Did you ever track the package of the product you ordered online from a distant retailer?
Maybe and may not be.
Let me share a short story to understand MPLS technology.
Suppose, you want to buy something online.
For this, you place an order. When your item is packed and shipped to your address, the merchant provides you an assignment number to track your order.
When you track the item, you only find the name of the place where your item has reached.
You are not provided with any other information except the destination’s name. You also don’t know how your product is being handled on its way to the destination. Anyway, you receive your item on time, most probably.
Now, let me come to the MPLS technology.
The same logic is applied to the IP routing in the internet world.
When an internet router receives an IP packet (like the e-commerce company receives your order), the router cannot find any information about the IP packet except a destination IP address.
There is no way out to get the information about how that packet will reach its destination or how it will be treated along the way.
Each router makes its own decision for each packet, based on the packet’s network-layer header. So, every time a packet reaches a router, the router thinks where the packet needs to be sent the next. This process is repeated at each hop along with the route until the packet finally reaches its destination.
But, all these performances are made by using sophisticated and complex routing tables. And in most cases, all the hops and individual routing decisions may lead to adverse performance for time-sensitive applications, especially voice over IP (VoIP) or video-conferencing.
That’s where the importance of MPLS technology is realized.
What is MPLS?
Multiprotocol Label Switching (MPLS) is a protocol. It addresses the of poor network performance by founding pre-determined and highly efficient routes. It speeds up and shapes network traffic flows by assigning specific forwarding equivalence class (FEC) to a packet when it enters the network.
MPLS link lets most packets get forwarded at the switching level (at Layer 2) rather than the routing level (Layer 3). Each router in the network is equipped with a table that indicates the way how to handle packets of a specific FEC type.
Therefore, once the packet enters the network, routers don’t need to perform header analysis. Instead, there are subsequent routers that use the label as an index into a table. The table further provides them with a new FEC for that packet.
Is MPLS Considered Layer 2 or Layer 3?
It’s a very important question as most of the executive networking professionals are confused whether the MPLS is a Layer 2 or Layer 3 service. But, MPLS doesn’t suit the Open System Interconnection (OSI) seven-layer hierarchy.
Instead, it can be used to create forwarding tables for any underlying protocol. In other words, we can say that MPLS is a technology to separate forwarding mechanisms from the underlying data-link service.
To be very honest, MPLS routers are technologically innovative and have the features to establish a label-switched path (LSP), which is a pre-defined path to route traffic in an MPLS network. MPLS forwarding occurs when the LSP is established successfully.
One key benefit of LSP is that it is unidirectional, so it diverts the direction of return traffic over a different LSP. When your networking engineer sends traffic into the MPLS network, an MPLS label is created by an ingress MPLS router, which is available on the network edge.
When discussed about the MPLS Label, it comprises four sub-parts:
Experimental: Experimental is used for enhancing QoS (Quality of Service). It enables you to prioritize the labeled packet like which packet should reach the destination earlier.
The Label: It’s a part of MPLS, holding every piece of information for the MPLS routers. Using the information, the routers determine the destination where the packet should be forwarded.
Time-To-Live: This refers to discard hops and packets by enabling you to determine the number of hops should be removed.
Bottom-of-Stack: Being one of the sub-parts of the MPLS technology, the Bottom-of-Stack lets the MPLS router know whether it is the last leg of the journey. No labels are left to connect with. This, generally, shows that the router is an egress router.
In this high-tech world where smooth communication and faster network speed is required with greater flexibility and scale-up and scale-down facility, MPLS has come to the top of the world. When you implement it within your organization, you can enjoy scalability, better bandwidth utilization, performance, lower network congestion and better end-user experience.