perpacket

Perpacket is a term used in networking and computer engineering to describe the processing or handling of data on a per-packet basis. It contrasts with approaches that aggregate work by flow, connection, or session, such as per-flow processing, where decisions are made based on a stream of packets tied to a single conversation. In perpacket mode, each individual packet is examined and acted upon according to its own headers and metadata, enabling fine-grained control and policy enforcement.

Common applications include packet filtering and stateful firewalling, where rules are evaluated per packet; deep packet inspection for security and compliance; perpacket encryption or encapsulation where each packet is independently processed; and per-packet accounting or QoS tagging used for fine-grained bandwidth management. Perpacket processing is essential in scenarios requiring immediate reaction to events that can occur within a single packet, such as anti-spoofing checks, NAT translations, or IPsec framing decisions.

Performance considerations: perpacket processing introduces overhead because actions must be taken for every packet, often increasing latency and reducing throughput if unoptimized. Modern network devices mitigate this with hardware acceleration, specialized ASICs, multi-core parallelism, and packet batching strategies that preserve perpacket correctness while improving efficiency.

Historically, early routers and security devices commonly employed perpacket workflows, while newer architectures blend perpacket with per-flow techniques to balance precision and performance.

See also: per-flow, per-connection, packet inspection, network security, NAT, QoS.