What is MPLS?

MPLS (Multi-Protocol Label Switching)

What is MPLS?

What is MPLS? MPLS (Multiprotocol Label Switching) is a technology and protocol for transmitting data between two or more locations.  It operates much like a switch and router does that currently exists on your business network.  In fact, on the OSI Model, MPLS sits between layers 2 and 3; between the switching and routing layers.  It is often considered to be layer 2.5.

Now that the technical overview is out of the way, let’s try to break it up into easier to understand chunks – and see if maybe an MPLS solution is right for your business.

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Traditonal Packet Switched Network

Quick Overview and Review

An IP based, packet switched, network is most likely what you’re currently using to view this very website.  When you visited us at onevoiceinc.com, our servers sent our website, one data packet at a time, to your computer.  These data packets crossed the internet hopping from Router to Router, across the country, until it got to the router that your business is connected to.  Most likely, your router then sent this packet to a Switch, which then sent the packet directly to your computer.  Your computer took all of the packets and recreated our webpage that you are viewing right now in your browser.

The drawback to a traditional IP based network is that each packet only has a destination IP address on it.  It doesn’t say anything about how that packet should get to the final destination, or how it should be treated along the way.  So in theory, this website packet could have bounced from Virginia, to Utah, to Colorado, to Florida, California, and then finally to wherever you are in the world.  Addtionally, all packets are treated the same – a voice call/web conference is treated with the same priority as a facebook message.  This can be a drawback for your organization when you need voice traffic to take priority over all other data coming into and leaving your network.

That’s where an MPLS Network changes things – by knowing exactly the path each packet should take, and how it should be treated from all other packets.

MPLS and the IP Network

Where does MPLS fit on the IP Network?

There are multiple ways to implement an MPLS network, but you can sort of think about it like a private internet for your company that uses routers designed to read MPLS labels.

An MPLS network router takes that same packet from earlier, applies an MPLS Label to it (more on this later), and sends that packet from MPLS router to MPLS router on a predetermined route based on the label.


Each of your multiple locations are connected to a private network using the MPLS Protocol – allowing your organization to send data to and from each location that is on the same MPLS network.  In addition, your carrier can help you setup priority for different packet types across this network – so if you need SIP Voice Packets to have the top priority across your private MPLS Network, you can arrange to have this done.

What is an MPLS Label?

An MPLS label is added by an ingress MPLS Router (A router that sits on the edge of an MPLS network, allowing traffic into the network).

The MPLS Label consists of 4 parts:

  1. Label
  2. Experimental (EXP)
  3. Bottom-of-Stack (S)
  4. Time-To-Live (TTL)



The label holds all of the information for the MPLS Routers to determine where on the network the packet should be forwarded to next.



The Experimental bits on the label are primarily used for Quality of Service (QoS) to determine the priority that the labeled packet should have on the MPLS Network.  This is great for networks that are transmitting live audio/video so those packets can get priority over regular data.



The Bottom-Of-Stack tells the MPLS Router if it is the last leg of the journey by telling it that the current label is at the bottom of the stack, and there are no more labels to be concerned with.  This usually means the current MPLS Router is an Egress Router, used specifically to forward the packet to a non-MPLS Router.



The Time-To-Live field is used for how many hops the packet can make before it should be discarded.

Is MPLS more secure?

Security is often a concern when it comes to an enterprise’s data and voice network.  If you have noticed so far, an MPLS Network only adds a label to an existing packet – and nothing more.  There is no additional encryption nor security embedded in this label.  People think that an MPLS is generally more secure than the public internet because it’s not accessible unless you have a router with access to that MPLS network.  However, it’s not completely impossible for a computer to get access to the network and to fool the network into believing it’s a node that should be receiving traffic.  However, without extensive knowledge of that network and physical access to it, it’s going to be quite a bit harder to intercept packets than on the open internet.

Some MPLS networks integrate VPN connections for added encryption and security – be sure to ask your service provider if their MPLS provides any additional security/encryption for your packets on their network.

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