PJON
Experimental, arduino-compatible, multi-master, multi-media network
...It was originally developed as an open-source alternative to i2c and 1-Wire but during development, its scope and features have been extended to cover use cases where IP is generally applied. PJON has been engineered to have a variable footprint (4.2-8.2 kB program memory) and overhead (5-35 bytes per packet) depending on its configuration.