A forwarding pipeline is a series of processes within a network device that handles the examination, decision-making, and direction of data packets to their next destination. It is a crucial component that determines how data moves through a network, affecting speed, efficiency, and traffic management.
The forwarding pipeline is an integral part of network infrastructure, allowing routers, switches, and firewalls to efficiently process and direct the flow of data. It is composed of several stages that each packet traverses:
Packet Parsing: Examines packet headers to understand the content structure and prepare for processing.
Header Processing and Forwarding Decision: Uses the extracted header information to decide the packet's next hop based on routing or forwarding tables.
Traffic Classification: May sort packets into queues for priority handling based on policies or Quality of Service (QoS) rules.
Packet Modification: Adjusts packet headers or content, such as applying NAT or encryption, suitable for its journey.
Routing and Switching: Determines the packet’s path within the network, aligning with either IP addresses for routing or MAC addresses for switching.
Modern forwarding pipelines often employ hardware acceleration to handle high-speed processing and may use flow-based methods to group similar packets for more efficient handling. Security considerations are also embedded to safeguard the data as it moves through the network.