of traffic – including MPLS. The advantage of SD-WAN is that an enterprise WAN-traffic architect can sit at a central point and easily apply policies across all WAN devices.

By contrast, with MPLS predetermined routes need to be painstakingly provisioned and once the fixed circuits are up, making changes is not a point-and-click exercise. But once an MPLS network is deployed, it delivers guaranteed performance for real-time traffic. SD-WAN can route traffic along the most efficient path, but once those IP packets hit the open Internet, there are no performance guarantees.

The most sensible strategy going forward will be to offload as much MPLS traffic as possible to the public Internet, but continue to use MPLS for time-sensitive applications that require guaranteed delivery. Nobody wants to get caught in the cross-hairs when the CEO's monthly videoconference with branch office employees drops off mid-sentence.

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