What operation does an iLER perform when it receives a packet?

The operation performed by an iLER (Ingress Label Edge Router) upon receiving a packet that is labeled involves pushing a new MPLS label onto the packet before forwarding it to the next Label Switching Router (LSR). This is a key part of the MPLS (Multiprotocol Label Switching) protocol, where the ingress router adds (or "pushes") a label to outbound packets to facilitate efficient and fast forwarding through the network.

The iLER is responsible for determining the appropriate label based on its forwarding table, which typically takes into account the destination of the packet as well as other criteria. By pushing a new MPLS label, the data packet gets a new identity that allows subsequent LSRs in the MPLS path to forward the packet based on this label, rather than requiring a deeper examination of the packet contents itself.

This process enhances network efficiency by reducing the need for every router along the path to perform complex route look-ups for each packet. Instead, they can simply read the MPLS labels to determine how to route the packets.

Other operations like swapping, forwarding unchanged, or popping the label are performed by different types of MPLS routers along the path, which is why they do not align with what an iLER does. The i