NNeves notes on how to compile LwIP 1.4.0 (opensource network stack for microcontrollers) on the MBed NXP LPC1768 without using an RTOS. 

This code is highly experimental and is a result of some code-gluing from serveral sources, based on the this original idea:
http://www.embeddedrelated.com/groups/lpc2000/show/53822.php

Also, have used a big hammer to iron some LwIP code to force it to compile without OS support, so be warned and please notice that this is experimental code only.

Now, my disclaimer: I don't really understand/master this code, just made some changes for it to do something basic, send TCP data from the MBED to another device (TCP Hello World).

Required hardware: MBed bundle with Ethernet breakout board 
(http://www.coolcomponents.co.uk/catalog/mbed-lpc1768-bundle-p-783.html)

Cross-compiling tool: use the same from the R2C2 project:
http://www.3dprinting-r2c2.com/?q=content/development#Installing_ARM_toolchain

//------------------------------

1) extract sourcecode 
2) open the main.c and change the destination IP address (ulIPAddrComputer) at line 219 currently set/hardcoded to my laptop ip 192.168.1.30 in hex notation
3) run 'make' commnad
4) copy the FLASH_RUN/lwip.bin to the MBED device (don not reset yet)
5) open extra shell and run $> sudo nc -lp 80 (pc will listen to incoming TCP data)
6) reset the MBED ... it will now initialize the Ethernet hardware and send TCP data to the configured destination ip ... netcat will then show the "Hello World" message.

No more time for aditional tests, but proof-of-concept acheived (for now)!

//------------------------------
Notes to myself (please ignore):
- requires arm-2010.09-51-arm-none-eabi-i686-pc-linux-gnu.tar.bz2 installed in some place like /usr/local/arm

  source: http://www.codesourcery.com/sgpp/lite/arm/portal/package7813/public/arm-none-eabi/arm-2010.09-51-arm-none-eabi-i686-pc-linux-gnu.tar.bz2

- set .bashrc line (restart shell):
    export PATH=$PATH:/usr/local/arm/arm-2010.09/bin