P4

P4 is a domain-specific language for programming packet processing devices, allowing developers to specify how packets are parsed, matched, and forwarded independently of underlying hardware and protocols.

P4 programs define header parsing, table matching criteria, actions, and forwarding logic that can be compiled to hardware targets like ASICs, FPGAs, or software switches.

Standardized by the P4 Language Consortium, it enables protocol agility, vendor neutrality, and integration with SDN controllers to create programmable, high-performance network data planes.