packetbypacket

Packetbypacket is a term used to describe an approach to processing network traffic in which decisions are made on an individual packet basis. In this paradigm, each incoming or outgoing packet is examined and acted upon independently, rather than grouping traffic into flows, sessions, or aggregated statistics.

This per-packet processing can occur in software on general-purpose servers, in network devices equipped with specialized hardware, or in programmable data planes. It is common in security devices such as firewalls and intrusion detection systems, but also used for quality of service, rate limiting, and detailed traffic measurement.

Key techniques include packet inspection, header and payload classification, and rule-based forwarding or dropping. Stateless per-packet processing handles packets independently, while stateful variants maintain context across packets to enforce more complex policies.

Benefits include fine-grained control and visibility, immediate enforcement for each packet, and compatibility with diverse protocols. The main drawbacks are higher computational overhead, potential latency, and scalability challenges. To mitigate these, implementations may use hardware acceleration, parallel processing, and selective sampling or batching at the edge.

The concept is related to packet switching, deep packet inspection, and programmable data planes such as P4, which enable per-packet decisions at line rate. It is frequently contrasted with flow-based processing, which groups traffic into flows for scalable analysis.