Which component of the Nokia 7750 SR is in charge of performing the longest prefix match lookup on packets that arrive on the physical interfaces?

The Input/Output Module (IOM) is the hardware component responsible for data plane processing in the Nokia 7750 SR. It contains the Forwarding Plane (FP) chipset, which houses the Forwarding Information Base (FIB). When a packet arrives at a Media Dependent Adapter (MDA), it is passed to the IOM. The FP on the IOM performs the longest prefix match lookup against the FIB to determine the packet's next hop and egress interface. This architecture allows for high-speed, line-rate packet forwarding, decoupled from the control plane.

A. The Control Processing Module (CMP) runs the control plane, building the routing tables (RIB), but does not perform the per-packet forwarding lookups.
B. The Media Dependent Adapter (MDA) provides the physical interfaces and handles Layer 1/2 functions, passing packets to the IOM for forwarding decisions.
C. The Switch Fabric (SF) is a high-speed backplane that interconnects IOMs, switching packets between them after the forwarding decision has been made.

1. Nokia Corporation. (2021). 7750 SR OS Basic System Configuration Guide, Release 21.5.R1. Document ID: DC21050039. Section: "System Overview > Hardware Components > IOM". This section details the IOM's role as the forwarding plane engine.

2. Nokia Corporation. (2020). Nokia 7750 Service Router Portfolio for Evolving Edge Networks Data Sheet. This document describes the hardware architecture, stating that the FP silicon on the IOMs provides the packet processing and forwarding capabilities.