What MPLS function should be performed by a router that receives a data packet containing an MPLS label value of 3?
What MPLS function should be performed by a router that receives a data packet containing an MPLS label value of 3?
When a router receives a data packet containing an MPLS label value of 3, it should perform the action of popping the label. The label value of 3 is designated as the implicit null label, which signals the last hop (or the penultimate hop) of the Label Switched Path (LSP) to remove the label before forwarding the packet to the final destination. This process is known as Penultimate Hop Popping (PHP). Therefore, the correct action for the router is to pop the label.
Label Value: 3 Implicit Null — Used by the last hop (tail) node of the LSP to signal the Penultimate Hop Popping (PHP) behavior. When the LSP’s penultimate hop (second to last hop) receives a label mapping of 3, it will not put the label value into the MPSL packets to send to the tail node. Instead, the penultimate hop router pops up the label for the tail node. An MPLS data packet ingress to a node with label value 3 should never exist.
So the answer is "C"
So the answer is "C" - The label 3 ir related to the implicit null label