lwIP

LwIP

Original author(s)	Adam Dunkels
Developer(s)	lwIP developers group
Stable release	1.4.1 / 17 December 2012
Development status	active
Written in	C
Operating system	multiple
Platform	embedded systems
Type	IP stack
License	Modified BSD license
Website	savannah.nongnu.org/projects/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 worldwide 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 Name System)
• 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

References

1. "Building Complex VDK/LwIP Applications Using Blackfin Processors ", Kaushal Sanghai, Analog Devices Inc. September 2008
2. Siva Velusamy, LightWeight IP (lwIP) Application Examples, Xilinx Inc. June 2009
3. (ed.), Yanwen Wu (2010). Software engineering and knowledge engineering : theory and practice. Berlin: Springer. p. 639. ISBN 978-3-642-03717-7.

External links

• Adam Dunkel's initial Lwip paper
• lwIP development
• lwIP documentation wiki
• lwIP functions documentation
• lwIP former homepage (obsolete)