P4 (Programming Protocol-independent Packet Processors)

💡 The Core Idea

P4 is a language that allows the controller to redefine how a switch parses and processes packets. Unlike OpenFlow, which relies on fixed tables and protocols, P4 makes the hardware Protocol Independent.

🧠 Key Goals

1. Reconfigurability: The controller can change how the switch parses packets (e.g., defining a new header type on the fly).
2. Protocol Independence: The switch isn’t hardcoded for IP or Ethernet. The controller defines the format.
3. Target Independence: The same P4 program can be compiled to run on different hardware (ASIC, FPGA, Software Switch).

⚙️ Workflow

• Configure: Program the parser to recognize specific headers.
• Populate: Add entries to the Match+Action tables to define policies.

🔗 Connections

• Source: Source - SDN Part 2 and Applications