MPLS: Making it simple
MPLS or Multi-Protocol Label Switching is a layer 2.5 label-based forwarding technique used to route traffic unto the network. During an MPLS packet forwarding, A 32-bit long label is injected in between the data-link and the network layer of the OSI protocol stack.
MPLS addresses the issue on the router overhead caused by the traditional IP routing. In order to reduce the router's processing time, MPLS uses a label to forward packets instead of forwarding packets based on IP address. This approach greatly increase the performance of the router. Advantage of using label switching is speed since it is not doing any IP look-up and is only basing its route using the label. Furthermore, we can also tunnel different traffic such as IPv6 into the MPLS network since due to the fact that this technology is using only labels to forward packets.
Each router in the MPLS network will tend to generate its own local label and assigns it to every network inside their routing table. Those labels will also get to be advertised to other routers in the MPLS network by the Label Distribution Protocol (LDP).
The path being used by the fully enabled MPLS network is called Label Switched Path (LSP). All the participating router in the MPLS that forward packets based on label is called Label Switch Router (LSR).
There are Three types of router under the MPLS network, they are the Provider Edge (PE), Customer Edge (CE) and Provider (P). PE is defined as the router on the MPLS network that is connecting to the customer router. CE is the router from the customer's location that will communicate to the PE. P are the routers that doesn't need to communicate to the customer.
On our network topology:
P routers are MPLS-R1 to MPLS-R5.
PE routers are PE-LocationA, PE-LocationB and PE-LocationC
CE routers are AAA/BBB at Location A, AAA/BBB at Location B and AAA/BBB at Location C
