What is MPLS, and why isn’t it dead yet?
Did you ever order something online from a distant retailer and then track the package as it makes strange and seemingly illogical stops all over the country?
That’s similar to the way IP routing on the Internet works. When an internet router receives an IP packet, that packet carries no information beyond a destination IP address. There is no instruction on how that packet should get to its destination or how it should be treated along the way.
Each router has to make an independent forwarding decision for each packet based solely on the packet’s network-layer header. Thus, every time a packet arrives at a router, the router has to “think through” where to send the packet next. The router does this by referring to complex routing tables.