INTRODUCTIONlwIP is a small independent implementation of the TCP/IP protocolsuite that has been developed by Adam Dunkels at the Computer andNetworks Architectures (CNA) lab at the Swedish Institute of ComputerScience (SICS).The focus of the lwIP TCP/IP implementation is to reduce the RAM usagewhile still having a full scale TCP. This making lwIP suitable for usein embedded systems with tenths of kilobytes of free RAM and room foraround 40 kilobytes of code ROM.FEATURES * IP (Internet Protocol) including packet forwarding over multiple   network interfaces * ICMP (Internet Control Message Protocol) for network maintenance   and debugging * UDP (User Datagram Protocol) including experimental UDP-lite   extensions * TCP (Transmission Control Protocol) with congestion control, RTT   estimation and fast recovery/fast retransmit * Specialized API for enhanced performance * Optional Berkeley socket APILICENSElwIP is freely available under a BSD license.DEVELOPMENTlwIP has grown into an excellent TCP/IP stack for embedded devices,and developers using the stack often submit bug fixes, improvements,and additions to the stack to further increase its usefulness.Development of lwIP is hosted on Savannah, a central point forsoftware development, maintenance and distribution. Everyone canhelp improve lwIP by use of Savannah's interface, CVS and themailing list. A core team of developers will commit changes to theCVS source tree.The lwIP TCP/IP stack is maintained in the 'lwip' CVS module andcontributions (such as platform ports) are in the 'contrib' module.The CVS main trunk is the stable branch, which contains bug fixes andtested features. The latest stable branch can be checked out by doing:  cvs -d:pserver:anoncvs@subversions.gnu.org:/cvsroot/lwip login  cvs -z3 -d:pserver:anoncvs@subversions.gnu.org:/cvsroot/lwip co lwipThe 'STABLE' tag in the stable branch will represent the most stablerevision (which may be somewhat older to protect us from errorsintroduced by merges). This 'STABLE' tagged version can be checked outby doing:  cvs -d:pserver:anoncvs@subversions.gnu.org:/cvsroot/lwip login  cvs -z3 -d:pserver:anoncvs@subversions.gnu.org:/cvsroot/lwip co -r STABLE lwipThe 'DEVEL' branch is the active development branch, which containsbleeding edge changes, and may be instable. It can be checkout by doing:  cvs -d:pserver:anoncvs@subversions.gnu.org:/cvsroot/lwip login  cvs -z3 -d:pserver:anoncvs@subversions.gnu.org:/cvsroot/lwip co -r DEVEL lwipThe current contrib CVS tree can be checked out by doing:  cvs -d:pserver:anoncvs@subversions.gnu.org:/cvsroot/lwip login  cvs -z3 -d:pserver:anoncvs@subversions.gnu.org:/cvsroot/lwip co contribLast night's CVS tar ball can be downloaded from:  http://savannah.gnu.org/cvs.backups/lwip.tar.gzThe current CVS trees are web-browsable:  http://savannah.nongnu.org/cgi-bin/viewcvs/lwip/lwip/  http://savannah.nongnu.org/cgi-bin/viewcvs/lwip/contrib/Submit patches and bugs via the lwIP project page:  http://savannah.nongnu.org/projects/lwip/DOCUMENTATIONThe original out-dated homepage of lwIP and Adam Dunkels' papers onlwIP are at the official lwIP home page:  http://www.sics.se/~adam/lwip/Self documentation of the source code is regularly extracted from thecurrent CVS sources and is available from this web page:  http://www.nongnu.org/lwip/Reading Adam's papers, the files in docs/, browsing the source codedocumentation and browsing the mailing list archives is a good way tobecome familiar with the design of lwIP.Adam Dunkels <adam@sics.se>Leon Woestenberg <leon.woestenberg@gmx.net>