lwIP

lwIP (lightweight IP) is a widely used open source TCP/IP stack designed for embedded systems. lwIP was originally developed by Adam Dunkels at the Swedish Institute of Computer Science and is now developed and maintained by a world wide network of developers.

lwIP is used by many manufacturers of embedded systems. Examples include Altera (in the Nios II operating system), Analog Devices (for the Blackfin DSP chip),^[1] Xilinx,^[2] Honeywell (for some of their FAA certified avionics systems) and Freescale Semiconductor (Ethernet Streaming SW for Automotive microcontrollers).

The focus of the lwIP TCP/IP implementation is to reduce resource usage while still having a full-scale TCP.^[3] This makes lwIP suitable for use in embedded systems with tens of kilobytes of free RAM and room for around 40 kilobytes of code ROM.

lwIP features

Internet layer

• IP (Internet Protocol) including packet forwarding over multiple network interfaces
• ICMP (Internet Control Message Protocol) for network maintenance and debugging
• IGMP (Internet Group Management Protocol) for multicast traffic management

Transport layer

• UDP (User Datagram Protocol) including experimental UDP-lite extensions
• TCP (Transmission Control Protocol) with congestion control, RTT estimation and fast recovery/fast retransmit

Application layer

• DNS (Domain names resolver)
• SNMP (Simple Network Management Protocol)
• DHCP (Dynamic Host Configuration Protocol)

Link layer

• PPP (Point-to-Point Protocol)
• ARP (Address Resolution Protocol) for Ethernet

Other

• Specialized raw/native API for enhanced performance
• Optional Berkeley-like socket API
• AUTOIP / Link-local address (for IPv4, conforms with RFC 3927)

See also

• uIP
• embedded IPsec (basic IPsec protocol implementation based on lwIP)

References

External links

• lwIP development
• lwIP documentation wiki
• lwIP functions documentation
• lwIP former homepage (obsolete)