01. MPLS Labels and Devices

MPLS header is in between the Ethernet and IP header. That’s why we call it a “layer 2.5” protocol.
CE (Customer Edge) = Customer network device
PE (Provider Edge) = LER (Label Edge Router)
P (Provider) = LSR (Label Switch Router) or transit router

There are three actions we can perform with labels:

Label push: when we add a label to a packet, we call it a label push.
Label swap: replacing a label with another value is called a label swap.
Label pop: removing the label is called a label pop. ( penultimate hop popping)

Reference : Network Lessons