Final answer:
Packets are forwarded in an MPLS domain using a label specified for each packet, not via traditional IP routing methods. Label switching enables more efficient and flexible traffic management.
Step-by-step explanation:
Packets in an MPLS domain are forwarded using a number that has been specified in a label. MPLS stands for Multi-Protocol Label Switching, and unlike traditional IP routing which uses the destination IP address to make forwarding decisions, MPLS uses labels appended to packets.
These labels are short, fixed-length identifiers that dictate the forwarding path through the network. MPLS routers, known as label switch routers (LSRs), use these labels to move packets along a predefined 'Label Switched Path' (LSP).
The process works by assigning an incoming packet a label at the ingress of the MPLS network. Each router along the way swaps the packet's label with a new one that tells the next router how to forward the packet. This label swapping continues until the packet reaches the egress of the MPLS network, where the label is removed before the packet is sent to its final destination.
The use of labels enables MPLS networks to support traffic engineering and virtual private networks (VPNs), allowing for more efficient and flexible routing than is possible with traditional IP routing.