dataforwarding

Data forwarding is the process by which a network device transfers a data unit from its input port to an appropriate output port. It is a core function of routers and switches, enabling packets or frames to move toward their destination. Forwarding is distinct from routing: routing determines the path through the network, while forwarding implements that path on each hop by selecting the correct output interface.

In IP networks, forwarding relies on a forwarding information base (FIB) or routing table that maps destination addresses to next-hop information and an output port. In Ethernet-based networks, switches use MAC address tables learned from traffic to decide on which port to forward a frame. Forwarding decisions are typically performed at high speed in the device’s forwarding plane, often with hardware acceleration.

Forwarding can be unicast (to a single destination), multicast (to multiple recipients), or broadcast (to all devices on a segment, subject to restrictions). Methods for moving data through the device include store-and-forward, where the entire packet/frame is received before forwarding; and cut-through (or fast-forward), where forwarding begins after reading enough header data to identify the output port. Some devices use adaptive switching that blends these approaches to reduce latency.

Modern networks separate the control plane (decision making) from the forwarding plane (packet processing). In software-defined networking (SDN) and similar architectures, forwarding rules can be installed and updated by centralized controllers. Network performance and security considerations for forwarding include latency, jitter, loss, QoS, and access control lists.