Which Label Operation Is Performed by an MPLS Ingress Router?

B

In the context of MPLS (Multiprotocol Label Switching) networks, the ingress router is the router that receives IP packets and initiates the MPLS label-switching process.

The MPLS ingress router performs the label operation known as "pushing" the label. This means that it adds a label to the IP packet before forwarding it into the MPLS network.

Here's how the MPLS label-switching process works:

1. The ingress router receives an IP packet from a customer network.
2. The ingress router assigns a label to the packet and pushes the label onto the packet.
3. The packet is then forwarded into the MPLS network, with the label used to determine the next hop for the packet.
4. When the packet reaches an egress router, the egress router "pops" the label off the packet and forwards the IP packet to its final destination.

In summary, the label operation performed by an MPLS ingress router is to "push" a label onto an IP packet before forwarding it into the MPLS network.